Effect of Chromium on Corrosion Resistance of Aluminum Brass

Atrace amount Cr was introduced into HAI77-2 aluminum- brass(denoted as Al-Cu) so as to improve its corrosion resistance in seawater and industrial cooling water.The corrosion rate and electrochemical behavior of six kinds of Al- Cu samples with different Cr dosage in 3.5%NaCl solution and 3.5%NaCl +0.5mol/L NH_4Cl solution were determined.The morphology and elemental composition of the corroded surfaces of the Al-Cu samples were analyzed by scanning electron microscopy and energy dispersive spectrometry,and the effect of Cr on their corrosion behavior was investigated.It was found that,on the one hand,Cr tended to agglomerate on Al-Cu alloy surface thereby reducing the corrosion resistance;on the other hand,Cr was able to form a passivation film on the alloy surface thereby improving the corrosion resistance.Moreover,the Al-Cu alloy containing 0.65%Cr exhibited good corrosion resistance in 3.5%NaCl,but Cr was unable to improve the corrosion resistance of the Al-Cu alloy in 3.5%NaCl +0.5 mol/L NH_4Cl solution.