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 °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.

The Ni-based coatings with different content of spherical tungsten carbide were deposited by plasma transfer arc welding (PTAW) method on 304 austenitic stainless steel sheets in this study. The microstructure and wear property of spherical tungsten carbide particle reinforced composite coatings were investigated by means of optical microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), electron probe microanalysis (EPMA) and sliding wear test. It is shown that the fraction of spherical tungsten carbides has an important influence on microstructure of Ni-based overlay. The Ni40 overlay consists of γ-Ni dendrites with interdendritic Ni-based eutectics, borides and carbides improving the wear resistance. In the case of composite coatings with different content of tungsten carbide, many new phases are observed, such as Ni₂W₄C and NiW. In addition, there are a large number of irregular structures in composite coatings, such as acicular structure and irregular stripe organization. The results of sliding wear test indicate that the mass loss of coatings is influenced by the content of tungsten carbide. The mass loss decreases with the increase of tungsten carbide fraction. At high load, the abrasive resistance of composite coating with 60 wt. % tungsten carbide is improved about 50-fold compared to that of Ni40 overlay.