Talk Composites - The Forum for Advanced Composites

Bonding carbon fibre into aluminium lugs

http://www.talkcomposites.com/Topic2643.aspx

By jake - 8/18/2012 12:23:54 PM

Hi,

Apologies if this has been covered, a search didn't throw anything up.

Can anyone recommend a product to bond carbon fibre tubes into aluminium lugs as part of repairing a bicycle frame of the same construction- so i would assume a structural adhesive is needed. Obviously high strength is needed, and presumably a very small amount of flex? maybe one of the permabonds (et515?)- not sure which one? I am also concerned about corrosion of the aluminium- is this a necessary worry, and are there any mitigations?

Supplementary question- i'd like to sand back refinish the carbon fibre- would the epoxy coating resin do the trick? does it require lacquering afterwards for a lovely shiny finish?

Thanks for any help!
By Paul (Staff) - 8/20/2012 8:44:53 AM

Hi Jake, Welcome to the forum!

You are right that the Permabond 515 would be suitable for this application, we have supplied this to many home frame-builders and always had good reports, the small degree of flex that it can handle it ideal for the highly shocked joints of a frame. If this is a repair you should really have to worry about corrosion issues the inside to the contacting tube will probably have been insulated from the Aluminium with a layer of glass cloth, not all frame manufacturers bother with this; Galvanic corrosion between a typical carbon laminate and aluminium is usually negligible and rarely results in failure.

As for preparation, simply key both faces with a coarse sand-paper (80 grit), degreasing both before and after, and then bond the joint as normal, leave the adhesive to fully cure; allow at least 48hrs somewhere warm before riding. There really shouldn't be much more to it than that.