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  • Chromatographie, Dünnschicht  (90)
  • Volumetrie  (69)
  • oxidation  (57)
  • Chemistry
  • Humans
  • Life and Medical Sciences
  • Springer  (220)
  • 1975-1979  (220)
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Year
  • 1
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    Calcified tissue international 23 (1977), S. 13-17 
    ISSN: 1432-0827
    Keywords: Dental calculus ; Glycopeptide ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component on cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.
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  • 2
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    Calcified tissue international 23 (1977), S. 39-44 
    ISSN: 1432-0827
    Keywords: Dental cementum ; Collagen ; Protein ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Cyanogen bromide (CNBr) peptides were prepared of the insoluble collagen of bovine dental cementum. Following chromatographic separation, the peptides were identified by their amino-acid composition. Type I collagen ([α1(I)]2α2) accounted for more than 90% of the organic matrix, while Type III collagen ([α1(III)]3) was present at a level of approximately 5%. Amino-acid analyses revealed that the CNBr peptides from α1(I) and α2 chains of cementum closely resembled the corresponding peptides from calf skin. The only systematic difference was a higher level of hydroxylation of prolyl and lysyl residues of the cementum peptides.
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  • 3
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    Calcified tissue international 23 (1977), S. 87-94 
    ISSN: 1432-0827
    Keywords: Calcium ; Osteoporosis ; Lactation ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.
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  • 4
    ISSN: 1573-4889
    Keywords: oxidation ; nickel-chromium alloys ; Group III–V elements ; reactive minor additions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The corrosion of a number of experimental ternary Ni-15 wt. % Cr-0.5wt. %X alloys (where X= Y, La, Ce, Sm, Th, U, Zr, or V) has been assessed in pure oxygen at 900° C for periods of exposure up to 450 hr, and compared with the behavior of an Ni-15% Cr control alloy. It has been established that while all of the alloys oxidize in accordance with a protective, approximately parabolic regime, considerable differences in oxidation rates are exhibited. In particular, additions of La, Ce, and Th bring about progressively enhanced rates of oxidation relative to the binary alloy, whereas Y, Sm, V, U, and Zr effect increasingly reduced rates of oxidation in the order given. The rate constant for the Th-bearing alloy is about two orders of magnitude larger than that for the alloy containing Zr. Such differences in behavior seem to be associated with subtle variations in the morphology/composition of the corrosion products from alloy to alloy. The observations are considered in the light of earlier published literature concerning the effects of rare-earth and other reactive elements on the oxidation behavior of Ni/Cr alloys.
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  • 5
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    Oxidation of metals 10 (1976), S. 189-223 
    ISSN: 1573-4889
    Keywords: oxidation ; platinum ; platinum-aluminum alloys ; alumina (Al2O3) ; oxide-scale adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The development, growth, and adhesion of α-Al2O3 scales on platinum-aluminum alloys containing between 0.5 and 6 wt.% aluminum have been studied at temperatures in the interval between 1000 and 1450° C. The morphologies and microstructures of the α-Al2O3 scales were found to be influenced by the temperature, oxygen pressure, and the microstructures of the alloys. The oxidation rates of the alloys appeared to be controlled by transport of oxygen along grain boundaries in the α-Al2O3 scales. The α-Al2O3 scales adhered to the platinum-aluminum substrates even after extensive periods of cyclic oxidation. The good adhesion of the α-Al2O3 may result from mechanical keying of the oxide to the alloys due to the development of irregular oxide-alloy interfaces.
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  • 6
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    Oxidation of metals 10 (1976), S. 277-289 
    ISSN: 1573-4889
    Keywords: alloy ; iron ; aluminum ; silicon ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Silicon or chromium can be used as an oxygen getter in iron-aluminum alloys to prevent the internal oxidation of aluminum. This suppresses the formation of the iron oxide nodules that tend to destroy binary iron-aluminum alloys during high-temperature oxidation. Alloys of iron containing aluminum and silicon in varying proportions were heated in flowing air for 50 hr at 1093°C. Of the alloys tested, one containing 6% aluminum and 1 % silicon was the most resistant to oxidation.
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  • 7
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    Oxidation of metals 10 (1976), S. 311-327 
    ISSN: 1573-4889
    Keywords: defect structure ; CoO ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The total concentration of point defects and deviation from stoichiometry in Co1-yO have been determined experimentally as functions of temperature and equilibrium oxygen pressure in the temperature range 1000–1250°C and oxygen pressure range 10−3-1 atm. This total concentration of defects has also been calculated from known values of the coefficients of chemical diffusion and tracer self-diffusion of cobalt. The results of the two methods agree well. It has been found in the investigated range of temperature and oxygen pressure that the defect structure of cobaltous oxide is composed not only of defects due to deviation from stoichiometry, singly ionized cation vacancies, and an equivalent amount of electron holes, but also of intrinsic defects, probably of the Frenkel type.
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  • 8
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    Oxidation of metals 10 (1976), S. 341-345 
    ISSN: 1573-4889
    Keywords: α-Al2O3 ; platinum ; oxidation ; adhesion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of externally located platinum on the isothermal stability of α-Al2O3 scales formed at high temperatures has been examined. It has been observed that a nickel-base alloy forms an external scale of α-Al2O3 during oxidation at 1200°C, but this scale breaks down isothermally, enabling a faster-growing Cr2O3-rich scale to develop. However, in the presence of platinum metal alongside the specimen in the furnace hot zone, the breakdown of the α-Al2O3 scale is postponed for a substantial period of time. It appears that platinum, as the volatile species PtO2, is incorporated into the growing α-Al2O3 scale where it either influences the stress relief mechanism at temperature or reduces oxidation growth stress generation and thus significantly enhances the isothermal stability of the scale.
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  • 9
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    Oxidation of metals 10 (1976), S. 377-401 
    ISSN: 1573-4889
    Keywords: oxidation ; iron ; Mössbauer ; electron re-emission ; ERM spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The results of an electron re-emission Mössbauer (ERM) spectroscopy study of the oxidation of metallic Fe at temperatures from 150 to 500°C in pure oxygen ( $${\text{p}}_{{\text{O}}_{\text{2}} } \approx {\text{ }}10$$ Torr) are presented. The oxidized samples were prepared from a metallic Fe sample enriched to 70% in the Mössbauer isotope Fe57 and the oxidation kinetics were determined volumetrically. Scanning electron microscopy was employed to characterize the morphology of the oxide films. The hematite, magnetite, and total-oxide thicknesses were determined from the ERM spectra using a theory recently developed in this laboratory, and the results were found to agree well with the measured oxygen content of the oxide films. For Fe and Fe-base alloys it is shown that the ERM technique is most useful in the oxide-thickness range of approximately 20–3000 Å within that range, oxide-phase identifications and thickness determinations are perhaps more readily determined by ERM spectroscopy than by any competing technique. In particular, the ERM measurement is nondestructive, and no supplementary measurements (such as surface-roughness determinations) or special sample preparations (such as oxide-film stripping) are required
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  • 10
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    Oxidation of metals 11 (1977), S. 57-62 
    ISSN: 1573-4889
    Keywords: oxidation ; scale growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Equations are presented to modify the classical theoretical expressions for the parabolic rate constant for the case in which the scale has a large composition range and a large variation in molar volume. The modifications appear as simple averages, together with a factor f.Evaluation of f for some hypothetical cases shows that it is near unity unless the composition gradient has an extreme deviation from linearity.
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  • 11
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    Oxidation of metals 11 (1977), S. 193-198 
    ISSN: 1573-4889
    Keywords: oxidation ; scaling ; wustite ; magnetite ; iron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The theory of the growth of two oxide layers by Yurek et al. has been applied to the oxidation of iron at 1100° C. The theoretical parabolic rate constants for the simultaneous growth of the two oxide layers were calculated from radioactive tracer diffusion coefficients for wustite and magnetite. Good agreement was found between the theoretical and experimental values of the ratio of scale thicknesses.
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  • 12
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    Oxidation of metals 12 (1978), S. 227-245 
    ISSN: 1573-4889
    Keywords: oxidation ; sulfidation ; iron-chromium-nickel alloy ; thermochemical diagram ; parabolic rate constant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Oxidation-sulfidation studies of Fe-Cr-8Ni alloys with 4, 12, and 22 wt. % Cr were conducted at 750 and 875°C in multicomponent gas mixtures that contained CO, CO2, CH4, H2, and H2S. The reaction processes resulted in parabolic kinetics. A chromium concentration in the range 0–12 wt. % in the alloy had a negligible effect on the parabolic rate constant; however, the rate constant for the alloy with 22 wt. % Cr was significantly lower. For a given sulfur partial pressure, the oxygen partial pressures required for the formation of a continuous oxide layer in an Fe-22Cr-8Ni alloy were ∼102 to 103 times those calculated for Cr-Cr2O3 equilibrium at temperatures of 875 and 750° C, respectively.
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  • 13
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    Oxidation of metals 12 (1978), S. 451-471 
    ISSN: 1573-4889
    Keywords: HCl gas ; H2O vapor ; Ni-Cr-Al alloy ; oxidation ; hot corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Moist air containing HCl gas caused the oxide formed on a Ni-Cr-Al alloy at 850°C to crack during the early stages of growth, and extensive blistering and spalling occurred on cooling. In dry air containing HCl gas no oxide cracking was observed at temperature although the oxide blistered and spalled on cooling. In dry or moist air free from HCl an adherent protective oxide formed which did not spall on cooling. The oxide cracking at temperature has been attributed to the production of hydrogen by reaction of Cr and Al in the alloy with water vapor and the removal of NiO as NiCl2 by reaction with HCl gas. Hydrogen produced by reaction of water vapor or HCl with Cr or Al dissolved in the alloy at temperature, but on cooling the hydrogen was released, causing the oxide to blister and spall. Preoxidation of the alloy in HCl-free atmospheres eliminated these effects of HCl gas in short-term isothermal tests.
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  • 14
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    Oxidation of metals 9 (1975), S. 45-67 
    ISSN: 1573-4889
    Keywords: oxidation ; hot corrosion ; nickel alloys ; composites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation and hot corrosion behavior of a tungsten-fiber, reinforced Ni~ 20Cr alloy has been examined under the following exposure conditions: (a) pure oxygen at 1 atm pressure; (b) sulfidation in H2–10 %H2S; (c) presulfidation in H2–10 %H2S followed by oxidation in oxygen; and (d) oxidation in 1 atm oxygen after precoating with approximately 1 mg/cm2 of Na2SO4. Rapid oxidation of the tungsten fibers causes considerable distortion of the matrix and catastrophic degradation of the matrix follows. Inter diffusion between the matrix and the fibers is also important. During sulfidation, only the matrix forms sulfides, the fibers remaining unaffected. Consequently, presulfidation, although having a dramatic effect on the oxidation of the matrix does not have a damaging effect on the fibres. Equally, the presence of sodium sulfate is not critical, although severe oxidation of the exposed tungsten fibers is still observed.
