Growth and structure of TiCxNy coatings chemically vapour deposited on graphite substrates

Abstract

TiCxNy coatings were grown on graphite substrates in a computer-controlled, hot-wall chemical vapour deposition (CVD) reactor, using gas mixtures of TiCl4-CH4-N-2-H-2 at a total pressure of 10.7 kPa (80 torr) and at a temperature of 1400 K. Growth rate, composition, morphology and crystallographic texture of the TiCxNy coatings were investigated as a function of the CH4/CH4 + N-2 ratio in the range 0-1 at a constant CH4 + N-2 flow rate of 370 standard cubic centimeters per minute (seem). The C/C + N ratio and growth rate of the TiCxNy coatings increased with increasing CH4/CH4 + N-2 ratio in the gas phase. The compositions of the coatings with C/C + N ratios in the range 0-1 were found to be between the thermodynamic and the kinetic predictions. Morphology and preferred orientation of the coatings were observed to be strongly affected by the CH4/CH4 + N-2 ratio in the gas phase.