Improvement of the oxidation and wear resistance of pure Ti by laser cladding at elevated temperature

Abstract

NiCrBSi and NiCrBSi/WC–Ni composite coatings were produced on pure Ti substrates by the laser cladding technology. Thermal gravimetric (TG) analysis was used to evaluate the high temperature oxidation resistance of the laser cladding coatings. The friction and wear behavior was tested through sliding against the Si3N4 ball at elevated temperatures of 300°C and 500°C. Besides, the morphologies of the worn surfaces and wear debris were analyzed by scanning electron microscopy (SEM) and three dimensional non-contact surface mapping. The results show that the microhardness, high temperature oxidation resistance and high temperature wear resistance of the pure Ti substrates are greatly increased. For the pure Ti substrate, the wear behavior is dominated by adhesive wear, abrasive wear and severe plastic deformation, while both laser cladding coatings, involving only mild abrasive and fatigue wear, are able to prevent the substrates from severe adhesion and abrasive wear. In particular, the laser cladding NiCrBSi/WC–Ni composite coating shows better high temperature wear resistance than the NiCrBSi coating, which is due to the formation of a hard WC phase in the composite coating.