High-performance, functional surfaces for industry, medical technology, aviation, and more

Plasma electrolytic oxidation (PEO), also known as micro arc oxidation (MAO), is a wet chemical process that enables the production of highly functionalizable oxide layers on metals whose oxides do not have electrical conductivity, such as aluminum, magnesium, or titanium. These coatings are hard, wear-resistant, heat-resistant, and porous, making them ideal for use in aerospace, medical technology, and other high-performance industries.

Porous oxide layers for adhesion, protection, and functionality

In contrast to conventional anodizing, plasma electrolytic oxidation uses high voltages of up to 500 volts to generate locally visible plasma discharges on the metal surface. This produces temperatures of 3,000 °C to 10,000 °C, which briefly melt the metal oxide and, when it solidifies again, result in a crystalline, porous oxide layer. This porous oxide layer has very good adhesion to the base material and offers the possibility of specifically functionalizing the surface, e.g., for:

• Adhesion promotion of subsequent coatings and adhesive bonds
• Photocatalytically active surfaces with self-cleaning or disinfecting effects under visible light
• Antibacterial surfaces by introducing active substances into the pores
• Surface smoothing of additively manufactured components made of e.g. titanium

In aluminum and magnesium alloys, PEO/MAO can also significantly increase corrosion resistance.

Advantages of PEO/MAO surface treatment at a glance:

• High level of hardness and wear resistance
• Versatile functionalization options, including through the porous structure
• More environmentally friendly than conventional electroplating processes
• Technically simple implementation

Although the energy consumption of the PEO/MAO process is higher than that of traditional surface treatment processes, it offers a decisive advantage, especially for smaller components and demanding applications: Surfaces of aluminum, magnesium, and titanium components can be functionalized in a targeted manner with minimal processing effort.

What are the typical areas of application for PEO/MAO coatings?

Depending on the material, process control, and composition of the electrolyte, the properties of the coating can be specifically influenced and optimized for a wide range of applications, for instance:

• Aerospace
• Medical Technology and Life Sciences
• Automotive and motorsports
• Energy sector (e.g., battery systems)
• Mechanical engineering