Heat Flux Controls by in Situ Laser Treatment on Thermal Sprayed Wc-Co Coatings

Cermet Tungsten-Cobalt Carbide (WC-Co) coatings are widely used in industry for wear protection owing to their high hardness and their high resistance to abrasion, corrosion or high temperature. WC with ductile metals such as Cobalt that cements the WC particles is deposited by thermal spray technique. However due to the temperature and  the interaction between WC, Co, oxygen in air and substrate, the thermal sprayed WC-Co coating exhibit multi-phase  microstructures that induces residual stress. The making of WC-Co coating with high hardness and high resistance depends on thermal aspects. The control of the thermal parameters of the substrate and the previous layers during the spraying of the WC  is a key to reduce the stress. 

Commonly to decrease the proportion of brittle phases of WC and residual stress in the coating, post-spray treatments such as heat treatment are employed. In this study during WC-Co spraying, in situ process based on laser is used to apply heat treatment and control thermal evolution of the coating. Several configurations are tested in order to reduce the stress.