Electro-corrosion machining of aluminum in alkaline solution and passivated mechanism

Aluminum mandrel was electrolyzed in 1 mol/L sodium hydroxide solution using the electrolytic corrosion device. The relationship between voltage and current was got by changing the voltage (4-28 V). The surface of aluminum was absolutely passivated when the voltage was higher than 28 V. Activation energy was obtained from data fitted by changing the electrolyte temperature (20-35 ℃). Images of surface passivation samples and non-passivated sample were got from SEM. Non-passivated and passivated samples were analyzed and characterized by XRD. The main component of surface passivation layer was bayerite. Surface reaction process and passivated mechanism were inferred from the main component of passivation product.