Aluminium and bronzes, such as copper nickel alloys like Hiduron® 130, are far enough apart in galvanic potential for galvanic corrosion to occur if they are inadvertently coupled. In that couple the aluminium acts as the anode and is preferentially attacked.
How to prevent it
The simplest safeguard is to combine only metals that sit relatively close together in galvanic potential, which limits or avoids the problem altogether. Where that is not possible, some intervention is needed:
- Isolate the two metals with gaskets or coatings. Take care, as this can create crevices and introduce a different corrosion problem.
- Add a third metal that is more likely to corrode than the other two, creating a sacrificial anode.
- Reduce the corrosive nature of the environment, for example with corrosion inhibitors in the solution.