Effect of Heating Rate of the Original ASD-4 Powder and the ASD-4 Powder Modified by the V2O5 Oxide on the Phase Composition of Oxidation Products

The article examines the technology of nitro-oxidation, which consists of nitriding in separated ammonia at the first organize and oxidation in water vapor at the second stage of the process, studied the structure and phase composition of the diffusion nitride-oxide layer, providing high physico-mechanical and physicochemical surface characteristics, competitively capable of galvanic strategies of getting a coating, the conceivable outcomes of regulating the structure and phase composition of the nitride-oxide layer are being investigated to obtain a diffusion coating composition with predetermined properties.

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Thermal Decomposition and Kinetics of Pentlandite-Bearing Ore Oxidation in the Air Atmosphere

Metals ◽

10.3390/met11091364 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1364

Author(s):

Kristina Božinović ◽

Nada Štrbac ◽

Aleksandra Mitovski ◽

Miroslav Sokić ◽

Duško Minić ◽

...

Keyword(s):

Reaction Mechanism ◽

Heating Rate ◽

Sulfur Removal ◽

Oxidation Products ◽

Energy Dispersive ◽

Dominant Factor ◽

Initial Sample ◽

Energy Dispersive Spectrometry Analysis ◽

X Ray ◽

Air Atmosphere

The roasting of sulfide ores and concentrates is one of the most important steps in pyrometallurgical metal production from primary raw materials, due to the necessity of excess sulfur removal, present in the virgin material. Pentlandite is one of the main sources for nickel pyrometallurgical production. The knowledge of its reaction mechanism, products distribution during oxidation and reaction kinetics is important for optimizing the production process. Raw pentlandite-bearing ore from the Levack mine (Ontario, Canada) was subjected to oxidative roasting in the air atmosphere. A chemical analysis of the initial sample was conducted according to EDXRF (Energy-Dispersive X-Ray Fluorescence) and AAS (Atomic Adsorption Spectrometry) results. The characterization of the initial sample and oxidation products was conducted by an XRD (X-ray Diffraction) and SEM/EDS (Scanning Electron Microscopy with Energy Dispersive Spectrometry) analysis. Thermodynamic calculations, a phase analysis and construction of Kellogg diagrams for Ni-S-O and Fe-S-O systems at 298 K, 773 K, 923 K and 1073 K were used for proposing the theoretical reaction mechanism. A thermal analysis (TG/DTA—Thermogravimetric and Differential Thermal Analyses) was conducted in temperature range 298–1273 K, under a heating rate of 15° min−1. A kinetic analysis was conducted according to the non-isothermal method of Daniels and Borchardt, under a heating rate of 15° min−1. Calculated activation energies of 113 kJ mol−1, 146 kJ mol−1 and 356 kJ mol−1 for three oxidation stages imply that in every examined stage of the oxidation process, temperature is a dominant factor determining the reaction rate.

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Structure and chemical and phase composition of the thermal oxidation products of Ni-Mo-B coatings plated by chemical catalytic reduction

Protection of Metals ◽

10.1134/s0033173206020020 ◽

2006 ◽

Vol 42 (2) ◽

pp. 119-124 ◽

Cited By ~ 1

Author(s):

V. A. Arslambekov ◽

A. B. Drovosekov ◽

M. V. Ivanov ◽

V. M. Krutskikh ◽

E. N. Lubnin ◽

...

Keyword(s):

Phase Composition ◽

Thermal Oxidation ◽

Catalytic Reduction ◽

Oxidation Products

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Study on Characteristic and Compressive Property of Porous NiTi Alloys Fabricated by Thermal Explosion Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.160-162.644 ◽

2010 ◽

Vol 160-162 ◽

pp. 644-649 ◽

Cited By ~ 1

Author(s):

Qiang Li ◽

Jing Yuan Yu ◽

Xu Dong Sun

Keyword(s):

Particle Size ◽

Phase Composition ◽

Heating Rate ◽

Thermal Explosion ◽

Compressive Property ◽

Porous Niti ◽

Ni Powder ◽

Explosion Method ◽

Tini Phase ◽

Niti Shape Memory Alloys

Porous NiTi shape memory alloys were fabricated by thermal explosion method using different Ti and Ni powder as initial materials. The effect of process parameters including heating rate, and particle size of Ti on pore characteristic and phase composition was analyzed. Microstructure, phase composition, and mechanical properties were studied by SEM, XRD, and compression test, respectively. The mechanism of thermal explosion reaction was studied. The results show higher heating rate and smaller Ti particle size result in higher porosity and bigger pores. The thermal explosion reaction starts with the melting of a eutectic between β-Ti(Ni) and Ti2Ni and the main phases of as-reacted products are TiNi phase which are the desired phases. NiTi2 and TiNi3 phases are also present in small amounts. The content of TiNi phase increases with increasing heating rate or decreasing Ti particle size. The compressive strength and Young’s modulus of compacts decrease with the increase of the porosity.

