Study On Electrochemical Performance Of Aluminum Alloy Sacrificial Anode Under Wet-dry Cycling Seawater Condition

Sacrificial Anode Method,which are used to protect the metal materials serviced in the marine environment. However, there will be some structures suffered soaking and drying environment interaction, inevitably. Make the performance went to bad, shorting the life time. In this paper, we studied the characteristics of sacrificial anode under drywet cycling environment, using the technology of conventional electrochemistry, combining with the potentiodynamic polarization curves, potentiostatic polarization and electrochemical impedance spectroscopy. The parameter of wet-dry cycling included wet-dry ratio, cycle time and temperature. The degradation mechanism of Al anode have been discussed under wet-dry cycling environments.In this work, self-corrosion behavior of Al-Zn-In-Mg-Ti sacrificial anode have been investigated in kinds of wet-dry cycling settings. The result show that the wet-dry cycling can accelerate the corrosion rate of Al alloy. The parameter of wet-dry cycling, which covered the wet-dry ratios, cycling time and temperature, can influence the properties of Al alloy clearly, which the temperature are mostly. The corrosion rate of 30? is four times of 10?. In the condition of high of wet-dry ratios, long of cycle time and high temperature, the performance of Al Alloy will be bad, the morphology be nonuniform, corrosion current became small, some corrosion production adhere to the surfaces. But the corrosion under wet-dry cycling haven't change the corrosion, it just accelerated the corrosion rate of Al Alloy, make the potential bigger.The self-discharge of Al Alloy anode-Q235-A have been reassessed under the condition of full immersion. In this condition, the performance of Al Alloy is perfect: CCP and Outputting Current is stalely, current efficiency is highly, morphology is uniformly, corrosion production is rarely adhered.As wet-dry ratio increased to 1:7, the current efficiency is lower than full immersion, CCP is unstable, the average outputting current is highly. In this environment, it will generates among of production in short time, covering the surface of Al alloy, reduce the performance of reactivation.With the extend of cycle time, the current efficiency have reduce by 15%, compared to the 8h, weighting losing fall off by 1%, the outputting current decreased sharply in the late of soaking, corrosion morphology became worse, and the resistance of surface corrosion have increased. The performance of reactivation will reduce.In system of self-discharge, increase of temperature will makes the output current and CCP of anode reach a steady state, quickly. The steady current, consumption is fast, easy generation, intergranular corrosion. In turn, affect the current efficiency, anode in the steady state of corrosion potential is negative, the corrosion current is larger, the anode consumption accelerated corrosion.