Preparation of titanium carbide plates by chemical vapour deposition

Abstract

Thick titanium carbide (TiC_x) plates were prepared by chemical vapour deposition using TiCl₄, CCl₄ and H₂ as source gases at deposition temperatures (T_dep) of 1573 to 1873 K, total gas pressures (P_tot) of 4 and 40 kPa, and source gas molar ratio (CCl₄/(TiCl₄ + CCl₄)) (m_c) of 0.13 to 0.91. The effects of deposition conditions on the microstructure, preferred orientation, deposition rate, lattice parameter and composition were investigated.

A plate-like TiC_x was obtained at m_c less than 0.5. The (110) plane was preferably oriented parallel to the deposition surface at T_dep of 1673 to 1873 K. The deposition rates showed a strong m_c dependence and the maximum rate was found at m_c = 0.3 to 0.5. The activation energies for the formation of TiC_x plates were 86 kJ mol⁻¹ at P_tot = 4 kPa and 95 kJ mol⁻¹ at ^P_tot= 40 kPa. When m_c values were in the range of 0.13 to 0.51, the lattice parameter increased with an increase in m_c and decreased with an increase in T_dep. The lattice parameter was almost constant beyond m_c = 0.72 at all T_dep. The atomic ratio (C to Ti) for TiC_x varied from 0.6 to 1.0 with deposition conditions.