Effects of Temperature and Pressure on The Density of Carbon-Carbon Nanocomposite Fabricated by Chemical Vapor Deposition

Abstract

In this study, the pyrocarbon deposition process from the methane/hydrogen gases mixture into the graphite- and coal tar-based nanocomposite in the low pressure condition was investigated. When adjusting vacuum of isotherm process and maintaining the gasses flow, the best deposition efficiency was observed at the pressure ranging from 15 - 30 kPa with enhanced nanocomposite density from 4.23 to 6.36 %. At this condition, the crystals were formed and grown from inside of the pores. At the same pressure condition and gasses ratio, the deposition temperature was of great effect on the density and porous property of nanocompsite as the density increased 4.26 % at the deposition tempearture of approximately 1,100 C. Study on the structure of nanocomposite samples before and after chemical vapor deposition indicated that at the deposition temperature of 1,100 C and pressure of 15 - 30 kPa, the gaps between fibers framework were filled with pyrocarbon with the crystals sizes of 3 - 5 µm.