Plating on Zirconium and Titanium

Question:

Do you have a recommended pretreatment cycle for zirconium and titanium prior to being plated with platinum?  Any suggestions would be greatly appreciated. R. G.

Answer:

Here are two pretreatment cycles that should work for you:

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Titanium Pretreatment Cycle Degrease in solvent or aqueous cleaner Rinse thoroughly in DI water
Acid dip in a solution (room temperature) of Sodium dichromate 400 g
Hydrofluoric acid (48%) 25 mL
Water to 1 L

Rinse thoroughly in DI water
Platinum plate from an ammoniacal plating solution. Periodic reverse is often used for this step. One sequence is cathodic (six sec), anodic (three sec), at a
CD of 45–50 asf.

Zirconium Pretreatment Cycle

Thoroughly clean in an alkaline cleaner
Rinse thoroughly
Chemically polish in a solution (room temperature) of
Ammonium bifluoride100 g
Fluosilicic acid (100% solution)80 g
Nitric acid (100% solution)400 g
Zirconium (dissolved in solution) 3.0–4.5 g
Water to 1 L
Rinse immediately
Acid dip for 1–3 minutes at 100°F in a solution of
Ammonium fluoride35 g
Hydrofluoric acid30 g/L
Water to 1 L
Thoroughly rinse
Nickel plate in a Watts nickel bath at a pH of 2.5, 140°F, 35–45 asf. Hydrogen peroxide is recommended as the antipit agent.
Rinse thoroughly
Bake 2–4 hours at 400°F
Vacuum heat treat at 1,300°F for 30 min
Clean in an alkaline cleaner
Acid dip in 50% hydrochloric acid
Rinse
Platinum plate from an ammoniacal plating solution. Periodic reverse is often used for this step. One sequence is cathodic (six sec), anodic (three sec), at a CD of 50–60 asf.

Please note that these procedures use materials that are very hazardous and must be treated with great care. Also note that in the case of zirconium the process is long and demanding.

Additional information on how to handle tough substrates can be found in Electroplating Engineering Handbook, 4th Edition, Lawrence J. Durney. The book is out-of-print but available at www.amazon.com.