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  • 15
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    Oxidation of metals 9 (1975), S. 275-305 
    ISSN: 1573-4889
    Keywords: oxidation ; Ni-Cr alloys ; rare-earth oxide dispersion ; dispersion-strengthened alloys
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of Ni-20%Cr alloys containing approximately 3 vol.% Y2O3, ThO2, and A12O3 as dispersed particles has been examined in the temperature range 900 to 1200° C in slowly flowing oxygen at 100 Torr. The results show that the oxidation behavior of the Y2O3-, ThO2-, Al2O3-, and Ce02-containing alloys is very similar and that some anomalies in the behavior of the ThO2-containing alloy might be explained by the slower rate of chromium diffusion in this coarse-grained alloy. Two Al2O3-containing alloys were studied. One with a relatively coarse dispersoid size behaved in a manner analogous to a dispersion-free Ni-30% Cr alloy at 1100°C. The other alloy contained a dispersion of fine Al2O3 particles and behaved exactly like the Y2O3-containing alloy at 1000 and 1100°C, but at 1200° C oxidized at a faster rate. It has been shown that the adherent scales on dispersion-containing alloys have a stabilized fine grain size, whereas the nonadherent scales on dispersion-free alloys undergo grain growth.
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  • 16
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    Oxidation of metals 9 (1975), S. 415-425 
    ISSN: 1573-4889
    Keywords: vanadium carbide ; vanadium oxycarbide ; oxidation ; parabolic rate law ; cubic rate law ; chemisorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of an oxycarbide of vanadium, VO0.6C0.7, and of a vanadium carbide, VC0.98, was studied athermally up to temperatures of 800° C and isothermally between 400 and 580° C at oxygen pressures ranging from 10−2 to 1 atm. The oxycarbide followed the parabolic rate law below 450° C with V2O5 forming as the only reaction product. The activation energy was 49 kcal/mole. VC0.98 did not form an oxide in this temperature range, but rather dissolved oxygen, the activation energy being 26.6 kcal/mole. No oxygen pressure dependence on the kinetics was found for either sample in this temperature range. Both samples followed the cubic rate law during oxidation in the range of 500–580° C during which V2O5 formed. There was a P1/3 dependence and the activation energy was the same for both materials, 51 kcal/mole. The cubic rate law and the positive pressure dependency (rather than an anticipated negative dependency) were attributed to an electric field associated with oxygen ions chemisorbed on a thin layer of V2O5.
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  • 17
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    Oxidation of metals 9 (1975), S. 459-472 
    ISSN: 1573-4889
    Keywords: Cr ; oxidation ; kinetics ; Cr2O3 grain size ; short-circuit diffusion ; surface ; preparation ; Fe-Cr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Cr was oxidized in 1 aim O2 at 980, 1090, and 1200°C. ElectropolishedCr and some orientations of etched Cr oxidize rapidly and develop compressive stress in the growing Cr2O3; other orientations oxidize slowly, apparently free of stress. SEM examination of fracture sections shows that the thick oxide is polycrystalline whereas the thin oxide on etched Cr is monocrystalline. It is deduced that the monocrystalline oxide grows by lattice diffusion of cations outward, and the polycrystalline layer by the two-way transport of cation diffusion outward and anion diffusion inward along oxide grain boundaries. The consequent formation of oxide within the body of the polycrystalline layer generates compressive stress and leads to wrinkling by plastic deformation. The activation energy for oxidation of Cr by cation lattice transport is 58 kcal/mole. Polycrystalline Cr2O3 forms on Fe-26Cr alloy, whether electropolished or etched; oxidation is accordingly rapid and accompanied by compressive stress.
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  • 18
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    Oxidation of metals 10 (1976), S. 85-95 
    ISSN: 1573-4889
    Keywords: boron carbide ; oxidation ; kinetics ; chromatography method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Thermogravimetry and gas-adsorption chromatography were used to study the kinetics of formation of solid and gaseous products during the hightemperature oxidation of compact boron carbide in oxygen at 740 Torr. Oxidation resistance was observed at temperatures up to 1200°C. The main oxidation products were B2O3 and CO2. Oxidation was paralinear; the carbon consumption exceeded the consumption of boron as compared to the ratio of these elements in the compound B4C. This difference resulted in carbon depletion of the carbide layer in the substrate near the scale〉.
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  • 19
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    Oxidation of metals 10 (1976), S. 255-276 
    ISSN: 1573-4889
    Keywords: Zircaloy-4 ; zirconium ; alloy ; oxidation ; microstructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The ZrO 2 scales formed on Zircaloy-4 PWR tubes during corrosion in steam in the temperature range of 1000–1300°C have been found to contain a metallic phase that is relatively rich in Sn. The precise composition of the metallic phase has not been determined. Most of the metallic phase is located in a line of metallic particles, which is oriented parallel to the alloy-scale interface and located near the center of the scale. The exact morphology of the scale on either side of the particle line has not been identified. The oxide between the metallic particles and the scale-steam interface contains very little Sn, except for a narrow zone adjacent to the scale-steam interface, which was formed in the beginning of the reaction. It appears that the scale between the metallic particles and the alloy-scale interface consists of thin columnar grains of ZrO 2 with a very fine metallic phase probably located at the ZrO 2 grain boundaries. The experimental evidence presently available indicates that the metallic phase exists in the scales at the reaction temperature. If the metallic particles were rich enough in Sn, then a liquid metallic phase would exist in the oxide during the reaction. Kinetic studies demonstrate that these particles move with respect to the scale-steam interface toward the center of the alloy during the course of the oxidation reaction. It appears that the presence of the line of metallic particles could, under certain conditions, markedly influence the mechanical properties of the oxide scales formed on Zircaloy-4.
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  • 20
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    Oxidation of metals 11 (1977), S. 23-56 
    ISSN: 1573-4889
    Keywords: oxidation ; carburization ; carbonaceous gases ; superalloys ; stainless steels ; film formation ; structure of oxide scales ; preoxidation ; metal dusting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Formation and deterioration of oxide films on several contemporary high-temperature alloys was studied in various carbonaceous gas atmospheres. Scanning electron microscopy and metallographic examination were applied to films on Fe-Cr-Ni and Ni-Cr-Al type alloy compositions exposed in CH 4/H2 and CO/CO2 atmospheres at temperatures up to 900° C and pressures up to 900 psi (6.2 × 106 N/m2). The effects of various preoxidation treatments were evaluated. Reduction of certain oxide phases is observed to promote catalytic gas decomposition. Al2O3 components in the films are observed to be stable under the reducing conditions experienced. Carbon uptake by various alloys is found to be quite sensitive to surface finish, with an observed increase in penetration with surface roughness.
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  • 21
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    Oxidation of metals 11 (1977), S. 225-239 
    ISSN: 1573-4889
    Keywords: tantalum ; oxidation ; high temperature ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of tantalum in oxygen-nitrogen and oxygen-inert gas mixtures at925°C has been studied. The oxygen pressure was close to 0.5 atm in all experiments, and partial pressures of the second component of from 0 to 180 Torr were employed. Spherical specimens were used to provide quantitatively significant kinetic data. A model has been proposed which suggests that the oxygen pressure at the reaction interface close to the metal surface is lower than the external pressure because of the finite permeability of the porous outer oxide layer, and that the inert gas effectively reduces the permeability. The model gives good quantitative agreement with the experimental results.
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  • 22
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    Oxidation of metals 12 (1978), S. 1-22 
    ISSN: 1573-4889
    Keywords: NaCl vapor ; Ni-Cr-Al alloy ; oxidation ; hot-salt corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A thin protective oxide formed on a Ni-19.7 Cr-2.4 Al alloy in air at 850°C. Microstructural examination of stripped films showed that the oxide was duplex with an inner chromium-rich layer of NiCr2O4 + Cr2O3 with probably some NiAl2O4 + Al2O3, and an outer nickel-rich layer, principally NiO. The oxide grew faster in the presence of NaCl and it differed significantly in microstructure and composition from a very early stage. The thicker regions of the oxide assumed regular polyhedral shapes in air + NaCl, rather than the irregular nodular shape exhibited in clean air, as well as becoming richer in chromium. The results suggest that chloride vapor increases cationic mobility in the oxide. It is proposed that Cl− ions are incorporated in the oxygen close-packed lattice, thereby increasing ionic mobility in Cr2O3.
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  • 23
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    Oxidation of metals 12 (1978), S. 83-110 
    ISSN: 1573-4889
    Keywords: oxidation ; iron ; chromium ; Fe-9% Cr alloy ; Auger electron spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation or general corrosion behavior of metals at pressures of 1 atm or more is usually investigated by oxidizing samples under prescribed conditions and then subsequently characterizing the surface produced using one or more of the experimental methods available. This article describes a method which obviates the necessity of transferring samples from the oxidizing environment to the instrument for analysis, is nondestructive, and monitors the oxidizing surface in situ. The oxidation of iron, chromium, and a 9% chromium-iron alloy in carbon dioxide at atmospheric pressure and at 773°K is described. The surfaces of these materials were analyzed by Auger electron spectroscopy during exposure to the gas. Spectra and diagrams illustrating the variation in surface composition as oxidation proceeded are shown and possible mechanisms for the oxidation reactions are briefly discussed. The formation of the surface oxide on iron and on the 9% Cr-Fe alloy appears to follow very similar paths under the conditions of oxidation used. In all the materials studied trace impurities such as sulfur participated in the oxidation reactions.
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  • 24
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    Oxidation of metals 13 (1979), S. 181-195 
    ISSN: 1573-4889
    Keywords: copper-manganese alloys ; oxidation ; scale composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of copper-manganese alloys (2–35 wt. % Mn) in pure oxygen at 760 Torr was investigated at 100° intervals between 550 and 850°C. Gravimetric measurements of the oxidation kinetics have been combined with microstructural studies of the reacted samples in order to evaluate the reaction mechanisms. The scales formed on Cu-2Mn, Cu-5Mn, Cu-10Mn are always composed of three different layers; in any case manganese is present only in the inner layer. The scales formed on Cu-20Mn and Cu-35Mn are composed of two layers, both containing manganese, with a more Cu-rich outer layer. In all the samples internal oxidation in combination with external scale formation is observed.
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  • 25
    ISSN: 1573-4889
    Keywords: Cu-Si alloys ; oxidation ; kinetics ; silica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of Cu-Si alloys (containing up to 4.75 wt. % Si) in $${\text{p}}_{O_2 } $$ =0.01 atm from 800 to 1000°C has been investigated using thermogravimetry and other techniques. A 0.04% Si alloy followed a parabolic oxidation law with a rate similar to that of pure Cu. As the Si concentration increased the rate decreased and became irregular owing to SiO2 particles or flakes at the alloy-scale interface. It is considered that sintering of SiO2 particles and rupture of the sinter because of contraction during sintering are responsible for the irregular kinetics. A SiO2 layer forms directly on the 4.75% Si alloy which oxidizes uniformly. The SiO2 was always amorphous. In pure CO2 a similar pattern of amorphous SiO2 particles, flakes, and layers occurs.
