title: Poly(vinylphosphonic acid) (PVPA) on titanium alloy acting as effective cartilage-like superlubricity coatings.
abstract: Poly(vinylphosphonic acid) (PVPA) is a type of hydrophilic polymer that can be used in surface modifications. In our study, PVPA coatings were formed on the surfaces of titanium alloy (Ti6Al4V) using a simple and novel method to achieve efficient lubrication at friction interfaces. The composition and 3D skeletal structure of the PVPA coatings were confirmed by X-ray photoelectron spectroscopy (XPS), focused ion beam/scanning electron microscopy (FIB/SEM), and solid-state nuclear magnetic resonance (NMR). The PVPA-modified Ti6Al4V/polytetrafluoroethylene (PTFE) interface shows a superlow friction coefficient (approximately 0.006) for at least 8 h under a contact pressure of 44.2 MPa (initial pressure), which means it falls into the superlubricity regime. Moreover, wear on the surfaces of both the Ti6Al4V and PTFE after the tribological experiment is superlow. It is proposed that the 3D skeletal structure of the PVPA coating and fluid-like manner at friction interfaces owing to the fast exchange of water molecules are the main factors accounting for the superlow friction and wear. The PVPA-modified Ti6Al4V has the potential uses in artificial cervical discs.
authors.affiliation: State Key Laboratory of Tribology, Tsinghua University , Beijing 100084, China.
authors.forename: Caixia
authors.initials: C
authors.lastname: Zhang
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Liu
authors.forename: Shizhu
authors.initials: S
authors.lastname: Wen
authors.forename: Song
authors.initials: S
authors.lastname: Wang
mesh_terms: D000497:Alloys; D002021:Buffers; D002356:Cartilage / Q000502:physiology*; D020099:Coated Materials, Biocompatible / Q000494:pharmacology*; D017276:Friction; D008153:Lubrication; D009682:Magnetic Resonance Spectroscopy; D063065:Organophosphonates / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D011138:Polytetrafluoroethylene / Q000737:chemistry; D011145:Polyvinyls / Q000737:chemistry*; D013696:Temperature; D014025:Titanium / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*
chemical_list: D000497:Alloys; D002021:Buffers; D020099:Coated Materials, Biocompatible; D063065:Organophosphonates; D011145:Polyvinyls; D014753:Vinyl Compounds; C000602303:poly(vinylphosphonic acid); C031462:titanium alloy (TiAl6V4); C433467:vinylphosphonic acid; D011138:Polytetrafluoroethylene; D014025:Titanium
keywords: Ti6Al4V; poly(vinylphosphonic acid); superlow wear; superlubricity; surface modification