Abstract
Reactive r.f. magnetron sputtering was employed to deposit (Ti,Al)N thin films on tool steel. The target made by inserting molten aluminum into drilled titanium bulk resulted in a well controlled film composition. The structure of (Ti,Al)N films was identified to be a cubic B1 structure with the grazing-incident X-ray diffraction. The Knoop hardness of (Ti,Al)N coating assembly surface was higher than that of pure TiN. With the coating of Ti 0.5 Al 0.5 N, the surface hardness was improved more than 4 times higher. However, if the Al percentage exceeded 50%, say for the Ti 0.42 Al 0.58 N film, the surface hardness was decreased. In the pull-off test, the adhesion strength between the deposited film and the substrate was adequate that the failure always occurred in the epoxy side. For the scratch testing, there existed more cracks in (Ti,Al)N films than TiN, which was attributed to the higher hardness of (Ti,Al)N films. No suddenly spalling or chipping failure was observed in both TiN and (Ti,Al)N films.