Control of Instability of Si₃N₄ during Pressureless Sintering

Abstract

The instabilities of Si₃N₄ and Si₃N₄ ceramics during sintering were reviewed. As a result of the instabilities, Si₃N₄ and Si₃N₄ ceramics lose their masses or decompose. The major mass loss reaction of Si₃N₄ ceramics is as follows.
Si₃N₄(s)+3SiO₂(l)=6SiO(g)+2N₂(g)
Regarding mass loss, decreasing the sintering temperature by 30K corresponds to increasing N₂ pressure in the furnace by one order of magnitude. By being well acquired with the mass loss phenomena, sintering of Si₃N₄ ceramics in N₂ gas at 0.1MPa or air will become the candidate conditions for the mass production of Si₃N₄ ceramics. The research to reduce the total cost of Si₃N₄ ceramics was discussed.