Laser treatment of HVOF coating: model study and characterization

Abstract

HVOF coating is widely used in industry for protective coating of the metallic surfaces. The coating is based on the mechanical anchoring of the splats onto the substrate surface and thermal integration among the splats in the coating is not possible during the spraying process due to the operation temperature, which is lower than the melting temperature of the coating material. This, in turn, results in the formation of non-homogeneous structures and voids in the coating. One of the techniques to avoid such situations is to integrate the spats through the controlled melting. This can be achieved through the laser melting process. In the present study, laser melting of HVOF coating is modeled to determine the melt layer thickness. A lump parameter analysis is introduced in the model study and simulations are carried out in relation to the actual laser melting conditions. The melt layer predicted is compared with the experimental measurements. The microstructural analyses prior and post laser melting process are carried out using SEM and EDS. It is found that the predictions of the melt layer are in good agreement with experimental results.