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  • 26
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    Oxidation of metals 13 (1979), S. 283-298 
    ISSN: 1573-4889
    Keywords: oxidation ; surface alloys ; Fe-Cr alloys ; iron ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of several surface and bulk Fe-Cr alloys and iron at 300°C and 4×10−6 Torr oxygen was studied. The surface alloys were fabricated by implantation of 25 keV Cr ions into the outermost 300Å of polycrystalline iron samples. The oxide thickness as a function of oxygen exposure was obtained using proton-excited X-ray analysis, and composition profiles of oxide films were obtained using Auger electron spectroscopy and ion sputtering. The addition of Cr to Fe by surface and bulk alloying caused the oxidation rate to decrease and changed the oxidation kinetics from parabolic (for Fe) to logarithmic (for Cr concentrations ≥4.7at.%). Interpretation of the data in terms of simple oxidation theories indicates that the Cr additions may reduce the oxidation rate by altering the electronic properties of the metal-oxide interface.
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    Oxidation of metals 13 (1979), S. 311-330 
    ISSN: 1573-4889
    Keywords: oxidation ; oxide maps ; alloying additives ; Fe-Ni-Al alloys
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    Notes: Abstract The oxidation behavior of iron-nickel-aluminum alloys containing 0–40 wt.% nickel and 0–30 wt.% aluminum has been investigated at 600 and 800° C. Through the construction of “oxide maps” it can be shown that three possible oxide morphologies may exist: Alloys containing less than approximately 5 wt.% aluminum form scales consisting of predominantly Fe2O3 and spinel; alloys with between 5 and 10 wt.% aluminum form Al2O3 scales interspersed by Fe2O3 nodules, and alloys with greater than 10 wt.% aluminum form predominantly γ-Al2O3 scales.
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    Oxidation of metals 13 (1979), S. 223-236 
    ISSN: 1573-4889
    Keywords: nickel ; oxidation ; surface reactions ; X-ray photoelectron spectroscopy
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    Notes: Abstract X-ray photoelectron spectroscopy has been used to study the oxidation of polycrystalline nickel metal. The results indicate that the oxidation process takes place in three stages; associative adsorption of molecular oxygen, followed by the combination of oxygen atoms with surface nickel atoms and, ultimately, the formation of bulk oxide. At room temperature only the first two stages can be detected. For exposures below 1 L the O 1s photoelectron spectrum is considered to be characteristic of an associatively adsorbed oxygen species, but for exposures above this value evidence for the formation of a monolayer of “NiO” is suggested by the development of an O 1s peak at 529.9 eV. Incorporation of oxygen into the nickel lattice is observed at temperatures 〉500°K. The activation energy for this place-exchange process was estimated at 1.80±0.06 eV.
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    Oxidation of metals 13 (1979), S. 255-272 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-C ; graphite deposition ; nonadherent oxide ; kinetics
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of Fe-C alloys containing 0.5 and 1.0% C was studied in 1 atm O2 at 700° C. The oxidation rate is considerably slower than for pure Fe. The oxide scale formed is detached, multilayered, and overoxidized, containing little or no FeO. A thin film of graphite was identified at the metal-oxide interface by electron diffraction. It is proposed that the slow oxidation and abnormal scale are caused by a residue of graphite left at the metal surface from the oxidation of Fe3C. This inhibition of the oxidation of Fe by carbon at 700°C is in contrast to the stimulation observed at 500°C.
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    Oxidation of metals 9 (1975), S. 69-97 
    ISSN: 1573-4889
    Keywords: oxidation ; decarburization ; Fe-C alloys ; effect of humidity ; effect of microstructure
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Isothermal oxidation treatments were carried out on an Fe-C alloy (0.4 % C): (a) in almost dry air around A1, and also with an Fe-C alloy (0.5% C) and IRSID pure iron; (b) in dry air ( $${\text{P}}_{H_2 O} \simeq 10^{ - 5} $$ nm Hg); (c) in almost dry air(1–2% water vapor) at 700° C; and (d) in moist air (31% water vapor). Theresults are as follows: The rate of oxidation at a temperature below A1depends chiefly on alloy structure, i.e., on thermal history of the sample.The water vapor content of the air strongly influences the scale adherenceas well as the rate of oxidation of the Fe-C alloys below A1, but has virtuallyno effect on the rate of oxidation of pure iron. Under the same conditions, avery light decarburization of metal occurs in air, whereas no decarburizationoccurred in air with 13% water vapor.
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    Oxidation of metals 9 (1975), S. 225-257 
    ISSN: 1573-4889
    Keywords: oxidation ; eutectic alloys ; refractory metals
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    Notes: Abstract The oxidation behavior of the directionally aligned eutectic alloy, TaC-Co50B, has been examined between 600 and 1155°C. Parabolic oxidation behavior, isotropic in nature, is found to 800°C. Above 800°C, the oxidation behavior is no longer either parabolic or isotropic. The interaction between the Co matrix alloy and the TaC fibers adjacent to the oxidizing interface is reported as a function of temperature in oxidation.
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  • 32
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    Oxidation of metals 9 (1975), S. 215-223 
    ISSN: 1573-4889
    Keywords: cation diffusion ; oxidation ; metal partition
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    Notes: Abstract An alternative mass balance at the alloy-scale interface is proposed for the Wagner theory of binary alloy oxidation. A simple relation between the bulk composition of the alloy and the scale composition at the alloy-scale interface, ξ′, is derived in terms of the transport properties of the scale and the limit of application of the relation defined. There is good agreement between calculated and measured values of ξ′.
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  • 33
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    Oxidation of metals 9 (1975), S. 427-440 
    ISSN: 1573-4889
    Keywords: cobalt ; cobalt-aluminum alloys ; oxidation ; thermal cycling
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    Notes: Abstract Most Ni and Co-base alloys used for high-temperature service rely on the production of a compact, stable Cr2O3 scale for their oxidation resistance. However, as operating temperatures have risen above 900–950° C, the loss of Cr2O3 as the volatile CrO3 has led to an inadequate life span of these alloys, particularly in rapidly flowing, turbulent gas streams. As a result of this, it has been necessary to examine the possibility of using Al2O3 as the protective scale. Al2O3 has a lower growth rate than Cr2O3, it is nonvolatile, and, unlike Cr-containing systems, it is less likely to form compound oxides such as spinels. In this study, the amount of Al which must be present in the Co-Al system to form a continuous layer of Al2O3 in the temperature range 800–1000° C has been determined. The quantity was found to rise from about 7–10 wt. % at 800° C to 10–13 wt. % at 900° C and 13 wt. % at 1000° C. Notice has also been taken of the abilities of the alumina-forming alloys to re-form a protective oxide in the event of spalling, blistering, or any other disruptions of the scale, and some “cyclic-oxidation” checks have been conducted on the Co13Al alloy at 900 and 1000° C.
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    Oxidation of metals 10 (1976), S. 97-103 
    ISSN: 1573-4889
    Keywords: silicon carbide ; oxidation ; molecular oxygen ; glow-discharge oxygen plasma ; kinetics
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    Notes: Abstract The oxidation kinetics and structure of the oxide scales formed on high-density SiC were studied in molecular oxygen at 740 Torr and in a glow-discharge oxygen plasma at 0.1 Torr at temperatures of 1000, 1100, and 1200°C. The monatomic oxygen formed by the glow discharge markedly increased the reaction rate and the vaporization of some of the oxidation products. The marked differences in kinetics suggest that the rate-controlling step during oxidation in molecular oxygen is the dissociation of adsorbed diatomic oxygen to the monatomic species. Films formed in molecular oxygen were mostly amorphous SiO2 with small inclusions of SiC and graphite, whereas films formed in dissociated oxygen were primarily amorphous SiO2 containing SiO, S2O3, and the coesite form of SiO2.
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  • 35
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    Oxidation of metals 11 (1977), S. 91-106 
    ISSN: 1573-4889
    Keywords: oxidation ; cyclic ; spallation ; stress
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    Notes: Abstract Several alloys (one iron base and five nickel base) were cyclically oxidized in a series of tests in which the higher temperature (1100 or 1200° C) of the cycle was fixed at a level to allow ample oxidation in reasonable time and the lower temperature was variable to allow cycle temperature differences (ΔT s ) of up to 1400°C. The alloys oxidized included those which formed simple oxides such as Al2O3 or Cr2O3, as well as those which formed complex scales. Cooling rates were relatively low to minimize thermal shock effects. Each cycle consisted of 1 hr at the higher temperature and 1/2 hr at the lower temperature. Samples were tested up to 370 cycles. The extent of attack was determined by specific weight change which was continuously monitored. For all nickel alloys, as ΔT increased the extent of spallation increased. This effect was attributed to thermal expansion mismatches between the oxide and the nickel substrate. The FeCrAl alloy was not sensitive to ΔTand resisted spalling at ΔT levels to 1400°C. FeCrAl, and the Al2O3 scale which forms on it, have thermal expansion coefficients which are substantially more alike than any of the other oxide-metal combinations tested.
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    Oxidation of metals 12 (1978), S. 215-225 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-Ni alloys ; kinetics ; scale morphology ; EPMA
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of an Fe—19.34 wt. % Ni alloy in dry CO2 has been studied at 700—1000°C using thermogravimetry, metallography, and EPMA. Weight gains for oxygen consumption followed a linear-parabolic-linear sequence at all temperatures. During the initial linear stage the scale consisted mainly of magnetite and the activation energy of 133±25 kJ · mole−1 is considered to be due to dissociation of CO2 into CO and adsorbed oxygen on the outer magnetite surface. During the parabolic oxidation stage a continuous Ni-rich layer containing ∼ 70% Ni forms a barrier to the diffusion which has an activation energy of 192±79 kJ · mole−1. The breakdown of the barrier layer causes a return to linear kinetics with an activation energy of 138±42 kJ · mole−1 for dissociation of CO2 on the outer surface. During the final linear stage there is pronounced general and intergranular subscale formation. Detailed information is presented of the Ni redistribution and concentrations during oxidation and its correlation with the kinetics and morphology.
