The morphology and growth mechanism of TiC whisker prepared by chemical vapour deposition

TiC whiskers with good quality and high yield are prepared by a modified chemical vapour deposition (CVD). The whisker morphology and factors affecting its formation have been investigated. Various whisker morphologies such as Wool-, Hassock-, Cluster-, bar-, Hedgehog-, and bamboo-like, are observed under different conditions. The morphologies of TiC whiskers are markedly affected by the gas flow rate and the C/Ti ratio, which is supposed to be related to concentration variation and the formation of Ni-Ti eutectic liquid phase. The growth characteristics of TiC whiskers are also affected by the stability of deposition parameters. It is found that in the course of whisker growth on nickel substrate, the well known VLS mechanism is not necessarily dominant. It is effective in the initial stage, but then might change to the VS mechanism with the dissipation of liquid droplets at the whisker tips. The deposition temperature plays an important role in changing from the VLS to the VS mechanism.