Control of instability of Si3N4 during pressureless sintering

Abstract

The instabilities of Si3N4 and Si3N4 ceramics during sintering are investigated. As a result of the instabilities, Si3N4 and Si3N4 ceramics lose their mass or decompose. The major mass loss reaction of Si3N4 ceramics is shown as follows. Si3N4(s) + 3SiO2 (I) = 6SiO (g) + 2N2 (g) Regarding the mass loss, decreasing the sintering temperature by 30 K corresponds to an increase in N2 pressure in the furnace by one order magnitude. By understanding well the mass loss phenomenon, Si3N4 ceramics will be produced commercially in 0.1 MPa N2 gas or air.