Journal ArticleDOI
Variation of the Oxidation Rate of Silicon Carbide with Water‐Vapor Pressure
TLDR
The power-law dependence of the parabolic oxidation rate on the partial pressure of water vapor at all temperatures of the study indicated that the molecular species was not the sole rate-limiting oxidant as discussed by the authors.Abstract:
Chemically vapor deposited silicon carbide (CVD SiC) was oxidized at temperatures of 1000°-1400°C in H2O/O2 gas mixtures with compositions of 10-90 vol% water vapor at a total pressure of 1 atm. Additional experiments were conducted in H2O/argon mixtures at a temperature of 1100°C. Experiments were designed to minimize impurity and volatility effects, so that only intrinsic water-vapor effects were observed. The oxidation kinetics increased as the water-vapor content increased. The parabolic oxidation rates in the range of 10-90 vol% water vapor (the balance being oxygen) were approximately one order of magnitude higher than the rates that were observed in dry oxygen for temperatures of 1200°-1400°C. The power-law dependence of the parabolic oxidation rate on the partial pressure of water vapor at all temperatures of the study indicated that the molecular species was not the sole rate-limiting oxidant. The determination of an activation energy for diffusion was complicated by variations in the oxidation mechanism and oxide-scale morphology with the partial pressure of water vapor and the temperature.read more
Citations
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Journal ArticleDOI
Handbook of SiC properties for fuel performance modeling
TL;DR: In this paper, a compilation of non-irradiated and irradiated properties of SiC are provided and reviewed and analyzed in terms of application to TRISO fuels, specifically in the high-temperature irradiation regime.
Journal ArticleDOI
The oxidation behaviour of metals and alloys at high temperatures in atmospheres containing water vapour: A review
TL;DR: In this paper, the effect of water vapour on the formation of a more porous scale is discussed. But, while there is experimental evidence for altered mechanical behaviour, there is very little data on relevant mechanical properties.
Journal ArticleDOI
SiC Recession Caused by SiO2 Scale Volatility under Combustion Conditions: I, Experimental Results and Empirical Model
TL;DR: In this article, a high-pressure burner rig was developed to evaluate the response of chemical-vapor-deposited SiC material during exposure to simulated gas turbine combustor conditions.
Journal ArticleDOI
Response of ytterbium disilicate-silicon environmental barrier coatings to thermal cycling in water vapor
Bradley T. Richards,Kelly A. Young,Foucault de Francqueville,Stephen Sehr,Matthew R. Begley,Haydn N. G. Wadley +5 more
TL;DR: In this article, a bi-layer environmental barrier coating (EBC) was designed to reduce the susceptibility of SiC composites to hot water vapor erosion is reported, which consisted of a silicon bond coat and a pore-free ytterbium disilicate (YbDS) topcoat.
Journal ArticleDOI
Plasma spray deposition of tri-layer environmental barrier coatings
TL;DR: In this paper, an air plasma spray process has been used to deposit tri-layer environmental barrier coatings consisting of a silicon bond coat, a mullite inter-diffusion barrier, and a Yb 2 SiO 5 top coat on SiC substrates.
References
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Journal ArticleDOI
General Relationship for the Thermal Oxidation of Silicon
Bruce E. Deal,A.S. Grove +1 more
TL;DR: In this paper, the thermaloxidation kinetics of silicon are examined in detail based on a simple model of oxidation which takes into account the reactions occurring at the two boundaries of the oxide layer as well as the diffusion process, the general relationship x02+Ax0=B(t+τ) is derived.
Journal ArticleDOI
Corrosion of Silicon-Based Ceramics in Combustion Environments
TL;DR: In this paper, the processes of passive oxidation, deposit-induced corrosion, active oxidation, scale/substance interactions, and scale volatility are studied in the case of high-purity SiC and Si3N4 in pure oxygen, giving attention to such secondary elements in the ceramics as water and CO2 oxidants, combustion environment impurities, and thermal cycling.
Journal ArticleDOI
Paralinear Oxidation of CVD SiC in Water Vapor
TL;DR: In this article, the long-term degradation rate of CVD SiC is determined by the volatility of the silica scale, which is observed as the water vapor oxidized the SiC and simultaneously volatilized the scale.
Journal ArticleDOI
ChemSage—A computer program for the calculation of complex chemical equilibria
Gunnar Eriksson,Klaus Hack +1 more
TL;DR: An extensive computer program called ChemSage, based upon the SOLGASMIX Gibbs energy minimizer, was designed to perform three types of thermochemical calculations in complex systems involving phases exhibiting nonideal mixing properties as mentioned in this paper.