Conversion Coating of Titanium Alloys

Question:

What can you tell me about conversion coatings for titanium alloys? I recently spoke with an individual who works for an aerospace metal finishing company. He mentioned that the company performs a fluoride/phosphate type conversion process. What is it? S. A.

Answer:

Yes, there is a fluoride/phosphate type conversion coating for titanium alloys. It is typically used to prepare the titanium alloy surface for anti-galling and organic finishes. The typical conversion bath has the formulation illustrated in Table II.
Typically, the parts after cleaning are immersed in this bath for 2–4 minutes. The bath temperature should be maintained at 80°F (plus or minus 10).

Before you even consider using this process you must obtain a copy of the specification and verify that you are equipped to work with the chemicals listed in the formulation. Details for this procedure can be found in the AMS Specification 2486D which is available from SAE Aerospace, (877) 606-7323, www.sae.org.