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1

Digitale Medien

Synthesis and crystal structure of 1-acetyl-3-bromo-3-phenylazetidine and 1-phenyl-2-(N-acetyl-N-formyl)-aminoethanone (1998)

Bartnik, R. ; Faure, R. ; Gebicki, K.

Springer

Journal of chemical crystallography 28 (1998), S. 119-123

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ISSN: 1572-8854

Schlagwort(e): Azetidine ; azetine ; ring opening ; oxidation

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: Abstract 1-Acetyl-3-bromo-3-phenylazetidine (1), C11H12BrNO, has been synthesized and characterized by spectroscopic methods and single crystal X-ray analysis. It crystallizes in the space group P2 1/c with a = 8.633(1), b = 7.461(1), c = 17.204(1) Å, β = 98.403(7)°, V = 1096.2(2) Å3, Z = 4, D calc = 1.540 g cm−3. The azetidine ring is nearly planar since the four atoms are within ±0.039(5) Å of the mean square plane calculated for the heterocycle. The attempt to obtain a highly strained 2-azetine derivative from the above compound gave, surprisingly, 1-phenyl-2-(N-acetyl-N-formyl)-aminoethanone (2), C11H11NO3. This compound has been also characterized by spectroscopic methods and single crystal X-ray analysis. It crystallizes in the space group P212121, with a = 5.4719(3), b = 8.3205(6), c = 23.298(3) Å, V = 1060.7(2) Å3, Z = 4, D calc = 1.286 g cm−3. The aminoethanone residue is in a near planar conformation where the torsion angles are 7(2)° for N–C–C–=O and −173(2)° for N–C–C–C(Ph).

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1022489729966

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2

Digitale Medien

Tetrachlorosilane Consumption in Radio Frequency Glow Discharge (1998)

Blinov, L. M. ; Golovkin, A. G. ; Kaganov, L. I. ; [weitere]

Springer

Plasma chemistry and plasma processing 18 (1998), S. 509-533

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ISSN: 1572-8986

Schlagwort(e): RF SiCl4 discharge ; mass spectrometry ; kinetics ; decomposition ; oxidation

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Maschinenbau , Technik allgemein

Notizen: Abstract Time-resolved mass spectrometry was used for analysis of the plasma reactions in radio frequency (RF) SiCl 4 and SiCl 4 −O 2 discharges as functions of starting partial pressure and electrical power. Molecular concentrations of the reactants and products from SiCl 4 alone and with O 2 were obtained from the mass spectra and used for plotting the kinetic curves. The SiCl 4 and O 2 consumption rates were calculated from the kinetic curves and compared with results of theoretical simulation of the reaction. Direct electron impact decomposition was found to be the main pathway for pure SiCl 4 conversion. On the contrary, the consumption of SiCl 4 in the SiCl 4 +O 2 mixtures was largely chemical. The experimental macrokinetics are in agreement with a model in which oxidation is caused by the atomic oxygen.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1021811316740

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3

Digitale Medien

The Effect of Al Implantation on the Thermal Oxidation of Stainless Steel in Aggressive Environments (2000)

Noli, F. ; Misaelides, P. ; Giorginis, G. ; [weitere]

Springer

Oxidation of metals 53 (2000), S. 303-323

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ISSN: 1573-4889

Schlagwort(e): ion implantation ; oxidation ; thermal ; stainless steel ; ion-beam analysis ; aluminum

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract AISI-321 steel samples were implanted with Al ions (implantation-energy:40 keV; dose: 2×1017 ions/cm2). Thermal oxidationof the samples was performed at 450, 550, 600, and 650°C for periodsvarying from 1 to 6 days in air and in a corrosive CO2-containingenvironment. Nuclear Reaction Analysis (NRA) and Rutherford BackscatteringSpectrometry (RBS) were used to investigate the oxidized samples. Asignificant improvement of the oxidation resistance of the implantedmaterial in comparison to the nonimplanted material was observed. Thisespecially applies for samples oxidized at high temperatures. The aluminumdepth distribution determined by NRA [using the resonance at 992 keV of the27Al(p, γ )28Si nuclear reaction] and RBS,indicated no variation of the Al profile in the temperature region450–600°C, whereas at 650°C a slight Al diffusion wasobserved. Scanning electron microscopy (SEM–EDS) was applied to studythe surface morphology and the constitution of the oxide scale formed, aswell as to explain the influence of Al implantation on the oxidation behaviorof AISI-321 austenitic stainless steel.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1004541220830

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4

Digitale Medien

Oxidation Behavior of a Sputtered Ni–5Cr–5Al Nanocrystalline Coating (2000)

