Aluminum and carbon fiber do not mix right! They kind of act like a battery because of the galvanic corrosion that takes place. What are the other alternatives to using metal with carbon fiber? Mainly for threaded inserts, rivets, dropouts, etc. etc… Insight on this would be great! Thanks in advance!
Insulate with fiberglass or epoxy
That’s it, just use fiberglass or epoxy?
Yes. As long as the metal part is isolated by a thin layer of fiberglass and/or epoxy, there will be no galvanic reaction.
That is easy enough! Thanks! What about anodizing? Will the epoxy stick to the anodize?
Aluminum and oxygen love to get together- hence why aluminum oxide is one of the most abundant thing on earth. Consequently it’s really tough to bond to aluminum and get adequate long-term bond strength without great surface prep like anodizing- and even then it’s highly dependent on the prep. Better left to the big boys like Boeing.
You want phosphoric acid anodizing. It was originally developed by Boeing as a structural bonding surface.
Thanks, will be looking into that more!
When assembled, expose a tiny area of bare carbon near the aluminum and a small area of bare aluminum. Do a resistance check between the two areas. If it shows anything other than full open you will most definitely get corrosion and the bond will not remain structurally sound long term.
I used the PACS system many times for a project with Textron, FedEx, for Sandia Labs
to test the use of bonded Boron for repairs to aircraft aluminum
https://www.heatcon.com/phosphoric-acid-containment-system-pacs-video/
This is the report from the project I was on
http://prod.sandia.gov/techlib/access-control.cgi/2007/074088.pdf
I have a VHS tape around here somwhere from it.
Back in the day when I was a composites instructor at an airline, I built a demonstrator device for this. 12"x12" sheets alternating 6ply 3K carbon laminates and .060" 7075T6 housed in a clear polycarbonate container. If I remember correctly is was six sheets of each. All wired up in parallel the box was filled with lemon water. Galvanic reaction in the device netted 1.3V and was used to power our class clock, which was just a standard single battery wall clock. The clock was still operating when I move on to another position.
Nothing demonstrates the power of the galvanic potential between carbon and aluminum like having it power a device.
Thanks for your advice, I didn’t know :blink1: