Microstructure and wear properties of ZrO2 nanoparticle-doped micro-arc oxidation coating on Ti6Al4V alloy at laser irradiation

To improve the wear resistance of titanium alloy, this study proposes a novel approach that combines laser irradiation and ZrO 2 nanoparticle (NP) doping in the fabrication of wear-resistant micro-arc oxidation (MAO) coating on Ti6Al4V (TC4) alloy. The obtained coatings were characterized by using laser scanning microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to analyze their surface morphologies, microstructure and chemical compositions. Tribological properties were evaluated via ball-on-disk sliding wear tests, along with the hardness and adhesion of the coating. The results show that the MAO coating prepared under laser irradiation and ZrO 2 nanoparticle doping (NA- L -MAO) exhibits enhancement in density, uniformity and thickness compared with nanoparticle-doped MAO (NA-MAO) or laser-assisted MAO ( L -MAO) alone. Compared with the MAO coating, the NA- L -MAO coating achieves a porosity of only 4.67%, representing a reduction of ∼41.3%. Meanwhile, its volumetric wear rate reaches 3.56 × 10 −5 mm 3 ·N −1 ·m −1 , which is decreased by ∼88.3% and nearly one order of magnitude lower than that of the MAO coating. The ZrO 2 nanoparticles participate in coating growth via melting or embedding behaviours, enabling filling of micropores and increasing coating thickness. Due to laser irradiation, more ZrO 2 nanoparticles enter the NA- L -MAO coating, and more stable phases (rutile-TiO 2 and t-ZrO 2 ) are formed. Simultaneously, laser irradiation promotes uniform coating growth, lower surface roughness and enhanced coating adhesion. The synergistic effect of laser irradiation and nanoparticle incorporation facilitates more particle penetration into the coating, elevates coating hardness and thus improves the anti-wear performance of the coating.