聚合物先驱体的结构对氮化硅陶瓷性能的影响

Preparation of silicon nitride ceramic derived by UV cure polymer ceramic precursor:The effect of polyceramic structure on pyrolyzate properties

以紫外光固化巯基/乙烯基硅氮烷共聚体系制备了不同结构的聚合物陶瓷先驱体,高温裂解后得到氮化硅陶瓷.采用X射线衍射仪,场发射扫描电镜和能谱仪等手段对巯基官能度、巯基化合物分子尺寸、巯基/乙烯基硅氮烷配比以及惰性填料进行了表征,研究了聚合物先驱体的结构对氮化硅陶瓷的结晶度和晶粒尺寸的影响.结果表明:巯基单体官能度和分子尺寸的增加导致先驱体陶瓷的结晶度提高以及平均晶粒尺寸降低;巯基单体相对含量的增加导致先驱体陶瓷的结晶度增加,乙烯基与巯基摩尔比为1:0.5时平均晶粒尺寸出现峰值;β-Si_3N_4粉体惰性填料的加入能明显抑制先驱体陶瓷的尺寸收缩.

The polymer ceramic precursors with varied structures were mode from UV cure thiol/vinyl silizane copolymer. Silicon nitride ceramic was obtained by pyrolyzing at high temperature. The effects of functionality of thiol, size of thiol molecular, thiol to vinyl ratio and the amount of inert filler on crystallinity and grain size were investigated and characterized by XRD, FESEM and energy spectrometer and investigated. It is found that the increase of functionality of thiol enhances the crystallinity of the ceramic, but makes the grain size decrease. Increasing the size of thiol molecular has the same effect. Increasing the ratio of thiol to vinyl can enhances the crystallinity of the ceramic,and there is a peak of the grain size when the ratio is 0.5：1. The incorporation of inert filler （β-Si3N4） can obviously depress the shrinkage of the size of ceramic.