Laser remelting of plasma-sprayed nanostructured Al2O3-20Â wt.% ZrO2 coatings onto 316L stainless steel

The nanostructured Al2O3-20 wt.% ZrO2 coatings were fabricated by atmospheric plasma spraying (APS) on the 316L stainless steel and the laser-remelted testing was carried out using a continuous CO2 laser. The effect of laser treatment on microstructure and mechanical properties of the nanostructured Al2O3-20 wt.% ZrO2 coatings were also investigated. The results indicate that microstructural inhomogeneity in the coatings such as pores, voids and lamellar structure can be eliminated after laser remelting. When the laser power keeps at a constant,the quantity of surface cavities decrease with the increase of scanning rate whereas the quantity of surface cracks tend to increase. Both cavities and cracks can minimize when the laser power reaches 600 W with the scanning rate of 1000 mm/min. The laser treatment can greatly improve the surface roughness, wear resistance, microhardness, elastic modulus and fracture toughness of the nanostructured Al2O3-20 wt.% ZrO2 coatings.