MODIFICATION OF SIC CERAMICS USING CHEMICAL-VAPOR-DEPOSITION SURFACE-TREATMENT

This paper describes experiments in depositing beta-SiC film onto SiC ceramics using a chemical vapor deposition surface treatment technique . The experimental results show that the best conditions for producing beta-SiC thin film are not at a specific ''point'' but rather within a ''region'' in the C/Si-T graph; that X-ray diffraction can be used t o monitor the thickness of the thin film; and that, for SiC ceramics, surface treatment can improve fracture strength (by about 20%), oxidat ion resistance (by a factor of about 5), and resistance to heat damage . A simple model based on surface healing is presented, and two condit ions for modifying ceramics are given.