论文部分内容阅读
结合差热分析 ,通过研究B2 O3 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B2 O3 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B2 O3 的反应是一个分步过程 ,低于 82 0℃时 ,B2 O3 与Al缓慢反应生成Al4 B2 O9;高于 82 0℃时 ,B2 O3 与Al剧烈反应生成Al4 B2 O9;高于 10 5 0℃时 ,Al与在低温生成的Al4 B2 O9反应生成Al18B4 O3 3 ;在更高的温度下 ,Al18B4 O3 3 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。
Combined with differential thermal analysis, the reaction mechanism of self-propagating reduction of B2 O3 AlN 2 to BN was studied by studying the reaction of B2 O3 and Al at different temperatures and the self-propagating experiments under different nitrogen pressures. The results show that the reaction of aluminothermic reduction of B2 O3 is a stepwise process. When the temperature is below 82 0 ℃, B2 O3 reacts slowly with Al to form Al4 B2 O9. Above 82 0 ℃, B2 O3 reacts violently with Al to form Al4 B2 O9. Above 10 5 0 ℃, Al reacts with Al4 B2 O9 formed at low temperature to form Al18B4 O3 3. At higher temperature, Al18B4 O3 3 continues to be reduced to B by Al. B produced by the reduction reaction is mostly amorphous, and the reduced B is nitrided to BN in high pressure nitrogen. BN generated, part of the hexagonal BN, the other part of unknown crystal structure of BN, the shape of an approximate cube.