Synthesis of High-Purity Si_3N_4 Powders by Ammonolysis of SiCl_4
Zhang Kehong; Deng ZongWu; Yuan Zheng;Lai Yueying; Wu Huawu; Xu Gonghua(Department of Chmistry, Tsinghun University Beijing 100084 China)
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%.