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  • Spektralphotometrie  (167)
  • oxidation  (57)
  • Springer  (224)
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wien : Geolog. Bundesanst.
  • 2010-2014
  • 2005-2009
  • 1975-1979  (224)
  • 1940-1944
Collection
Publisher
  • Springer  (224)
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wien : Geolog. Bundesanst.
Years
Year
  • 1
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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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  • 2
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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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  • 3
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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
    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 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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  • 4
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    Oxidation of metals 13 (1979), S. 223-236 
    ISSN: 1573-4889
    Keywords: nickel ; oxidation ; surface reactions ; X-ray photoelectron spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    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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  • 5
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    Oxidation of metals 13 (1979), S. 255-272 
    ISSN: 1573-4889
    Keywords: oxidation ; Fe-C ; graphite deposition ; nonadherent oxide ; 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 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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  • 6
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    Oxidation of metals 13 (1979), S. 519-543 
    ISSN: 1573-4889
    Keywords: nickel ; oxidation ; transport ; tracer ; duplex scale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    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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  • 7
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    Oxidation of metals 13 (1979), S. 159-180 
    ISSN: 1573-4889
    Keywords: nickel-chromium alloys ; oxidation ; high temperature ; cerium
    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-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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  • 8
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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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  • 9
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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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  • 10
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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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  • 11
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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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  • 12
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 367-372 
    ISSN: 1618-2650
    Keywords: Best. von Lanthaniden, Europium, Dysprosium, Erbium, Samarium in Uran ; Spektralphotometrie ; Atomabsorption ; Graphitofen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Studies were conducted on the assay of Sm, Eu, Dy and Er separated from uranium using aqueous standards by electrothermal AAS with Massmann type graphite furnace. The working curves were found to be linear in the ranges Sm (1–10 μg/ml), Eu (0.05–0.6 μg/ml), Dy (0.1–0.8 μg/ml) and Er (0.1–1.0 μg/ml). The values obtained for synthetic samples agreed favourably with those obtained by emission spectrographic method. Experiments using pyrolytic carbon coated tubes with and without pretreatment by La, Ta and Y have shown an enhancement with treatment upto a maximum of 15% and improve the memory effect marginally. The effect of Ta treatment was found to be singularly useful in improving the general behaviour of Sm. The interference effects of lanthanides, other than the analyte, were found to be negligible. However, the presence of uranium was found to affect the absorbance. The absorbance of Eu was found to be nearly independent of uranium after an initial increase. On the other hand, the absorbance of other elements studied was found to drastically decrease after an initial enhancement. Detailed investigations of temperature dependence of absorbance were carried out using Eu, Dy and Er. The differences in the behaviour of these elements is attributed to probable differences in the modes of their atomization.
    Notes: Zusammenfassung Die Untersuchungen wurden mit Hilfe des Graphitrohrofens nach Maßmann durchgeführt. In folgenden Bereichen ergaben sich lineare Eichkurven: Sm 1–10 μg/ml, Eu 0,05–0,6 μg/ml, Dy 0,1–0,8 μg/ml, Er 0,1μ-1,0 μg/ml. Die aus synthetischen Proben erhaltenen Ergebnisse stimmten gut mit den durch Emissionsspektrographie erhaltenen überein. Versuche wurden mit Röhren mit pyrolytischen Kohlenstoffüberzug mit und ohne Vorbehandlung durch La, Ta und Y durchgeführt und ergaben eine bis 15%ige Steigerung durch die Behandlung sowie eine mäßige Besserung des Memoryeffektes. Eine Behandlung mit Ta war besonders für Sm vorteilhaft. Störungen durch andere Lanthanide waren vernachlässigbar. Uran beeinflußte jedoch die Absorption. Im Falle von Eu zeigte sich nach anfänglicher Zunahme fast eine Unabhängigkeit, während bei den anderen untersuchten Elementen nach anfänglicher Zunahme eine beträchtliche Abnahme auftrat. Mit Eu, Dy und Er wurde ebenfalls die Temperaturabhängigkeit der Absorption untersucht. Festgestellte Unterschiede im Verhalten werden auf unterschiedliche Atomisierung zurückgeführt.
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  • 13
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 284-284 
    ISSN: 1618-2650
    Keywords: Best. von Uran(VI) mit Chlorphosphonazo III ; Spektralphotometrie ; Trioctylamin-Extraktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 14
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 285-285 
    ISSN: 1618-2650
    Keywords: Best. von Phosphat in Ferrosilicium ; Spektralphotometrie ; Cer/Xylenolorange, indirekt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 15
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 413-413 
    ISSN: 1618-2650
    Keywords: Best. von Kobalt mit Pyridin und Azid ; Spektralphotometrie ; Aussalzungsmittel, Mischkomplex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 16
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 270-270 
    ISSN: 1618-2650
    Keywords: Best. von Cer(IV) ; Spektralphotometrie ; indirekt, Fe(III)-Resacetophenonoximat-Komplex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 17
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    Fresenius' Zeitschrift für analytische Chemie 299 (1979), S. 264-266 
    ISSN: 1618-2650
    Keywords: Best. von Kohlenhydraten in Huminsäuren ; Spektralphotometrie ; Anthronmethode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Eine modifizierte Anthronmethode zur Bestimmung des Kohlenhydratgehaltes in Fraktionen von Huminsäure-Blei(II)-Chelatverbindungen, die mit chemischen und gelchromatographischen Methoden getrennt wurden, wird beschrieben. Um die Störung der Methode durch die Absorption der Huminsäuren, die mit abnehmender Wellenlänge ansteigt, gering zu halten, wird die Extinktion des Anthron-Kohlenhydrat-Reaktionsproduktes bei 620 nm gemessen. Die Huminsäurekonzentration darf 0,1 g/dl nicht überschreiten. Da die molare Extinktion des Anthron-Reaktionsproduktes von der Art des Kohlenhydrates abhängt, wird der Kohlenhydratgehalt auf das Hauptkohlenhydrat des Huminsäurehydrolysats berechnet (d.h. Glucose).
