In-situ Synthesized TiN/Ti₃Al Composite Coating by Laser Gas Nitriding and Its High-Temperature Erosion Resistance

TiN/Ti₃Al composite coating was in-situ synthesized on the surface of Ti-6Al-4V alloy by laser gas nitriding technique with the aluminium powder mixed in the nitrogen. The micromorphology, phase composition, hardness distribution and the anti-erosion performance with high-temperature high-velocity steam containing SiC and SiO₂ particles of the coating were studied. The results show that the surface hardness of the coating was (1 400±50) HV, four times higher than that of Ti-6Al-4V titanium alloy. After erosion with SiC particles during a relatively short period or with SiO₂ particles, the erosion mass loss of the coating increased with the increase of erosion angle, while that of the Ti-6Al-4V titanium alloy decreased. At the same erosion angle, the erosion mass loss of the coating increased with the increase of erosion particle hardness, and that of the Ti-6Al-4V titanium alloy followed this rule at relatively small erosion angles while changed little at relatively large erosion angles.