Self-lubrication and enhanced wear and corrosion resistance of calcium silicate hydrate nanostructures on Ti-based micro-arc oxidized coatings

Abstract

Nanostructured coatings for titanium (Ti)-based implants are well-known for their biological properties; however, they are highly fragile in service. The debris generated by wear and coating destruction can lead to chronic inflammatory response, bone resorption, and, consequently, implant loosening. Therefore, the development of highly wear-resistant micro/nanostructured coatings is essential for the long-term service stability of Ti-based implants. In this study, calcium silicate hydrate nanostructures (CSHNs) were generated on micro-arc oxidation (MAO)-treated Ti surfaces via hydrothermal treatment (HT). Owing to the layered crystal feature of the CSHNs, as-prepared micro/nanostructured coatings exhibit typical self-lubricating performance under dry-sliding conditions, with their coefficients of friction measured to be ≤ 0.2. Meanwhile, the appropriate growth of CSHNs on MAO coatings is beneficial for reduced wear rate and enhanced corrosion resistance due to self-lubrication and increased coating crystallinity, respectively. However, in turn, the overgrowth of CSHNs with prolonged HT duration can compromise the wear and corrosion resistance owing to the potential risk of crack formation on MAO coatings. Overall, the results indicate that CSHNs are potential nanostructures for MAO coatings to achieve self-lubrication as well as enhanced wear and corrosion resistance.