Current efficiency distribution in aluminium anode metallurgical and electrochemical studies

摘要

A LUMINIUM ANODES (Al-Zn-Mg-In) were prepared under various casting conditions and were electrically coupled to steel structures to provide cathodic protection. The current efficiency was found to be dependent on the microstructures of the cast anodes which, in turn, vary with the locations in the cast structure. Anodes from the edges have, in general, a higher current efficiency than those from the centre, and exhibited a more-negative closed-circuit potential of - 1.10V (SCE) as opposed to - 1.06V (SCE).It is believed that the precipitation or microsegregation due to varying solidification rates make such differences in current efficiency, as well as the galvanic potential. The precipitates dispersed uniformly in the whole grain of the outer anodes, but accumulated along the grain boundary in anodes from the central part of the cast.