Phase formation and microstructure evolution of reactively r.f. magnetron sputtered Cr-Zr oxynitride thin films

These coating structures developed over a wide range of oxygen and nitrogen gas flow settings and substrate positions. It indicates that oxygen determines the microstructure evolution under the chosen experimental conditions, and only little nitrogen contents can be incorporated into these oxide structures. For high nitrogen gas flows (i.e. N2/(N2 + O2) > 0.75) this situation changed significantly, and only coatings with face-centered-cubic CrN structures were grown. These contained up to 11.4 at.% oxygen and were clearly understoichiometric in the non-metal sites. All deposited coatings exhibited hardness values between 15 GPa and 27 GPa, indicating their suitability as protective coatings.