Effect of Electrical Parameters on the Structure and Properties of Aluminum Foil Microarc Oxidation Film

Abstract

Through a three-factor, two-level orthogonal experiment, the effects of varying electrical parameters (voltage, frequency, and duty cycle) on the thickness, pressure resistance, corrosion resistance, morphology, and phase composition of the micro-arc oxidized film of aluminum foil in constant voltage mode were investigated. The aluminum foil was oxidized by micro-arc oxidation for 50 min. Eddy-current thickness gauges were used to measure the oxide film’s thickness, TV characterization testers were used to test the film’s resistance to pressure, kinetic potential polarization curves were used to examine the oxide film’s resistance to electrochemical corrosion, and SEM and XRD composition were used to examine the microstructures and phase compositions of the oxide films that were produced. The oxide film’s thickness was increased from 7 μm to 22 μm and the voltage was increased from 350 V to 450 V. The oxide film’s ramp-up time at a frequency and duty cycle of 2000 Hz and 15% could reach 3 s, and the resistance value could reach 98% of the micro-arc oxidation voltage. The oxide film’s icorr decreased by an order of magnitude at high voltage compared to low voltage and the Rp value increased by an order of magnitude, which improved the corrosion resistance. The oxide film’s thickness increased as the voltage increased. Meanwhile, SEM was used to enhance the corrosion resistance. The oxide film thickens as the voltage increases. At the same voltage, the oxide film with a high frequency and low duty cycle has the best voltage resistance. The oxide film generated under high-voltage conditions has regular and dense surface holes, the oxide film’s α-Al2O3 phase increases, and the corrosion resistance in the NaCl medium is enhanced.