    Notes: Summary A modified anthrone method is described for the determination of carbohydrates in fractions of lead(II)-chelate compounds of humic acids separated with chemical as well as gel-chromatographic methods. To reduce the disturbance of the method by the absorption of humic acids increasing with the decrease of wavelength, the absorbance of the anthronecarbohydrate reaction products is measured at 620 nm and the humic acid concentration is not allowed to exceed 0.1 g/dl. Because the molar absorptivity of the anthrone reaction-products depends on the type of carbohydrate investigated, the content is calculated for the main carbohydrate of the humic-acid hydrolysate (i.e. glucose).
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  • 18
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 366-370 
    ISSN: 1618-2650
    Keywords: Best. von Quecksilber, Silber mit Formazanen ; Spektralphotometrie ; chelatbildende Ionenaustauscher
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Darstellung substituierter Formazane und ihre chemische Fixierung an Cellulose, amino- und chlormethyliertem Polystyrol wird beschrieben. Die Kapazitäten der Austauscher liegen zwischen 0,05 mÄq/g (Cellulose) und 0,6 mÄq/g (Polystyrol). In neutralem Medium zeigen sie eine besondere Affinität zu Hg(II), Pd(II) und Ag(I), aber keine Affinität zu Cu(II). Weiterhin wurde eine spektrophotometrische Bestimmung von Hg(II) und Ag(I) mit dem wasserlöslichen Formazan (FII)-NO2 ausgearbeitet [Hg(II): ɛ546=23 000 l Mol−1 cm−1, Ag(I): ɛ546 =38 000 l Mol−1 cm−1].
    Notes: Summary The preparation of substituted formazans and their fixation on cellulose, amino- and chloromethylated polystyrene is described. The capacities of the exchangers vary from 0.05 meq/g (cellulose) to 0.6 meq/g (polystyrene). They show in neutral medium greater affinity to Hg(II), Pd(II) and Ag(I), but no affinity to Cu(II). Further, a spectrophotometric determination of Hg(II) and Ag(I) with the watersoluble formazan (FII)-NO2 has been worked out. [Hg(II): ɛ546=23 000 l Mol−1 cm−1, Ag(I): ɛ546=38 000 l Mol−1 cm−1].
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  • 19
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 356-360 
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Mechanisierung, Prinzip, Optimierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Das Prinzip der Automatisierung der photometrischen Analyse mit kontinuierlichem Reagentienfluß und die speziellen Vorteile der Verwendung von Bausteinen der Flüssigkeits-Chromatographie werden ausführlich diskutiert. Die Optimierung folgender Parameter wird besprochen: Verweilzeit (Reaktionszeit), Einspritzmenge, Pumpgeschwindigkeit, Säulenabmessungen, Partikeldurchmesser.
    Notes: Summary The principle of automation of photometric analysis by the continuous flow method and the particular advantages of the use of component parts of liquid chromatography are discussed in detail. The optimization of the following parameters is pointed out: residence (reaction) time, injection volume, pumping rate, column dimensions and particle diameter.
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  • 20
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 47-47 
    ISSN: 1618-2650
    Keywords: Best. von Vanadium in Stahl ; Spektralphotometrie ; Hydroxyphenyl-p-tolylbenzamidin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 21
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 393-397 
    ISSN: 1618-2650
    Keywords: Best. von Tensiden in Wasser ; Spektralphotometrie ; Aniontenside, Reinigungsstufen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Aniontenside werden an Feststoffen der Gewässer wie auch der Kläranlagen adsorbiert und teilweise angereichert. Ihre analytische Bestimmung erfordert eine mehrstufige Vorarbeit. Sie führt über die Extraktion des Probengutes, die Abtrennung der Tenside von Störstoffen durch Ausblasen (grobe Vorreinigung) und die chromatographische Reinigung der Rohfraktion auf Kieselgelschichten. Die Konzentration der reinen Tensidfraktion kann colorimetrisch oder IR-spektrometrisch bestimmt werden.
    Notes: Summary Anion tensides are adsorbed on solids in surface waters and sewage treatment plants and enriched to some extent. Their analytical determination requires multi-stage preparations, including sampling, separation of the tensides from disturbing material by air stripping (rough preliminary cleaning), and chromatographic cleaning of the raw fraction on silica gel. The concentration of the pure tenside fraction can be determined colorimetrically or by way of IR spectrometry.
