You likely know that anodizing processing involves various oxidation techniques, with the more common ones being hard anodizing, standard anodizing, conductive anodizing, and colored anodizing, among others. However, today, we want to introduce to you a more advanced oxidation technique with higher market technical content: micro-arc oxidation technology.
Aluminum alloy micro-arc oxidation, also known as ceramic layer oxidation technology for aluminum alloys, involves placing aluminum alloy workpieces in a weakly alkaline electrolyte solution under conditions of higher voltage and current. Initially, a thin oxide insulating layer is formed on the aluminum surface. As the anodic oxidation voltage continues to rise, when it exceeds a certain critical value, the insulating layer breaks down and discharges, creating a micro-arc zone. This discharge generates thousands of Kelvin of high temperature, melting and even vaporizing the oxide film and base metal. The metal elements and oxygen elements undergo intense diffusion and react within the discharge channel to form new compounds. These newly formed molten substances, upon contacting the electrolyte solution, rapidly cool to form a ceramic film layer.
The aluminum alloy micro-arc oxidation process, in the formation of micro-arc oxidation aluminum ceramic layer, theoretically belongs to a method that does not consume electrolyte and electrode materials. Therefore, non-consumable stainless steel can be used as the cathode, avoiding the pollution of the environment due to heavy metal ions dissolving into the cathode and being discharged with wastewater. Hence, the aluminum alloy micro-arc oxidation is also known as a clean anodic oxidation process. The film obtained through micro-arc anodic oxidation has high hardness, wear resistance, and corrosion resistance, which cannot be compared with the oxidation film layer obtained through conventional anodic oxidation in terms of hardness, wear resistance, or corrosion resistance. This technology was initially mainly applied in high-tech fields such as aviation, aerospace, and military engineering.
Over the past decade and more, as this technology has matured and gained wider adoption, it has found significant applications in civil sectors such as machinery, electronics, and decoration. The film obtained through micro-arc oxidation technology boasts significant performance advantages over that from conventional anodic oxidation. However, it also has a notable drawback: high energy consumption and lower film formation efficiency. Researchers in related fields domestically have conducted extensive studies on adding substances to electrolyte solutions (such as sodium tungstate, EDTA, citrates, and glycerin in silicate electrolyte solutions) and optimizing the selection of power waveform and frequency to enhance the film formation efficiency of micro-arc oxidation and reduce energy consumption, achieving considerable success. Yet, there is still a way to go before this technology can be widely adopted in small and medium-sized enterprises.
