Electrochemical Behavior of TiN/CrN Bilayer Composite Coatings Fabricated by Cathodic Arc Physical Vapor Deposition on High-Speed Steel

Hard nanocoatings such as titanium nitride (TiN) and chromium nitride (CrN) are widely used in various industries, especially for coating cutting tools and dies, due to their unique properties including high hardness, thermal stability, and resistance to wear and corrosion. When these coatings are applied as multilayer composites, they exhibit significantly improved mechanical and chemical performance. In this research, a TiN/CrN bilayer coating was applied onto a ۱.۳۲۵۵ high-speed tool steel substrate using the physical vapor deposition (PVD) method with a cathodic arc (Arc-PVD). Precise substrate surface preparation and optimal coating parameter selection were carried out based on previous studies. Grazing incidence X-ray diffraction (GIXRD) was performed to identify the crystalline structure of the coating, and electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests were conducted to investigate corrosion resistance. The GIXRD results indicated the successful formation of TiN and CrN phases with a preferred crystalline orientation in the (۱۱۱) plane for TiN and the presence of slight residual stresses. Analysis of the Nyquist plots and their fitting with an equivalent circuit showed a significant increase in polarization resistance (from ۱۱۰۷ Ω·cm² to ۱۴۵۰ Ω·cm²) and a decrease in the double-layer capacitance, confirming the effective protective performance of the coating. Furthermore, the polarization test results indicated a reduction in corrosion current density (from ۴.۵۸ to ۱.۲۰ μA/cm²) and a shift in the corrosion potential towards more noble values (from -۶۳۸ to -۴۶۱ mV).

کلیدواژه ها:

TiN/CrN Bilayer Composite Coatings ، cathodic arc physical vapor deposition (Arc-PVD) ، Electrochemical Corrosion Resistance ، High-Speed Steel ، پوشش دولایه کامپوزیتی TiN/CrN ، لایه نشانی فیزیکی از فاز بخار با استفاده از قوس کاتدی ، فولاد تندبر ، مقاومت خوردگی الکتروشیمیایی