Microstructural and Tribological Evaluation of TiC, CrN, and AlTiN Coatings Deposited on Gas-Nitrided AISI H13 Steel

The study investigates a duplex surface-engineering approach combining gas nitriding and hard ceramic coatings to improve the tribomechanical performance of AISI H13 tool steel. Gas nitriding was performed at temperatures ranging from [Formula: see text]C to [Formula: see text]C for durations of 12–36 h to identify optimal treatment conditions based on hardness and microstructural stability. The optimal condition was [Formula: see text]C for 24 h, yielding a surface hardness of approximately 1065 HV. Subsequently, TiC, CrN, and AlTiN coatings were deposited on the optimized nitride substrate. Microstructural and phase analyses using SEM, EDS, and XRD confirmed uniform coating deposition and phase stability. Among the investigated coatings, AlTiN exhibited the highest surface hardness ([Formula: see text]2811 HV) and the lowest wear rate. Tribological tests combined with Response Surface Methodology (RSM) revealed that coating type and applied load were the most influential parameters affecting wear behavior. The developed regression model showed strong predictive capability ([Formula: see text]%). The results demonstrate that duplex treatment involving gas nitriding followed by AlTiN coating significantly enhances the wear resistance of AISI H13 tool steel.