Characterization of a HVOF-sprayed WC-CoCr coating before and after laser-assisted turning

HVOF-sprayed WC based coatings are widely used as high quality wear protective coatings. For many applications, as-sprayed coatings do not meet the requirements on surface quality and thus must be finished. Today, they are usually grinded or afterwards polished using diamond tools. A new turning process "laser-assisted turning" has recently been developed and successfully applied to finish Si3N4 ceramics. This process can also become a promising alternative to grinding of WC based coatings, because the cutting resistance of the coatings can be reduced thanks to enhanced local surface temperatures by laser heating compared to conventional turning, thus leading to improved surface qualities and reduced wear of turning tools. In this study, a WC-CoCr coating was produced using a HVOF spray system K2. The coating was characterized in terms of its surface morphology, microstructure, phase composition, hardness and wear resistance. In the next step, the coating was turned with the aid of laser heating and the turned coating was characterized concerning the above mentioned aspects. In this way, the feasibility of laser-assisted turning of WC based coatings was evaluated.