Galvanic corrosion is an important topic in corrosion research and modelling can help us better understand this phenomena, especially at the joint interface between dissimilar metals. The objective of this work is to provide a simple to use and easily accessible one-dimensional analytical modelling tool that can be implemented within a spreadsheet program.

This work is a further development of the modular analytical modelling approach introduced by G.L. Song in 2010.¹ Three new types of building blocks (an “inert” block, a “linear transition” building block and a “sigmoid transition” building block) are introduced to the original set of three types of building blocks (a “left” building block, a “bridge” building block and a “right” building block) for this analytical modelling approach. This enhanced model also takes into account electrical resistivity of the electronic current path through the substrate material, which is important for materials that can have significant electrical resistivity, such as carbon composite materials and zinc-rich paints. With these new developments, this one-dimensional analytical modelling approach is now able to model a greater range of corrosion phenomena than previously possible, as the restrictions of having a constant solution resistivity and zero substrate electrical resistivity across all building blocks are removed.

Case studies published in the corrosion literature are analyzed with this model to examine its validity and accuracy. An experimental system of zinc-rich paint on carbon steel was also investigated and analyzed with this model. The benefits and limitations of this approach will be discussed and possible techniques to improve the analytical model accuracy by judicious selection of input values and generation of “performance envelopes” shared.

Reference:

1. G. L. Song, Corros. Sci., 52, 455–480 (2010).