Carbon Fiber and Aluminum?

[scooter2131]

I didn't find any mention of this on the forums after a brief search so I apologize in advance if it was in fact covered somewhere else.

I've heard that the epoxy/resin used in carbon fiber layup causes aluminum to corrode. Can any composite junkies tell me more about this? Can the aluminum be surface treated even just clear coated in order for the corrosion to be prevented?

If that is not possible, will prepreg evoke the same problems with aluminum? What metals, other than steel, will the resin interact with without corrosion?

[scooter2131]

I didn't find any mention of this on the forums after a brief search so I apologize in advance if it was in fact covered somewhere else.

I've heard that the epoxy/resin used in carbon fiber layup causes aluminum to corrode. Can any composite junkies tell me more about this? Can the aluminum be surface treated even just clear coated in order for the corrosion to be prevented?

If that is not possible, will prepreg evoke the same problems with aluminum? What metals, other than steel, will the resin interact with without corrosion?

[MikeWaggoner at UW]

No. Epoxy does not corrode aluminum. Epoxy in fact serves a good insulator for galvanic corrosion. Galvanic corrosion, with aluminum as the anode and carbon as the cathode. If the aluminum is larger in area than that carbon, you likely won't have problems.

That said, I've worked on a number of cars, and looked at team's previous cars, and haven't seen much galvanic corrosion. Even the most run cars only get ~200 hours outdoors time (unless maybe you store outside), and it'll probably take longer than that unless you're running on salted parking lots or something.

I recommend reading about galvanic corrosion a little.

BTW, if you try to protect the Al with clear coat or additional layers of epoxy, you're basically making your bond shitty in strength and less stiff.

[Travis Garrison]

Mike's right on the money...technically it's a problem, and you may get quizzed about it in the design tent...but realistically its a non issue for us...

The standard method used to insulate carbon plys from aluminum honeycomb in aerospace is a barrier layer of fiberglass...coatings may also do the trick but a single thin ply of fiberglass is just easier to deal with in most cases...

[nathan s]

Are we talking about honeycomb, like Travis is talking about, or just carbon to aluminum pieces? I ask because I think there would be problems having the resin to stick to the flat surface. If not, how do you get it to stick? I have always heard of people glueing carbon to aluminum.