碳热法合成AlN纤维的形貌及反应机理

Morphology and Reaction Mechanism of AlN Fibers by Carbothermic Nitridation

笔者以Al2O3纤维为原料,采用碳热还原法合成AlN纤维,研究了其形貌及结构,实验结果表明:纤维由粒径为1 μm左右的AlN晶粒构成,纤维为空心棒状,其直径为4～6 μm,长径比为20～30。合成反应中,主要是碳把氧化铝还原为铝的低价氧化物,并进一步与氮反应生成氮化铝。其反应是在氮化铝层的两个界面上同时进行的。

AlN fibers were synthesized by carbothermic nitridation with Al2O3 fibers as raw material. The morphology and microstructure of AlN fibers were investigated. The fibers formed by small AlN grains were pipe-shaped, of which the particle size is about 1 祄, diameter 4～6 祄, length/diameter ratio 20～30. Alumina was reduced with carbon to lower-valent aluminum oxide, which further reacted with nitrogen to AlN. When the alumina fibers were coated by AlN layer, the reaction took place simultaneously on both interfaces of the AlN layer.