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 159-160 
    ISSN: 1618-2650
    Keywords: Best. von Vanadium(V) mit p-Hydroxybenzaldehyd und Hydroxyamidin ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 23
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 158-158 
    ISSN: 1618-2650
    Keywords: Best. von Palladium, Ruthenium ; Spektralphotometrie ; Isonitrosodibenzoylmethan
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    Topics: Chemistry and Pharmacology
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  • 24
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 160-160 
    ISSN: 1618-2650
    Keywords: Best. von Ruthenium(III) mit 3-Hydroxy-3-(p-dimethylaminophenyl)-1-phenyltriazen ; Spektralphotometrie
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  • 25
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 45-45 
    ISSN: 1618-2650
    Keywords: Best. von o-Dichlorbenzol ; Spektralphotometrie ; UV
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  • 26
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 46-46 
    ISSN: 1618-2650
    Keywords: Best. von p-Methylaminophenolsulfat, Metol ; Spektralphotometrie
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    Topics: Chemistry and Pharmacology
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  • 27
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 406-407 
    ISSN: 1618-2650
    Keywords: Best. von Ligninsulfonsäure, Huminsäure in Wasser ; Spektralphotometrie ; UV
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  • 28
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 383-385 
    ISSN: 1618-2650
    Keywords: Best. von Bor in Silicaten ; Spektralphotometrie ; Pyrohydrolyse, Carminsäure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary This simple method for the determination of boron takes a total time of 20 min. Samples are mixed with CaF2 suprapur in the ratio 3∶1 and pyrohydrolized in a Leco induction furnace for 15 min under steam of H2O. The BF3 liberated is collected in a NaOH-Na2CO3 solution (10 g NaOH +1 g Na2CO3 per liter). This solution is filled up to 200 ml with twice distilled water; 2 ml of this solution is mixed with conc. sulphuric acid and carminic acid solution and filled up to 50 ml. The absorption is measured by a Zeiss Elko II photometer with filter S 59. Analyses of four internations reference samples show excellent precision with a relative standard deviation of less than 5% (e.g. for a boron content of 2.1 ppm in granite G-2).
    Notes: Zusammenfassung Die Borbestimmung mit dieser schnellen und einfachen Methode benötigt ca. 20 min. Die Proben werden mit CaF2 Suprapur im Verhältnis 3∶1 vermischt und in einem Leco-Induktionsofen 15 min unter Einleitung von Wasserdampf pyrohydrolysiert. Das entstandene BF3 wird in einer NaOH-Na2CO3-Lösung(10 g NaOH+1 gNa2CO3pro Liter) aufgefangen. Diese Lösung wird mit zweifach destilliertem Wasser auf 200 ml aufgefüllt; 2 ml dieser Lösung werden mit konz. Schwefelsäure und Carminsäure-Lösung versetzt und auf 50 ml aufgefüllt, bevor ihre Absorption mit einem Zeiss — Elko II — Photometer mit Filter S 59 gemessen wird. Analysen von 4 internationalen Referenzproben zeigen eine hohe Präzision mit einer relativen Standardabweichung von weniger als 5% (z. B. für einen Gehalt von 2,1 ppm Bor im Granit G-2 des USGS).
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 407-408 
    ISSN: 1618-2650
    Keywords: Best. von N-p-Tolylbenzohydroxamsäure ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 296 (1979), S. 414-415 
    ISSN: 1618-2650
    Keywords: Best. von Quecksilber(II) mit 3-Methyl-5-pyrazolon-4-dithiocarbonsäure ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 286-286 
    ISSN: 1618-2650
    Keywords: Best. von Aminen mit Isothiocyanatodioxotolyldihydrobenzisochinolin ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 285-285 
    ISSN: 1618-2650
    Keywords: Best. von Eisen(III), Chrom(VI) mit Helasolviolett 4R ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 119-121 
    ISSN: 1618-2650
    Keywords: Best. von Wolfram(VI) mit Thioglykolsäure ; Spektralphotometrie ; Chelatbildung, Carbonsäuren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung W(VI) bildet mit Thioglykolsäure und Glykolsäure mäßig stabile Fünfringchelate der Zusammensetzung WR2, mit Glycin ein sehr schwaches WR. Chelate mit den Sechsringbildnern 3-Mercaptopropionsäure und o-Mercaptobenzoesäure sind nicht nachweisbar. Das Thioglykolsäurechelat kristallisiert aus Methanol als gelbes Na-Salz WO2(SCH2COONa)2·2CH3OH und ist mit Di-phenylguanidin als Ionenpaar in Butanol extrahierbar. Die photometrische Wolframbestimmung mit Thioglykolsäure in wäßriger Lösung erreicht eine Bestimmungsgrenze von $$\underline c $$ = 0,92 ppm W (P=99,9%;M=2) und eine Standardabweichung vons=0,24 ppm W (f=21).
    Notes: Summary W(VI) forms moderately stable, five-membered ring chelates of the composition WR2 with thioglycolic and glycolic acid, and a very weak WR with glycine. Chelation with the six-ring forming 3-mercaptopropionic acid and o-mercaptobenzoic acid could not be detected. The chelate with thioglycolic acid crystallizes from methanol as the yellow sodium salt WO2(SCH2COONa)2·2CH3OH and can be extracted into butanol as an ion pair with diphenylguanidine. The photometric determination of tungsten with thioglycolic acid has a determination limit of $$\underline c $$ = 0.92 ppm W (P=99.9%;M=2) and a standard deviations=0.24 ppmW (f=21).
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 122-124 
    ISSN: 1618-2650
    Keywords: Best. von Sulfat in Umweltmaterial ; Wasser ; Spektralphotometrie ; Durchflußsystem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Sulphate in various environmental samples was determined by measuring the optical absorbance upon reaction with the barium(II) dimethylsulphonazo(III) complex. The measurement took place in a flow-through system. Interferences from phosphate, metal ions and others were eliminated. The results of a turbidimetric measurement, a spectrophotometric measurement with thorin, an automatic titration and the proposed method are compared. The latter allows the determination of sulphate in the range of 1.4–60 μmol·l−1. The standard deviation is 0.3–0.6 μmol·l−1, depending on the type of sample (water) analysed. A determination takes 1.5min.
