直接氮化法制备Si_3N_4粉体过程研究

Preparation of Si_3N_4 Powders by the Direct Nitridation of Silicon

采用直接氮化的工艺方法,以Si粉为初始原料,采用Fe粉为催化剂,在高温下直接进行氮化,制备了Si_3N_4粉体。着重讨论了催化剂含量和氮化工艺条件对粉体的氮化率、粒径、形貌和相含量等方面的影响。实验结果表明:催化剂含量,球磨工艺,烧结制度是影响Si_3N_4粉体最终性能的3个主要因素,并且在掺杂Fe为0.5%,球磨时间为2h,采用分阶段保温升温的方法,在氮化温度为1400～1350℃下氮化2～3 h,制备了氮化率95%左右,α相含量接近90%,形状为等轴状的Si_3N_4粉体。

Si3N4 powders were prepared by the direct nitridation of Si with Fe as the additives which was conducted at high temperature in N2. The effects of the synthesis conditions and the contents of Fe on the nitridation rate, the content of α -Si3N4, the powder size and the microstructure were studied. The contents of Fe, the grinding time and sintering process were turned out to be the important factors that affected the structures of the produced Si3N4. The addition of Fe greatly improved the nitridation rate of Si3N4. However, its effects on the content of α -Si3N4 was implicated which needs further study. Finally, the Si3N4 powders of 90% α phase with 95% nitridation and good shapes were prepared by doping 0.5% Fe into the reactions and sintering at 1400～1350℃ for 2～3 h.