Oxidation behavior of silicon nitride sintered with Lu2O3 additive

Kyocera SN282 silicon nitride ceramics sintered with 5.35 wt% Lu2O3 were oxidized in dry oxygen at 930–1,200 C. Oxidation of SN282 follows a parabolic rate law. SN282 exhibits significantly lower parabolic rate constants and better oxide morphological stability than silicon nitride containing other sintering additives under similar conditions. The activation energy for oxidation of SN282 is 107 ± 5 kJ/mol K, suggesting inward diffusion of molecular oxygen in the oxide layer as the ratelimiting mechanism.