    Notes: Zusammenfassung Sulfat wurde in verschiedenen Umweltproben durch Messung der Extinktion nach Reaktion mit dem Barium(II)-dimethylsulfonazo(III)-komplex im Durchflußsystem bestimmt. Störungen von Phosphat, Metallionen, u.a. wurden beseitigt. Die Ergebnisse einer turbidimetrischen, einer photometrischen, einer automatischen Titration und der vorgeschlagenen Methode werden verglichen. Die Methode ermöglicht die Sulfatbestimmung im Bereich von 1,4–60 μmol·l−1. Die Standardabweichung beträgt 0,3–0,6 μmol· l−1 je nach Typ des Probematerials (Wasser). Eine Bestimmung erfordert 1,5min.
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 271-271 
    ISSN: 1618-2650
    Keywords: Best. von Blei in Wasser, Abwasser, Staub ; Spektralphotometrie ; Dithizon
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 413-413 
    ISSN: 1618-2650
    Keywords: Best. von Platin(IV) mit Chlorpromazin ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 419-419 
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Bouguer-Lambert-Beersches Gesetz, neues Konzept
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 160-160 
    ISSN: 1618-2650
    Keywords: Best. von Phenothiazinen ; Spektralphotometrie ; Silicowolframsäure
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 43-44 
    ISSN: 1618-2650
    Keywords: Best. von Salicylaldehyd ; Spektralphotometrie ; konz. Schwefelsäure
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 46-46 
    ISSN: 1618-2650
    Keywords: Best. von Osmium mit N-Benzoyl-o-tolylhydroxylamin ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 415-416 
    ISSN: 1618-2650
    Keywords: Best. von Albumin in Serum ; Spektralphotometrie ; Isothiocyanatodioxo-tolyldihydro-benzisochinolin, Rinderserum
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    Fresenius' Zeitschrift für analytische Chemie 299 (1979), S. 128-128 
    ISSN: 1618-2650
    Keywords: Best. von Ruthenium mit 2-Methyl-1,4-naphtochinon-monoxim ; Spektralphotometrie ; Extraktion
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    Fresenius' Zeitschrift für analytische Chemie 295 (1979), S. 412-413 
    ISSN: 1618-2650
    Keywords: Best. von Palladium(II), Ruthenium(III) mit Isonitrosobenzoylacetone ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 297 (1979), S. 384-387 
    ISSN: 1618-2650
    Keywords: Best. von Uran ; Spektralphotometrie ; Spuren, Extraktion mit Triphenylarsinoxid in Chloroform
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wurde eine einfache, vielseitig anwendbare spektralphotometrische Uranbestimmung für U6+-Mengen bis in den ng-Bereich ausgearbeitet, bei der über 60 Kationen und etwa 20 Anionen in weiten Grenzen nicht stören. Das mit Triphenylarsinoxid in CHCl3 aus der zu untersuchenden Lösung extrahierte Uran wird mit oxalsäurehaltiger 5,5 M HClO4 zurückextrahiert und in den Arsenazo III-Komplex überführt. Die mit diesem Schritt verbundene Aufkonzentrierung erlaubt noch bis zu 0,01 μg Uran in 200 ml Ausgangslösung spektralphotometrisch bei 655 nm zu bestimmen. Im günstigsten Arbeitsbereich beträgt die relative Standardabweichung ±1%. 4 Probelösungen können in 1 h analysiert werden.
    Notes: Summary A simple and versatile spectrophotometric method for the determination of uranium down to the μg range was worked out. About 60 cations and 20 anions were found not to cause interferences in a wide concentration range. U6+ is extracted with triphenylarsine oxide in chloroform, back-extracted with 5.5 M perchloric acid containing oxalic acid and converted to the arsenazo III-complex. The concentration step involved allows the spectrophotometric determination of 0.01 μg of uranium in 200 ml of original solution at 655 nm. A standard deviation of ±1 % can be achieved and it is possible to analyse about 4 solutions per hour.
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 156-157 
    ISSN: 1618-2650
    Keywords: Best. von Sulfat in Wasser ; Spektralphotometrie ; Ionenaustausch, Dimethylsulfonazo(III)
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    Fresenius' Zeitschrift für analytische Chemie 298 (1979), S. 150-154 
    ISSN: 1618-2650
    Keywords: Best. von Kupfer mit Fluoronen ; Spektralphotometrie ; Übersicht über die Fluorone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Fluorone, Verbindungen des 2,3,7-Trihydroxyisoxanthenons-(6), eignen sich als empfindliche Reagentien für die spektralphotometrische Analyse zahlreicher Metallionen im sichtbaren Teil des Spektrums. Neben einigen grundsätzlichen Anmerkungen zur Herstellung, zu den Eigenschaften und Reaktionen der Fluorone mit Metallionen wird die Verwendung des Cyclohexylfluorons (CHF) für die photometrische Bestimmung von Cu(II)-Ion beschrieben; hierbei ergibt sich ein molarer Extinktionskoeffizient von 191000 l/Mol · cm und eine Standardabweichung von ±0,2 ng/ml. Der Anwendungsbereich liegt bei 6–60 ng Cu/ml. Bi, Fe(II/III) und Sb müssen zuvor abgetrennt werden.