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  • 37
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    Oxidation of metals 12 (1978), S. 35-66 
    ISSN: 1573-4889
    Keywords: CoCrAl ; oxidation ; oxide scale adherence ; rare-earth effect ; hafnium ; yttrium
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    Notes: Abstract The effect of small amounts of yttrium (up to 1 wt. %) and hafnium (up to 1.5 wt.%) on the oxidation behavior of Co-Cr-Al alloys in the temperature range 1000–1200°C for times up to 1000 hr in air has been studied. The major portion of the study has been concerned with Co-10Cr-11Al base alloys. Both isothermal and cyclic tests have been carried out; the cycle used consisted of 20 hr at temperature, followed by cooling to room temperature. Both additions reduce the overall oxidation, Hf somewhat more so than Y. In part, this is due to the improved adhesion between scale and alloy reducing scale spallation at temperature, and in part due to possible modification of the Al2O3 grain size. The former factor is far more critical under thermal cycling conditions. Under isothermal conditions the oxidation rate increases with increasing Hf content with all but the 1.5 wt.% alloy oxidizing more slowly than the Hf-free alloy; increase in Y content has the reverse effect. Under thermal cycling conditions the 0.3 and 1.0 wt.% Hf alloys show the lowest overall weight gain. Metallographic evidence suggests that the improved scale adhesion is due principally to a pegging mechanism; the active elements promote the growth of intrusions of Al2O3 into the alloy. However, if the intrusions are too large, they can act as initiators of scale failure.
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  • 38
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    Oxidation of metals 12 (1978), S. 139-156 
    ISSN: 1573-4889
    Keywords: Rosenburg method ; oxidation ; CoO
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The Rosenburg continuous kinetic method is proposed for the determination of the parabolic rate constants of metal oxidation as a function of temperature and oxidant pressure. Using this method, it is possible to make numerous measurements in a continuous manner on a single metal sample left in situ in the furnace, thus eliminating systematic errors due to differences between samples. Moreover, using this method it is possible to determine directly from a given kinetic curve such important parameters as the coefficients of chemical diffusion and self-diffusion of the more mobile species in the studied compound and the total equilibrium defect concentration. The latter parameter has been inaccessible up to now by the experimental method. The limits of applicability of this method are given in the paper. As an example of this method, the kinetics of cobalt oxidation are investigated in the range of temperature 1000–1250°C and oxygen pressure 10−3−1 atm; the results compare favorably with those obtained by other authors. The method is, however, applicable to certain other systems, namely, metal oxides and sulfides.
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    Oxidation of metals 12 (1978), S. 173-181 
    ISSN: 1573-4889
    Keywords: oxidation ; hot corrosion ; sulfidation ; preoxidation ; scale penetration
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The transport of sulfur through growing scales may occur by chemical (solution and diffusion) or physical (gas molecule permeation) mechanisms. Both possibilities are examined theoretically for the case of NiO growing on nickel. Experiments are designed and carried out to establish which mechanism plays the major role in sulfur transport. The results indicate that the physical mechanism is likely to be predominant.
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    Oxidation of metals 13 (1979), S. 519-543 
    ISSN: 1573-4889
    Keywords: nickel ; oxidation ; transport ; tracer ; duplex scale
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    Notes: Abstract Experimental techniques have been developed for determining Ni63 and O18 tracer distributions in NiO scales ranging in thickness from ∼0.1 to 100 μ. These have been used to investigate Ni and O transport in scales on {100} Ni crystals and polycrystalline Ni in the temperature range 500–1300° C. NiO grown on {100} Ni crystals at 1000°C was uniform and compact and grew by the bulk diffusion of Ni in NiO by a vacancy mechanism. At temperatures below 800°C the principal transport mechanism was short-circuit diffusion of Ni in NiO. At all temperatures short-circuit diffusion of oxygen contributed to scale growth on polycrystalline Ni and was responsible for growth of the inner layer of duplex scales. The oxygen diffusion paths are believed to be micro-cracks induced by growth stresses.
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  • 41
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    Oxidation of metals 13 (1979), S. 159-180 
    ISSN: 1573-4889
    Keywords: nickel-chromium alloys ; oxidation ; high temperature ; cerium
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of Ni-50Cr alloys with minor cerium additions was studied between 800 and 1100° Cin oxygen, air, and oxygen at reduced partial pressures. Optical and scanning electron metallography, X-ray diffraction, and electron-probe microanalysis techniques were used to characterize the changes in scale and substrate morphology and to identify the oxidation products. Platinum markers were used to determine the direction of ionic transport. The effects of cold work, initial alloy phase distribution, and cyclic oxidation were also studied. The Cr 2 O 3 scales on the cerium-containing alloys grew while being largely separated from the metal substrate. Oxidation rate, oxide grain growth, and the tendency of scales to spall on cooling were reduced substantially with increasing alloy cerium content. The first two effects are suggested to result from the interaction of cerium ions and cerium oxide particles with oxide grain boundaries in reducing grain-boundary diffusion and oxide-boundary mobility. The third is suggested to result from the thinner, finer-grained scales formed on the Ce-containing alloys.
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    Oxidation of metals 9 (1975), S. 99-116 
    ISSN: 1573-4889
    Keywords: oxidation ; kinetics ; ilmenite ; rutile ; pseudobrookite
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of ilmenite (FeTiO3) in air and dry oxygen was investigated over the temperature interval 600 to 970°C. Dense platelets of ilmenite crystals as well as powder samples of ilmenite were oxidized. The weight data were recorded employing a thermobalance. The oxidation kinetics of ilmenite platelets were parabolic except for the initial stages during which logarithmic kinetics were observed. For powder samples the logarithmic rate law was followed primarily. The logarithmic rate law was attributed to free penetration of oxygen through cracks and short-circuit paths. The activation energies associated with the logarithmic rate law were nearly one-half of those obtained from parabolic oxidation. The growth morphology of the products of oxidation of ilmenite was observed with a scanning electron microscope. The effect of growth morphology on the kinetics is discussed, and a probable reaction mechanism is suggested for the oxidation of ilmenite.
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    Oxidation of metals 10 (1976), S. 1-22 
    ISSN: 1573-4889
    Keywords: oxidation ; film spalling ; fayalite ; internal oxidation
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation behavior of Fe-14Cr-14Ni (wt.%) and of the same alloy with additions of 1 and 4% silicon was studied in air over the range of 900-1100° C. The presence of silicon completely changed the nature of the oxide scale formed during oxidation. The base alloy (no silicon) formed a thick outer scale of all three iron oxides and an internally oxidized zone of (Fe,Cr,Ni) spinels. The alloy containing 4% silicon formed an outer layer of Cr2O3 and an inner layer of either (or possibly both) SiO2 and Fe2SiO4. The formation of the iron oxides was completely suppressed. The oxidation rate of the 4% silicon alloy was about 200 times less than that of the base alloy, whereas the 1% silicon alloy exhibited a rate intermediate to the other two alloys. The actual ratio of the oxidation rates may be less than 200 due to possible weight losses by the oxidation of Cr2O3 to the gaseous phase CrO3. The lower oxidation rate of the 4% silicon alloy was attributed to the suppression of iron-oxide formation and the presence of Cr2O3, which is a much more protective scale.
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  • 44
    ISSN: 1573-4889
    Keywords: kinetics ; oxidation ; microcalorimetry ; thermogravimetry
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    Notes: Abstract In the kinetic theories of Bodenstein or Semenov the expression for the rate of a chemical reaction with several elementary stages can be expressed by different physical parameters. If two experimental methods are used, one method of necessity being microcalorimetry to measure the thermal flux produced by the reaction, it is possible to distinguish a pure kinetics case from a mixed one. The two-method technique has been verified by a study of the oxidation of niobium.
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    Oxidation of metals 11 (1977), S. 109-125 
    ISSN: 1573-4889
    Keywords: nickel-vanadium ; oxidation
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    Notes: Abstract The oxidation behavior of nickel and dilute Ni-V alloys has been studied in flowing oxygen at 1 atm pressure, using various kinetic and electron-optical techniques. The oxidation rate rises progressively as the alloy vanadium content is increased from 0 to 0.8% and then to 1.7%. However, further additions to 4.2% cause only a slight further increase. These increases in oxidation rate are largely controlled by the extent of doping of the NiO, particularly for the two more dilute alloys, although internal oxidation, spinel blocking effects in the oxide, and dissociation of the NiO affect the weight gains to some extent, particularly for the case of the Ni-4.2% V alloy.
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    Oxidation of metals 11 (1977), S. 163-191 
    ISSN: 1573-4889
    Keywords: cobalt-chromium ; oxidation ; oxygen
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The isothermal oxidation of Co-Cr alloys containing 0–30% Cr in 760 Torr oxygen at 1000° C has been studied kinetically and by appropriate physical techniques. Chromium additions to cobalt increase the parabolic oxidation rate to an almost constant level from 2 to 15% Cr, while further additions to 20–30% Cr decrease the rate. All the alloys produce a virtually pure CoO layer outside a layer containing Co-Cr spinel particles in a Cr3+ -doped CoO matrix. The variation of oxidation rate with alloy chromium content is explained in terms of the complex interplay of doping, blocking of cation transport by voids and spinel particles and short circuiting by transport of dissociative oxygen across these voids and other processes, internal oxidation making a negligible direct contribution to weight gain. Complete spinel layers are never quite developed under the conditions studied, although formation of spinel does slow the oxidation rate. The improved protection eventually obtained at higher chromium levels is produced by the tendency to form a Cr2O3 healing layer.
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    Oxidation of metals 12 (1978), S. 23-34 
    ISSN: 1573-4889
    Keywords: cobalt ; oxidation ; sulfidation ; conjoint attack
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    Notes: Abstract The attack of cobalt by sulfur and oygen simultaneously in Ar-SO2 atmospheres in the temperature range 500–900°C has been found to conform to the pattern established by the attack of other metals under similar conditions. A thermodynamic and kinetic interpretation of the mechanism has been proposed. The results also indicate that during the initial stages sulfur diffuses through the initially formed oxide layer, eventually leading to formation of the commonly observed duplex sulfide and oxide scale.
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    Oxidation of metals 12 (1978), S. 67-82 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-C ; kinetics ; oxide grain size ; grain-boundary diffusion
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Fe-C alloys containing 0.1, 0.5, and 1.0% C were oxidized in 1 atm O2 at 500°C. Two specimen preparations were used: annealed followed by slow cooling to form coarse pearlite plus proeutectoid ferrite or cementite; and cold-worked by abrading after annealing. The cold-worked alloys oxidize more rapidly. Annealed pearlite oxidizes faster than annealed ferrite. The differences in oxidation rate are caused by differences in the Fe3O4 grain size, that is, by the number of oxide grain boundaries available to act as easy diffusion paths for the outward diffusion of Fe through the Fe3O4. The oxidation rate constant is 10 times larger for fine-grained poly crystalline oxide than for oxide in which the Fe3O4 is monocrystalline.
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  • 49
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    Oxidation of metals 11 (1977), S. 289-305 
    ISSN: 1573-4889
    Keywords: superalloys ; oxidation ; oxides ; volatilization
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Volatilization of oxides during cyclic oxidation of commercial Nichrome, Inconel 750, René 41, Stellite 6B, and GE-1541 was studied at 1200°C in static air. Quantitative analysis of oxide vapor deposits revealed that oxides of tungsten, molybdenum, niobium, manganese, and chromium volatilized preferentially from the oxide scales. Aluminum and silicon were not detected in vapor deposits. For all the alloys except GE-1541 chromium was found to be the main metallic element in the oxide scales.
