Influence of TiB2 addition on the mechanical and tribological properties of NiCrBSi deposited by flame spraying

Influence of TiB2 addition in nickel-based coatings is studied from different point of views, microstructural (phases identification and porosity rate), mechanical (hardness and elastic modulus by instrumented indentation) and mechanical behavior (wear resistance by pin-on-disk system). In the two coatings containing 2.5 and 10% of TiB2, we note the presence of silicide, carbide and boride but only the presence of titanium oxide for 10% of TiB2. The porosity rate is higher (6%) when TiB2 amount is lower, it is of 1.2% for the other coating. After discussing about the indentation size effect and the influence of porosity on the mechanical properties measurement by indentation, hardness is found to be similar in the two cases, around 3 GPa, whereas the elastic modulus seems to be slightly higher (175 GPa against 150 GPa) for the highest content in TiB2. Finally, the friction coefficient is higher in the transition or running zone before reaching the same mean value of 0.6 in the stationary stage.