Study of growth rate and failure mode of chemically vapour deposited TiN,TiCxNy and TiC on cemented tungsten carbide

The effects of deposition temperature and mole ratio of CH₄ to TiCl₄ on the growth rate of titanium compound coatings were investigated. Activation energies of TiN, TiC_xN_y and TiC deposition reactions of 4.8×10⁴, 1.9×10⁵ and 2.8×10⁵ J mol^–1, respectively, were obtained experimentally. The carbon content of TiC_xN_y deposit was increased as the CH₄ flow rate and deposition temperature increased. It was found that TiC_xN_y grain size was finer than TiC and TiN.The cutting temperatures of TiN-coated and TiC-coated tools were 10% (TiN) and 20% (TiC) lower than that of uncoated tools. Feed force and reaction force of coated tools were 30% and 18% less than those of uncoated tools, respectively. The dominant failure mode of coated tools was due to the microchipping of the cutting edge.