EVALUATION OF ALLOY ANODES FOR ALUMINUM-AIR BATTERIES - CORROSION STUDIES

Aluminum alloys containing small amounts of Zn, Bi, Te, In, Ga, Pb, and Tl, either individually or in various combinations, have been investigated as possible fuels for alkaline aluminum-air batteries. The binary alloys, containing generally less than 1 percent of the alloying elements, exhibit corrosion rates in 4 M KOH at 50 C that are higher than that for pure aluminum in the same medium. Addition of two or more alloying elements can result in a reduction in the open circuit corrosion rate to below that for aluminum, and several alloys containing Ga, In, Tl, and P that appear promising as high performance fuels were identified. Mechanical processing left bracket cold working (CW) right bracket was found to have little reproducible effect on the corrosion rate except for Al-0. 5 percent Ga in which case the corrosion rate was found to pass through a minimum at 50 percent CW. The corrosion rate data also demonstrate that low concentrations of the alloying elements are sufficient to achieve inhibition and that little is gained by exceeding the critical levels.