    Notes: Summary Fluorones, derivates of 2,3,7-trihydroxyisoxanthenone-(6), are sensitive reagents for the spectrophotometric determination of many metal ions in aqueous solution. Besides some principal remarks on the synthesis, properties and reactions of fluorones, the application of cyclohexylfluorone for the determination of Cu(II) ion is described in detail. This method is applicable in the concentration range 6–60 ng of Cu/ml. The molar absorptivity is 1910001/Mol · cm and the standard deviation is ±0.2 ng/ml. Bi, Fe(II, III) and Sb have to be separated prior to the determination.
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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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    Oxidation of metals 12 (1978), S. 451-471 
    ISSN: 1573-4889
    Keywords: HCl gas ; H2O vapor ; Ni-Cr-Al alloy ; oxidation ; hot corrosion
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    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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    Oxidation of metals 12 (1978), S. 1-22 
    ISSN: 1573-4889
    Keywords: NaCl vapor ; Ni-Cr-Al alloy ; oxidation ; hot-salt corrosion
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    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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    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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    ISSN: 1573-4889
    Keywords: Cu-Si alloys ; oxidation ; kinetics ; silica
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    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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    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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    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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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    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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    Oxidation of metals 12 (1978), S. 139-156 
    ISSN: 1573-4889
    Keywords: Rosenburg method ; oxidation ; CoO
    Source: Springer Online Journal Archives 1860-2000
    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 12 (1978), S. 23-34 
    ISSN: 1573-4889
    Keywords: cobalt ; oxidation ; sulfidation ; conjoint attack
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    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
    Source: Springer Online Journal Archives 1860-2000
    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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    Oxidation of metals 12 (1978), S. 503-526 
    ISSN: 1573-4889
    Keywords: nickel ; sulfur dioxide ; oxidation ; sulfidation
    Source: Springer Online Journal Archives 1860-2000
    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
    Source: Springer Online Journal Archives 1860-2000
    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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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 416-416 
    ISSN: 1618-2650
    Keywords: Best von Vitamin D2 ; Spektralphotometrie ; HCl, Tetrachloräthan
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    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 416-416 
    ISSN: 1618-2650
    Keywords: Best. von Pikrinsäure ; Spektralphotometrie ; Zink und Ammoniumchlorid
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 43-44 
    ISSN: 1618-2650
    Keywords: Best. von Uran(VI) mit Arsenazo III ; Spektralphotometrie ; starksaure Lösung
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    Topics: Chemistry and Pharmacology
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 46-47 
    ISSN: 1618-2650
    Keywords: Best. von Thallium(I), Dimethylthalliumverbindungen ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 233-235 
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Ableitungen höherer Ordnung, Analogdifferenzierer, Derivativverfahren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird über eine neu entwickelte Analog-Recheneinheit berichtet, mit der man Ableitungen von Spektren und anderen Meßsignalen erstmalig bis zur 7. Ordnung on-line verwirklichen kann. Wie die Prüfungen ergaben, ist die optimale Auflösung in den meisten Fällen mit der 4. Ableitung erreicht. Dann sind nämlich alle Schultern und Wendepunkte der Kurven in bipolare Signale übergeführt. Eine Aufstellung der wichtigsten bisherigen Anwendungsgebiete wird gegeben.
    Notes: Summary This report deals with a newly developed analogue computing accessory by which derivations of spectra and other electric signals up to the seventh order were realized on-line. A thorough study of this apparatus showed that in most cases fine-resolving is reached by the fourth derivation. In this case, all shoulders and points of inflections are resolved to bipolar signals. A number of examples for applying derivative spectrophotometry of higher order (DSHO-method) is also given.
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 400-402 
    ISSN: 1618-2650
    Keywords: Bestimmung von Meclozin, Pyridoxin in pharmazeutischen Produkten ; Spektralphotometrie ; Orthogonalfunktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A rapid spectrophotometric method for the analysis of tablets containing the title compounds without preliminary separation is developed. Thus, pyridoxine is determined by measurement at λ max while the six-points quadratic orthogonal polynomial has been used to determine meclozine. The mean percentage recoveries (8 determinations) were found to be 101.71±0.64 and 99.77±0.62% (P=0.05) for meclozine and pyridoxine hydrochlorides, respectively. Neither the Vierordt's nor the absorbance ratio methods gave accurate results as the proposed method. The method was applied successfully to the analysis of market preparations.
    Notes: Zusammenfassung Es wurde ein Verfahren zur schnellen Bestimmung der beiden Verbindungen ohne Vortrennung ausgearbeitet. Pyridoxin wird durch Messung beim Absorptionsmaximum von 292 nm bestimmt, Meclozin wird mit Hilfe eines quadratischen Sechspunkte-Orthogonalpolynoms berechnet. Die Wiederfindungsrate (8 Bestimmungen) lag bei 101,71±0,64 bzw. 99,77±0,62% (P=0,05). Vergleichsbestimmungen nach der Methode von Vierordt und dem Verfahren der Extinktionsverhältnisse gaben weniger genaue Resultate. Die vorgeschlagene Methode wurde mit gutem Erfolg auf handelsübliche Präparate angewendet.
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 220-221 
    ISSN: 1618-2650
    Keywords: Best. von Magnesium ; Spektralphotometrie ; Trimethin-Reagentien aus Aminochalkogenuracilen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Bekanntlich werden Trimethinfarbstoffe, als Reagentien für die photometrische Magnesiumbestimmung, durch die Kondensation von Malonaldehyd und Barbitursäure bzw. ihren Derivaten hergestellt. Auf ähnliche Weise erhält man mit 4(6)-Amino(2)-chalkogeno-uracilen und Malonaldehyd die Ammoniumsalze der Trimethinfarbstoffe, die sich ohne weitere Aufarbeitung als Reagentien für die photometrische Bestimmung einsetzen lassen. Die Herstellung der Verbindungen wird beschrieben.