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    Oxidation of metals 12 (1978), S. 503-526 
    ISSN: 1573-4889
    Keywords: nickel ; sulfur dioxide ; oxidation ; sulfidation
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The reaction of nickel with SO2 has been studied in the temperature range 650–1100°C at SO2 pressures from 10 to 760 Torr. Reaction kinetics have been studied by thermogravimetry; the reacted specimens have been characterized by means of metallography, scanning electron microscopy, and electron microprobe analysis. The reaction involves oxidation and sulfidation except at sufficiently high temperatures and low pressures of SO2 (e.g., 1000°C and 10 Torr SO2) where only formation of NiO takes place. Approximately linear reaction kinetics are observed between 650 and 900°C. Reaction mechanisms are discussed, and the relative importance of oxide formation and sulfidation is interpreted in terms of the thermodynamics of the Ni-O-S system.
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    Oxidation of metals 12 (1978), S. 247-256 
    ISSN: 1573-4889
    Keywords: oxidation ; iron ; magnetite ; oxide thickness ; electron back-scattering Mössbauer spectroscopy
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Magnetite films in the range 265–4520 Å have been grown on natural iron substrates and subsequently investigated by electron back-scattering Mössbauer spectroscopy. In particular, the percentage, P, of the total spectrum area contributed by the oxide has been determined as a function of oxide thickness, d. It was found that d up to ≈ 3000Å may be expressed (to an accuracy of ∼ 5%) by d (Å)=−1.95 × 103 ln (1–0.01 P). The experimental data have been compared with the theoretical predictions of both Huffman and Bainbridge. Good agreement between experiment and Huffman's predictions of P is obtained using values of the electron attenuation coefficient, μ, of 1.10 × 104 cm2 g−1 for the 7.3 keV electrons and 1.73 × 104 cm2 g−1 for the 5.4 keV electrons. A good fit of our data to Bainbridge's expression requires a somewhat lower effective μ, value of 0.8 × 104 cm2 g−1. The experimental P value for the thickest oxide (4520 Å) is lower than the theoretical predictions, probably as a result of a neglected mechanism recently identified by Tricker, Ash, and Cranshaw.
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    Oxidation of metals 12 (1978), S. 387-404 
    ISSN: 1573-4889
    Keywords: carburization ; oxidation ; austenitic Fe-Ni-Cr alloys ; internal carbide formation ; high-temperature corrosion and creep
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The carburization of NiCr 32 20 and NiCrSi 60 16 has been studied in CH4-H2 mixtures in the temperature range 900–1100°C. The methods included thermogravimetric measurements and studies on reacted specimens by X-ray diffraction, metallographic, and chemical analysis. Upon carburization internal carbides M7C3 and M23C6 are formed (M=mainly Cr); the rate of carburization is determined by carbon diffusion in the Fe-Ni matrix with carbide precipitations. The effect of the alloying elements Ni and Si on the carburization resistance of austenitic alloys is explained. By the same methods the oxidation and carburization in CO-H2O-H2 mixtures have been studied. The important role of a stable chromium oxide layer for the carburization resistance was confirmed. Creep tests at 1000°C in a CO-H2O-H2 atmosphere where Cr2O3 is stable showed carburization occurring through cracks in the oxide layer. At high strain rates premature failure occurs by carburization, which is followed by internal oxidation and formation of cracks, voids, and holes.
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    Oxidation of metals 13 (1979), S. 437-456 
    ISSN: 1573-4889
    Keywords: Fe-Cr ; oxidation ; kinetics ; oxide morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ferritic polycrystalline Fe-24 wt.% Cr was oxidized in pure oxygen at 190 ≤ T≤490° C and pressures in the range 5.3×10−2–13.3 Pa for periods of up to 5 hr. The reaction proceeded in three stages. An initial period of accelerating rate was accompanied by oxide island nucleation and growth. Following island coalescence the rate was approximately logarithmic at low temperatures and somewhat slower than parabolic at high temperatures. Rate control during this period was thought to be due to mass transport through the oxide grain boundaries left by the island impingement process. During these first two stages the oxide formed was γ-M2O3 with possibly some spinel. The final stage of reaction involved the appearance of α-M2O3 on the outer oxide surface and a substantial slowing of the oxidation rate due to the low diffusivity in this phase.
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    Oxidation of metals 13 (1979), S. 119-158 
    ISSN: 1573-4889
    Keywords: nickel-chromium alloys ; oxidation ; high temperature ; kinetics ; mechanisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of binary Ni-Cr alloys containing 44 and 50 wt. % Cr has been studied over a range of oxygen partial pressures at temperatures between 800 and 1100°C. The effects of cold work, surface preparation, and distribution of the Cr-rich second phase have been studied. The oxidation behavior is complex and cannot be described by a single model. The oxide grows by short-circuit diffusion as well as bulk transport through Cr 2 O 3 scales. The scale-growth mechanism includes extensive metal-oxide separation requiring Cr vapor transport to the scale, compressive stresses within the oxide which result in scale bulging and cracking, and the formation of a second oxide layer which results in voids being incorporated into the scale. Any factor which reduces the oxide grain size, such as cold work, finer distribution of the Cr-rich α phase or reduced oxygen pressure, results in an increased oxidation rate of binary alloys because of an increased number of grain-boundary short-circuit diffusion paths.
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    Oxidation of metals 13 (1979), S. 331-351 
    ISSN: 1573-4889
    Keywords: oxidation ; copper ; thin films ; electron microscopy ; electron diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The oxidation of thin single-crystal (100) and (111) films of copper at pressures of around 10−5 Torr and temperatures of 400 to 700°C has been observed by medium-energy electron diffraction, scanning electron microscopy, scanning and conventional microscopy using diffracted electron beams in the reflection mode, transmission electron microscopy, and transmission electron diffraction. Epitaxed nuclei of oxide are observed to grow into very thin single-crystal plates, using oxygen previously trapped in the copper film. There is considerable diffusion of the copper film. There is considerable diffusion of the copper away from the oxide. Between the oxide crystallites the copper surfaces appear to be unoxidized. A mottled contrast of the diffracted beam images of the copper surface is shown to result from many-beam dynamical diffraction effects.
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    Oxidation of metals 13 (1979), S. 381-401 
    ISSN: 1573-4889
    Keywords: Co-Cr-Al ; oxidation ; dispersed oxides ; oxide scale adherence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The improvement in oxidation resistance produced by small additions of active elements to Al 2O3-forming CoCrAl alloys is primarily dependent on the formation of oxide pegs which grow into the alloy around the internal oxide particles of the active element; void formation at the alloy-scale interface is also suppressed. The distribution of these pegs is critical and this paper demonstrates that an internal oxidation pretreatment can be used to convert the active element to its oxide in a controlled manner, thereby optimizing the peg distribution. Al2O3-forming CoCrAl containing 1% Hf or Ce is internally oxidized in a sealed quartz capsule containing a 50/50 powder mixture of CoAl-Al2O3; it was not possible to oxidize internally Y-containing alloys. The isothermal and cyclic oxidation resistance of these alloys is superior to that of alloys not given a prior treatment. Detailed metallographic examination indicates that the prior internal oxidation treatment produces a finer, more uniform distribution of oxide pegs penetrating into the alloy which is more efficient in combatting scale spallation. Furthermore, the lower residual hafnium content in the alloy minimizes large HfO2 precipitates and the formation of gross Al2O3 intrusions, which can initiate scale failure. Thus, by internally oxidizing the alloy first, the advantages of a high alloy Hf content (1%) in producing sufficient oxide pegs, but of the right size, coupled with minimal thickening of the surface scale, can be achieved.
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    Oxidation of metals 9 (1975), S. 259-274 
    ISSN: 1573-4889
    Keywords: stress ; oxidation ; austenitic steel ; CO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The stresses developed during oxidation of Fe-Cr-Ni alloys in a CO 2 atmosphere at 600 and 700°C have been estimated by measuring the deflection of thin foil specimens oxidized on one side only. One side of the specimen was protected from oxidation by an Al-Au film which was oxidized prior to the deflection experiment. The character and magnitude of the stresses measured are explained by electron microscope and x-ray measurements. During the initial stage of oxidation, high stresses are formed due to epitaxial growth of the oxide. These stresses are high enough to plastically deform the alloy. As oxidation proceeds, the stress decreases and eventually reaches a “steady-state” value. During this stage, the alteration in composition and molecular volume of the oxide, the formation of carbides, and the growth of whiskers determine the stresses.
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    Oxidation of metals 9 (1975), S. 409-413 
    ISSN: 1573-4889
    Keywords: cobalt ; cobalt-chromium alloys ; silicon ; oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Some investigators have reported that Co-25 wt.% Cr oxidizes slowly at temperatures in the range 1000–1200°C forming a protective Cr2O3 scale; and this is the normal behavior of cobalt-base superalloys. Others have reported very rapid oxidation, forming a two-layer scale: an outer CoO layer and an inner mixture of Cr2O3 and CoCr2O4 particles in a CoO matrix. This investigation shows that the principal reason for this behavior is the purity of the material; it appears that the rapid mode of oxidation is the intrinsic behavior for high purity material. The most probable impurity to produce the slower mode is silicon, and it is shown that as little as 0.05 wt. % Si is sufficient to change the mode of oxidation provided sufficient oxygen is also present in the alloy: it seems probable therefore that a fine dispersion of SiO2 is responsible.
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    ISSN: 1432-0878
    Keywords: Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fat globules of the cream fractions of human and rat milk were stained with ruthenium red. Under the electron microscope, discrete granules and an amorphous coat of lesser density are seen at the surface of the milk fat globules. Since ruthenium red binds anionic groups selectively, it is probable that the granules containe the greatest concentration of these groups. The cream fraction of rat milk contains hexoses, hexosamines, methylpentoses and sialic acid. Methylpentoses and hexosamines are significantly enriched in the cream fraction. It is concluded that the finding of a surface coat in milk fat globules is in keeping with the Bargmann-Knoop model and suggests a distinct mechanism for carrying certain complex carbohydrates in milk. The role of the negative charges at the outer surface of the membrane coat in maintaining fat globules in suspension and in binding certain cations such as calcium is suggested.
