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AlCrON coatings were deposited on plasma nitrided steel substrates by multi-arc ion plating under different oxygen flow rates. The surface morphology, structure, composition, mechanical properties, and tribological behavior were investigated systematically. The coating surface roughness increases with increasing oxygen flow rate. The structural analysis show as-deposited coatings exhibit B1 NaCl like solid solution phases, transformed from fcc-(Cr, Al)N to fcc-(Cr, Al)ON followed by fcc-(Cr, Al)2O3 phase structure for coating deposited at the oxygen flow rate of 300 sccm. The hardness and elastic modulus of the coating decrease with increasing oxygen content due to phase transformation. The minimum friction coefficient of 0.52 and the lowest wear rate of 1.57 × 10−16 m3/(N∙m) at 600 °C are obtained for the coating deposited at 150 sccm, which is attributed to the excellent adhesion and thermal stability.

The AlCrN and AlCrON coatings were deposited on plasma nitrided H13 steels through ion-source-enhanced arc ion plating, and their structures, mechanical properties, thermal stabilities, and tribological properties were investigated. Structural analysis showed that the monolayer AlCrN and AlCrON bilayered coatings were mainly composed of fcc-AlCrN and fcc-AlCrON solid solution phases respectively. Upon the addition of thin AlCrON layer, the hardness of AlCrN/AlCrON coating slightly decreased from about 30.5 GPa to 28.6 GPa, and the thermal stability was improved after annealing at 700 &deg, C. Both coatings exhibited excellent wear resistance at room temperature, while all wear process involved a combination of wear mechanisms, including severe abrasion and oxidation at an evaluated temperature. The AlCrON bilayered coating showed better wear resistance than that of AlCrN coating due to a dense anti-oxidation layer and better adhesion at a high temperature, making it suitable for die tool protection coatings.