Substrate-dependent microstructure and nano-mechanical behavior of RF-sputtered CrN thin films on titanium alloys

Résumé fourni par la source

Abstract Titanium alloys such as Ti–6Al–4V and Ti–3Al–2.5V are commonly utilized in the aerospace industry and medical sectors, but their low surface hardness and poor wear resistance may reduce their service life. In this study, CrN thin-film coatings were deposited on both alloys using RF magnetron sputtering to investigate the influence of substrate composition on coating microstructure, crystallinity, nano-mechanical behavior, and scratch resistance. The coatings were characterized using 3D profilometry, field emission scanning electron microscopy/energy dispersive x-ray spectroscopy, x-ray diffraction (XRD), nanoindentation, and scratch testing. Dense and uniform CrN coatings with an average thickness of approximately 460 nm were successfully obtained. XRD confirmed the formation of single-phase crystalline CrN, while the coating on Ti–3Al–2.5V exhibited broader diffraction peaks, indicating substrate-dependent differences in crystallinity. Nanoindentation showed a significant increase in hardness from 6.01 to 12.57 GPa for Ti–6Al–4V (109.2% increase) and from 6.77 to 16.49 GPa for Ti–3Al–2.5V (143.6% increase). The residual indentation depth decreased by 36.3% for CrN G5 and 61.3% for CrN G9, indicating improved resistance to permanent deformation and enhanced elastic recovery. Scratch testing demonstrated good adhesion for both coatings, with critical loads of 372 and 532 mN for CrN G5 and 428 and 476 mN for CrN G9. The coating on Ti–3Al–2.5V showed better resistance to crack initiation, whereas the coating on Ti–6Al–4V exhibited greater resistance to crack propagation. Overall, RF-sputtered CrN coatings significantly improved the nano-mechanical performance and scratch resistance of both titanium alloys, highlighting the important role of substrate composition in determining coating behavior.

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