Effect of Temperature on Preparing Boron Nitride Interface on Fiber Surface by Chemical Vapor Deposition

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.