Peroxide Etching of titanium for bonding

[will123]

We are currently experiencing some problems with bonding titanium 6Al-4V to epoxy resins- the geometry of the joint in question leaves a lack of access for our standard titanium preparation method; abrasion and then exposure to plasma. Therefore we would like to run some bonding trials after the titanium has been pretreated by etching using a Hydrogen Peroxide based solution as some of my colleagues have successfully used this method in the past. However they do not know the exact formulation of the etchant used nor the time and temperature of treatment.
Is there anyone who could provide me with this information - I have spent quite a bit of time on the web with no success!

Thank you in advance for your assistance.

 

[MintJulep]

From:

Surface Preparation and Pretreatment of Structural Adhesives
-Ciba Adhesives

Titanium
Degrease. Abrade with emery cloth or steel wool, and degrease again.
Alternatively, either degrease with trichloroethylene, abrade with a rotary steel brush and degrease again;
or degrease with trichloroethylene, etch for 3 minutes at room temperature in hydrofluoric acid 15%*, wash off
brownish deposit immediately, and dry.

 

[tomwalz]

I have done it by electro etching in a 15% NaOH solution at 150 F for 4 minutes. The big secret is to keep it under water or whatever) so it doesn’t re-oxidize.

I have several formulas for removing TiN if you think those might help.

I would also try finishing.com for this.

tom


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

 

[will123]

While I appreciate your reply. There are a few reported concerns with acid based etching of titanium alloys, namely waste disposal, hydrogen embrittlement of the titanium material and durability of the subsequent bond in high humid and high temperature environments. For these reasons coupled with positive results obtained previously by colleagues I am specifically interested a formulation for an alkaline peroxide etchants rather than acid.

 

[unclesyd]

Here are several sources of information on the use of alkaline H2O2 for prepping Ti/Ti alloys for adhesive bonding. The NASA report gives the formulations of the enchants they used.

Based on my experience with bonding Ti (Gr2) you will be remiss if you don't use a primer for you adhesive. We used an anodized surface for our work.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20040086632_2004090672.pdf

http://cat.inist.fr/?aModele=afficheN&cpsidt=1496500

http://www.sae.org/technical/standards/ARP1843A