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 CaCl2-CaC2. The effect of the concentration of CaC2, 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 CaCl2–2 wt% CaC2 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 m2/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. [Display omitted] •The efficient salt-thermal dipping method was first presented to prepare Carbide coatings.•TiC coatings were synthesized in situ on Ti substrates by one step using the efficient salt-thermal dipping method.•The thickness and microhardness of TiC coating reached 105 μm and 1279 HV, respectively.