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    Fresenius' Zeitschrift für analytische Chemie 278 (1976), S. 363-363 
    ISSN: 1618-2650
    Keywords: Trenn, von Nickel, Mangan, Kobalt, Kupfer, Eisen, Zink ; Chromatographie, Dünnschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 279 (1976), S. 206-206 
    ISSN: 1618-2650
    Keywords: Best. von Eisen(II) mit Diphenylthioviolursäure als Indicator ; Volumetrie ; EDTA
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    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 276 (1975), S. 205-207 
    ISSN: 1618-2650
    Keywords: Trenn. von Methylolaminen, Melaminharzen ; Chromatographie, Dünnschicht ; Celluloseschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Identifizierung der Komponenten in einem Methylolmelamin-Gemisch mittels Dünnschicht-Chromatographie wurde möglich, nachdem die einzelnen Methylolmelamine (Mono-, Di-, Tri-, Tetra-, Penta- und Hexamethylolmelamin) rein dargestellt werden konnten. Aus der zweidimensionalen dünnschichtchromatographischen Entwicklung des Methylolmelamin-Gemisches folgt, daß während der Dauer der Entwicklung keine Änderung der Zusammensetzung des Methylolmelamin-Gemisches stattfindet. Die Chromatographie wurde auf Celluloseschichten mit Butanol/Äthanol/Wasser (4∶1∶2) als Fließmittel und ammoniakalkalischer Silbernitratlösung als Nachweisreagens durchgeführt.
    Notes: Abstract Identification of the components in a methylolmelamine mixture by thin-layer chromatography was facilitated after obtaining each of the individual methylolmelamines (mono-, di-, tri-, tetra-, penta- and hexamethylolmelamine). By the use of two-dimensional thin-layer chromatography it was noted that no change in the composition of the mixture takes place during the time of Chromatographic development. Separation was achieved on cellulose layers using butanol/ethanol/water (4∶1∶2) as solvent and ammonia-alkaline AgNO3 solution as detection reagent.
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    Fresenius' Zeitschrift für analytische Chemie 276 (1975), S. 201-204 
    ISSN: 1618-2650
    Keywords: Best. von Glykolaldehyd, Glycerinaldehyd, Hydroxyaldehyden ; Volumetrie ; Dimere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurden die Möglichkeiten für die titrimetrische Bestimmung von dimerem Glykolaldehyd (Fp: 94–96° C) und dl-Glycerinaldehyd (Fp: 138–141° C) untersucht. Die systematischen Fehler der auf Grund verschiedener funktioneller Gruppen durchführbaren Messungen sind von der Stabilität ihrer cyclischen Halbacetale sowie von den ihrer Depolymerisation folgenden weiteren Gleichgewichten bestimmt. Das aus dem dl-Glycerinaldehyd gebildete Halbacetal besitzt höhere Stabilität als dasjenige aus dem Glykolaldehyd. Mit der Hydrogensulfit-Methode werden 95–96%, mit der Hydroxylamin-Methode dagegen 98–99% vom wahren Wert gefunden. In Wasser gelöst zersetzt sich der Glykolaldehyd verhältnismäßig rasch, und das Gleichgewicht kann durch beide Aldehydreaktionen quantitativ gegen die Monomerenform verschoben werden. Unsere Untersuchungen ergaben, daß die Hydroxylamin-Methode zur Bestimmung der in Form cyclischer Halbacetale kristallisierenden, dimeren Hydroxyaldehyde Vorteile gegenüber der Hydrogensulfit-Methode bietet.
    Notes: Abstract Possibilities for the titrimetric determination of dimeric glycolaldehyde (m.p. 94–96° C) and dl-glyceraldehyde (m.p. 138–141° C) have been investigated. The systematic errors based on different functional groups depend on the stability of the cyclic semiacetals and on the subsequent equilibria established after their depolimerisation. The semiacetal of dl-glyceraldehyde is more stable than that of glycolaldehyde. 95–96% and 98–99% of the real content were found by the hydrogensulphite and hydroxylamine methods, respectively. Glycolaldehyde decomposes rather quickly in aqueous solution and the equilibrium can be shifted towards the monomeric form by both the aldehyde reactions. The hydroxylamine method proved to be more advantageous for the determination of the dimeric hydroxyaldehydes, which cristallise in the form of cyclic semiacetals.
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    Fresenius' Zeitschrift für analytische Chemie 278 (1976), S. 128-128 
    ISSN: 1618-2650
    Keywords: Best. von Mercaptanen mit Kobalt(III) ; Volumetrie
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    Fresenius' Zeitschrift für analytische Chemie 280 (1976), S. 373-376 
    ISSN: 1618-2650
    Keywords: Best. von Hydrazin, Ammoniak, Anilin, Hydroxylamin, Thiocyanat, Dimethylhydrazin im Gemisch ; Volumetrie ; thermometrisch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Binary mixtures of hydrazine and one of the following N-containing bases: ammonia, aniline, hydroxylamine, thiocyanate and unsymmetrical dimethyl hydrazine have been assayed thermometrically. The titrations are based both on the basic and the reducing properties of the compounds. For example, whilst for mixtures of hydrazine and ammonia, the total base content is determined by an acid/base titration, and the hydrazine component is determined by oxidation with bromate ion; for mixtures containing aniline or hydroxylamine, serial titration with bromate ensures that all the hydrazine is oxidised before the onset of oxidation of the other component. Mixtures of hydrazine and UDMH have been assayed in both aqueous and non-aqueous media and a comparison of results has been reported. The main advantage of the proposed methods is that they can be applied to industrial samples, which would render other methods impossible.
    Notes: Zusammenfassung Binäre Mischungen von Hydrazin mit Ammoniak, Anilin, Hydroxylamin, Thiocyanat und asymmetrischem Dimethylhydrazin wurden thermometrisch analysiert. Sowohl die basischen als auch die reduzierenden Eigenschaften des Hydrazins bilden die Grundlage der Titrationen. Zum Beispiel wird im Gemisch Hydrazin/Ammoniak der Gesamtbasengehalt acidimetrisch ermittelt und die Hydrazinkomponente durch Oxydation mit Bromat bestimmt. Im Gemisch Anilin/Hydrazin oder Hydroxylamin/Hydrazin wird mit Bromat zunächst alles Hydrazin oxydiert, bevor die Oxydation der zweiten Komponente einsetzt. Mischungen von Hydrazin mit asym. Dimethylhydrazin werden in wäßrigem und auch in nichtwäßrigem Medium ausgeführt und die Ergebnisse verglichen. Der Hauptvorteil der beschriebenen Verfahren besteht darin, daß auch industrielle Proben untersucht werden können, bei denen andere Verfahren versagen würden.
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 358-362 
    ISSN: 1618-2650
    Keywords: Best von Kryptanden, Kryptaten ; Volumetrie ; HCl, Metall-Standardlösung, Standardzugabeverfahren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Using bromocresol green as a visual endpoint indicator solutions of the cryptands [2.2.1] and [2.2.2] can be determined by titration with HCl in the concentration range of 10−1–10−3 M with relative standard deviations of 0.2–0.4 %. If both cryptand and cryptate are present in one solution, then the sum of them can be determined titrimetrically in the same way. It is also possible to determine the contents of [2.2.1] and [2.2.2] by using a calcium or barium standard solution and the unknown cryptand solution as a titrant. By evaluation of the pH-curve thus obtained, the endpoint of the titration can be determined. In the concentration range of 10−1–10−2 M relative standard deviations of about 0.5% are obtained. [2.2.1] cryptand solutions are determined by using the standard addition technique of Gran with a calcium chloride solution. An ion-selective electrode is used as a probe for calcium ions. If this method is applied, the relative standard deviation in the range of 10−2–10−4 M solutions is approximately 3%. With this technique cryptand can be analysed even when cryptate is present in the solution.
    Notes: Zusammenfassung Bei Verwendung von Bromkresolgrün als visueller Endpunktindicator kann man [2.2.1] und [2.2.2] Kryptandlösungen im Konzentrationsbereich 10−1–10−3 M mit relativen Standardabweichungen von 0,2–0,4% mit HCl titrieren. Wenn in einer Lösung sowohl Kryptand als auch Kryptat vorhanden ist, ist die Summe beider Substanzen auf die gleiche Weise bestimmbar. [2.2.1] und [2.2.2] können auch dadurch bestimmt werden, daß eine Calciumbzw. Barium-Standardlösung mit der Kryptandlösung unbekannter Konzentration titriert wird. Die Auswertung der dabei erhaltenen pH-Kurve ergibt den Titrationsendpunkt, wobei hierdurch im Konzentrationsbereich von 10−1–10−2 M Kryptandlösungen relative Standardabweichungen von etwa 0,5% erreicht werden. [2.2.1] Kryptandlösungen werden außerdem mit der Standard-Additionstechnik nach Gran bestimmt, wobei eine calciumselektive Elektrode als Indicatorelektrode dient. Dabei werden im Konzentrationsbereich von 10−2–10−4 M relative Standardabweichungen von etwa 3 % erhalten. Diese Methode kann auch überschüssigen Kryptand neben Kryptat bestimmen.
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 413-415 
    ISSN: 1618-2650
    Keywords: Best. von Sulfat in Umweltmaterial ; Volumetrie ; Durchflußsystem, Dimethylsulfonazo als Indicator
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 287-287 
    ISSN: 1618-2650
    Keywords: Nachw. von Carbamatpesticiden in biolog. Material ; Chromatographie, Dünnschicht
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 361-365 
    ISSN: 1618-2650
    Keywords: Chromatographie, Dünnschicht ; Informationsgehalt und »Äquivokation«
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A method has been developed for the calculation of information contents of one-channel identification procedures, which is especially applicable in the area of thin-layer chromatography (TLC). The method can be considered as a refinement of the one proposed by Massart and can easily be extended to the combination of one-channel procedures. In addition, the quantity ‘equivocation’, which is complementary to the information content, is introduced. As an example the best TLC-systems and the best combinations of two TLC-systems for the identification of DDT and twelve related compounds are selected by using information contents or equivocations. The results for the individual systems are compared with those obtained by Massart.
    Notes: Zusammenfassung Eine Methode zur Berechnung von Informationsgehalten von Einkanal-Identifizierungsverfahren wurde entwickelt, die besonders gut für das Gebiet der Dünnschicht-Chromatographie (DC) anwendbar ist. Sie kann als eine Verfeinerung der von Massart vorgeschlagenen Methode angesehen werden und kann auf einfache Weise für Kombinationen von Einkanal-Verfahren erweitert werden. Dabei wird der Begriff »Äquivokation«, komplementär zum Informationsgehalt, eingeführt. Als Beispiel wurden die besten DC-Systeme und Kombinationen von zwei DC-Systemen für die Identifizierung von DDT und zwölf verwandten Verbindungen unter Benutzung von Informationsgehalten oder »Äquivokationen« ausgewählt. Die Ergebnisse für die einzelnen Systeme werden mit den nach Massart gefundenen verglichen.