Chen, Guofeng ; Lou, Hanyi

Springer

Oxidation of metals 53 (2000), S. 467-479

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ISSN: 1573-4889

Schlagwort(e): Ni–5Cr–5Al ; oxidation ; magnetron sputtering ; nanocrystalline coating

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract A NiO-forming Ni–5Cr–5Al (at.%) alloy has been developed anddeposited as a sputtered nanocrystalline coating. The oxide formation andoxidation behavior of this coating have been studied at 1000°C inair. The oxidation rate markedly decreased with time and the oxidationkinetics obeyed the fourth power law. Complex oxide scales, consisting ofNiO, NiAl2O4 and α-Al2O3,were formed during 200 hr oxidation. The outer oxide layer consisted of NiOand NiAl2O4 and an inner oxide layer ofα-Al2O3. The sputtered Ni–5Cr–5Alnanocrystalline coating showed good oxidation resistance due to theformation of an α-Al2O3 inner layer andexcellent adhesion of the complex oxide scales.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1004628925414

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5

Digitale Medien

High-Temperature Oxidation of Ti0.3Al0.2N0.5 Thin Films Deposited on a Steel Substrate by Ion Plating (2000)

Woo, J. H. ; Lee, J. K. ; Lee, S. R. ; [weitere]

Springer

Oxidation of metals 53 (2000), S. 529-537

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ISSN: 1573-4889

Schlagwort(e): ion plating ; steel ; TiAlN coating ; oxidation

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract To improve the high-temperature oxidation resistance of STD61 steels used ashot dies or cutting tools, Ti0.3Al0.2N0.5films were deposited on STD61 steel substrates by arc-ion plating. Thedeposited film consisted of Ti3Al2N2 andTi2N phases. The oxidation characteristics were studied attemperatures ranging from 700 to 900°C in air. The deposited STD61steels displayed excellent oxidation resistance up to 800°C, butexhibited large weight gains and breakaway oxidation at 900°C. Theoxidation products were primarily Fe2O3, TiO, TiO2,and α-Al2O3, the relative amount of each oxidebeing dependent on the oxidation condition. Among various oxides, TiO2and α-Al2O3 were the major oxides at 800°Cfor at least up to 16 hr. However, at a higher temperature or a longeroxidation period, the significant outward diffusion of iron from thesubstrate resulted in the formation of iron oxides, together with otheroxides of Ti and Al.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1004685010393

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6

Digitale Medien

Effect of Nanocrystallization on the Oxidation Behavior of a Ni–8Cr–3.5Al Alloy (2000)

Chen, Guofeng ; Lou, Hanyi

Springer

Oxidation of metals 54 (2000), S. 155-162

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ISSN: 1573-4889

Schlagwort(e): Ni–8Cr–3.5Al ; nanocrystallization ; oxidation

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract Magnetron-sputter deposition was used to produce a Ni–8Cr–3.5Al(wt.%) nanocrystalline coating on substrates of the same alloy. Theoxidation behavior of the cast Ni–8Cr–3.5Al alloy and itssputtered coating were investigated at 1000°C in air. Complex,layered-oxide scales composed of Cr2O3 outer layer,mixed spinel NiAl2O4 and NiCr2O4middle layer, and α-Al2O3 inner layer were formedon the Ni–8Cr–3.5Al nanocrystalline coating during 200-hroxidation, whereas Cr2O3, with some NiCr2O4external layer with internal Al2O3, formed on the castalloy. Because of the formation of this α-Al2O3inner layer on the coating, the sputtered Ni–8Cr–3.5Al coatingshowed better oxidation resistance than the cast alloy. The effect ofnanocrystallization on oxide formation is discussed. It was indicated thatthe formation of this α-Al2O3 inner layer was closely related to therapid diffusion of Al through grain boundaries in the nanocrystallinecoating and the relatively high Cr content in Ni–8Cr–3.5Al.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1004610931447

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7

Digitale Medien

Effects of Chromium on the Oxidation Performance of β-FeAlCr Coatings (2000)

Liu, Zhenyu ; Gao, Wei

Springer

Oxidation of metals 54 (2000), S. 189-209

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ISSN: 1573-4889

Schlagwort(e): oxidation ; β-FeAlCr ; coatings ; magnetron sputter-deposition ; ridge-type oxide ; Al2O3 phase transformation

