Plating On Commercially Pure Titanium

Q. Our company has been asked to develop a procedure for plating on commercially pure titanium. Can you give me a procedure for this process? B.W.

 

A. As you have probably found out, plating on titanium is not easy. Titanium forms a tenacious oxide on the surface and in order to obtain a satisfactory plated layer this oxide layer must be removed. In addition, it’s thought that to get the best adhesion the surface must be converted to titanium hydride. Once the plate has been applied the hydrogen is removed from the hydride by baking for a short period of time.

There are a number of ways to generate the hydrogen necessary for this step. Typically an acid treatment of some type is used. A typical process can be found in the Electroplating Engineering Handbook, Fourth Edition, by Lawrence J. Durney, available at www.amazon.com. The process is as follows:

1. Thoroughly clean
2. Rinse
3. Pickle in a 25%/75% hydrofluoric/nitric acid solution until red fumes are evolved
4. Rinse
5. Etch in a 33 oz/gal solution of sodium dichromate at 180–200°F for 20 min
6. Rinse
7. Plate with copper or nickel. An acid copper bath should be used for copper or a Watts or sulfamate bath for nickel
8. If other metals must be deposited, nickel should be deposited as a strike
9. After plating, heat treat 10–15 minutes at 400–450°C to improve adhesion.

Other processes are available, but all require use of some rather nasty materials. Plating on titanium is not a “slam dunk” by any means.