An efficient salt-thermo-carburizing method to prepare titanium carbide coating

Titanium carbide (TiC) coating was prepared by in-situ carbonization of titanium using a novel salt-thermo-carburizing (STC) method in molten CaCl 2 -CaC 2 . The effect of the concentration of CaC 2 , the temperature of the melt and the reaction duration on the composition, structure and thickness of the carbide coating were systematically investigated. The optimized immersion bath was CaCl 2 –2 wt% CaC 2 at 900 °C. The thickness of the coating was increasing with the immersion time and it can reach 105 μm within 8 h. It was found that the growth kinetics of TiC coating follows a parabolic law in the temperature range of 850 to 900 °C, the obtained growth rate constants ( k ) is 1.43 × 10 −15 at 850 °C, 68.38 × 10 −15 at 875 °C, and 320.17 × 10 −15  m 2 /s at 900 °C, respectively. In addition, the microhardness of the TiC coating obtained at 850 °C and 8 h is over 740 HV, which is more than five times that of the Ti substrate. This work offers a universal and facile method to prepare metallic carbide coating on the respective metal substrate.