Laser remelting of plasma-sprayed coatings on cobalt-based alloys

Laser remelting of plasma-sprayed coatings can eliminate porosity and develop metallurgical bonding at the coating-substrate interface. In the present study, stellite no. 6 powder was plasma sprayed onto an AISI 1020 carbon steel. Suitable operating conditions for plasma spraying were initially determined. Under such conditions, the effects of laser remelting on the surface roughness, shear bonding strength and wear resistance were studied. The results show that surface roughness is reduced by the remelting process, and little porosity can be found in the remelted regions. The shear bonding strength is apparently increased by the remelting process. The improvement increases with the heat input of laser processing. Wear resistance against high stress abrasion is improved by the remelting process. However, for low stress abrasion, wear resistance is improved only by some remelting processes. The wear resistance increases with laser processing power for both wear tests.