Akademik Veri Yönetim Sistemi
International Journal of Applied Ceramic Technology, cilt.23, sa.3, 2026 (SCI-Expanded, Scopus)
This study investigates the structural, mechanical, and tribological performance of two functionally graded diamond-like carbon (DLC) coatings—Ti–TiC–TiNbC–a:C and Ti–TiC–TiNbC–TiNbCN–a:C—deposited on AISI M2 high-speed steel via closed-field unbalanced magnetron sputtering. The multilayer design was developed to mitigate residual stress and adhesion limitations commonly observed in conventional DLC films. Cross-sectional SEM and XRD analyses confirmed the formation of dense, nanocrystalline TiC, NbC, and Ti(C,N)/TiN phases embedded in an amorphous carbon matrix, with significant niobium enrichment verified by EDS. Mechanical testing revealed that the Ti–TiC–TiNbC–a:C coating achieved a hardness of 1250 HK0.01, while nitrogen incorporation in the Ti–TiC–TiNbC–TiNbCN–a:C structure increased hardness further to 1500 HK0.01. Both coatings maintained ultralow and stable friction coefficients (0.10–0.11), yet the nitrogen-enriched film exhibited a higher wear rate (8.0 × 10−5 vs. 3.2 × 10−5 mm3/N·m). Scratch adhesion tests showed superior interfacial strength for the thinner Ti–TiC–TiNbC–a:C coating (37 N) compared to the thicker Ti–TiC–TiNbC–TiNbCN–a:C variant (28 N), suggesting that excessive layer thickness and nitrogen incorporation exacerbate residual stresses and reduce adhesion. Overall, the findings demonstrate that while Nb- and N-rich graded DLC architectures improve hardness, they compromise wear resistance and adhesion, emphasizing the importance of carefully optimizing layer composition, thickness, and stress management for practical industrial applications.