Study On Al-Zn-In Sacrificial Anodes Resistant To High Temperature Media

Aluminum alloys have been employed extensively as sacrificial anode materials,among which Al-Zn-In alloys have the most applications.However,aluminum alloys still encounter the problems of lower current efficiency and nonuniform dissolution in high temperature media(> 50℃).In this paper,based on Al-Zn-In anodes,alloying and heat treatment methods were used to improve their electrochemical performance in high temperature(80℃)media under oil wells so as to meet the protection requirements of oil fields.In this paper,ten kinds of aluminum alloy materials were firstly tested to identify the materials with good high temperature electrochemical performance.Then,based on the selected materials,the effects of solution treatment and alloying with rare earth element Ce on their performance were investigated.In 3.5% NaCl at different temperatures(30℃,60℃,80℃)and 80℃ oilfield formation water,the electrochemical properties of the ten kinds of anode materials(A-J)were evaluated by the 4 days test method according to GB/T 17848-1999.The metallographic structures of seven kinds of anode materials(D-J)and the polarization curves of F,H and I anode materials were tested.According to the real capacity,current efficiency and corrosion morphology of these anodes,F(Al-Zn-In-Mg-Si-Sn),H(Al-Zn-In-0.185Si-0.0055Sn)and I(Al-Zn-In)anodes were selected for their better performance in high temperature(80℃),and they were used for the further study on the effects of heat treatment and alloying on their high temperature performance.F,H and I materials were treated using solution treatments at different temperatures and were alloyed with Ce,and their electrochemical performance in 80 ℃ oilfield formation water were evaluated.The results show that the solution treatment at 510 ℃ has the best effect,which has obvious improvement on the performance of the F material but has little effect on the properties of H and I materials.After the solution treatment at 510 ℃,the current efficiency of the F material increased from 55.38% to 63.61%,the real capacity reached 1856 Ah/kg and the hydrogen evolution rate decreased obviously.Alloying with 0.5% Ce accelerates the hydrogen evolution rate of the F and H materials and makes their electrochemical properties worse apparently,however,has no obvious effect on the I material and just slightly increases its current efficiency.In general,alloying with 0.5% Ce does not improve the high temperature resistant performance of the selected anode materials.