%0 journal article
%@ 0010-938X
%A Nwaogu, U.C., Blawert, C., Scharnagl, N., Dietzel, W., Kainer, K.U.

%D 2009
%J Corrosion Science
%N 11
%P 2544-2556 
%R doi:10.1016/j.corsci.2009.06.045
%T Influence of inorganic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet
%U https://doi.org/10.1016/j.corsci.2009.06.045
11 
%X In this study, the effect of inorganic acid pickling on the corrosion behaviour of a commercial AZ31 magnesium alloy sheet was investigated. Sulphuric, nitric and phosphoric acids of different concentrations were used to clean the alloy for various pickling times. The surface morphology, composition and phases were elucidated using scanning electron microscopy, X-ray fluorescence analysis, spark discharge-optical emission spectroscopy, energy dispersive X-ray spectroscopy and infrared spectroscopy. The effect of surface cleaning on the corrosion properties was studied using salt spray test and electrochemical impedance spectroscopy. The experimental results show that acid pickling reduces the surface impurities and therefore enhances the corrosion resistance of the alloy. The cleaning efficiency of the three acids used and the corrosion protection mechanisms were found to be remarkably different. Best corrosion results were obtained with nitric acid, followed closely by phosphoric acid. Only the sulphuric acid failed more or less when cleaning the AZ31 sheet. However, to obtain reasonable corrosion resistance at least 5 μm of the surface of AZ31 magnesium alloy sheet have to be removed.