Ultrasound-Auxiliary Micro-arc Oxidation (UMAO) is an emerging composite surface modification technology that significantly optimises the uniformity, compactness, and functional properties of traditional micro-arc oxidation (MAO) coatings through the synergistic interaction of ultrasonic cavitation effects and plasma discharge. In recent years, this technology has demonstrated unique potential in biomedical materials and marine engineering applications.

The ultrasonic cavitation effects enhance electrolyte mass transfer, promote discharge uniformity, and suppress coating defects, thereby optimising the growth kinetics of MAO coatings. For instance, in the fabrication of Cu-doped TiO₂ coatings on titanium-based implants, ultrasonic assistance significantly improves the homogeneous incorporation of Cu, forming a dual-layered structure (an outer amorphous Ca-P-Cu composite layer and an inner porous TiO₂ layer). This structure simultaneously enhances corrosion resistance, interfacial adhesion, antibacterial capability, and cytocompatibility. In marine engineering materials, such as manganese-aluminium bronze (MAB) alloys, UMAO technology successfully prepares composite ceramic coatings with an Al₂O₃/SiO₂ matrix embedded with nano-Cu particles by regulating coating thickness (increased by 35%) and porosity (reduced by 32%). These coatings exhibit corrosion resistance improved by two orders of magnitude compared to conventional MAO coatings, along with excellent anti-biofouling capabilities.

UMAO technology provides novel insights for designing multifunctional coatings across diverse fields. By exploring the scientific principles, challenges in industrial translation, and the interdisciplinary integration potential of UMAO, this work offers theoretical references for researchers and practitioners in surface engineering.