Chemical vapour deposition of pyrolytic carbon from impinging jets

Pyrolytic carbon coatings were deposited on a graphite substrate by chemical vapour deposition technique from impinging jets of ethylene gas. The growth and structure of the coatings were investigated as a function of gas flow velocity. The deposition rate of the coatings increased linearly with the square root of gas velocity or flow rate of ethylene. This behaviour was explained by a mass-transport theory. The coatings exhibited cone-like morphology at low gas velocities and cauliflower-like morphology at high gas velocities. Textural analyses revealed that all the coatings were preferentially oriented in the < 001 > direction perpendicular to the substrate. (C) 1996 Elsevier Science Limited and Techna S.r.l.