温度对CVD-TaC涂层组成、形貌与结构的影响

Effect of temperature on composition, surface morphology and microstructure of CVD-TaC coating

利用TaCl52C3H62H22Ar反应体系,用化学气相沉积法(CVD)成功地在C/C复合材料表面沉积TaC涂层及C2TaC复合涂层。研究了温度对TaC涂层的相组成和表面形貌的影响以及CVD2TaC涂层的沉积机理。结果表明:在1373～1673K温度范围内能够在C/C复合材料表面制备碳化钽涂层,它由TaC和游离碳组成。提高沉积温度和H2/C3H6的流量比,TaC涂层中游离碳的含量减少;随着沉积温度的升高,TaC涂层的颗粒尺寸增大,均匀程度下降;在1573K时颗粒间出现明显的烧结界面,结构致密无裂纹。制备出成分波动的C2TaC复合涂层,该涂层与基体间具有良好的机械相容性。分析了低应力、无裂纹TaC复合涂层的形成机制。

The TaC coating and C-TaC composite coating on the surface of carbon/carbon composites were prepared by CVD method in TaCl_5-C_3H_6-H_2-Ar system. The influences of temperature on phase composition and surface morphology of TaC coating as well as the mechanism of depositing TaC were studied. The experimental results show that TaC coating is composed of TaC and carbon which can be prepared at 13731673K. With the increase of temperature and H_2/C_3H_6 ratio, the content of free carbon is decreased. The crystallites of TaC are small and distribute homogeneously at lower temperature, while larger crystallites of TaC are formed at higher temperature, resulting in a coating of poor quality. Dense sintered interfaces without cracks appear in the TaC coating at 1573K. The composition of TaC coating is fluctuated and the coating has a good mechanical compatibility to the matrix. The mechanism of forming composite TaC coating with low stress and without crack was analyzed.