【摘要】 本文对激光气相合成的非晶纳米Ｓｉ３Ｎ４粉在１２００～１７００℃进行热处理，用ＴＥＭ、ＸＲＤ及ＢＥＴ对粉的结晶转变及粒子生长过程进行了表征．实验发现，粉体从１２５０℃开始晶化，有少量的β－Ｓｉ３Ｎ４形成，到１３００℃有α－Ｓｉ３Ｎ４形成，在晶化初期非晶粒子靠表面扩散发生硬团聚．在１４００～１６００℃晶化加速，α相急增，此阶段粒子快速生长，在１７００℃粉体发生碳化，与炉中ＣＯ反应形成部分β－ＳｉＣ，同时，发生Ｓｉ３Ｎ４的α－β转变．更多还原

【Abstract】 The laser-synthesized nanometric amorphous St3N4 powders were annealed between 1200 and 1700 ℃, and the crystallization and particulate growth process were characterized by TEM, XRD and BET techniques. It was fo find that the crystallization happened at 1250℃ and a small amount of β-Si3N4 formed at 1250 ℃. a-St3N4 appeared at 1300 ℃.In the initial stage of the crystallization,the amorphous St3N4 particles formed hard agglomerates by the interparticle surfactal diffusion. The crystallization proceeded rapidly between 1400￣1600℃ during which or-St3N4 increased steeply and the particles grew rapidly. The liquid sintering of the particles happened at 1600℃ which was due to the formation of liquid SiO2 provided by the native amorphous SiO2 on the particles of the powders. It was found that there was some β-SiC formed at 1700℃ due to the reaction of St3N4 and CO gas, and the transformation of α-St3N4 to β-St3N. also happened at 1700℃.更多还原