高能球磨对碳热还原合成氮化铝的作用

EFFECTS OF HIGH ENERGY BALL MILLING ON AIN SNYTHESIS FROM Al2O3 BY CARBOTHERMAL REDUCTION NITRIDATION

研究了氧化铝球磨对碳热还原反应合成氮化铝的作用。结果表明：氧化铝高能球磨几分钟后，晶粒细化至纳米级，随球磨时间增加，晶粒尺寸变化不大，而点阵畸变持续增加。氧化铝经球磨后，对碳热还原反应有促进作用：高能球磨氧化铝２０ｈ，碳热还原反应开始温度降至１０００℃左右，完全反应的温度降至１２５０℃。球磨产生的机械化学作用，如晶粒细化、晶格畸变和大量缺陷及表面断键作用，是球磨促进碳热还原反应的主要原因。细化晶粒有利于反应的进行。

The influence of particle size of reactants after high energy ball milling on the AIN synthesis from alumina by carbothermal reduction was investigated.The crystallite size of alumina decreased to nanometer after high energy ball milling for a few minutes and varied slowly with prolonged milling,while the lattice strain increased with milling time.The carbothermal reduction nitridation reaction was promoted greatly after the milling of alumina for 20 hours.The results showed that the commenced temperature of AIN formation from alumina decreased to 1000and reaction rate increased markedly after high energy ball milling of reactants comparing with that of the raw reactants.It was believed that the mechanochemical effects,for example,the fining of crystallite size,crystal lattice distortion,defects and broken bands,etc.were the main cause for the promotion of the carbothermal reduction nitridation after the high energy ball milling.Though fining of the powders was the favorable element,it was not the single dominant element for the reaction.