Originally Posted by sospan
Originally Posted by Themorganeer
Have used stainless steel screws to sheet aluminium without galvanic corrosion problems by applying clear mastic sealant to the screw threads and thin rubber washers under the screw head.

Excluding water equals no electrolyte equals no corrosion.

Mixed metals+moisture = corrosion.
An electrolytic cell is formed with resulting corrosion, usually one of the metal components, depending on what metals they are. Think sacrificial anodes often used in marine environments. The zinc( usual metal) corrodes instead of the steel hull of a ship.
The usual simple option is to remove one of the components ( moisture or change metals) to prevent or manage the effect. Separating the metals with non conductive material also helps.

Its well documented the potential (pun?) of galvanic corrosion between stainless and aluminium but this is mitigated if the latter is of a large surface area.

Richard

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