Wear behaviour of laser-treated plasma-sprayed ZrO2 coatings

The effect of laser remelting on the wear behaviour of plasma-sprayed ZrO₂ ceramic coatings was studied. The results showed that the porosity and roughness of the coatings were reduced significantly after laser treatment, and the bonding strength was apparently increased by the remelting process. However, there were extensive network cracks, as well as a few large bubbles, in the laser-treated coatings. Unlubricated pin-on-disc wear tests revealed that, when compared with as-sprayed ceramic coatings, the wear resistance was improved significantly after laser treatment. The wear resistance of laser-treated specimens increased with increasing laser power, and the minimum weight loss of the coating specimen occurred at a specific travel speed in laser processing. The main wear mechanism of the as-sprayed coatings was spallation of the coating, whereas the wear of laser-remelted specimens was dominated by ploughing and gouging (scratching).