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract β-FeAl coatings containing various Cr contents of 6.5–45 wt.%were produced with a closed-field, unbalanced magnetron sputter (CFUMS)deposition technique. Cyclic oxidation tests at 1100°C in air for100 1-hr cycles and isothermal exposures at 1000°C in pure O2 for100 hr were carried out with the coatings and an as-cast FeAlspecimen. All of the coatings showed good scale-spallation resistanceduring cyclic oxidation and the coating with 6.5 wt.% Cr exhibited thelowest oxidation rates in both cyclic and isothermal oxidationexposures. After oxidation, fine-grain ridge-type oxide scales formed onthe coatings, while the oxide scale formed on the cast FeAl showed alarge quantity of θ-Al2O3 blades and large interfacial voids on thebase–alloy surface. The transformation from θ to α-Al2O3was accelerated due to the presence of Cr in the coatings. The fasttransformation considerably reduced oxidation rates, suppressed fastoutward Al diffusion for the growth of a θ-Al2O3 scale, and preventedthe formation of interfacial voids that played a major role in causing thescale spallation.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1004669126961

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8

Digitale Medien

Metastable Chromium-Rich Oxide Formed during Plasma Spraying of High-Alloy Steel (2000)

Leitner, J. ; Dubsky, J. ; Had, J. ; [weitere]

Springer

Oxidation of metals 54 (2000), S. 549-558

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ISSN: 1573-4889

Schlagwort(e): plasma spraying ; chromium steel ; oxidation ; Fe–Cr spinel oxide

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract During plasma spraying of metals in air, rapid-oxidation reactions occur, inmost cases. In oxidation products of Cr-rich steels, Fe–Cr spineloxide is often found as a dominant oxide phase. A thermodynamic analysisof a system composed of Fe–13%Cr alloy and water vapor or air showedthat the oxidation product in a wide range of high temperatures isFe3-wCrwO4 (w〉2). This tetragonallydistorted spinel oxide is not stable at room temperature. Water vapor andair were considered as limits of the gaseous-phase composition inatmospheric spraying by a water-stabilized plasma gun, where the compositionof the plasma plume is modified by air entrainment. The equilibriumcalculations enabled determination of the effects of temperature andgas-to-solid ratio on w. To show the existence of chromium-rich,tetragonally distorted spinel oxide experimentally, a typical productresulting from oxidation of 13%Cr–steel particles during their flightin the plasma plume was studied after rapid solidific ation. This was madepossible by trapping and quenching the flying particles in liquid nitrogenat a distance from the plasma-gun nozzle corresponding to thenozzle–substrate distance in conventional plasma spraying. The resultsobtained by X-ray diffraction, Mössbauer spectroscopy, and X-rayfluorescence analysis showed that this oxide, in which w≈2.4, constitutedthe dominant phase in the oxidation product.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1004650904113

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9

Digitale Medien

A Contribution to the Mechanism of Formation of Humic Acids in Coal (2000)

Turčániová, L'udmila ; Škvarla, Jiří ; Baláž, Peter

Springer

Journal of materials synthesis and processing 8 (2000), S. 359-363

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ISSN: 1573-4870

Schlagwort(e): Mechanical activation ; brown coal ; electrophoretic mobility ; oxidation ; humic acids

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract This paper presents a study of the influence of mechanochemical activation of coal on the process of formation and degradation of humic acids. The increasing period of mechanical activation of coal causes an increase in hydrophility, electrophoretic mobility, and of electrokinetic potential of surface layers as a result of acidic carboxyl and phenolic OH groups. The effective activation requires a short period of grinding. The increased time of activation causes the secondary processes of grain agglomeration and degradation of humic acids.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1011358831253

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10

Digitale Medien

Influence of chromium on the oxidation of titanium between 550° and 700°C (1984)

Chaze, A. M. ; Coddet, C.

Springer

Oxidation of metals 21 (1984), S. 205-231

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ISSN: 1573-4889

Schlagwort(e): oxidation ; titanium ; chromium ; adherence

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract The oxidation behavior of Ti-Cr alloys (1, 4, 11, and 19% chromium by weight) was investigated, between 550 and 700°C, in air and in oxygen, for a maximum duration of about 800 hr. The kinetics results revealed a significant influence of the chromium content with a maximum, in the unfavorable sense, around 4%. Moreover, the analysis of kinetics curves showed that stable rate constants could be obtained only if the duration of oxidation was sufficiently long. The oxide layers were duplex with a much higher chromium content in the inner layer. The morphological investigations performed on cross-sections of the oxidized specimens showed that the chromium modifies the crystallization of the oxide layers. The adherence of the oxide layers evolves nonmonotonically as a function of chromium content for the same degree of progression of the reaction and as a function of the oxidation rate, which is itself dependent on chromium content.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00741471

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