Structural modulation and frictional, antibacterial and biocompatible properties of Ag-incorporated DLC films: Dependence on Ag precipitation behavior

Abstract

Ag-incorporated DLC (Ag-DLC) film attracted widespread attention in the bio-alloy implants field due to its excellent mechanical, biocompatible, and antibacterial properties. However, how to balance the short-term efficient antibacterial and biocompatibility of films, and the correlation between Ag precipitation and structural properties are still unclear. Hence, Ag-DLC films with different Ag contents were deposited by modulating Ag target current, focusing on the influence of Ag precipitation behavior. Results show that Ag dopants exist in the form of Ag crystals rather than bond with carbon matrix, which can easily precipitate and aggregate to film surface. The precipitated Ag amount with Ag target current enhances from 2.75% to 35.04% while promotes the formation of sp(2 )carbon structure catalyzed by Ag, corresponding to decreased mechanical property. Interestingly, a small number of Ag dopants could effectively improve the friction behavior due to the lubrication effect of soft metal Ag and the friction interface transformation. Importantly, the best antibacterial property of film is obtained at high Ag precipitation content, while the surfaces with low Ag precipitation content are more favorable for cell adhesion and cytotoxicity reduction. Therefore, the Ag target current for better comprehensive performance is suggested within the range of 0.4 to 0.6 A.