High-temperature oxidation and wear properties of laser cladded Ti-Al-N composite coatings

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 & DEG;C. The oxidation product of the coating contained a mixed oxide layer of TiO2 and Al2O3 at 900 and 1000 & DEG;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 0.025x10-4mm3 & BULL;N-1 & BULL;m-1 at 800 & DEG;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.