3rd TAGRA

H13 hot-work tool steel is widely preferred in hot forging, extrusion, and die-casting applications due to its high hardness, good thermal fatigue resistance, and dimensional stability at elevated temperatures; however, its wear resistance and surface durability under severe thermal and mechanical loading remain limited, necessitating protective surface coatings. In this study, Cr/CrN/CrAlN and Cr/CrN/CrAlCN multilayer coatings were deposited on H13 substrates using the Closed Field Unbalanced Magnetron Sputtering (CFUBMS) technique. The structural, mechanical, adhesion, and tribological properties of both coating systems were comparatively investigated at room temperature (25 °C) and at 400 °C, 600 °C, 800 °C, and 1000 °C. Microstructural and phase characterization was performed using XRD, SEM, and EDS, while mechanical properties were evaluated by nanoindentation and microhardness measurements. Adhesion strength at the coating-substrate interface was assessed by scratch testing, and tribological performance was compared through friction coefficient and wear rate values obtained from ball-on-disk tests at different temperatures.The results show that both the CrAlN and CrAlCN top layers form protective oxide layers at elevated temperatures, enhancing oxidation resistance and tribological stability, with the carbon-containing CrAlCN layer providing additional lubricating effect and lower friction coefficients up to moderate temperatures. As temperature increased, the dominant wear mechanism shifted from adhesive to oxidative/abrasive wear for both coatings. The CrN interlayer mitigated stress transitions between the Cr bonding layer and the top layers, improving adhesion strength and delaying interlayer delamination at high temperatures. Even at 1000 °C, both coatings largely retained their structural integrity, attributed to the dense, low-porosity microstructure achieved by CFUBMS.Cr/CrN/CrAlN and Cr/CrN/CrAlCN coatings produced by CFUBMS represent effective surface engineering solutions for enhancing the wear resistance and service life of H13 tool steel in high-temperature applications such as hot forging and extrusion dies.