Influence of TaCl5 partial pressure on texture structure of TaC coating deposited by chemical vapor deposition
Influence of TaCl5 partial pressure on texture structure of TaC coating deposited by chemical vapor deposition
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DOI：
10.1016/j.apsusc.2010.11.172
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发表时间：
2011-02
影响因子：
6.7
通讯作者：
Z. Chen;X. Xiong;Ying Long
中科院分区：
文献类型：
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作者：
Z. Chen;X. Xiong;Ying Long
在800°C和1200°C下，采用化学气相沉积法在不同TaCl5分压的石墨衬底上沉积TaC。利用X射线衍射仪和扫描电镜研究了涂层的显微组织和织构结构。当涂层沉积过程由表面反应动力学控制时（800°C），TaCl5分压对涂层的微观结构和织构结构影响不大。当涂层形成过程受扩散动力学控制时（1200°C），所制备的TaC晶粒的显微结构、织构结构随TaCl5分压的变化而发生较大变化。在扩散控制过程中，TaCl 5分压的增加会导致气体过饱和度的变化，从而发生二次形核，这是导致涂层形貌和织构结构变化的主要原因。借助（100）和（111）方向的竞争生长，详细讨论了不同纹理涂层的形成机制。此外，还提出了沉积组分在台阶边缘拐角处的扩散模型来解释织构薄膜的生长机理。
TaC was deposited on graphite substrate with different TaCl5partial pressure at 800°C and 1200°C by chemical vapor deposition. Microstructures and texture structures of the prepared coatings were researched with X-ray diffraction and scanning electronic microscopy. When the coating deposition process is controlled by surface reaction kinetics (800°C), TaCl5partial pressure had little influence on the microstructure and texture structure of the coating. When the coating formation process is controlled by diffusion kinetics (1200°C), the microstructure, texture structure of the prepared TaC grains vary greatly with TaCl5partial pressure. In the diffusion controlled process, the increasing of TaCl5partial pressure will result in the changing of gas supersaturation, and then the occurrence of secondary nucleation, which is the main reason for the changing of coating morphology and texture structure. With the help of competitive growth in (100) and (111) directions, the formation mechanism of the different texture coatings are discussed in detail. In addition, a diffusion model of deposition species around step-edge-corner was also proposed to explain the growth mechanism of the texture coatings.