(哈爾濱工業(yè)大學 復合材料研究所， 哈爾濱 150001)
摘 要: 結合差熱分析， 通過研究B2O3和Al在不同溫度下的反應以及在不同氮氣壓力中的自蔓延實驗， 探討了B2O3-Al-N2體系自蔓延還原合成BN的反應機理。 結果表明：鋁熱還原B2O3的反應是一個分步過程，低于820℃時， B2O3與Al緩慢反應生成Al4B2O9；高于820℃時， B2O3與Al劇烈反應生成Al4B2O9；高于1050℃時，Al與在低溫生成的Al4B2O9反應生成Al18B4O33；在更高的溫度下，Al18B4O33繼續(xù)被Al還原成B。 還原反應生成的B多為無定形態(tài)，還原出的B在高壓氮氣中被氮化成BN。 生成的BN中，部分為六方BN，另一部分為未知晶體結構的BN， 其形態(tài)近似立方體。
關鍵字: 自蔓延高溫合成； 鋁熱還原反應； 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
