Hardness, adhesion, and wear behavior of magnetron cosputtered Ti:Zr-O-N thin films

Reactive magnetron sputtering was used to deposit Ti:Zr-O-N thin films, by using a single Zr target, with Ti ribbons placed on the erosion track of the Zr sputtering target. Zr-O-N thin films have been also deposited in the same chamber to be used as reference films. The number of Ti ribbons, the applied sputtering current, and the reactive gas flow were the variable parameters. The films were analyzed in terms of structural development and mechanical properties (instrumented indentation, adhesion scratch testing, and wear analysis). The films are either amorphous or composed of a mixture of crystalline phases based on zirconium and titanium oxides or nitrides. Hardness values are situated between ∼10 and 11 GPa for the reference films (deposited without Ti) and up to ∼22 GPa for one of the Ti:Zr-O-N films. The films deposited without Ti behave slightly better in terms of adhesion to the substrate in comparison to the remaining samples in relation to the occurrence of first cracks (Lc1, critical load 1) and for first delamination (Lc2, critical load 2), a phenomenon probably related to the lower hardness of these films, which can accommodate the plastic deformation caused by the diamond indenter, prior to the occurrence of delamination. Adhesion to the substrate is a critical characteristic during wear tests since some of the coatings exhibit severe delamination.