Micro-arc oxidation (MAO), also known as plasma electrolytic oxidation (PEO), is an advanced surface treatment technology used to enhance the properties of aluminum alloy castings. This process involves the generation of a ceramic-like oxide layer on the surface of the aluminum alloy through the application of high voltage in an electrolytic solution.

During the MAO process, the aluminum alloy casting is immersed in an electrolyte solution, typically composed of alkaline salts. When a high voltage is applied, micro-arc discharges occur on the surface of the aluminum, leading to the formation of a dense, hard, and adherent oxide layer. This layer significantly improves the surface properties of the aluminum alloy, including increased hardness, wear resistance, corrosion resistance, and thermal stability.

The MAO process offers several advantages:

1. Enhanced Surface Properties: The oxide layer formed is highly durable and resistant to wear and corrosion.

2. Improved Adhesion: The oxide layer has excellent adhesion to the base metal, ensuring long-lasting performance.

3. Environmental Friendliness: The process is environmentally friendly, as it does not involve harmful chemicals or produce toxic by-products.

4. Versatility: MAO can be applied to complex shapes and sizes, making it suitable for a wide range of aluminum alloy castings.

Overall, micro-arc oxidation is a highly effective method for improving the performance and longevity of aluminum alloy castings in various industrial applications, including aerospace, automotive, and marine industries.