Corrosion-resistant behavior and structural optimization of Ti/Cr, Ti/Cu, Cr/Cu, Ti/Cr/Cu multimetallic layer coatings in simulated seawater

Abstract

This article is based on the sacrificial anode cathodic protection principle and the optimization method of multilayer structure. According to the standard electrode potential of metals, starting from the corrosion-resistant passive film formed by the metal itself, Ti/Cr, Ti/Cu, Cr/Cu, and Ti/Cr/Cu coatings were prepared on a 316L stainless steel substrate using magnetron sputtering technology. The corrosion performance of the coatings was studied to explore the interaction patterns between them. The results showed that in artificial seawater, the Cr/Cu, Ti/Cu, and Ti/Cr metal bilayer film coatings exhibited an increasing impedance arc radius and widening phase angle plateau in the electrochemical impedance spectroscopy. In the polarization curve, the self-corrosion current, the self-corrosion potential and polarization resistance are all better than the substrate. In the static immersion test, the weight loss rate of the metal multi-layer film gradually decreased, with all samples showing a lower weight loss rate in the second week compared to the first week, ranging from 27% to 52%. By further designing the microstructure of the coating to mitigate the contradiction between hardness and toughness, and reduce the generation of pores, the corrosion performance of the new Ti/Cr/Cu coating is significantly improved. The coating can repair surface defects of the material, fill in micro and nano gaps, and enhance the cathodic protection effect of sacrificial anodes.