Physical Properties of Silicon Nitride Ceramics by Pressureless Sintering

Abstract

Abstract: Silicon nitride ceramics were sintered by pressureless sintering with α-Si₃N₄ powder as raw material, and Y₂O₃ combined with MgAl₂O₄ as sintering aids. The effects of sintering temperature, holding time, content of sintering aids and composition ratio on the densification and mechanical properties of the silicon nitride ceramics were studied. The results show that silicon nitride ceramics can be fully densified by the addition of Y₂O₃ and MgAl₂O₄ sintering aids. Using Y₂O₃ and MgAl₂O₄ as sintering aids system, when the sintering temperature is 1 600 ℃,the holding time is 4 h, the content of sintering aids is 12.5% (mass fraction), and the mass ratio of Y₂O₃ and MgAl₂O₄ is 1∶1,the pressureless sintered silicon nitride ceramics achieve the best comprehensive properties with apparent porosity of 0.21%, the relative density of 98.10%, the bending strength of 598 MPa and Vickers hardness of 15.55 GPa.

Key words: silicon nitride, pressureless sintering, apparent porosity, relative density, bending strength, Vickers hardness

CLC Number:

TQ174

WU Zhenfei, WANG Yuechao, LU Lifang, ZHANG Hongyi. Physical Properties of Silicon Nitride Ceramics by Pressureless Sintering[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2022, 41(5): 1782-1787.

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