刚玉氮化硅复合材料表面氧化膜的形成动力学

Formation Kinetics of Surface Oxidation Film of Corundum-silicon Nitride Composites

以刚玉粉和氮化硅粉为原料,借助微量热分析天平,结合X射线衍射和扫瞄电镜等检测手段,对刚玉氮化硅复合材料表面氧化膜的形成动力学机理进行了研究,并推导出了动力学方程。研究结果表明材料表面氧化膜的形成动力学可分为三个阶段:化学反应速度控制阶段,动力学方程为△W=Kc·t,其中Kc=52.21exp(-73806.3/RT);混合控制阶段,动力学方程为(△W)2+KO/Kc(△W)=Km·t,其中Km=253.81exp(-85644.2/RT);扩散速度控制阶段,动力学方程为(△W)2=Kd·t,其中Kd=31.12exp(-66522.1/RT)。

The formation mechanism of oxidation film on the surface of corundum-silicon nitride composites were investigated by means of Paucity thermobalance,XRD and SEM. The starting materials were corundum and silicon nitride powder. The kinetics equation has been worked out. The results showed that the formation kinetics of oxidation flim at the surface of the composites included three stages. Control by chemical reaction-the kinetics equation is △ W = Kc · t, in which Kc = 52.21exp （-73806.3/RT）. Mixed control-the kinetics equation is （ △W）^2 ＋ K0/Kc （ △W） = Km · t ,in which Km =253.81exp（-85644.2/RT） control by diffusion rate-the kinetics formula is （ △ W）^2 = Kd. t, in which Kd = 31.12exp （456522.1/RT）.