SiCl_4氨解法制备高纯度的Si_3N_4粉的研究

Synthesis of High-Purity Si_3N_4 Powders by Ammonolysis of SiCl_4

本文研究了影响Ｓｉ３Ｎ４粉中杂质氧和氯的含量的因素和如何提高粉料的纯度．实验表明：原料ＳｉＣｌ４（液）和ＮＨ３（汽）的纯度对粉料中杂质氧和氯的含量影响不大．制备粉料过程中，加热温度越高，加热时间越长，粉料中杂质氯的含量越低；不同的保护气氛对粉料中杂质氧和氯的含量的影响大，保护气氛为真空，得到的粉料质量很差，粉料中杂质氧和氨的含量均很高．在高纯Ｎ２气氛中制粉，得到的粉料其纯度亦很低，含氧量达４％～６％，含氯量达０．０５％～０．０３％，在ＮＨ３气氛中制粉，得到的粉料其含氮量为３８．８％～３９．６％、含氧量在１％左右，含氯量在０．００５％左右．

O and Cl contents of the SiCl4 powders which prepared from ammonolysis of SiCl4 were measured.Experimental results showed the purities of raw material of SiCl4(1) and NH3(g) had nearly no effect on O and Cl content of the Si3N4 powders. With increase in beding temperature and time there occurred decrease in Cl content of the Si3N4 powders. The effect of different atmosphere played key role on O and Cl content of the powders. Si3N4 powders synthesized in vacuum had higher impurity content. In N2 atmosphere O content was 4～6wt% and Cl content was 0.05～0.03wt% in the Si3N4 powders, however, O and Cl concentrations were notably decreased in NH3 atmosphere, N content was 38.8%～39.6%, O content was about 1wt% and Cl content was about 0.005wt%.