Electrochemical characterization of trc 7072AA for heat exchangers

Abstract

We present the results of corrosion potential measurements of DC and TRC cast 7072AA used as a fin material in mechanical heat exchanger applications. The alloys used were continuously cast to two different gauges and Zn,Ti Fe and Si content, using twin roll casting technology. Optic and electron microscopy was used to correlate the electrochemical results with microstructure at the surface. It was shown that higher solidification rates developed during twin roll casting at much thinner gauges resulted in much lower corrosion potentials. This in turn made us possible to reduce Zn content to improve the thermal conductivity while maintaining the desired corrosion potential. Unlike Zn and Ti, higher concentrations of Fe and Si added with the purpose of retaining adequate strength at much thinner thicknesses do not have an adverse effect on corrosion potentials.