Electroless Nickel on Titanium Revisited

One of our readers had a suggestion for getting a stronger bond between electroless nickel and the titanium substrate. The suggestion is to add a bake step after the deposition of the electroless nickel. The original question and answer is repeated below with the bake step added.

Question:

How can we deposit electroless nickel on titanium parts? F. A.

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Answer:

The key to getting a good adhesive layer of electroless nickel on titanium is proper preparation of the titanium substrate. In the book, Electroless Nickel Plating, Wolfgang Riedel, ASM International, www.asm-intl.org, the following procedure is suggested:

1. Vapor degrease
2. Blast using 220 mesh alumina at 4 bar
3. Rinse thoroughly
4. Etch using 400 g/L HNO3 + 5 g/L HF for 5 minutes
5. Rinse thoroughly
6. Activate using a Wood’s nickel strike
7. Rinse thoroughly
8. Electroless nickel plate
9. Bake at 750oF for 30–60 minutes (added step)

The important thing to remember is that titanium forms a rather tenacious oxide on the surface almost instantaneously when exposed to the atmosphere. Hence, the steps in the above process must be performed rapidly.