Abstract:Ti-Al-N composite coatings were in-situ synthesized on TC4 surfaces by laser cladding. The oxidation behaviors and wear properties of the as-obtained composite coatings and TC4 matrix were studied at various temperatures. The results showed the formation of a TiO₂-dominated multilayer film on the composite coating surface at temperatures below 800 °C. The oxidation product of the coating contained a mixed oxide layer of TiO₂ and Al₂O₃ at 900 and 1000 °C. The coatings exhibited good oxidation resistance at high temperatures. The thickening of the oxide film and distribution of the self-lubricating phase Ti₂AlN in the coating decreased the friction coefficient to 0.2091. Also, the wear rate diminished to 0.025×10^-4 mm³×N^-1×m^-1 at 800 °C, which is 1.43% that of the TC4 substrate. In the tested temperature range, the composite coatings showed mainly abrasive wear behavior, while an obvious lubrication effect was observed for oxide at high temperatures.

Key words: laser cladding; Ti-Al-N composite coatings; self-lubricating; oxidation; abrasive wear