【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。更多还原

【Abstract】 Si3N4 powder was prepared by the self-propagating high-temperature 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 controlled during the reaction. Because of the existence of the NH4Cl,the reaction involves not only the silicon nitriding mechanism, but also other mechanisms. Considering the combustion temperature,the SHS Si3N4 process involves three mechanisms: low-temperature mechanism, moderate-temperature mechanism, high-temperature mechanism. During the process Si3N4 powder must be introduced as starting raw materia1 in order to control reaction temperature and obtain the desired α content 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.更多还原