原位生长棒晶氧化铝陶瓷的制备

FABRICATION OF PLATELIKE GRAIN ALUMINA CERAMICS BY INSITU GROWTH

α-Al2 O3 中加入CAS (CaO -Al2 O3-SiO2 )添加剂 ,在≥15 5 0℃ ,3h条件下无压烧结 ,制备出原位生长棒晶自增韧氧化铝陶瓷 .烧结行为和显微结构研究表明 :15 0 0℃烧结时棒晶开始生成 ,15 5 0℃完全生成棒晶 ,棒晶的大小均匀 ,样品的相对密度达到>97% ,烧结温度升至 16 0 0℃时 ,烧结对棒晶的尺寸几乎无影响 .不含CAS添加剂的样品在 130 0～ 16 0 0℃烧结不能生成氧化铝棒晶 ,而 0 .1%～ 0 .5 % (质量分数计 ,下同 )CAS的加入可引发氧化铝晶粒异向生长 ,形成棒晶 .CAS的添加量从 0 .1%增加到 0 .5 %对氧化铝棒晶的显微结构没有明显的影响 .

The platelike grain alumina ceramics were fabricated by adding small amount of CAS (CaO-Al 2O 3-SiO 2) glass powder into fine alpha alumina powder and sintering at ≥1 550 ℃for 3 h pressurelessly. The sintering behavior and microstructure development were studied. The results show that the platelike grains can be formed by sintering at 1 500 ℃, but the grains formed platelike grains completely at 1 550 ℃. The theoretical densities of the samples sintered at 1 550 ℃ reach to >97%, higher sintering temperature do not increase the densities much, so 1 550 ℃ was the optimal sintering temperature. The platelike grains con not be formed without adding CAS, even sintered at 1 600 ℃, but 0.1% to 0.5%(in mass) CAS additives con trigger the anisotropic grain growth and formed platelike grains. The grain growth conditions of platelike alumina were satisfied by the existence of liquid phase as the CaO 2-Al 2O 3-SiO 2 liquid phase created favorable thermodynamic and kinetic conditions for anisotropic grain growth. The amount of CAS increasing from 0.1% to 0.5% (in mass) has no significant effect on the microstructure, but the sinterability decreased slightly.