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 407-407 
    ISSN: 1618-2650
    Keywords: Trenn. von Arylbenzolsulfonylthiocarbamiden ; Chromatographie, Dünnschicht
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 269-270 
    ISSN: 1618-2650
    Keywords: Untersuchungen an Bor-Curcumin-Chelaten ; Thermodifferentialanalyse ; Volumetrie ; DMSO
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 380-381 
    ISSN: 1618-2650
    Keywords: Best. von Wasser in Chlorcyan ; Volumetrie ; Karl Fischer, Ethylenglykol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird eine Methode zur Bestimmung von Wasserspuren in verflüssigtem Chlorcyan beschrieben. Nach Hinzufügen von Chlorcyan zu Ethylenglykol wird das Chlorcyan durch Verdampfen entfernt. Das durch das Ethylenglykol zurückgehaltene Wasser wird mit Karl-Fischer-Lösung titriert. Die Standardabweichungen sind im Bereich von 0,004–0,007 (0,1–0,4 g H2O/100 ml ClCN).
    Notes: Summary A description is given of a method for determining traces of water in liquefied cyanogen chloride. Following the addition to ethylene glycol, cyanogen chloride is removed by evaporation. The water retained by ethylene glycol is then titrated by Karl-Fischer solution. Standard deviations are in the range of 0.004–0.007 (0.1–0.4 g H2O/100 ml ClCN).
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 398-401 
    ISSN: 1618-2650
    Keywords: Analyse von pharmazeut. Produkten ; Chromatographie, Dünnschicht ; halogenfreie Fließmittelsysteme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Mit 2 sauren, 2 basischen und einem neutralen Fließmittel mit unterschiedlichen Polaritäten und guten Trennleistungen konnten 151 von 157 geprüften Arzneisubstanzen mit hRf-Werten zwischen 10 und 90 chromatographiert werden.
    Notes: Summary Using two acidic, two alkaline and a neutral mobile phase of different polarities and high separation efficiencies 151 of 157 tested drug substances could be chromatographed with hRf-values between 10 and 90.
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 381-384 
    ISSN: 1618-2650
    Keywords: Best. von Aminen, aromat. ; Chromatographie, Dünnschicht ; Remissionsmessung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird eine Methode zur quantitativen Bestimmung von aromatischen Aminen beschrieben. Diese werden dünnschicht-chromatographisch auf Kieselgel 60 F254 Fertigplatten in den Laufmitteln n-Propanol/Methanol/Wasser/Eisessig (65∶15∶15∶20; Vol.) oder n-Butanol/Wasser/Eisessig (66∶17∶17; Vol.) von den Begleitstoffen abgetrennt. Die getrennten Aminflecke werden entweder im Ultraviolett-Bereich oder nach Diazotierung im sichtbaren Bereich mit dem Chromatogramm-Spektralphotometer PMQ II nach der Remissionsmethode gemessen und anhand der auf derselben Platte aufgestellten Eichgerade ausgewertet. Die quantitative Bestimmung wird anhand der beiden Amine 5-Amino-2,4,6-trijod-isophthalsäurebis-(2,3-dihydroxy-propyl-N-methylamid) (I) und 2,4,6-Trijod-3-aminobenzoesäure (II) in Röntgenkontrastmittelpräparaten (RKP) demonstriert. Sowohl im UV- als auch im sichtbaren Bereich, läßt sich in 3000 μg RK-Säure (RKS) noch 0,1 μg freies aromatisches Amin, das sind 0,003%, bezogen auf die eingesetzte Menge RKS, mit einer maximalen relativen Standardabweichung von 4% bestimmen. Diese Methode ist spezifischer und empfindlicher als die der Diazotierung in Lösung.
    Notes: Summary The aromatic amines are separated from impurities by thin-layer chromatography on silica gel 60 F254 precoated plates in the mobile solvents n-propanol/methanol/water/glacial acetic acid (65∶15∶15∶20; vol.) or n-butanol/water/glacial acetic acid (66∶17∶17; vol.). The separated amine spots are measured by the remission method by means of the TLC densitometer PMQ II, either in the u.v. region or, after diazotization, in the visible region, and evaluated on the basis of the linear calibration curve set up on the same plate. Quantitative determination is demonstrated by means of the two amines, 5-amino-2,4,6-triiodoisophthalic acid-bis-(2,3-dihydroxypropyl-N-methylamide) (I) and 2,4,6-triiodo-3-aminobenzoic acid (II), in radiopaque contrast media (RCM). Both in the u.v. and visible regions, it is still possible to determine 0.1 μg of free aromatic amine in 3000 μg of radiopaque contrast medium acid (RCA), or 0.003% in terms of the amount of RCA used, with a maximum relative standard deviation of 4%. This method is more specific and more sensitive than that of diazotization in solution.
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 414-414 
    ISSN: 1618-2650
    Keywords: Best. von Aminen, aromat. primäre ; Volumetrie ; Nitrit, Hämatoxylin als Indicator
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    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 155-156 
    ISSN: 1618-2650
    Keywords: Best. der Alkalität von Umweltmaterial ; Volumetrie ; Durchflußsystem
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 135-137 
    ISSN: 1618-2650
    Keywords: Analyse von Desodorantien, Phenolderivaten in Kosmetika ; Chromatographie, Dünnschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Phenolische Desodorantien in kosmetischen Präparaten lassen sich durch Umsetzung mit Echtrotsalz Al (Anthrachinondiazonium-chlorid-1) in wäßrig-alkalischer Lösung, Extraktion des gebildeten Azofarbstoffes mit einem organischen Lösungsmittel und anschließender Dünnschicht-Chromatographie schnell identifizieren. In den meisten Fällen ist die Abhängigkeit zwischen der Extinktion der Farbstofflösung und der eingesetzten Menge des betreffenden Desodorants linear, wodurch dann auch quantitative Bestimmungen möglich sind.
    Notes: Summary Phenolic compounds, used as deodorants in cosmetic products can be identified quickly by reaction with anthraquinonediazonium chloride-1 (Echtrotsalz Al) in aqueous alkaline medium, extraction of the azo dye with an organic solvent and separation by thinlayer chromatography. The relation between the absorbance of the coloured solution and the concentration of the deodorant concerned is generally linear; in these cases quantitative determinations are always possible.
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    Fresenius' Zeitschrift für analytische Chemie 291 (1978), S. 39-41 
    ISSN: 1618-2650
    Keywords: Best. von Nickel, Jodid ; Volumetrie ; magnetisch, Meßanordnung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine einfache Meßanordnung für die magnetische Titration wird vorgestellt. Anhand der Umsetzung von [Ni(NH3)6]2+ mit CN− und von J− mit Cr2O7 2− wird gezeigt, daß sich dieses Meßverfahren unter bestimmten Voraussetzungen in der quantitativen Analyse einsetzen läßt. Zur Auswertung der Titrationskurven wird eine Auftragung der Kraft im Magnetfeld gegen das reziproke Gesamtvolumen vorgeschlagen.
    Notes: Summary A simple measuring equipment for magnetic titration is described. On the basis of the reaction of [Ni(NH3)6]2+ with CN− and J− with Cr2O7 2− it is shown that under certain conditions this method is useful in quantitative analysis. For evaluation of the titration curves, a plot of the force in the magnetic field against the reciprocal of the total volume is proposed.
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    Fresenius' Zeitschrift für analytische Chemie 291 (1978), S. 366-368 
    ISSN: 1618-2650
    Keywords: Nachw. von N-Heterocycl. Verbindungen ; Chromatographie, Dünnschicht ; CuSO4-imprägnierte Schichten, Fluorescenz
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Durch die charakteristischen Fluorescenzfarben und die Fluorescenz-Thermochromie der CuJ-Komplexe lassen sich N-Heterocyclen auf Chromatogrammen meist einwandfrei identifizieren. Eine wesentliche Vereinfachung wird durch die Verwendung CuSO4-imprägnierter Kieselgelschichten erreicht. Die Nachweisempfindlichkeiten insbesondere bei tiefer Temperatur ändern sich im Vergleich zur ursprünglichen Technik kaum.
    Notes: Summary N-Heterocycles can usually be identified with certainty through the characteristic fluorescence colours and fluorescence-thermochromism of the CuI-complexes. The use of CuSO4-impregnated silica gel layers facilitates the procedure considerably, and scarcely reduces the sensitivity of detection, particularly at low temperature.
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 24-29 
    ISSN: 1618-2650
    Keywords: Best. von Polycyclen in Wasser ; Chromatographie, Dünnschicht ; Änderung der Fluorescenzintensität
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Nach der Verordnung über Trinkwasser und Brauchwasser für Lebensmittelbetriebe (Trinkwasserverordnung) vom 31. Januar 1975 müssen 6 Einzelverbindungen aus der Gruppe der polycyclischen aromatischen Kohlenwasserstoffe nachgewiesen werden. Das empfohlene Analysenverfahren basiert auf der Messung der Fluorescenz nach vorangegangener chromatographischer Trennung auf Adsorberschichten. Sowohl bei dieser Trennung als auch in der anschließenden Zeit verändert sich die Fluorescenzintensität einzelner Verbindungen z.T. beträchtlich. Systematische Untersuchungen an Kieselgel und an Mischschichten aus Aluminiumoxid und Acetylcellulose sollen die kritischen Punkte und die möglichen Fehlerquoten offen legen.
    Notes: Summary According to the regulation on the use of drinking and industrial water in food industry (Drinking Water Regulation) of 31 January, 1975, six individual compounds of the group of polycyclic aromatic hydrocarbons must be traced. The analytical procedure recommended is based on the measurement of fluorescence after preceding Chromatographic separation on adsorber layers. In the course of this separation and during the time that follows, the fluorescence intensity of various compounds changes, in some cases considerably. Systematic studies with silica gel and mixed layers of aluminium oxide and acetyl cellulose are intended to reveal critical points and possible ranges of error.
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 126-131 
    ISSN: 1618-2650
    Keywords: Volumetrie ; Einzelproben, automatisches Analysengerät
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Voraussetzungen einer effektiven Automation der individuellen titrimetrischen Analyse werden dargestellt. Ein nach diesen Gesichtspunkten entwickeltes Gerät wird beschrieben und seine Anwendung in den Gebieten der Farbstoffe, Agrochemikalien, Additiven und Pharmaka aufgezeigt.
    Notes: Summary Criteria for effective automation of individual titrimetric analyses are presented. Based on these, an automatic titration system has been developed which is described. Its performance and its applicability in the field of dyestuffs, agrochemicals, additives and pharmaceuticals has been investigated.
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 138-143 
    ISSN: 1618-2650
    Keywords: Trenn, der Metallchelate von 8-Mercaptochinolin ; Chromatographie, Dünnschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung 8-Mercaptochinolin (Thiooxin) eignet sich zum Nachweis und zur Trennung von Metallen mit Hilfe der Dünnschicht-Chromatographie. Es bildet Neutralkomplexe definierter Zusammensetzung, die in wäßriger Phase schwerlöslich sind und in Chloroform extrahiert werden können. Fällung und Extraktion sind vom pH-Wert abhängig, wodurch eine Vortrennung der Metalle möglich ist. Beschrieben wird das dünnschicht-chromatographische Verhalten von 17 Metallchelaten. Die intensive Eigenfärbung der Komplexe erübrigt den Gebrauch von Anfärbereagentien. Die visuelle Nachweisgrenze der Metalle liegt zwischen 5 und 20 ng (Fluorescenzlöschung bei 254 nm). Spektralphotometrische Auswertung der Chromatogramme läßt eine Erniedrigung der Nachweisgrenze um etwa eine Zehnerpotenz erwarten.
