Development of Microstructure and Properties of Multicomponent MoS2/HA/PEEK Coatings on a Titanium Alloy Via Electrophoretic Deposition and Heat Treatment

Abstract

In this study, molybdenum disulfide nanosheets, bioactive hydroxyapatite particles of two types in various amounts, and PEEK 704 microparticles were electrophoretically co-deposited to fabricate multicomponent coatings on Ti-13Nb-13Zr alloy substrates. A mixture of pure ethanol and cationic chitosan polyelectrolyte was used as a dispersion medium. The kinetics and mechanism of deposition were investigated. The kinetics depended significantly on the suspension’s chemical composition and the voltage used during EPD. Cationic chitosan provided the steric stabilization of the suspension and enabled cathodic co-deposition of all coating components. Green macroscopically homogeneous coatings were subsequently heat treated. The treatment densified the coatings and caused the formation of a stable semi-crystalline PEEK matrix consisting of spherulites. The MoS2 nanosheet packages, separate HA particles and their agglomerates were embedded in the coating matrix. After heat treatment, both types of coatings, differing in HA type, were characterized by excellent adhesion to the substrate and moderate scratch resistance. During surface topography investigation, it was found that coatings containing smaller HA nanoparticles had a slightly lower surface roughness. The coatings raised the corrosion resistance of the titanium alloy substrate in Ringer’s solution. The possibility of the electrophoretic co-deposition of various ceramic and PEEK particles to develop multicomponent coatings, as well as their contribution to enhancing titanium alloy surface properties, represents an important input in further developing superior bioactive titanium implants.