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High-temperature oxidation of Moss—Mo3Si alloys doped with Sc or Y in air and in a steam-air mixture

Corrosion Materials Protection ◽

10.31044/1813-7016-2021-0-5-12-22 ◽

2021 ◽

pp. 12-22

Author(s):

L.Yu. Udoeva ◽

◽

A.V. Larionov ◽

K.V. Pikulin ◽

S.N. Agafonov ◽

...

Keyword(s):

Rare Earth ◽

Phase Composition ◽

High Temperature ◽

Rare Earth Elements ◽

High Temperature Oxidation ◽

Oxidation Products ◽

Metal Silicide ◽

Temperature Oxidation ◽

Molybdenum Alloys ◽

Isothermal Mode

For continuation of investigations aimed at studying the effect of rare earth elements (RRE) on the behavior of metal-silicide molybdenum alloys in oxidizing environments, the results of experimental modeling of high-temperature oxidation of alloys based on Mo—15 (at.%) Si and doped with Sc or Y in the isothermal mode in the air and in a steam-air environment are presented. New data on the effect of REE on oxidation resistance of alloys of the Mo—Si system of hypoeutectic composition, the formation of scale on their surface, the phase composition and the structure of oxidation products was obtained.

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X-ray diffraction study of the phase composition of nonequilibrium oxidation products of refractory compounds

Soviet Powder Metallurgy and Metal Ceramics ◽

10.1007/bf00791764 ◽

1980 ◽

Vol 19 (6) ◽

pp. 421-422

Author(s):

S. I. Alyamovskii ◽

Yu. G. Zainulin ◽

V. S. Zhilyaev

Keyword(s):

Phase Composition ◽

Diffraction Study ◽

Oxidation Products ◽

X Ray Diffraction ◽

X Ray ◽

Refractory Compounds

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A TEM study of the influence of microstructure on the superplastic behavior of a U-5.8 wt.% Nb alloy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144310 ◽

1986 ◽

Vol 44 ◽

pp. 568-569

Author(s):

G. Mackiewicz Ludtka

Keyword(s):

Grain Size ◽

Heating Rate ◽

Phase Field ◽

Single Phase ◽

Superplastic Behavior ◽

Two Phase ◽

Single Phase Field

Historically, metals exhibit superplasticity only while forming in a two-phase field because a two-phase microstructure helps ensure a fine, stable grain size. In the U-5.8 Nb alloy, superplastici ty exists for up to 2 h in the single phase field (γ1) at 670°C. This is above the equilibrium monotectoid temperature of 647°C. Utilizing dilatometry, the superplastic (SP) U-5.8 Nb alloy requires superheating to 658°C to initiate the α+γ2 → γ1 transformation at a heating rate of 1.5°C/s. Hence, the U-5.8 Nb alloy exhibits an anomolous superplastic behavior.

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The Anticoagulant Activity of 3.3’-(p-Alkylthio-Benzylidene)-Bis-4-Hydroxycoumarins and Their Oxidation Products

Thrombosis and Haemostasis ◽

10.1055/s-0038-1654103 ◽

1967 ◽

Vol 17 (01/02) ◽

pp. 277-286 ◽

Cited By ~ 2

Author(s):

Maria Gumińska ◽

M Eckstein ◽

Barbara Stachurska ◽

J Sulko

Keyword(s):

Biological Activity ◽

Anticoagulant Activity ◽

Oxidation Products ◽

Para Position ◽

Sulphur Atom ◽

Group I ◽

One Step

SummaryThe anticoagulant activity of 3.3’-(benzylidene)-bis-4-hydroxycoumarin derivatives has been estimated by one step Quick’s method. The derivatives contained the following groups in the para position of benzylidene residue: NCS- (I), CH3-S- (II), CH3-SO-(III), CH3-S02- (IV), C2H5-S- (V), C2H5-SO- (VI), C2H5-S02- (VII). All these compounds were much more active than 3.3’-(benzylidene)-bis-4-hydroxycoumarin itself.Compounds possessing the ethyl chain at the sulphur atom (V, VI, VII) were more active than methyl homologues (II, III, IV). Comparison of the activity of the series of thio-, sulphoxy-, and sulphonyl-derivatives showed that among methyl- and ethyl-derivatives those with the sulphoxy grouping (III, VI) displayed the greatest anticoagulant activity. The action of sulphonyl (IV, VII) and thio-derivatives (II, V) was weaker and shortest. The derivative with the NCS-group (I) possessed a relatively the lowest activity among the investigated compounds. 3.3’-(p-Ethylsulphoxybenzyl-idene)-bis-4-hydroxycoumarin (VI), with distinct biological activity reached about ½ of dicoumarol activity.

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