Corrosion behavior of aluminum finstock alloys

A number of wrought AlFeSi and AlFeMnSi alloys are used for fin applications, which require an adequate corrosion resistance. The corrosion resistance of different finstock materials was compared on the basis of electrochemical passivation, pitting and salt spray experiments. The passivity and passivity breakdown (pitting) behavior of these materials were investigated using potantiodynamic polarization techniques in buffer solutions containing sulfate, chloride ions (solutions) and mixtures of these two. As the aluminum fins are often used in configurations with Cu tubes, galvanic corrosion tests were also carried out to understand how different aluminum alloys behave when in contact with copper. Copper decoration method was employed in order to identify the electrochemical activity of intermetallic particles in finstock materials. Samples from pitting experiments and those submitted to the decoration technique were examined to find out about the effect of intermetallic particles on the pitting behavior of finstock materials. An attempt was made to correlate these results with those from the salt spray tests.