Performance of Aluminum in Bimetallic Assemblies

This paper discusses the corrosion performance of aluminum alloys for automotive applications when employed in bimetal assemblies. The basic electromechanical principles of galvanic corrosion are reviewed, and a series of accelerated corrosion tests performed on dissimilar metal assemblies is described. The relevant factors most severely affecting the degree of corrosion are: type of dissimilar metal, anode-to-cathode area relationship, and type of environment. Approaches to combating galvanic corrosion of aluminum include use of compatible parts, paint coatings, sealants, tapes, and gaskets.