Bonding Metals to Carbon Fibre Panels

[ozzy]

Hi guys
I know lots of you are doing it, I have had a big search through the forums but can't find any details on what adhesive you are using. Specifically, we would like to bond structural carbon panels to our steel spaceframe.

We would be able to fasten it as well, but we would like to use some adhesive to give it more strength

Thanks

[ozzy]

Hi guys
I know lots of you are doing it, I have had a big search through the forums but can't find any details on what adhesive you are using. Specifically, we would like to bond structural carbon panels to our steel spaceframe.

We would be able to fasten it as well, but we would like to use some adhesive to give it more strength

Thanks

[Travis Garrison]

You might try simply scuffing your tubes and doing a wet layup...if not that then I would suggest flipping through Loctite's catolog. We made good use of products like their room temp 120min cure epoxy (E120HP I believe? James will probably jump in here and correct me)

On something like bonding to a space frame I really would look at the shape of your joint, try and avoid the line contact you're going to get if you simply bond flat pannels onto a tube...That pannel really needs to wrap completely around whatever you are bonding it to if at all possible. Do that right and you could probably get away with something as nasty as 5min epoxy from the hardware store.

Travis Garrison

[fsae_alum]

I work for a aeorspace composite part manufacturer and I just asked our resident bonding guru your question. He recommended using Hysol Loctite EA 9394. He said that it's about $100/quart. He also recommended getting online to Loctite's website and thoroughly reviewing their surface preparation guidelines as THAT makes a huge difference. Also, I'd follow the advice mentioned in the post directly above mine with regards to wrapping the material around the tube.

[Erik C]

I agree, 9394 (Hysol) is incredible stuff. With a good bond prep, the bond is stronger then the interlamminar shear strength of the laminate. i.e. the laminate will fail before the bond does. Just be sure not to unknowingly get it on your cloths, and then sit in your street car. Bad news..... http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Jon]

Aren't there corrosion issues with having carbon composites in direct contact with steel?

[fsae racer]

Another product to check out is 3M's dp420, dp460ns, or dp460. If you do check all the specs and find some good deals on either the 3m or the locite prices, please let me know. Thanks. Oh, and I definitely agree about surface prep and wrapping the carbon around the tube its bonded to.

[James Waltman]

ozzy,
Do a search for "Epoxy"�. Some of the results will be helpful.

I think that a wet layup over the tubes would be the strongest way to attach panels. Getting it to look nice would be a horrendous. I think that the whole process would be a nightmare.

You mention that you would be able to fasten it as well. What do you have in mind?

Travis is right: Loctite's E120HP is awesome stuff. The EA 9394/C-2 requires an elevated temperature cure. If you are willing to do an elevated temp cure there are better options with one-part epoxies. You really need to know what you are doing if you want to use elevated temp.

Surface prep is absolutely critical (already mentioned several times above this). Our testing showed that the E120HP bond (aluminum to carbon fiber) was also stronger than the interlaminar shear strength of the carbon fiber. It was cool to see the joint fail because the top layer of carbon fiber ripped off - not because the bond was bad. The shear strength for the E120HP is several times higher than that of 3M's DP460 (through our testing).

Travis had a really good idea for attaching panels the other night but I'll let him share if he wants.

[Erik C]

You don't necessarily need to cure 9394 at an elevated temp. It does speed the cure time up quite a bit though. At room temp, you are required to cure for 7 days. But it's fairly easy to make a small tent and use heat guns to elevate the temp to around 120F, at which it takes only 6 hrs to cure. At 180F, a full cure can be achieved in 3 hrs.

As an interesting side note, when testing lap shear specimens. The bond strength goes up at elevated temp/wet, where the strength of the laminate decreases. This is most likely due to the fact that the laminate gets "softer" at ETW, which reduces the peel loads at the edges of the bond. Now if we could just get a mathematical model to predict this...or at least one that works. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Carlos Roldan]

Does anyone have any experience with using 3M's VHB foam tapes for bonding metal parts to Carbon fiber panels or vice versa?

I'm looking for a waterproof yet slightly flexible "permanent" bond.

[kapps]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jon:
Aren't there corrosion issues with having carbon composites in direct contact with steel? </div></BLOCKQUOTE>

Not so much with steel. Aluminum, definitely.