Due to their excellent biocompatibility, outstanding
mechanical
properties, high strength-to-weight ratio, and good corrosion resistance,
titanium (Ti) alloys are extensively used as implant materials in
artificial joints. However, Ti alloys suffer from poor wear resistance,
resulting in a considerably short lifetime. In this study, we demonstrate
that the chemical self-assembly of novel two-dimensional (2D) diamond
nanosheet coatings on Ti alloys combined with natural silk fibroin
used as a novel lubricating fluid synergistically results in excellent
friction and wear performance. Linear-reciprocating sliding tests
verify that the coefficient of friction and the wear rate of the diamond
nanosheet coating under silk fibroin lubrication are reduced by 54
and 98%, respectively, compared to those of the uncoated Ti alloy
under water lubrication. The lubricating mechanism of the newly designed
system was revealed by a detailed analysis of the involved microstructural
and chemical changes. The outstanding tribological behavior was attributed
to the establishment of artificial joint lubrication induced by the
cross binding between the diamond nanosheets and silk fibroin. Additionally,
excellent biocompatibility of the lubricating system was verified
by cell viability, which altogether paves the way for the application
of diamond coatings in artificial Ti joint implants.