    Notes: Summary It is known that trimethine dyes used for the photometrie determination of magnesium ions can be prepared by the condensation of malonicaldehyde with barbituric acid or its derivatives; In a similar way it is possible to use 4(6)-amino-2-chalcogeno-uracils giving with malonicaldehyde ammonium salts of the trimethine dyes, which are suited for the photometric determination without further manipulations. The preparation is described.
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    ISSN: 1618-2650
    Keywords: Best. von Nickel, Kobalt mit 2-Carboxy-2′-hydroxy-3′,5′-dimethylazobenzol-4-sulfonsäure ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 302-303 
    ISSN: 1618-2650
    Keywords: Best. von Aldehyden, aromat. mit Barbitursäure ; Spektralphotometrie. Best. von Barbitursäure mit p-Dimethylaminobenzaldehyd ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 359-361 
    ISSN: 1618-2650
    Keywords: Best. von Uran in Wasser ; Spektralphotometrie ; Arsenazo, Fällg. mit Al-Phosphat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Zur schnellen und genauen Bestimmung von Uranspuren in natürlichen, auch salzhaltigen Wässern, wird Uran durch Spurenfällung mit Aluminiumphosphat abgetrennt. Durch Auflösen des mit Zinkpulver vermengten Niederschlages erfolgt Reduktion zu U(IV), das mit Arsenazo III bestimmt wird. Der Extinktionskoeffizient beträgt 97000 cm2/Mol.
    Notes: Summary For the precise and accurate determination of uranium in natural, even saline, waters, it is separated by coprecipitation with Al-phosphate. The precipitate is mixed with zinc powder, dissolved and thus reduced to U(IV), which is determined with Arsenazo III. The molar absorptivity is 97000 cm2/mol.
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    ISSN: 1618-2650
    Keywords: Best. von Phosphat neben Silicium, Arsen, Germanium ; Spektralphotometrie ; Extraktion mit Benzophenon, Molybdatmethode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A new type of separation of phosphate ion, along with its spectrophotometric determination, was established by liquid-liquid extraction, where the yellow heteropoly acid formed by the reaction with ammonium molybdate in acid solution is quantitatively extracted into molten benzophenone at a temperature of about 60° C. When cooled down to room temperature, the benzophenone extract converts from the liquid state to the solid state. The resulting solidified extract is dissolved in methyl propionate, and the phosphate ion in the solvent is determined spectrophotometrically by the blue heteropoly acid method. Possible interference by Si, As and Ge is eliminated by the separation procedure.
    Notes: Zusammenfassung Bei dem beschriebenen Verfahren wird die mit Ammoniummolybdat in saurer Lösung gebildete gelbe Heteropolysäure bei 60° C in geschmolzenes Benzophenon extrahiert. Dieses wird durch Abkühlen verfestigt, in Methylpropionat gelöst und in dieser Lösung das Phosphat spektralphotometrisch als blaue Heteropolysäure bestimmt. Si, As und Ge, die ebenfalls mit Molybdat reagieren, werden durch die Extraktion abgetrennt.
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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
    Source: Springer Online Journal Archives 1860-2000
    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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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 115-117 
    ISSN: 1618-2650
    Keywords: Best. von Palladium(II) mit Formazanen ; Spektralphotometrie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die o-Cl-substituierten Formazane-I und -II werden erstmalig dargestellt und ihre Eignung als photometrische Reagentien für Palladium überprüft. Formazan-I reagiert nur im Dioxan-WasserGemisch bei pH 3,5 zu einem grünen 1∶2-Pd-Komplex, während Formazan-II einen wasserlöslichen Komplex bildet, mit maximaler Absorption bei pH 3 (λmax= 633 nm, ɛ623=11.5·1031 Mol−1 cm−1 Das Beersche Gesetz ist im Bereich von 0,02–11 μg Pd/ml erfüllt.
    Notes: Summary The o-Cl substituted formazans I und II where newly synthesized and their application to the spectrophotometric determination of palladium has been evaluated. Formazan I reacts only in dioxanwater medium at pH 3.5 resulting in a green 1∶2 Pd-complex, whereas formazan II forms a water-soluble complex with maximum absorption at pH 3 (λmax= 633 nm, ɛ623=11.5×1031 Mol−1 cm−1). This system obeys Beer's law from 0.02–11 μg Pd/ml.
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 29-33 
    ISSN: 1618-2650
    Keywords: Best. von Carbamaten, N-monosubstitutierte ; Spektralphotometrie ; Fearon-Reaktion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung N-Monosubstituierte Carbamate werden mit 1,3-Diaminopropan in Gegenwart geringer Mengen Natriumhydroxid zu einem Harnstoffderivat umgesetzt, das seinerseits mit Hilfe der „Carbamid-Reaktion“ nach Fearon bestimmt wird. Die Erfassungsgrenze liegt für N-Methylcarbamate im Bereich von 20 nmol. Im Falle der N-Methylcarbamate ließ sich das Harnstoff-Zwischenprodukt als N-Methyl-N′-(3-aminopropyl)-harnstoff identifizieren; diese Substanz entsteht bei der Amidierung in nahezu quantitativer Ausbeute.
