摘 要: 研究了自蔓燃高温合成方法制备氮化硅粉体, 借助于 XRD、 SEM 等检测方法, 分析了自蔓燃高温合成氮化硅过程中硅粉粒度、 氮气、温度、稀释剂与孔隙率等方面对反应产物的影响, 并对反应机 理进行了分析。由于有添加剂氯化铵的存在, 反应中不是单纯的硅粉 氮化反应。只要控制反应中的工艺参数, 就可以采用自蔓燃得到不同 相含量的 Si₃N₄ 粉体; 考虑到燃烧温度, 在氮化硅粉体的合成过程中, 涉及到 3 个反应机制: 低温机制、中温机制、高温机制; 氮气压力下硅 粉的自蔓燃合成反应, 必须要引入 Si₃N₄ 稀释剂, 来控制反应温度和 反应速度, 获得不同相含量的粉体。压坯气孔率控制在 30%～70%, 否则反应不能进行金属硅粉的粒度细, 合成的 Si₃N₄ 中 α相含量高。 

关键词: 自蔓燃高温合成; 氮化硅粉体; 反应机理

Abstract: Si₃N₄ powder was prepared by the self-propagating high-tem perature synthesis (SHS) and examined by X-ray diffraction and SEM. It was studied how the following parameters influenced the final product: nitrogen purity and pressure, combustion temperature, diluents content, the porosity, and so on. The experimental shows that the different type of Si₃N₄ powder can be prepared by SHS as long as the parameters be con trolled during the reaction. Because of the existence of the NH₄Cl, the re action involves not only the silicon nitriding mechanism, but also other mechanisms. Considering the combustion temperature, the SHS Si₃N₄process involves three mechanisms: low-temperature mechanism, mod erate-temperature mechanism, high-temperature mechanism. During the process Si₃N₄ powder must be introduced as starting raw materia1 in or der to control reaction temperature and obtain the desired αcontent of Si₃N₄ powder, the porosity of body should be controlled at 30%～70%,otherwise, SHS reaction will not carry on the Si₃N₄ powder with high α phase content can be prepared when fine silicon metal powder used. 

Keywords: self-propagating high-temperature synthesis; silicon mitride powder; reaction mechanism