Oxidation behavior of laser remelted plasma sprayed NiCrAlY and NiCrAlY–Al2O3 coatings

Two types of plasma sprayed coatings (NiCrAlY and NiCrAlY–Al2O3) were remelted by continuous wave CO2 laser. A homogeneous dense remelted layer without voids, cavities, unmelted particles and microcracks was formed. As a result of isothermal oxidation tests at 1000°C, the weight gains of laser remelted coatings, especially laser remelted NiCrAlY–Al2O3 coatings, were obviously lower than plasma sprayed coatings. The effects of both laser remelting and incorporation of Al2O3 second phase in NiCiAlY matrix on high temperature oxidation resistance of plasma sprayed coatings was discussed.