硅溶胶的凝胶化包覆对氧化铝烧结性能的影响

Influence of Gelation Coating of Colloidal Silica on Sintering Properties of Al_2O_3 Ceramics

在探讨影响硅溶胶凝胶化因素的基础上,通过控制硅溶胶的凝胶化条件使其包覆在氧化铝粉体表面,进而研究了不同硅溶胶添加量对氧化铝陶瓷烧结性能的影响规律。结果发现:控制体系的pH值5～7、固含量10%～15%时,硅溶胶极易发生凝胶化转变,而且随着环境温度的升高,凝胶化进程加快;当在氧化铝粉体中添加2%～10%的硅溶胶时,1650℃烧结后均可获得致密结构的陶瓷,且有大量莫来石生成,而过多硅溶胶的添加(超过15%)将不利于陶瓷体的致密烧结。

Based on the gelation process of colloidal silica, the sintering properties of Al2O3 ceramics enwrapped with colloidal silica were investigated by controlling the gelation factors of silica sol. Results show that the transformation from sol to gel was easy by controlling the pH value of 5-7 and the SiO2 concentration in colloidal silica of 10 wt%-15 wt%, and the gelation progress was accelerated by increasing the bath temperature. Enwrapped with 2-10 wt% colloidal silica, the Al2O3 ceramics achieved compacted structure sintered at 1650 ℃ with a great deal of mullite occurring. However, the ceramic was porous when the content of colloidal silica was higher than 15 wt%.