scholarly journals Thermodynamic analysis of the interaction of components in the Si–C–O system in the carbothermic synthesis of silicon carbide

2019 ◽  
Vol 484 (5) ◽  
pp. 559-562
Author(s):  
A. S. Lebedev ◽  
V. E. Eremyashev ◽  
E. A. Trofimov ◽  
V. N. Anfilogov
Keyword(s):  
Silicon Carbide ◽  
Phase Equilibria ◽  
Gas Phase ◽  
Silicon Oxide ◽  
Synthesis Temperature ◽  
Protective Atmosphere ◽  
Optimal Conditions ◽  
Oxide Melt ◽  
Interaction Of Components ◽  
Carbothermic Synthesis

Phase equilibria in the Si–C–O system at temperatures of 1400–1700°C were modeled to theoretically determine the optimal conditions for implementing our proposed method of carbothermic synthesis of silicon carbide in reactors with an autonomous protective atmosphere. It was found that, depending on the ratio between the initial components and the synthesis temperature, the equilibrium products of the synthesis can be various combinations of silicon carbide, a gas phase, residual amounts of silicon oxide and carbon, andan oxide melt formed at high temperatures.

scholarly journals Corrosion and oxidation of silicon carbide on the nitride bond in the side lining of aluminum electrolysis cells

2019 ◽  
pp. 43-48
Author(s):  
A. L. Yurkov ◽  
A. P. Malakho ◽  
V. V. Avdeev
Keyword(s):  
Silicon Carbide ◽  
Gas Phase ◽  
Silicon Oxide ◽  
Aluminum Electrolysis ◽  
Main Question ◽  
Material Degradation ◽  
Molten Electrolyte ◽  
Electrolysis Cells ◽  
Pass Through ◽  
Corrosion And Oxidation

The main question for understanding the corrosion of silicon carbide on the nitride-silicon bond onboard linings is whether corrosion of Si3N4‒SiC material with gases (and, in particular, oxidation) is preceded by corrosion by molten electrolyte, or corrosion by molten electrolyte plays its own role in material degradation during service. It is more likely that the reactions of SiC and Si3N4 with cryolite melt pass through a preoxidation stage. Calculations show that most of the possible reactions of SiC and Si3N4 with oxygen and carbon monoxide and carbon dioxide have a positive volumetric effect, which reduces the porosity of the material, but may cause cracks in it. The resulting silicon oxide is dissolved in the electrolyte melt, and can also react with electrolyte components in the gas phase. Ill. 6. Ref. 24. Tab. 2.

Reactions in solution

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Phase Equilibria ◽  
Gas Phase ◽  
First Principles ◽  
Unique Feature ◽  
Life Sciences ◽  
Equilibrium Mixture ◽  
Second Law ◽  
Ideal Solution ◽  
Coupled Reactions ◽  
Definition Of

Another key chapter, examining reactions in solution. Starting with the definition of an ideal solution, and then introducing Raoult’s law and Henry’s law, this chapter then draws on the results of Chapter 14 (gas phase equilibria) to derive the corresponding results for equilibria in an ideal solution. A unique feature of this chapter is the analysis of coupled reactions, once again using first principles to show how the coupling of an endergonic reaction to a suitable exergonic reaction results in an equilibrium mixture in which the products of the endergonic reaction are present in much higher quantity. This demonstrates how coupled reactions can cause entropy-reducing events to take place without breaking the Second Law, so setting the scene for the future chapters on applications of thermodynamics to the life sciences, especially chapter 24 on bioenergetics.

scholarly journals Towards High Efficacy of Pd-Au/C Catalyst for Tetrachloromethane Hydrodechlorination

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 338-359
Author(s):  
Magdalena Bonarowska ◽  
Zbigniew Kaszkur ◽  
Krzysztof Matus ◽  
Alicja Drelinkiewicz ◽  
Tomasz Szumełda ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Gas Phase ◽  
Thermal Activation ◽  
Supported Catalysts ◽  
Carbon Support ◽  
Thermal Reduction ◽  
Microwave Oven ◽  
Optimal Conditions ◽  
Catalyst Activation ◽  
Critical Part

We present an efficient strategy for synthesising the PdAu catalysts with a homogeneous PdAu alloy phase for environmentally important hydrodechlorination of tetrachloromethane in the gas phase. The synthesis of carbon-supported catalysts involved two major steps: (i) incorporation of palladium and gold nanoparticles into carbon support and (ii) activation of the catalysts. The critical part of this work was to find the optimal conditions for both steps. Thus, the incorporation of the nanoparticles was carried out in two ways, by impregnation and direct redox reaction method using acetone solutions of metal precursor salts. The activation was performed either by a conventional thermal reduction in hydrogen or flash irradiation in a microwave oven. The homogeneity and structure of the PdAu alloy were found to depend on the catalyst activation method critically. In all cases, we observed better homogeneity for catalysts that were subject to microwave irradiation. Moreover, the flash microwave irradiation of prepared catalysts provided catalysts of better stability and selectivity towards the desired products (hydrocarbons) in the hydrodechlorination of tetrachloromethane as compared to the catalyst obtained by conventional thermal activation in hydrogen.

Effect of a Nonstationary Electric Current on the Oxide Melt–Gas Phase System

2018 ◽  
Vol 2018 (2) ◽  
pp. 197-200 ◽  
Author(s):  
S. A. Krasikov ◽  
B. T. Utelbaev ◽  
E. N. Suleimenov
Keyword(s):  
Electric Current ◽  
Gas Phase ◽  
Phase System ◽  
Oxide Melt

In Situ Optical Analysis of the Gas Phase during the Deposition of Silicon Carbide from Methyltrichlorosilane

1996 ◽  
Vol 143 (5) ◽  
pp. 1654-1661 ◽  
Author(s):  
M. Ganz ◽  
N. Dorval ◽  
M. Lefebvre ◽  
M. Péalat ◽  
F. Loumagne ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Gas Phase ◽  
Optical Analysis

Theoretical Study of Gas-Phase Thermodynamics Relevant to Silicon Carbide Chemical Vapor Deiposition

1991 ◽  
Vol 250 ◽  
Author(s):  
Mark D. Allendorf ◽  
Carl F. Melius
Keyword(s):  
Silicon Carbide ◽  
Gas Phase ◽  
Theoretical Study ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Equilibrium Calculations

AbstractEquilibrium calculations are reported for conditions typical of silicon carbide (SiC) deposition from mixtures of silane and hydrocarbons. Included are 34 molecules containing both silicon and carbon, allowing an assessment to be made of the importance of organosilicon species (and organosilicon radicals in particular) to the deposition process. The results are used to suggest strategies for improved operation of SiC CVD processes.

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