Platinum on Niobium and Titanium


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Q. I want to plate platinum on niobium and titanium substrates. Can this be done and, if so, what process do you recommend? K.F.


A. Yes, you can plate on these two substrates, but there are a number of intermediate steps before the actual platinum plating step. Neither procedure is exactly easy, and the titanium procedure, in particular, requires some “nasty” process steps.
A procedure for plating on niobium is given in the book Electroplating Engineering Handbook, Fourth Edition, by Lawrence J. Durney: 

Soak in an alkaline cleaning solution at 195°F for 2 min
Rinse thoroughly
Anodic etch in 10% sodium hydroxide solution at 70–80°F using 5 v to produce a yellow straw color
Rinse thoroughly
Plate in a Wood’s nickel strike bath at 85°F and 30 ASF.
Nickel plate in a Watts-type bath at a pH of 4, at 150°F and 50 ASF
Activate the nickel surface by dipping in a dilute acid dip (50 mL sulfuric acid/L)
Rinse thoroughly but quickly
Platinum plate using an ammoniacal plating bath

The same reference (available on Amazon.com) also gives a procedure for plating on titanium:

Thoroughly rinse
Pickle in a solution of hydrofluoric/nitric acid (25/75%) solution until red fumes are evolved. This step requires extreme caution. Hydrofluoric acid is nasty stuff, and so are the red fumes evolved during this step
Etch at 180–212°F in a solution of sodium dichromate (33 oz/gal) and hydrofluoric acid (4.8%)
Rinse thoroughly but quickly
Nickel strike
Platinum plate using an ammoniacal plating bath