The effect of vapor phase on the growth of TiC whiskers prepared by chemical vapor deposition

Abstract

Quality TiC whiskers with high yield are prepared by a modified chemical vapor deposition (CVD) method. The appropriate deposition parameters are found. The effect of vapor phase on the whisker morphology at fixed temperature is studied in detail. It is found that the morphology and size of TiC whiskers are significantly affected by both the flow rate of vapor phase and the C/Ti ratio. The C/Ti effect is supposed to be related to the formation of Ni–Ti eutectic liquid phase according to the vapor–liquid–solid (VLS) mechanism which is confirmed in this experiment. It is also found that the morphologies of TiC deposits are different at different locations of the substrate depending on the variation of the contacting time and axial effective concentration of vapor phase along the vertical reaction tube. The high whisker yield is closely related to the movement of the vapor phase. A fast vapor fluid spouting upwards and diverging into the annulus makes the radial concentration of the vapor phase more homogeneous, and it also increases the collision of the vapor species on to the growing fronts and accelerates the mass transition of the CVD process.