Improvement of the Oxidation and Wear Resistance of Pure Ti by Laser-Cladding Ti3Al Coating at Elevated Temperature

Ti3Al coating was in situ synthesized successfully on pure Ti substrate by laser-cladding technology using aluminum powder as the precursor. The composition and microstructure of the prepared coating were analyzed by transmission electron microscopy, scanning electron microscopy (SEM), and X-ray diffraction technique. Thermal gravimetric analysis was used to evaluate the high-temperature oxidation resistance of the Ti3Al coating. The friction and wear behavior was tested through sliding against Si3N4 ball at elevated temperature of 20, 100, 300, and 500°C. The morphologies of the worn surfaces and wear debris were also analyzed by SEM and three-dimensional non-contact surface mapping. The results show that the Ti3Al coating with high microhardness, high-temperature oxidation resistance, and high temperature wear resistance. The pure Ti substrate is dominated by severe adhesion wear, abrasive wear, fracture, and severe plastic deformation at lower temperature, and severe adhesion wear, abrasive wear, plastic deformation, oxidation, and nitriding wear at higher temperature, whereas the Ti3Al coating experiences only moderate abrasive and adhesive wear when sliding against the Si3N4 ceramic ball counterpart. In addition, the wear debris of the laser-cladding Ti3Al coating sliding and Si3N4 friction pairs are much smaller than that of pure Ti substrate and Si3N4 friction pairs at elevated temperature.