Alloying Elements And Thermal Processing On The Organization And Performance Of The Magnesium Anode

The properties of electrochemical and corrosion resistance of magnesium anode depend on the alloy component and microstructure. In this work, the influences of Hg, Ga, Sn and Zn elements, rolling and heat treatment on the microstructure and electrochemical properties of Mg anodes were researched, and offered theoretic foundation for producing Mg anode materials of high electrochemical activity and low corrosion rate. The concents are as follows:1. The effects of Hg, Ga, Sn and Zn elements and their contents on the microstructure and electrochemical properties of Mg anodes were studied. The results demonstrate that the four kinds of binary magnesium anodes have the similar as-cast microstructure, which are eutectic structures consisted with a-Mg and the second phases. The Hg element can improve the electrochemical activity of Mg anodes significantly, but reduce the corrosion resistance of Mg anode at the same time. The effects of Ga, Sn and Zn are to enhance the corrosion resistance and improve the electrochemical activity slightly.2. The influences of rolling and heat treatment on the microstructure and electrochemical properties of Mg-Hg-Ga anode were studied. The results show that the homogenizing at 400℃for 24 h can eliminate the alloying elements segregation of the cast Mg-Hg-Ga anode and improve its electrochemical properties. When the Mg anode anneal at 150℃to 300℃after rolling, the amounts and size of dispersed spherical second-phases increase with the temperature rising, the corrosion resistance of Mg anode plate reduce with the temperature rising, and the electrochemical activity increase when the temperature is lower than 250℃and then reduce. Mg anode plate gained the best performances at 250℃annealing.3. The activity mechanism of Hg and Ga elements were researched. The ions of Hg and Ga are reduced by Mg and form Mg amalgam with Mg, which react with water quickly and produce further precipitation of Hg and Ga. The circle of reaction accelerates activation. At the same time, the precipitation layer can block corrosion products and activate the Mg-Hg-Ga anode.