镁热自蔓延法制备B_(4)C微粉

Preparation of Boron Carbide by Magnesium Reducing-SHS

利用自蔓延制粉技术过程简单、纯度高、粒度小等优点,以B2O3、Mg粉和C为原料制备B4C粉末·通过对B2O3 Mg C反应体系的绝热温度计算,确定该体系自蔓延反应进行的可行性·通过X射线衍射分析推测其反应机理·由扫描电镜分析知B4C晶粒细小,由电子衍射图谱知B4C为发育完整的单晶,但是有发育不完整的多晶存在·由光谱分析知B4C的纯度不低于98%,而容量分析结果表明B4C的纯度偏低·

It was suggested that B_4C micropowder would be produced by self-propagating high-temperature synthesis(SHS),with taking B_4O and C raw materials and Mg powder as reducing agent,which has many advantages such as simple process,high purity and fine granularity of product. The adiabatic temperature of the B_2O_3-Mg-C reaction system was calculated in order to verify the feasibility of the SHS reaction. The results of X-ray diffraction analysis of the products show that B_4C will be gained through SHS and there is little C in the product. It is found that the B_4C grain is very fine by SEM,and it is observed that in B_4C powder the single crystal is fully growing together with incompletely growing polycrystal by electronic diffraction patterns. Purity of B_4C is shown not lower than 98% by spectrum analysis,while it is slightly lower by chemical analysis. Special attention is paid to the reaction mechanism of SHS.