Effects of laser power on friction–wear behaviors of NiCoCrAlY coatings at high temperature

Abstract

NiCoCrAlY coatings were fabricated at the laser power of 1000, 1200 and 1400 W on TC4 alloy using a laser cladding (LC). The surface and cross–section morphologies of obtained coatings were observed using a scanning electronic microscope (SEM), and the phases were analyzed using an x–ray diffraction (XRD). The effects of laser power on the friction–wear performances at 600 °C were investigated using a ball–on–disc wear tester, and the distributions of chemical elements on the worn tracks were analyzed using a line scan analysis. The results show that the laser cladded NiCoCrAlY coatings are primarily composed of Ti4Fe2O, Co2Ti4O, Ni2Ti4O, Fe2Ti4O, NiTi2 and Ti2Ni phases. The average coefficients of friction (COFs) of NiCoCrAlY coatings fabricated at the laser power of 1000, 1200 and 1400 W are 0.536, 0.568, and 0.509, respectively, showing that the friction reduction performance fabricated at the laser power of 1400 W is the best among the three kinds of laser power; and the corresponding wear rates are 0.042 × 10–3, 0.013 × 10–3 and 0.038 × 10–3 mm3· N−1·m−1, respectively, among them, the wear rate of NiCoCrAlY coating fabricated at the laser power of 1200 W is the lowest. The oxides of Cr, Al and Ni are formed in the high temperature wear process, which enhance the wear resistance of NiCoCrAlY coatings, the wear mechanism are abrasive wear.