(哈尔滨工业大学 复合材料研究所， 哈尔滨 150001)
摘 要: 结合差热分析， 通过研究B2O3和Al在不同温度下的反应以及在不同氮气压力中的自蔓延实验， 探讨了B2O3-Al-N2体系自蔓延还原合成BN的反应机理。 结果表明：铝热还原B2O3的反应是一个分步过程，低于820℃时， B2O3与Al缓慢反应生成Al4B2O9；高于820℃时， B2O3与Al剧烈反应生成Al4B2O9；高于1050℃时，Al与在低温生成的Al4B2O9反应生成Al18B4O33；在更高的温度下，Al18B4O33继续被Al还原成B。 还原反应生成的B多为无定形态，还原出的B在高压氮气中被氮化成BN。 生成的BN中，部分为六方BN，另一部分为未知晶体结构的BN， 其形态近似立方体。
关键字: 自蔓延高温合成； 铝热还原反应； 氮化硼
synthesis BN by thermite reaction
（Center for Composite Materials, Harbin Institute of Technology,Harbin 150001, P.R.China）
Abstract:An understanding to the nature of selfpropagating hightemperature synthesis (SHS) of BN by thermite reaction was obtained from the results of differential thermal analysis (DTA), reaction at different temperatures for 30 min and SHS experiments. The thermite reaction of Al-B2O3 system is a multistep one: B2O3 slowly reacts with Al, and forms Al4B2O9 and B below 820 ℃; B2O3 severely reacts with Al at about 820℃; Al4B2O9 reacts with Al, and forms Al18B4O33 and B at about 1050℃; Al18B4O33 reacts with Al and forms Al2O3and B at higher temperatures. The reduced B is amorphous. Two kinds of crystal structure of BN were synthesized by SHS with thermite reaction in nitrogen at high pressures, one is hexagonal, the other is cubic.
Key words: selfpropagation hightemperature synthesis; thermite reaction; BN
