Solid-gas reaction during sintering of Si3N4 ceramics (part 7) - Temperature dependence of mass loss of sintered Si3N4 ceramics during heat treatment

The relationship between mass loss of Si3N4 ceramics during heat treatment and heat treatment temperature was quantitatively examined to elucidate the rate-determining factor of mass loss. Sintered Si3N4 ceramics were heat-tr eated at 1823-2098 K under 0.1 MPa N-2 and mass loss during heat treatment was measured. The mass loss increased with increasing temperature and the s lope of the Arrhenius plot of the mass loss rate was similar to that of the equilibrium gas pressure of SiO generated from the mass loss reaction of S i3N4 ceramics. This finding suggests that the rate-determining factor of ma ss loss is the diffusion rate of SiO to the outside of the sagger.