温度对氮化硅粉烧结密度的影响

Influence of sintering temperature on densification of Si_3N_4 powder

用改进燃烧合成法制备的α、β不同相含量的氮化硅粉料,通过配比组成多组不同相含量的粉料。经过混料、成型、烧结、密度测试,考察烧结温度对各组粉料烧结密度的影响;并对比了A、B两种不同烧结助剂配方。结果表明,多数粉料在1740～1780℃的温区内烧结密度达到峰值,烧结密度在97%以上。A配方适合于β-Si3N4粉、B配方相对更适合于α-Si3N4粉。采用A配方,处理后的β相粉料烧结几乎完全致密,且烧结致密温区下移并变宽。粉料的团聚影响素坯密度,晶粒粗大的粉料则不利于成型。

The influence of the sintering temperature on densities of silicon nitride ceramics was investigated. The Si3N4 powder with different phase compositions synthesized from modified self-propagating combustion synthesis was used. Both α-Si3N4 and β-Si3N4 were used as part of starting powder. The powders were mixed, formed then sintered. The density of the sintered bodies vs sintering temperature was analyzed. Two kinds of sintering aids A and B were used. The experimental results showed that most powder mixture got top densification at sintering temperature of 1 740-1 780 ℃. Their relative densities were above 97%. Aids A were suitable for β-Si3N4 powder, while aids B were more suitable for α-Si3N4 powder. With aids A, fine ground β-Si3N4 powder almost gained fully density. Also the range of sintering temperature was decreased and wider than others. The agglomeration of the powder brought looser green density, and coarse grains caused difficulties in molding process.