Advanced tribological performance of PVD AlTiCrN and TiCrN coatings under dry and lubricated conditions

Abstract

TiCrN and AlTiCrN multilayer coatings were fabricated on H13 steel substrates through the cathodic arc physical vapor deposition (PVD) technique. Comprehensive structural, mechanical, and tribological characterizations were performed to evaluate their behavior under dry and lubricated sliding conditions. When the mechanical properties of the coatings are evaluated, it is observed that although the AlTiCrN coating exhibits higher hardness (29.38 GPa) compared to the TiCrN coating (24.15 GPa), its adhesion strength is lower, corresponding to an HF4 classification. XRD and Raman analyses confirmed the formation of both coatings with a preferred (200) orientation and characteristic Ti–Cr–Al–N vibrational modes. AFM results demonstrated higher surface roughness for AlTiCrN due to increased droplet density. Tribological tests showed that TiCrN provided superior friction and wear performance under dry conditions, whereas AlTiCrN exhibited better tribological response under lubrication and wear resistance at lower loads, though localized spallation occurred at higher loads, indicating load-dependent degradation. SEM/EDX analysis revealed oxide formation on the wear scars of the TiCrN coating, which contributed to its lower COF under dry conditions, whereas the AlTiCrN coating preserved its constituent elements without oxide formation or substrate exposure. Under lubricated conditions, TiCrN showed localized Fe signals indicating partial substrate exposure and abrasive wear, whereas AlTiCrN retained its surface composition, confirming better wear protection.