Characterization by Dynamic Indentation on Laser-treated WC-Ti Coatings Deposited via Cold Gas Spray

The present work is focused on the characterization of WC-Ti coatings via dynamic indentation, by which the elastic modulus and hardness were evaluated. The coatings were obtained by Cold Gas Spray (CGS) and then post-treated with a diode laser, to promote the in-situ formation of TiC through a controlled decarburization of the WC phase and the following reaction with the metallic Ti. WC-Ti is, in fact, a promising composition for wear applications due to the high content of carbides following the heat treatment, and to the presence of Ti as the metallic binder as a suitable alternative to the more common cobalt. The characterization of the WC-Ti coatings is thus necessary to verify their suitability as a possible alternative to other hardmetal formulations, such as WCCo-based thermal sprayed coatings. Dynamic indentations were performed on the as-sprayed as well as on the laser-treated coatings. The laser power-scan rate scenarios used in this study were 250 W-8 mm/s and 350W8 mm/s.Two loads, 500 mN and 1000 mN, were applied. The resulting load/penetration curves were then elaborated using the Oliver-Pharr theory for dynamic indentations, by which Young’s modulus and the hardness were finally calculated. Results showed an increase in the elastic modulus of the laser-treated samples, with the highest values – around 300 GPa, versus the 195 GPa evaluated on the as-sprayed sample - registered for the sample treated with the 350W- 8 mm/s set of parameters.