Multifunctional Ag-doped Ti/TiN coatings: tailoring microstructure, mechanical, and antibacterial properties through silver content

This study utilized magnetron sputtering technology to deposit Ti/TiN-Ag composite coatings with varying silver (Ag) contents onto 304 stainless steel substrates. The influence of Ag content on the microstructure, adhesion strength, friction characteristics, corrosion resistance, and antibacterial properties of the coatings was systematically investigated. The results demonstrate that as the Ag content increases (from 0 at.% to 15.57 at.%), Ag particles progressively precipitate and coarsen within the coating. The bond strength exhibits an initial increase followed by a decrease, reaching an optimum value of 18.3 N at an Ag content of 6.45 at.%. At this composition, the coating also displays the lowest friction coefficient and the highest antibacterial efficacy, with an antibacterial rate of 79.37%. An appropriate Ag content enhances both lubricity and antibacterial performance. However, excessive Ag leads to particle agglomeration and degradation of properties. Although the incorporation of Ag slightly reduces the corrosion resistance of the coatings, the Ti/TiN–Ag coating with 6.45 at.% Ag offers a favorable overall performance. These characteristics make it a suitable candidate for surface modification of medical implant devices.