    Notes: Summary 8-Mercaptoquinoline (thiooxine) is qualified for the detection and separation of metals by thin-layer chromatography. It forms neutral complexes in definite composition, which are insoluble in aqueous solution, but readily soluble in CHCl3. Precipitation and extraction are dependent on the pH value, whereby pre-separation of metals is possible. The thin-layer chromatographic behaviour of 17 metal chelates is described. No spraying is necessary for detection, since the complexes show different, characteristic colours. The visual detection limits of the metals are between 5 and 20 ng (fluorescence quenching at 254 nm). Spectrophotometric determination of the chromatograms lowers the detection limit by one power of ten.
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 144-147 
    ISSN: 1618-2650
    Keywords: Trenn. der Metallchelate von 1-Hydroxy-2-pyridinthion ; Chromatographie, Dünnschicht
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung 1-Hydroxy-2-pyridinthion (HPT) bildet mit den Metallen der 8. Nebengruppe des Periodensystems intensiv gefärbte Chelatkomplexe. Führt man die Reaktion in wäßriger Phase bei pH 7 aus, so werden alle Elemente der Gruppe erfaßt und als schwerlösliche Neutralkomplexe gefällt. Diese lassen sich mit Chloroform extrahieren und dünnschichtchromatographisch trennen. Die Nachweisgrenze der Metalle liegt zwischen 3 und 40 ng (Fluorescenzlöschung bei 254 nm). Spektralphotometrische Auswertung der Chromatogramme läßt eine Erniedrigung der Nachweisgrenze um eine Zehnerpotenz erwarten.
    Notes: Summary 1-Hydroxy-2-pyridinethione (HPT) forms highly coloured chelate complexes with the metals of the 8th sub-group. If the reaction is carried out in aqueous solution at pH 7, all elements of the group precipitate as insoluble neutral complexes. They can be extracted with CHCl3 and separated by thin-layer chromatography. The detection limit is between 3 and 40 ng (fluorescence quenching at 254 nm). Spectrophotometric determination of the chromatograms lowers the detection limit by one power of ten.
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 159-159 
    ISSN: 1618-2650
    Keywords: Best. von Strontium in Strontiumferriten ; Volumetrie ; Ausfällung bzw. Maskierung von Eisen
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 43-43 
    ISSN: 1618-2650
    Keywords: Best. von Chlorid ; Volumetrie ; Dithizon, AgCl
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 44-44 
    ISSN: 1618-2650
    Keywords: Trenn. von Guanylpyrazolnitraten ; Chromatographie, Dünnschicht
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 415-416 
    ISSN: 1618-2650
    Keywords: Trenn. von Anorgan. Ionen ; Chromatographie, Dünnschicht ; mit p-Toluidin imprägnierte Schichten
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 159-159 
    ISSN: 1618-2650
    Keywords: Best. von Indigo und Vanadat ; Volumetrie ; photometr. Endpunkt
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 269-272 
    ISSN: 1618-2650
    Keywords: Analyse von Bronze in archäolog. Material ; Volumetrie ; Korundstäbchen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung In Fortsetzung einer früheren Arbeit über Kupfer und Messing wird in dieser Mitteilung die Zinnbestimmung in Abstrichen beschrieben. Metazinnsäure wird durch Filtration mit Hilfe eines besonderen Gerätes abgetrennt, zu SnS2 umgesetzt, in HCl gelöst und die Sn-Bestimmung wird dann durch Rücktitration eines EDTA-Überschusses mit Zinksulfat durchgeführt.
    Notes: Summary In continuation of an earlier paper on copper and brass this communication describes the determination of tin in streak samples. Metastannic acid is isolated by filtration using a specially designed apparatus. It is converted to SnS2, dissolved in HCl and Sn is determined by back-titration of excess EDTA with zink sulphate.
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    Fresenius' Zeitschrift für analytische Chemie 277 (1975), S. 105-110 
    ISSN: 1618-2650
    Keywords: Chromatographie, Dünnschicht ; Auswertung über die Kubelka-Munk-Funktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine quantitative Auswertung von Dünnschicht-Chromatogrammen über die Kubelka-Munk-Funktion wird beschrieben. Die mathematische Ableitung erfolgt über zwei Ansätze: Differentialgleichung und hyperbolisch-trigonometrische Funktionen. Es zeigt sich, daß beim Zweiwellenlängen-Densitometer die Bestimmung absoluter Remissionswerte entfällt, und das erhaltene Meßsignal mit geringem Aufwand linearisiert werden kann. Die Auswertung erfolgt über die Peakhöhe, ermittelt durch Zig-Zag-Scantechnik (Shimadzu CS 900). Meß- und Vergleichswellenlänge sollen dicht beieinander liegen, um ähnliche Streukoeffizienten zu erhalten. Vermessen wird Coffein im Bereich von 0,25–20 μg, in dem die Linearisierung noch einwandfrei arbeitet. Der Fehler liegt als relative Standardabweichung bei 1,9% (c=4–20μg,n=15) bzw. 2,7% (c=0,25–2 μg,n=22).
    Notes: Abstract The mathematical derivation is given by two different statements: differential equation and hyperbolic-trigonometric functions. It is shown that measurement of absolute values of remission is inapplicable. The signal is easily to be linearized. The evaluation is given by the maximum peak value obtained by the zig-zag scan technique (Shimadzu CS 900). To get similar scatter values sample and reference wave-length should be tuned as close as possible. Caffeine is measured from 0.25 to 20 μg. In this range the linearizer works unobjectionably and the error as relative standard deviation is in the order of 1.9% (4–20 μg,n=15) and 2.7% (0.25–2 μg,n=22), respectively.
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 45-45 
    ISSN: 1618-2650
    Keywords: Chromatographie, Dünnschicht ; Diphenylamin als Detektionsmittel
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    Fresenius' Zeitschrift für analytische Chemie 277 (1975), S. 125-125 
    ISSN: 1618-2650
    Keywords: Sulfonamiden mit N-Bromsuccinimid ; Volumetrie
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    Fresenius' Zeitschrift für analytische Chemie 277 (1975), S. 126-126 
    ISSN: 1618-2650
    Keywords: Trenn. von Anorgan. Ionen als Xanthate ; Chromatographie, Dünnschicht
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    Fresenius' Zeitschrift für analytische Chemie 277 (1975), S. 207-207 
    ISSN: 1618-2650
    Keywords: Best. von Fluorid in Wasser ; Volumetrie ; SPADNS und Thoriumnitrat
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    Fresenius' Zeitschrift für analytische Chemie 277 (1975), S. 208-208 
    ISSN: 1618-2650
    Keywords: Nachw. von Diphenylpyralin im Urin ; Chromatographie, Dünnschicht ; UV-Bestimmung, N-Oxid und Desmethylderivat
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 160-160 
    ISSN: 1618-2650
    Keywords: Best. von Kobalt mit Pyrrolidindithiocarbaminat ; Volumetrie ; Jod-Azid-Reaktion
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 369-373 
    ISSN: 1618-2650
    Keywords: Chromatographie, Dünnschicht ; vollautomat. Auswertung von Chromatogrammen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es werden vollautomatische DC-Photometer beschrieben, bei denen ein Rechner die optimale Positionierung der DC-Flecke im Meßspalt steuert. Es lassen sich nicht nur die normalen Meßkurven, sondern auch die gemäß der Kubelka-Munk-Funktion transformierten Kurven für die Auswertung heranziehen. Infolge der Steuerung des Wellenlängenantriebes lassen sich auch Zweiwellenlängentechniken simulieren. Für die Auswertung eignet sich auch die 1. Ableitung der Meßkurve. Die Genauigkeit und Reproduzierbarkeit wird gesondert nach Auftragefehler, Meßfehler, Positionierfehler und Fehler der Chromatographie ausgewiesen.
    Notes: Summary Automated photometers for evaluating TLC plates by an optimized positioning of the spots in respect to the centre of the light beam are described. The evaluation can be performed by using the original measuring curve or a transformed one in respect to the Kubelka-Munk function. Two-wavelength techniques can be simulated, for the monochromator is controlled by the computer. This method has an advantage in measuring not well separated spots. In this case also an evaluation of the first derivative is often successful. The accuracy and reproducibility is given in respect to the different sources of errors: spotting, measurement, positioning and chromatography.
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 396-399 
    ISSN: 1618-2650
    Keywords: Best. von Aminen mit Salicylaldeyd ; Volumetrie ; primäre, sekundäre, krit. Untersuchung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The salicylaldehyde method for the differentiation of primary and secondary amines in mixtures has been critically evaluated. This method yields best results in acetonitrile. In mixtures of amines one can expect high results for the primary amine with correspondingly low results for the secondary amine. Corrections can be made with known mixtures of the amines.
    Notes: Zusammenfassung Das Salicylaldehydverfahren zur Unterscheidung primärer und sekundärer Amine im Gemisch wurde kritisch bewertet. Die besten Ergebnisse wurden in Acetonitril erhalten. In Gemischen sind für primäre Amine zu hohe und für sekundäre entsprechend zu niedrige Werte zu erwarten. Mit Hilfe bekannter Mischungen können Korrekturen durchgeführt werden.
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    Bulletin of experimental biology and medicine 86 (1978), S. 1158-1160 
    ISSN: 1573-8221
    Keywords: synaptosomes ; oxidation ; glutamine ; glutamate ; γ-aminobutyric acid
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    Topics: Biology , Medicine
    Notes: Abstract Experiments in vitro showed that the addition of Ca++ inhibits respiration of rat brain synaptosomes in the presence of glutamate and glutamine. The addition of GABA potentiates the inhibitory effect of Ca++ on the oxidation of glutamine but not of glutamate. GABA itself has no effect on the oxidation of either glutamate or glutamine.
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    Bulletin of experimental biology and medicine 80 (1975), S. 1193-1194 
    ISSN: 1573-8221
    Keywords: isolated cells ; hydroxylation ; oxidative phosphorylation ; oxidation
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    Topics: Biology , Medicine
    Notes: Abstract Isolated cells were obtained by using EDTA and mechanical action to dissociate rat liver tissue. The presence of oxidative phosphorylation reactions in the hepatocytes was taken as an indication of their integrity. The hepatocytes were able to hydroxylate dimethylaniline, ethylmorphine, and aminopyrine. The maximal velocity of hydroxylation was higher in the cells than in microsomes, when calculated per nmole cytochrome P-450. The NAD·H2 formed by oxidation of glutamate and malate in isolated cells can be used for the hydroxylation reactions.
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