Corrosion Protection of Low Carbon Steels By Electrodeposited Aluminum Alloys

This paper will discuss recent results from the authors' labs on the corrosion protection of low carbon steels using aluminum alloys. Aluminum based layers were electrodeposited from room temperature molten salts such as mixtures of 1-ethyl-3-methyl imidazolium chloride ([EMIm]Cl) and AlCl₃. These layers are promising candidates for the replacement of cadmium in aerospace applications.  The effect of various process parameters (current density, alloying elements, etc.) on the microstructure and corrosion properties of the coatings will be discussed. As an example uniform and smooth deposits were obtained at current densities of approx. 6 mA/cm² from a bath containing 0.2 mol/L MnCl₂. The resulting Al-Mn alloy contained 20 at-% Mn and showed excellent corrosion protection of the low carbon steel substrate.