    Notes: Summary N-Monosubstituted carbamates are converted to urea derivates by reaction with 1,3-diaminopropane in the presence of small amounts of sodium hydroxide. The urea derivatives are determined by Fearon's “carbamide reaction”. The detection limit for N-methylcarbamates is in the range of 20 nmoles. In the case of N-methylcarbamates, N-methyl-N′-(3-aminopropyl)-urea was found to be the intermediate urea derivative, which is formed in nearly quantitative yield.
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 299-299 
    ISSN: 1618-2650
    Keywords: Best. von Titan ; Spektralphotometrie ; Salicylsäure als Reagens
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    Fresenius' Zeitschrift für analytische Chemie 289 (1978), S. 282-284 
    ISSN: 1618-2650
    Keywords: Best. von Aromat. Aldehyden mit Diphenylamin ; Spektralphotometrie ; allg. Verfahren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Aromatic aldehydes and some of their binary mixtures can be determined spectrophotometrically with diphenylamine in the presence of hydrochloric acid. Errors are in the range of 6–10%. Various other organic compounds do not interfere.
    Notes: Zusammenfassung Aromatische Aldehyde und einige ihrer binären Gemische können mit Diphenylamin in salzsaurer Lösung spektralphotometrisch bestimmt werden. Fehler sind im Bereich von 6–10%. Eine große Zahl anderer organischer Verbindungen stört nicht.
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    Fresenius' Zeitschrift für analytische Chemie 289 (1978), S. 285-285 
    ISSN: 1618-2650
    Keywords: Best. von Ameisensäurederivaten ; Spektralphotometrie ; Decarbonylierung
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 47-47 
    ISSN: 1618-2650
    Keywords: Best. von Wolfram ; Spektralphotometrie ; SalicylsÄure als Reagens
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 104-105 
    ISSN: 1618-2650
    Keywords: Best. von Kallikrein in Plasma ; Spektralphotometrie ; chromogenes Peptidsubstrat
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 116-117 
    ISSN: 1618-2650
    Keywords: Best. von Säure-Base-Gleichgewichten ; Spektralphotometrie ; Mehrwellenlängen
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 117-118 
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Spektrometrische Titration ; Molekülstruktur ; Lösung
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 118-119 
    ISSN: 1618-2650
    Keywords: Kinetische Analyse ; Spektralphotometrie ; Mehrwellenlängen ; Stopped-flow
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 126-127 
    ISSN: 1618-2650
    Keywords: Spektralphotometrie ; Zentrifugalanalysator, Küvetten längs zum Lichtstrahl
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  • 84
    ISSN: 1618-2650
    Keywords: Best. von Proteolytischen Enzymen, Arylamidasen in Liquor ; Spektralphotometrie
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 174-175 
    ISSN: 1618-2650
    Keywords: Best. von Lipase in Serum ; Spektralphotometrie ; Zentrifugalanalysator
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    Fresenius' Zeitschrift für analytische Chemie 290 (1978), S. 179-180 
    ISSN: 1618-2650
    Keywords: Best. von D-Xylose ; Spektralphotometrie ; Xylose-NADP-oxidoreductase
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 286-289 
    ISSN: 1618-2650
    Keywords: Best. von Fluorid mit Thoriumnitrat ; Spektralphotometrie ; Alizarin S als Indicator, automatisch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Für Fluoridgehalte zwischen 1 und 20 mg in 85 ml Lösung wurde die photometrische Titration mit Thoriumnitrat und Alizarin S automatisiert und die Arbeitsbedingungen optimiert. Ausgewählte Matrixeinflüsse werden eingehender untersucht. Dieses Verfahren ist besonders für die Bestimmung von Fluorid aus Peroxid-Aufschlüssen geeignet.
    Notes: Summary The photometric titration of fluoride with thorium nitrate and Alizarin S as indicator has been automated and optimized for fluoride levels between 1 and 20 mg/85 ml solution. The interference of several ions has been investigated. This procedure is particularly useful for the determination of fluoride after fusion with peroxides as fluxing agents.
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    Fresenius' Zeitschrift für analytische Chemie 293 (1978), S. 411-412 
    ISSN: 1618-2650
    Keywords: Best. von Aminen, aliphat, primär ; Spektralphotometrie ; o-Phthaldialdehyd und Mercaptoäthanol
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 293-295 
    ISSN: 1618-2650
    Keywords: Best. von Chlorid in Mineralien, Gesteinen ; Spektralphotometrie ; Pyrohydrolyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary This simple method for the determination of chloride takes a total time of 15 min. Samples are mixed with silica in the ratio 1∶1, and the chloride is liberated in an induction furnace by pyrohydrolysis within ca. 10 min. The chloride is collected in a 0.020 M sodium-hydroxide solution. This solution is filled up to 200 ml with twice distilled water and absorption is measured with ferric ammonium sulphate and mercury(II) thiocyanate solution by a Zeiss Elko II photometer. Analysis of three international reference samples show excellent accuracy with a standard deviation of less than 4% (e.g. for a chloride content of 117 ppm in Andesite AGV-1).
