Study on the Structure and Corrosion Resistance of Cr/CrCN Multilayer Coatings Prepared by HiPIMS

The Cr coating deposited by PVD method is difficult to apply on a large scale due to its poor corrosion resistance.The use of composite multilayer coating structure design can interrupt the growth of penetrating columnar crystals, reduce porosity and improve the corrosion resistance of PVD deposited Cr coatings.In this work,Cr/CrCN multilayer coatings were deposited on the surface of 316L stainless steel substrate by high-power pulsed magnetron sputtering (HiPIMS) coupled with synchronous pulse bias technology.The morphology, composition and microstructure of the coating were characterized using SEM,XRD,EDS and Raman.The corrosion resistance of Cr/CrCN multilayer coatings prepared under four different methane flow rates (5, 15, 25, 35 sccm) was studied by electrochemical and acid salt spray tests.Results showed that the introduction of CrCN intermediate layer effectively interrupted the penetrating growth of columnar crystals, and the coating exhibited a dense and flat surface morphology.All four Cr/CrCN multilayer coatings had a good protective effect on the substrate, and the corrosion current density of the coating modified samples decreased compared to the substrate.After 48 h of acidic salt spray corrosion, the surface of the multi-layer coating prepared with a methane flow rate of 25 sccm did not show obvious pitting corrosion,demonstrating the best corrosion resistance performance.In general, the Cr/CrCN multilayer coatings prepared by HiPIMS could effectively improve the corrosion resistance of 316L stainless steel, which provided reference for the optimization design and industrial application of corrosion resistance of PVD Cr plated coatings.