Tribological properties of AlTIN coating in sliding contact with Ti6Al4V: A helpful tool for disentangling the phenomena complexity during real turning operations

The study focuses on the evaluation of the parameters affecting friction, wear performance and mechanisms of uncoated and AlTiN coated WC-Co against Ti6Al4V. To this purpose tribological and turning tests were carried out. The tribological tests highlighted that the friction coefficient increased by increasing temperature, while decreased by enhancing sliding speed. Titanium transfer on both coated and uncoated balls was observed, indicating that adhesion phenomena occurred in large extent. As the main effect, AlTiN hindered Ti6Al4V adhesion, thus increasing the friction coefficient, which was linearly proportional to the amount of material transfer from the titanium alloy to the ball surface. Analogously, craterisation phenomena, usually caused by adhesion, were less evident in turning operation when using AlTiN coated tools. Also the highest temperature at the workpiece-cutting tool interface could be partially explained by the highest friction coefficient observed for AlTiN materials.