Optimization of MAO Process Parameters and Effect of Subsequent Sealing Treatment on Corrosion Resistance of Aluminum Alloy

Abstract:

Micro-arc oxidation (MAO) coatings were obtained on the substrate of AlSi12Cu aluminum alloy in Na₂SiO₃ electrolyte. Then, the MAO coatings were sealed in stearic acid and sodium silicate solution, respectively. Experiments were conducted by varying current density, oxidation time and the frequency. L₉ (3³) of orthogonal experiments were chosen to optimize the processing parameters in the process of MAO technique. Through the above orthogonal experiments, the optimal process conditions were determined: the current density of 30 A/dm², the oxidation time of 20 min, and the frequency of 600 Hz. The results showed that the MAO coating consisted of α-Al₂O₃ and γ-Al₂O₃. There were lots of pores and micro-cracks on the coating surface. The corrosion current of the aluminum alloy after MAO combination with stearic acid sealing treatments was significantly reduced, decreased 100 times more than the substrate and the corrosion potential increased 272 mV, signifying enhanced corrosion resistance. The corrosion rate of the aluminum alloy after MAO treatment in the washing powder solution decreased 25 times more than that of the substrate.

• Periodical: Materials Science Forum (Volume 898)
• Pages: 1438-1446
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.898.1438
• Online since: June 2017
• Authors: Duc Thu Bui*, Sen Yang
• Keywords: Aluminum Alloy, Corrosion Resistance, Micro-Arc Oxidation, Optimization, Sealing Treatment

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