Kinetics of corrosion of Si sub 3 N sub 4 and SiC-Si sub 3 N sub 4 composite in oxygen/chlorine environments
The kinetics of corrosion of silicon nitride and nitride bonded silicon carbide materials in flowing gas mixtures consisting of argon, oxygen and chlorine was investigated by thermogravimetric analysis. The corrosion process was characterized by two categories; one is volatilization type of attack in which the corrosion proceeds primarily by a formation of volatile corrosion product in low ratio of oxygen to chlorine environments between 900 C and 1100 C. Another is bubble formation type of corrosion in which the reaction proceeds with a small increase in weight due to the formation of bubble in oxide layer in high ratio of oxygen to chlorine environments at 1200 C and 1300 C. Examination of the corroded specimens by scanning electron microscopy, X-ray analysis and transmission electron microscopy indicated that the SiC was selectively attacked in the nitride bonded materials and that in general, the silicon nitride was more resistant to attack than the silicon carbide under mixed oxidation condition. This may be related to the nature of the silicon dioxide films on the two materials because the stability of silicon dioxide becomes a key to whether or not further attack may occur.
- Research Organization:
- Illinois Univ., Chicago, IL (USA)
- OSTI ID:
- 6066486
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360205* -- Ceramics
Cermets
& Refractories-- Corrosion & Erosion
ARGON
BUBBLES
CARBIDES
CARBON COMPOUNDS
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHLORINE
COMPOSITE MATERIALS
CORROSION
CORROSION PRODUCTS
CORROSION RESISTANCE
CORROSIVE EFFECTS
ELECTRON MICROSCOPY
ELEMENTS
FLUIDS
GASES
GRAVIMETRIC ANALYSIS
HALOGENS
KINETICS
MATERIALS
MICROSCOPY
NITRIDES
NITROGEN COMPOUNDS
NONMETALS
OXYGEN
PNICTIDES
QUANTITATIVE CHEMICAL ANALYSIS
RARE GASES
REACTION KINETICS
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS