添加剂对Si粉直接氮化工艺中α-Si3N4含量的影响

Effects of Additives on the Content of α-Phase in Si_3N_4 Synthesized by Direct Nitidation of Si Powder

通常情况下,Si粉直接氮化法和自蔓延法所制得Si3N4粉体主要以β-Si3N4为主,而为了使Si3N4陶瓷有更好的烧结性能,需要得到高α相含量的Si3N4粉。本研究以Si粉直接氮化法为基础,通过添加NH4Cl、FeCl3来制备高α相含量的Si3N4粉。经XRD和SEM检测分析发现,添加适量NH4Cl、FeCl3可大幅提高Si3N4粉体中α-Si3N4的含量,最高可达88.3%,但FeCl3的含量过高时,则可显著降低α-Si3N4的含量。研究还发现添加NH4Cl、FeCl3还可降低Si粉发生氮化反应的起始温度。

The already acquired experience has shown that direct nitridation and combustion nitridation of Si powder largely results in products with high β-Si3N4 content. However, a final product rich in α-Si3N4 is rather desirable. Based on direct nitridation of Si, our study synthesized a final product rich in α-Si3N4 by adding NH4Cl and FeCl3. After analyzing the final product by XRD and SEM,our study shows that NH4Cl and FeCl3 addition can significantly increase the content of α-Si3N4, the maximum up to 88.3%,and the excess FeCl3 content can significantly decrease the content of α-Si3N4 .The study also finds that NH4Cl and FeCl3 addition can decrease the initiative temperature of nitidation.