温度对CVD法在纤维表面制备BN涂层的影响

摘要

Boron nitride interface was deposited on SiC fibers by chemical vapor deposition at different temperatures from BCl3-NH3-H2 mixtures. The effect of temperature on deposition rate, morphology, composition and structure of the interface was studied. The results show that in the low temperature range of 700-900℃, the deposition rate increases with increasing temperature complying with Arrhenius law, and the apparent active energy calculated is 57. 2kJ/mol. The interface is smooth and dense and uniformly deposited on fibers, the deposition rate is controlled by surface reaction. At 900℃, the deposition rate reaches a maximum (174nm/h), at the same time, surface reaction control is changed to be mass-transportation control. Above 900℃, the deposition rate decreases with the increasing temperature due to the gas-phase nucleation, and the interface surface becomes loose and rough. BN interface is turbostratic structure with stoichiometric ratio 1:1, and the order degree increases with increasing temperature.%采用BCl3-NH3-H2体系,在不同温度下通过化学气相沉积法在SiC纤维表面沉积BN涂层.研究温度对BN涂层的沉积速率、形貌、组成以及结构的影响.结果表明:在低温阶段(700~900℃),生长速率随着温度的增加而增大,该结果与阿仑尼乌斯定律相一致,计算得出该反应表观活化能为57. 2kJ/mol.涂层表面光滑致密,沉积均匀,沉积速率受表面反应控制.在900℃时,反应速率达到最大值 (174nm/h),此时,反应速率由表面反应控制转变为物质运输控制.在高于900℃时,由于气相成核的缘故,沉积速率随着温度的增加而减小,涂层变得疏松粗糙.BN涂层为化学计量比1: 1的乱层结构,有序度随着制备温度的升高而增大.