溶胶-凝胶法制备纳米Si_3N_4(Y_2O_3)粉末的研究

本文以硅溶胶、尿素和炭黑为原料，采用溶胶-凝胶碳热氮化法在1500℃、2h条件下制得粒径为50～80nm的Si3N4纳米粉末．比较了由硅溶胶与尿素经氨解合成的前驱体和硅溶胶二种不同起始物料的反应活性，研究了氮化条件对合成反应的影响．结果表明：氨解前驱体使硅溶胶中的结构水排除，有助于加快反应速率，提高产物氮含量．本文同时以Y（NO3）3为添加剂，在溶液状态与硅源混合，合成了Si3N4－Y2O3纳米复合粉末.

Preparatio of Nanosized Si_3N_4-Y_2O_3 Powders by Sol-Gel Processing

Nanosized silicon nitride powders were synthesized by using silica sol, urea, and carbon black with the process of sol-gel and carbothermal reduction. Ammonolysis of the aqueous solution of silica sol and urea resulted in the formation of an ammono precursor. The effect of ammono precur-sor and silica sol on the synthesis of Si3N4 powders was investigated. The results showed that using arnmono precursor dehydrated can accelerate the reaction rate and increase the nitrogen content of Si3N4 powders. Synthesis of nanosized Si3N4-Y2O3 composite powders from the homogeneous mixture of Y(NO3)3 and silica sol in the liquid state was also studied.