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High Temperature Corrosion of Silicon Carbide and Silicon Nitride in Water VaporSilicon carbide (SiC) and silicon nitride (Si3N4) are proposed for applications in high temperature combustion environments containing water vapor. Both SiC and Si3N4 react with water vapor to form a silica (SiO2) scale. It is therefore important to understand the durability of SiC, Si3N4 and SiO2 in water vapor. Thermogravimetric analyses, furnace exposures and burner rig results were obtained for these materials in water vapor at temperatures between 1100 and 1450 C and water vapor partial pressures ranging from 0.1 to 3.1 atm. First, the oxidation of SiC and Si3N4 in water vapor is considered. The parabolic kinetic rate law, rate dependence on water vapor partial pressure, and oxidation mechanism are discussed. Second, the volatilization of silica to form Si(OH)4(g) is examined. Mass spectrometric results, the linear kinetic rate law and a volatilization model based on diffusion through a gas boundary layer are discussed. Finally, the combined oxidation and volatilization reactions, which occur when SiC or Si3N4 are exposed in a water vapor-containing environment, are presented. Both experimental evidence and a model for the paralinear kinetic rate law are shown for these simultaneous oxidation and volatilization reactions.
Document ID
Acquisition Source
Glenn Research Center
Document Type
Preprint (Draft being sent to journal)
Opila, E. J.
(Cleveland State Univ. Cleveland, OH United States)
Robinson, Raymond C.
(QSS Group, Inc. United States)
Cuy, Michael D.
(NASA Glenn Research Center Cleveland, OH United States)
Gray, Hugh R.
Date Acquired
September 7, 2013
Publication Date
January 1, 2002
Subject Category
Nonmetallic Materials
Meeting Information
Meeting: 10th International Conferences on Modern Materials and Technologies (CIMTEC 2002)
Country: Unknown
Start Date: January 1, 2002
Funding Number(s)
PROJECT: RTOP 714-04-30
Distribution Limits
Work of the US Gov. Public Use Permitted.
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