T. Narushima et al., HIGH-TEMPERATURE ACTIVE OXIDATION AND ACTIVE-TO-PASSIVE TRANSITION OFCHEMICALLY VAPOR-DEPOSITED SILICON-NITRIDE IN N-2 O-2 AND AR O-2 ATMOSPHERES, Journal of the American Ceramic Society, 77(9), 1994, pp. 2369-2375
The oxidation behavior of chemically vapor-deposited silicon nitride i
n N-2-O-2 acid Ar-O-2 atmospheres was studied using a thermogravimetri
c technique at temperatures 1823 to 1923 K. Active oxidation was obser
ved at low oxygen partial pressures. The active oxidation rates increa
sed with increasing oxygen partial pressure (P-O2) up to a certain P-O
2 and then passive oxidation occurred. The transition oxygen partial p
ressures from active to passive oxidation were determined. The rate-co
ntrolling step for the active oxidation could be oxygen diffusion thro
ugh a gaseous boundary layer near the S3N4 surface. Decomposition of S
I3N4 does not seem to be associated with the mass loss behavior. The W
agner model was employed to explain the oxidation behavior.