The Kinetics of Chemical Vapor Infiltration of Pyrolytic Carbon from Propylene Using a Model Array of Capillaries.

A well-defined substrate with an array of capillaries was infiltrated at a temperature of 1223 K, a pressure of 40 kPa and a residence time of 0.56 s. After 75 h deposition, the thickness of pyrolytic carbon layer in the capillary was determined along its depth. By coupling a detailed gas-phase reaction mechanism with the parallel-consecutive reaction model, the pyrolytic carbon deposition from propylene pyrolysis was accurately simulated within capillaries. From the simulated results, it was observed that pore sealing could be relieved by reducing residence time. The texture of pyrolytic carbon at the mouth of the capillary was also determined. In addition, Kinetic Monte Carlo simulations were used to analyze how residence time and substrate surface affect the transition in texture of pyrolytic carbon. According to these calculations, it appears that texture is mainly affected by interactions between residence time and active sites on the substrate surface. [ABSTRACT FROM AUTHOR]