T. Narushima et al., OXIDATION OF CHEMICALLY VAPOR-DEPOSITED SILICON-NITRIDE IN DRY OXYGENAT 1923-K TO 2003-K, Journal of the American Ceramic Society, 76(4), 1993, pp. 1047-1051
Oxidation of chemically vapor-deposited Si3N4 was studied in dry oxyge
n between 1923 and 2003 K under a total pressure of 0.1 MPa using a th
ermogravimetric technique. At 1923 to 1953 K, a parabolic rate mechani
sm prevailed for the oxidation reaction. From 1973 K, the oxidation re
action exhibited a mixed linear-parabolic rate mechanism. At 2003 K, o
n the other hand, the oxidation of Si3N4 showed a linear behavior. Bot
h amorphous silica and cristobalite were identified as reaction produc
ts on the oxidized Si3N4 surface using X-ray diffraction analysis. The
percentage of cristobalite in the surface oxide scale was determined
from the X-ray diffraction pattern. It was found that, at 2003 K, only
amorphous silica was formed. The parabolic rate constants (K(p)) obta
ined from this study were close to those obtained in the literature.