The Study On Al Zn In Sacrificial Anode Polarization Property And Field Sea Experiment

Aluminum alloys sacrificial anode has a big drive potential for metalconstruction, high theoretical capacity,rich resource, low cost, convenient construction,and many other advantages, so it not only has been widely used in steel structureequipment cathodic protection of marine engineering,but also is currently the mostwidely used sacrificial anode. GB/T17848is a traditional method to evaluate thesacrificial anode nowadays.Its trial period is10days,another rapid testing standard isDNVRP401. Its trial period is4days.These methods mainly evaluate sacrificial anodeopen, closed circuit potential, current efficiency, corrosion morphology, but theyignore anode polarization property.But polarization performance relates to thedischarge capacity of the anode, the anode discharge capacity determines anode initialdischarge current. The anode whether release a larger current is closely related with thepolarization property,and polarization resistance Rp is an important parameter tocharacterize the polarization property.A variety of electrochemical testing techniquescan study sacrificial anode polarization property, which is a great significance foranode research and actual production to evaluate the sacrificial anode quality throughpolarization property.In the present dissertation,4kinds of Al Zn In sacrificial anodes are chosen asthe research material.The relationship of polarization resistance at open potential andworking potential are studied by using open potential,constant current test, cyclicvoltammetry curve, and electrochemical impedance spectroscopy,so it can studypolarization property.Finally by means of the selected anode field sea experiment itcan study electric capacity and polarization property.Electrochemical experimental test results show that due to the presence of oxidefilm sacrificial anodes are difficult to dissolve at open potential. Constant current testand electrochemical impedance spectroscopy show that the sacrificial anode oxide film is gradually destroyed, the polarization resistance decreases, and the double layercapacitance increases with anodic polarization. Cyclic voltammetry and ACimpedance show that the polarization resistance increases with the polarizationpotential decreasing rapidly, and finally becomes stable. The anode material withsmaller polarization resistance has a good electrochemical performance, this isconsistent with4d accelerated test evaluation results.The field sea experiment of sacrificial anode results show that the currentefficiency of the two sacrificial anodes in field sea are higher than that of four daysaccelerated test in the lab. The corrosion morphology of the two anode materials aregood, there is not localized corrosion,and the corrosion products are easily to falloff.Among that the current efficiency of Al Zn In Mg Ti anode is higher than that ofAl Zn In Si. Al Zn In Mg Ti anode can output higher current in the same exposedarea, the current density of the two kinds of sacrifice anodes increase with the cathodeand anode area ratio becoming larger. The discharge capacity of anode is closelyrelated to its polarization resistance value, cyclic voltammetry is able to characterizethe anode initial polarization property,anode current is inversely proportional to thepolarization resistance of sacrificial anode.So it can get the conclusion that the anodepolarization properties play an essential role on the quality of sacrificial anode.