Fretting wear properties and microstructure evolution in micro-arc oxidation bioceramic coating pretreated using laser remelting

To improve fretting wear resistance, bio-ceramic coatings were successfully fabricated on TC6 alloy substrates using a combination of laser remelting (LRM) and micro-arc oxidation (MAO). The surface morphology, composition, and residual stress distribution of the coatings were characterized using scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, ultra-deep field three-dimensional microscopy, and X-ray stress analysis. The influence of LRM pretreatment on the fretting wear behaviour of MAO bioceramic coatings was investigated. The LRM pre-treatment did not change the phase composition of the MAO coatings, which were all composed of Al₂TiO₅, rutile TiO₂, and anatase TiO₂ phases. However, increasing the content of the rutile TiO₂ phase from 68 to 89% improved the uniformity and density of the coatings and decreased the porosity by 2.8%. The fretting wear test results showed that the LRM pretreated MAO coating exhibited the best performance against fretting wear in a simulated body fluid environment. In this case, the fretting wear mechanism was attributed to slight delamination and fatigue wear.