Microstructure and properties of TC4 titanium alloy micro-arc oxide composite coating based on laser surface texturing

Abstract

Abstract Micro-arc oxidation technology is one of the important means to improve the tribological properties of titanium alloys, but the bonding performance between the micro-arc oxidation film and the substrate material limits the further application of the micro-arc oxidation film. This study investigates TC4 titanium alloy as a model system, the microstructure and properties of the composite coating were obtained by laser surface texturing composite micro-arc oxidation process. The microstructure, phase composition, and worn morphology of the Micro-arc oxidation coating were characterized using X-ray diffraction, field emission scanning electron microscopy, and optical microscopy, respectively. Mechanical properties, including hardness, friction coefficient, and adhesion strength, were assessed using microhardness tester, Bruker tribometer, and micro/nano scratch tester, respectively. Results revealed that the Micro-arc oxidation coatings predominantly consist of Rutile TiO₂ and Anatase TiO₂ phases. The coating thickness in the mixed electrolyte reached up to 23.82 μm, with a maximum hardness of 467.56 HV₀.₅. Additionally, the friction coefficient of the laser-textured Micro-arc oxidation coatings decreased to 0.3. Laser surface texturing significantly enhanced the adhesion strength between the coating and substrate while simultaneously improving the tribological performance.