Any special high strength epoxies for bonding composites together?

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#1

I am going to be making a structural part that will require a lot of strength. What I will need to do is bond 2 seperate CF parts together once they are cured and I need the bond between them to be very strong and provide structural stability. Any recommendations for this? What products to use?

Also what I might need to do is bond (again structural application) some CF to steel. What would be suitable for this? Does steel take well to epoxy? Would I need to abbrade the steel surface for better mechanical adhesion? Would aluminum be better then steel (corosion wise) ?

Thanks!

#2

Well, any metal with CF will end up with some sort of galvanic corrosion. Most of the time there is a layer or 2 of glass between the materials. There might be some other sort of coating for the metal also to prevent corrosion.

For adhesion, check out “silane solutions”, or coupling agents (gelest, Dow, etc). It’s a coating you can put on one or 2 materials to help aid bonding. I put it on aluminum to help the nylon and PP stick better. (after grit blasting and cleaning)
It does something down in the molecular area of materials, not really a glue. Just a helper.

as for epoxy. I’ve had luck structurally with Hysol 9394. It’s a slightly metal filled epoxy. I think most metal filled epoxies are pretty good.

good luck!

#3

thanks good info again.

Any pics of the things you have done with using said appliaction?

#4

Riff, I have looked into the silane products from DOW and think that their 3-6060 product would do the job. http://www3.dowcorning.com/DataFiles/090007c8800023d5.pdf

Just to clarify, the silane solution would be applied to the steel/aluminum bracket and then a bit on the composite where it will be bonded then I apply the Hysol right after and bond the two together? I’m not sure how to use the silane, if it needs to evaporate first or when to apply the hysol…?

I’m going to be doing a lot of googleing, but could you point me in the right direction if you have any info. Thanks.

#5

Well you have to mate the silane with what metal and resin you are using. Check out Gelest for some better app. notes. They might be able to help you out if you call and tell them your application as well. The DOW link looks like something for silicone, not epoxy.
The one I use is for bonding nylon 6 to aluminum. It’s just one out of hundreds they have. I mixed 95% ethanol with 5% water, adjusted the PH to I think 4-5 with acetic acid. after that, added 2% silane. Mixed for a good 10min, dipped my metals, rinsed with straight ethanol (dunno why, seems odd), oven dried, and then processed it. I did not apply any to the nylon, since it melts.

Same thing with composites I would imagine. You would just coat the metal before you put it in the composite, or bond it with glue.

There are several ways to go about what you need I’m sure. COuld be that just gritblasting/sanding the metal will be good enough. Depends on the epoxy compatibility.

#6

Ah, I see, very good thanks again. I will peruse the gelest site for sure.

#7

I’ve had good luck with 3m 8115 panelbond. It’s made for bonding fiberglass to metal. I’ve used it for gussets and end bonding with very small bonding area with very good results.

#8

Thanks! Good to have another option, btw…what’s a gusset?:smiley:

#9

A gusset is usually a third member that is added to strengthen the other two members. Picture a triangle… two sides are the main members, the third member joins the two to strengthen the whole.

#10

Also a rude word in UK !

#11

I agree with Riff, hysol works very well and is extensively used in the auto racing and aircraft field. There are many varieties to choose from.I got mine from a place called, On Hand Adhesives,I think.

#12

I’m gonna have to check out that hysol stuff.

Is the stuff they sell at home depot or autoparts stores too weak? They come in two cylinders joined at the hip with a joined plunger so equal amounts come out together.

#13

if you can use aluminum that would be best, just get the aluminum part(s) anodized, there are many places that do anodizing

#14

REZCAR, I just used some of that HomeDepot quick epoxy glue to glue together some tiny brackets onto the backside of two parts. It seems to be very strong initially ( after a 24hr cure time), but I don’t know how well it would hold up long term and if it is for sturctural purpose best to use what the pro’s use.

Here is the name of the stuff i just used for cosmetic parts brackets… SuperGlue Instant Set Epoxy “sets in 90 seconds” again my parts are just cosmetic.

For a decent price epoxy glue try fiberglasssupply , they sell System Three epoxy glue. It is reasonably priced.
http://www.fiberglasssupply.com/Product_Catalog/Epoxy/epoxy.html#SystemThree

One thing that concerns me about the Hysol 50ml kit is i think it intermixes the resin before it comes out the tip. This would mean it is a one-shot use kit. I don’t like that idea because i use only a tiny amount of epoxy glue each time for what i do. I use maybe 3 grams at a time.

#15

I used that “sets in 5 seconds” or was it 30 seconds stuff once, was waaay too fast!

#16

No, it doesn’t mix before it comes out of the tip. You’re thinking of a static mixer tip that can be added to the cartridge. The cartridges can be used over and over again.