Abstract
Micro-arc Oxidation (MAO) is a technology for non-ferrous metal surface treatment through growth ceramic coating in situ. To determine the influence of the power supply mode and the loading parameters on the film forming of magnesium alloy micro-arc oxidation processing, the different power supply modes of pulsed direct current DC, pulsed bipolar current (BC) and the pulsed with a discharge loop current (DLC) was used with MAO technology on the AZ91D magnesium alloy. The power load parameters were optimized. The average energy consumption was calculated. Results showed that the role of the negative voltage in the bipolar pulse power supply is to restrain the large arc tendency. Under the pulse power supply with a discharge loop, the current and energy consumption decreases with the increase of the discharge resistance at the same pulse parameters. The big arc phenomenon can be effectively avoided and the impact of load capacitance could be effectively avoided by using the pulse power supply with a discharge loop. Moreover, the processing of the micro-arc oxidation is stable, the arc point is uniform, the surface of the film is smooth, the hole is uniform and the coating is dense, and the film efficiency is improved effectively.
Highlights
Micro-arc oxidation (MAO) is a novel surface engineering technique of forming ceramic coatings on some non-ferrous metals, such as Mg, Al, Ti, etc., and their alloys
The MAO method forms an excellent adhesion of ceramic coatings, which would effectively improve the surface properties, such as wear and corrosion resistance, electrical insulation, and thermal properties [1,2,3,4,5,6]
The pulse forms of pulsed direct current (DC), pulsed bipolar current (BC) and the pulsed with a discharge loop current (DLC) were used to prepare the MAO coatings respectively
Summary
Micro-arc oxidation (MAO) is a novel surface engineering technique of forming ceramic coatings on some non-ferrous metals, such as Mg, Al, Ti, etc., and their alloys It is known as anodic spark deposition or micro-arc discharge oxidation. The MAO method forms an excellent adhesion of ceramic coatings, which would effectively improve the surface properties, such as wear and corrosion resistance, electrical insulation, and thermal properties [1,2,3,4,5,6]. It is well-known that MAO technology has ease of controlling and is environmentally friendly. The MAO process was main influenced by the non-electric parameters (solution, temperature, oxidation time, etc.) [13,14]
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