Structural and mechanical characterization of Ti/TiC cermet coatings synthesized by laser melting

Laser surface alloying is an attractive technique for surface treatment: by depositing suitable ceramic powder on a titanium substrate, a Ti/TiC cermet coating is obtained by melting a part of the underlying titanium. Graphite or titanium carbide powders were pre-deposited on a titanium foil with the aim to synthesize Ti/TiC cermets. After optimization of the Nd-YAG laser processing parameters, four thicknesses of the both deposited ceramic powders were used: 10, 20, 30 and 40 mu m. The cermet coatings produced have a uniform microstructure and excellent bonding with the titanium substrate, and are free of pores and cracks. Their hardness can reach 520 HV in depth. The volume ratio of TiC phase formed and dispersed in the titanium matrix is dependent on the kind and thickness of the pre-deposited powder. The results of the microstructural investigations achieved after X-ray diffraction are correlated with the hardening phenomenon.