Wear resistant WC-Ti coatings obtained by high pressure cold spraying

This work is focused on deposition and characterization of WC-Ti nanocomposite cermet coatings obtained by Cold Gas Spray (CGS) technique.

Starting powders (Ti-WC) were produced by mechanical alloying and deposited by CGS system at different deposition temperatures.

The microstructure shows a good distribution of carbides, with a dimension from 5 microns down to 100 nanometers and partially rounded, probably due to the ball milling process.

Several heat treatments were carried out in order to promote a partial decarburization of WC and the in situ nucleation of titanium carbide micro/nano-precipitates: the aim was to improve the hardness and the wear resistance of the cermet coating. Preliminary results show that heat treatments roughly double the hardness of the coatings.

Moreover the effect of laser surface treatments aimed at enhancing the tribological properties of the coatings was investigated: also in this case the right selection of laser treatment parameters permits to effectively increase the hardness of the cermet.

Dynamic indentation and tribology tests (dry conditions, block on ring configuration) were performed both on as sprayed and treated coatings in order to evaluate the effect of the high temperature and laser treatments on the Young’s modulus and wear resistance of the coatings.