Thermodynamics and Phase Constituents of Laser Induced In-Situ-Fabrication of TiB2 Ceramic Coating on Ti-6Al-4V

In-situ fabrication of TiB ceramic coating by laser cladding technology (LC) was investigated. Pulsed YAG laser with the power of 500 W was used. The mixture of Titanium powder (with the size of 20 m) and B powder (with the size of 140 m) were utilized as the precursor. The reactive transformation mechanism and phase constituents of the in-situ fabricating coating during the laser cladding process were studied by thermodynamics analysis, as well as XRD methods. Gibbs free energy theory was used to calculate the increment of Gibbs free energy at different temperature. The results show that the increment of the Gibbs free energy for the reaction equation to the in-situ fabricate TiB2 keep to be negative within the temperature of 3000K, this indicate that TiB2 can be obtained by laser cladding the mixture powder of Ti and B. XRD results show that the main phases of the coating are TiB2, TiO2 and B2O3 with relative percentage of 67.6%, 18.0% and 14.4%, respectively.