Friday, April 20, 2012

Epoxying Carbon Fiber Composite To Aluminum

It appears that there are some corrosion problems with epoxying carbon fiber composite to aluminum. Loctite's Hysol is apparently the preferred method of doing this.

4 comments:

Rorschach said...

so instead of using aluminum use Stainless Steel. problem solved. then you can use much cheaper (and almost as strong) epoxy like JB Weld. the weight difference would be virtually irrelevant. AND it would be a buffer between the Carbon fiber and the aluminum blocks. Here's the thing though, I don't believe corrosion is going to be an issue because the epoxy is an insulator. now if it were a mountian bike schlogging through mud and being put away wet and dirty that might be a different story, but we are talking about a precision optical instrument that is going to be cared for like a baby. not quite the same thing.

Mauser said...

Yeah, we have to use seal between Aluminum and Carbon Fiber on aircraft to prevent corrosion. (Imagine the Bathtub caulk from hell, and make it carcinogenic. That's daily work for me.)

Anonymous said...

The corrosion issue is real, and relevant in aircraft and marine and perhaps bicycle applications, but I doubt that it will be relevant in your application.

If you do it right, you will have a dielectric layer of epoxy intervening against any direct contact between exposed carbon fiber and aluminum. Just be certain that you have enough clearance to maintain the epoxy layer when the joint is fitted.

Without the set screw, you also have no fasteners that penetrate or bear upon both materials.

In an aircraft and marine applications, you have joints that experience extensive flexing over the life cycle, and that can have substantial exposure to water.

Your application is nearly static, is not going to be used in sea water or salt spray, and will not kill even one person, much less hundreds, if it fails.

Anonymous said...

IIRC the galvanic pair of aluminum and graphite has the highest potential voltage of any common pair. So I imagine that aluminum and carbon fiber are close behind.

Does it matter on a telescope used in a desert? Probably not.