沉积位置对HfC涂层微观结构的影响

Effect of deposition position on microstructure of HfC coating

为了研究沉积位置对HfC涂层微观结构的影响,采用HfCl4-C3H6-H2反应体系,低压下在C/C复合材料表面沉积了HfC涂层。采用X射线衍射和扫描电镜等方法,分析了沉积位置对涂层的相组成、生长取向、表面形貌和沉积速率的影响。研究结果显示,在距离进气口20～25 cm处制备的HfC涂层具有单一成分,涂层均匀致密;随着沉积位置逐步远离进气口,反应物的过饱和度降低,涂层沉积速率降低,颗粒尺寸减小;HfC涂层生长出现择优取向,逐渐偏向(200)方向生长。

In order to research the effect of deposition position on HfC coating,the coating was prepared on the surface of C/C composites by LPCVD （ low pressure chemical vapor deposition ）, using HfCl4 -C3 n6-H2 reaction system. The phase composition, grown orientation,surface morphology and the deposition rate were analyzed by X-ray diffraetometer and scanning electron micro- scope. Results show that a fiat and compact HfC coating with no carbon phase was obtained at 20 - 25 em above the gas inlet. As the deposition position became far away from gas inlet, the coating deposition rate tends to decrease due to the reduction of reactants concentration. Moreover, the grain size is also reduced obviously, and the coating behaves preferred orientation growth following （200） plane.