    Notes: Zusammenfassung Diese einfache Methode zur Bestimmung des Chloridions benötigt eine Gesamtzeit von 15 min. Die Proben wurden mit Kieselsäure im Verhältnis 1∶1 vermischt und in einem Induktionsofen 10 min lang pyrohydrolysiert. Das entstandene HCl wurde in einer 0,020 M Nariumhydroxidlösung aufgefangen. Diese Lösung wurde mit zweifach dest. Wasser auf 200 ml aufgefüllt, mit Eisenammoniumsulfat- und Quecksilberthiocyanatlösung versetzt und deren Absorption mit einem Zeiss-Elko II-Photometer gemessen. Die Analysen von 3 internationalen Referenzproben zeigen eine hohe Präzision mit einer relativen Standardabweichung von weniger als 4% (z. B. für einen Gehalt von 117 ppm Chlor in Andesit AGV-1).
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    Fresenius' Zeitschrift für analytische Chemie 292 (1978), S. 413-413 
    ISSN: 1618-2650
    Keywords: Best. von Saccharin in Getränken, Limonaden (Fruchtsäften) ; Spektralphotometrie ; Chlorophenothiazin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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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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  • 92
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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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  • 93
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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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  • 94
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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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  • 95
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    Oxidation of metals 11 (1977), S. 91-106 
    ISSN: 1573-4889
    Keywords: oxidation ; cyclic ; spallation ; stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    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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  • 96
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    Oxidation of metals 11 (1977), S. 109-125 
    ISSN: 1573-4889
    Keywords: nickel-vanadium ; 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 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
    Source: Springer Online Journal Archives 1860-2000
    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 11 (1977), S. 289-305 
    ISSN: 1573-4889
    Keywords: superalloys ; oxidation ; oxides ; volatilization
    Source: Springer Online Journal Archives 1860-2000
    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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    Fresenius' Zeitschrift für analytische Chemie 283 (1977), S. 195-197 
    ISSN: 1618-2650
    Keywords: Best. von Zucker, reduz., Glucose, Maltose mit 3,5-Dinitrosalicylsäure ; Spektralphotometrie ; Messung bei verschiedenen pH-Werten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A Spectrophotometric method of estimation of glucose and maltose using 3,5-dinitrosalicylic acid and measuring the color intensity at two different pH values is described. The concentrations of sugars in unknown solutions are calculated from a linear plot which is obtained when the difference in absorbances at 560 nm for solutions with pH 12.5 and 5.0 (ΔA=A pH12.5−ApH5.0) is drawn against concentrations of sugars (up to 3 mg/ 25 ml). This method eliminates the interference caused by the unreacted reagent present in the conventional method. The present method can be used for the estimation of glucose and maltose upto a concentration of 1.5 mg/ml with an error of ±2.0%.
    Notes: Zusammenfassung Die Bestimmung von Glucose und Maltose wird mit 3,5-Dinitrosalicylsäure durch Messung bei zwei verschiedenen pH-Werten durchgeführt. Eine lineare Eichkurve wird bis 3 mg/25 ml erhalten, wenn man die Extinktionsdifferenz für pH 12,5 und 5,0 bei 560 nm gegen die Konzentration aufträgt. Durch dieses Verfahren wird die bei der konventionellen Methode auftretende Störung durch nicht umgesetztes Reagens ausgeschaltet. Bis zu 1,5 mg/ml der Zucker können mit einem Fehler von ±2% bestimmt werden.
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    Fresenius' Zeitschrift für analytische Chemie 283 (1977), S. 275-279 
    ISSN: 1618-2650
    Keywords: Best. von Dibenzthion, Senfölbildnern, 2H-Tetrahydro-1,3,5-thiadiazin-2-thionen ; Spektralphotometrie ; Cuoder Ni-Benzyldithiocarbamidat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Bildungskinetik gefärbter Chelate Me(R3-NH-CS2)2 mit Me=Cu oder Ni gestattet eine einfache Bestimmung des synthetischen Senfölbildners D47. Mit Kupferseifen lassen sich bis zu 10−7 Mol D47 in gewissen CHCl3-haltigen Medien bei 420 bzw. 440 nm über die Beziehung Δ/trE/Δt=K · c 0 schnell bestimmen. Spuren an Verunreinigungen sind dabei auszuschließen. In Zweifelsfällen ist eine Standardzusatz-Variante mit einem relativen Fehler von 2–3% anzuwenden. Die allmähliche Bildung eines stabilen Chelates mit NiCl2 · 6 H2O erwies sich als beste Methode zur spezifischen Bestimmung von D47 und dessen Homologen in Gegenwart der Zerfallsprodukte. Bei 440 nm stören lediglich Mineralsäuren sowie größere Mengen an Basen, organischen Säuren und aprotisch-dipolaren Lösungsmitteln. Das Beersche Gesetz wird im untersuchten Bereich von 10–1000 μg D47/ml gut erfüllt. Medieneinflüsse und kinetische Besonderheiten werden kurz diskutiert.
    Notes: Abstract Kinetics of forming the coloured chelates Me(R3-NH-CS2)2) with Me = Cu or Ni permit a simple determination of the synthetic mustard oil former D47. Using copper soaps, only 10−7 mol of D47 can rapidly be determined in certain CHCl3-containing media at 420 or 440 nm, resp., by aid of the expression Δ√E/gDt=K · c 0. Trace impurities must be absent. A standard addition variant with a relative error of 2–3 % may be applied to doubtful cases. The gradual formation of a stable chelate with NiCl2 · 6 H2O was found to be the best method for a specific determination of D47 and its homologues in presence of their degradation products. At 440 nm, only mineral acids or larger amounts of bases, organic acids, and aprotic dipolar solvents interfere. Beer's law is well obeyed in the studied range of 10–1000 μg of D47/ml. The influences of media and kinetic peculiarities are discussed briefly.
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