Quote:
Originally Posted by Bob Kuykendall
I have definitely seen it. It mostly happens when you lay carbon up directly on aluminum. It is a galvanic reaction between the carbon and the aluminum that causes the aluminum to corrode. It is especially nasty if the carbon/aluminum interface gets wet.
I haven't seen this reaction happen when bolting or riveting aluminum to cured carbon. The epoxy resin does tend to encapsulate the carbon and prevent the direct contact that results in the galvanic reaction. However, just to be on the safe side I generally include a thin glass laminate anywhere I am bonding in a metal part such as a bearing in a spot that is difficult to access or inspect.
Bob K.
www.hpaircraft.com/hp-24
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To add to that and FWIIW - The earlier Bombardier Challenger aircraft had a serious problem with carbon floorboards that were attached directly to the aluminum floor beams. Some corroded so bad they had to have beams replaced within the first few years of service. The fix, if within limits, was to treat the corrosion, paint the beams with epoxy paint, then apply a vinyl tape between, before the boards went back down.
Virtually all new larger corporate aircraft such as Gulfstreams and Challengers have carbon floorboards to save weight and are fitted with a barrier system so carbon can't touch the aluminum. They coat the beams with the epoxy paint also.
Don