以CaO、B2O3、Mg粉为原料燃烧合成制备了CaB6粉末.考察了不同反应体系的差热曲线,采用XRD、SEM以及粒度分析技术对燃烧产物、浸出产物进行了表征.结果表明:Mg-B2O3-CaO反应体系872℃附近放热峰的表观活化能E=15.71kJ·mol^-1,反应级数n=1.1,反应的表观活化能很小,说明合成CaB6的反应容易发生.燃烧产物由MgO、CaB6以及少量的Mg3B2O6和Ca3B2O6等组成,在空气中进行燃烧合成反应并不生成氮化物;燃烧产物经硫酸浸出处理后CaB6纯度达92.5%;随着制样压力的增大,CaB6粒度逐渐变小.
CaB6 powder was prepared by combustion synthesis with CaO, B2O3 and Mg as reactants. The DTA curves of the different reaction systems were investigated. Combustion products and leached products were characterized by XRD, SEM and particle size distribution techniques. The results indicate that apparent activation energy(E) of the exothermic peak near 872℃ for reaction Mg+3B2O3+CaO=CaB6+10MgO is 15.71kJ.mol^-1 and its reaction order(n) is 1.1. The apparent activation energy is lower, so the reaction occurs easily. Combustion products consist of MgO, CaB6 and a little amount of Mg3B2O6 and Ca3B2O6, and no nitrides form during the combustion process in air. CaB6 powder purity is 92.5% after combustion products are leached with acid. CaB6 particles become finer with the increasing of the preparing sample pressure.