Metal prep for bonding Ti/CF

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#1

I’m curious for those that bond Ti into their CF/epoxy composites what prep they do on the TI part?

Specifically a secondary bond with an epoxy adhesive to a cured CF/epoxy part.

Thanks

#2

depending on app, grit blast, acetone and then IPA/Ethanol clean. You can also sand with good sandpaper (380grit) and cheese cloth wipe it. There are also various silane solutions, but I don’t know what would work…

#3

I’ve been using the grit blast and then IPA clean approach.

I talked to 3M and they told me Ti has a very active surface and they recommened all kinds of acids and primers before the adhesive.

I’m using DP420.

I’m curious what others do in practice. My specific use would be bonding a carbon fiber tube inside of another tube (Ti).

#4

Go to frameforum.net. Guys will help you. As far I know from them, they use 80 grid sand paper. I read few studies about which grid has best bond properties results and they recommended 80 grid sandpaper. You will not have any problems with galvanic corrosion so you don’t have to take care about it. When I was working on my carbon bike frame I had to use light layer of fiberglass to prevent from galvanic corrosion between carbon and 7075 Al alloy.

#5

Nice frame!

did they recomend etching primer or epoxy primer?

#6

layer of glass cloth between the 2 parts… good idea.

#7

Thanks Carbon Mike regarding Frame forum. I am a member there already.

I wanted to get an idea of what people on this forum were doing. I thought people here might be more aerospace or motorsport orietned?

Here is what I received from 3M after a few e-mails.

From their tech support: “I have been advised that its the surface energy on Titanium that can make a
difference on successful bonding.”

Below is suggested procedures to preparation the Titanium surface prior to
using the 3M Adhesive:

Titanium CP or 6AI 4V both Turco 5578* and improved phosphate fluoride
processing have been used

  1. Vapor hone 140 grit in water – rinse thoroughly with clear running tap
    water.
  2. Degrease – solvent or alkaline process.
  3. Immerse for 15 minutes at 185 ± 5°F in the following bath:
    Turco* 5578 – 420 grams
    Distilled water – Balance to make 1 liter
  4. Immerse for 1 minute in 170 ± 5°F distilled water.
  5. Spray rinse for 5 minutes in hot tap water ~ 130°F.
  6. Air dry for 10 to 20 minutes.
  7. Force dry for 15 minutes at 140°F (maximum).
  8. It is advisable to bond or prime freshly cleaned surfaces within four
    hours.
    *Available from Elf Atochem.

Following is the suggested Primer:

“If you can use MEK or IPA (Isopropyl Alcohol) and abrade the titanium,
clean with solvent, then try the 3M Primer 1945, should increase the
bonding adhesion to the titanium.”

#8

sounds like a difficult process 3M recomended. Turco and 3M primer etc etc.

I myself would 40 grit sand the titanium, clean it with solvent, then iso propyl alcohol… then primer with epoxy primer lightly to not burry the sanding scratches completely. then two thin layers of fiberglass then cf tube.

Not sure if you have checked out their product offerings but Loctite has some awesome epoxy bonding adhesive. Fiberglass will prevent any corrossion from the cf to metal.

#9

any grit paper higher than 150p is just going to polish titanium. Not good for a mechanical bond… that is why i say 40 or 60 grit. I’ve worked a lot with CP and 6-4 ti.

#10

Well, from what I am hearing, Ti and CF will obviously corrode, but it all depends on the application. The largest problem is the CTE mismatch. It you, say, slide a CF tube onto a Ti tube at room-temp, in cold weather, the Ti will shrink and disbond from the CF, unless a strong and compliant adhesive is used. However, if you piece the tubes together while COLD…won’t have the issue.
As for the corrosion, a simple glass skrim can be used, as long as there is no physical contact between the CF and Ti.