α-Si_3N_4陶瓷的液相烧结及其介电性能

Liquid Phase Sintering and Dielectric Property of α-Si_3N_4 Ceramics

以MgO、Al2O3和SiO2作为烧结助剂,采用放电等离子烧结(SPS)方法制备密度可控的α-Si3N4陶瓷材料。讨论了SPS方法制备α-Si3N4陶瓷材料的烧结行为和烧结机理,以及烧结助剂添加量和烧结温度等影响因素与材料密度的关系。结果表明:当烧结温度为1400～1500℃,烧结助剂添加量为9%～28.5%(质量分数,下同)时,可以制备出密度可控,且密度变化范围为2.48～3.09g/cm3的α-Si3N4陶瓷材料,试样的主相为α-Si3N4,烧结机理为SPS低温液相烧结,材料在频率为1MHz时的介电常数为5～7.5,与密度关系密切。

Spark plasma sintering （SPS） was applied to prepare α-Si3N4 ceramics of different controlled densities with magnesia, silicon dioxide, alumina as the sintering aids and the relationship between density of samples, the content of sintering aids and dielectric property was explored. The sintering behavior of SPS method and mechanism of liquid phase sintering （LPS） were discussed and the factors of the content of sintering aids and sintering temperature influencing the density of the prepared samples were analyzed. The results show that the ceramics with controllable density 2.48 g/cm^3 to 3.09 g/cm^3 could be prepared successfully when the sintering temperature was 1400-1500 ℃ and the amount of sintering aids was 9wt% -28.5wt %. The main phase was α-Si3N4 and the sintering mechanism was liquid phase sintering. The dielectric constant below 1 MHz frequency ranged from 5 to 7.5 and was closely dependent on the density of obtained samples.