氧化铝对无压烧结氮氧化硅微观组织的影响

The Effect of Alumina on the Microstructure of Pressureless Sintered Nitrogen Oxide Silicon

摘要: 首先以单质硅和二氧化硅在氮气氛围下，采用流延法制备出质量分数ω ≥ 90%的氮氧化硅，通过凝胶注模方式制备生胚，分别于50℃、80℃、120℃、160℃四个阶段进行脱水和初步脱脂，最终在1450℃氮气氛围常压烧结下进行氮氧化硅烧结实验，研究不同含量下的氧化铝(0wt.%, 10 wt.%, 15 wt.%, 20 wt.%)烧结助剂对氮氧化硅陶瓷微观形貌和相组成的影响，后续选出两组氧化铝最优添加量进行温度梯度(1350℃~1480℃)烧结。结果表明氧化铝的最佳添加量为15 wt.%时，对氮氧化硅陶瓷性能提升最为明显，最佳烧结温度在1450℃，能避免氮氧化硅分解的同时，最大限度提升其各项性能。

Abstract: Initially, silicon nitride ceramics with a mass fraction of ω ≥ 90% were prepared by the slip casting method using elemental silicon and silica under a nitrogen atmosphere. Green bodies were formed using gel-casting, followed by dehydration and preliminary degreasing at four stages: 50˚C, 80˚C, 120˚C, and 160˚C. The final sintering experiments were conducted under atmospheric pressure in a nitrogen atmosphere at 1450˚C. The effects of various alumina sintering aids (0 wt.%, 10 wt.%, 15 wt.%, 20 wt.%) on the microstructure and phase composition of the silicon nitride ceramics were studied. Subsequently, two optimal alumina additive amounts were selected for temperature gradient sintering from 1350˚C to 1480˚C. The results indicated that the most significant improvement in the properties of silicon nitride ceramics was achieved with 15 wt.% alumina, with the optimal sintering temperature being 1450˚C, which avoided the decomposition of silicon nitride while maximally enhancing its properties.