沉积温度及热处理对低压化学气相沉积氮化硅涂层的影响（英文）

Deposition Temperature and Heat Treatment on Silicon Nitride Coating Deposited by LPCVD

以SiCl4-NH3-H2为前驱体,在750~1250℃范围内通过低压化学气相沉积技术于碳纤维布上制备氮化硅涂层,系统研究了沉积温度对氮化硅涂层的生长动力学、形貌、化学组成和结合态的影响。研究结果表明,在沉积温度低于1050℃的情况下,随着沉积温度的升高,沉积速率单调增大。而当沉积温度高于1050℃时,沉积速率随温度升高逐渐下降。在整个沉积温度范围内,随着沉积温度的升高,涂层表面形态逐渐向菜花状转变,同时涂层表面变得愈加粗糙。涂层的最佳沉积温度在750~950℃之间。随着沉积温度的升高,涂层中氮含量先降低后升高,而硅含量不断增加,氧含量在整个温度范围内逐渐降低。原始沉积涂层均呈无定形态,经高于1300℃热处理后实现晶化,并伴随着表面形貌的显著变化。此时涂层仅由a-Si3N4构成,不存在任何b-Si3N4相。

Silicon nitride coatings on carbon fiber cloth were prepared by Low Pressure Chemical Vapor Deposition(LPCVD) from gas mixtures of SiCl4-NH3-H2 at temperatures ranging from 750 ℃to 1250 ℃. The effects of deposition temperature on the growth kinetics, morphologies, chemical composition and bonding state of the coatings were investigated. The results showed that deposition rate increased monotonously with temperature up to 1050 ℃, then it reversely decreased. In the whole temperature range, the coating surface morphology became gradually coarse with cauliflower-like grains as the deposition temperature increased. The optimal deposition temperature for infiltration was in the range between 750 and 950 ℃. Chemical composition analysis demonstrated that the nitrogen content of the coating firstly decreased and then increased with temperature increase, while the silicon content continuously increased and the oxygen content gradually decreased in the whole temperature range. Heat treatment at 1300 ℃ and above crystallized the coating. Concurrently, a significant change in its surface morphology was observed. All heat-treated coatings were exclusively composed of a-Si3N4, without the presence of any b-Si3N4.