Corrosion Inhibition And Electrochemical Behaviors Of Aluminum In Alkaline Solutions

In this thesis, the applied history of aluminum in electrochemical batteries as well as the development in various kinds of aluminum batteries was firstly reviewed. Then, the author introduced the research development on corrosion electrochemistry of pure aluminum and aluminum alloy anodes, including corrosion mechanism and solution-phase inhibitors, etc. Based on this, the corrosion and electrochemical behaviors of aluminum in the inhibitor-containing alkaline solutions were systemically investigated.In the third chapter, the cooperative effects of alkaline earth metal ions and EDTA on the corrosion inhibitor of pure aluminum in alkaline solutions were investigated. It was found that the corrosion of aluminum in 4 mol·dm^-3 KOH solution can be greatly inhibited by the addition of alkaline earth metal hydroxides, and calcium hydroxide is found to give largest inhibition effect. Their inhibition is enhanced by the addition of EDTA, while EDTA itself has only a little inhibition effect. The analyses on EIS and EDAX reveal that alkaline earth metal ions and EDTA chelate complexes may produce the inhibition effect on the corrosion of aluminum by adsorbing on the active sites of aluminum surface. And they act as interface inhibitor rather than inter-phase one.In the fourth chapter, the effects of ZnO as inter-phase inhibitor were investigated. The corrosion of aluminum can be greatly inhibited by the addition of ZnO. When the alkaline solution only contains ZnO, loose and spongy zinc is deposited on the aluminum surface and easy to fall into the solution. This process consumes more ZnO and aluminum. The inhibition effect of ZnO is further enhanced by the addition of DE at certain concentrations, while DE itself has little inhibitioneffect. EIS and SEM analyses revealed that the addition of DE can greatly improve the deposition of zinc layer, which increases the adhesion between the zinc layer and the aluminum.At the last part of this thesis, in chapter five, the author attempted to employ the alkaline solution with ZnO and PEG as electrolyte and investigated the behavior of aluminum in the solution. The experimental results showed that the inhibition effect is enhanced with the increase in molecular weight of PEG. Among all the PEGs, the inhibition effect of PEG 200 is the lowest. When the concentration of PEG 1000 is 0.001.5 mol-dm'3, its inhibition effect is the highest. It was also found that aluminum shows an excellent discharge performance in the 4 mol-dm"3 KOH solution with 0.2 mol-dm"3 ZnO and 0.0015 mol-dm"3 PEG 1000 , and the inhibition of the additives on the corrosion of aluminum displays some reversibility.