SiO_2-BN-Si_3N_4系复相陶瓷制备及性能

Fabrication and Properties of SiO_2-BN-Si_3N_4 Composites

以Y2O3和Al2O3陶瓷粉体作为烧结助剂,对不同含量BN原料配比无压烧结制备SiO2-BN-Si3N4系复相陶瓷,生坯采用注凝成型制备,然后在1780℃保温2h烧结,烧结体主要由板条状的Si2N2O及长柱状的β-Si3N4晶粒构成,BN晶粒弥散在各晶粒之间。Si2N2O相通过反应SiO2+Si3N4=2Si2N2O原位生成。Si2N2O具有优异的抗氧化性,Si3N4具有高的强度,而BN的加入大大提高了材料的可加工性能,材料结合了各相的优异性能。实验结果表明:材料热冲击性能优异,热冲击温差在800℃时,材料的弯曲强度还略有提高,1200℃时,材料的残余弯曲强度保持不变。

SiO2-BN-Si3N4 composites were prepared by in-situ liquid pressureless sintering process using Y2O3 and Al2O3 powders as sintering additives. The green body was fabricated by gel-casting process, and then sintered at 1780 ℃ for 2 h. The sintered body was mainly composed of the plate-like Si2N2O and rod-like a-Si3N4 grains. BN was dispersed in the grains. The Si2N2O phase was obtained by in-situ reaction of SiO2＋Si3N4→2Si2N2O. Si2N2O possesses the excellent oxidation resistance, Si3N4 has high strength, and the addition of BN can improve the machining property. The excellent properties of all phases are combined into the materials. The results show that the materials have good thermal shock resistance. When the temperature of the thermal shock is 800℃, the residual strength is improved slightly and when the temperature was 1200 ℃, the residual strength is unchangeable.