SermeTel vs. Electroplating ceramic surfaces vs. other High Temperature Finishes for Aircraft

A. Not exactly what you were looking for but we have put sacrificial fibreglass layers over aluminium for stone chip protection on 727 flaps. I can't see why it wouldn't be as effective to stop the corrosion you mention. Only the service temp would be an issue but 350 °F is pretty common for fibreglass prepreg service capabilities. It does also put you in the realms of specialist repair facilities which may be expensive. It's just another avenue to consider.

A. Dennis, Sermetel W Class 4 can be a good choice for you.

Regards
Anders S

A. There is a whole world out there of folks plating nonconductive surfaces such ceramics and plastics. The trick is you have to liquid sensitize your part with palladium chloride and tin chloride. After that you can electroless plate nickel or copper. Once nickel or copper plated, you can plate just about anything else you want. Contact your local chemical supplier; they can help you.

A. Dear Nabila,

Plating of ceramics with aluminium is not easy by aqueous plating; it's easy by vacuum. But if you want to plate it with other metals [copper-nickel-gold for example] this is the procedure:
etching: by HF or mixture of [ammonium bifluoride with nitric acid]
activation: by [Pd-tin ] activator
electroless plating
nickel or copper electroplating
acid copper, nickel, etc.

A. Our company does nickel coating on ceramics and other non-conductive materials by the Chemical Vapour Deposition process. We have developed our process to handle a variety of substrates, using direct heating and radiant heating of the substrate. The temperature of nickel deposition (the gas decomposition) is 180deg.C, so that enables us to deposit nickel on many types of material.

A. We use a commercially available aluminum paint (for boat hulls) as the base, to give a conductive surface...

no pre-etching--

just a dip in degreaser and a wash...
attach the electrodes, and into a brine with a chrome anode for about 5 minutes
then another wash,
and a 2 hour plating session with copper (we uses roofing plates).

After two hours, the pieces are washed, patinated and sealed...

---

Thanks, Sam! But a chrome anode? More than 40 years in the electroplating industry and I've never heard of a chrome anode :-)

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

A. Out of plating bath and into a vacuum chamber... you may try PVD!

PVD is certainly an option. It helps if the ceramic is electrically conducting, which most are not. What ceramic are you dealing with? Why do you want the chrome on the surface?

A. Hi Cain. Nickel and electroless nickel passivate pretty rapidly, and after heat treating the surface is probably very passive. Have you tried or considered trying a Wood's Nickel Strike before the chrome plating?

Regards,

A. Ceramic can be plated as follows:
Sensitising ceramic in bath containing 10 gm of stannous chloride dissolved in 100 g ml of HCl per lt of solution; rinse and then put in a bath containing 0.1 gm Pd Cl and 10 ml HCl for one minute.

Then introduce the part in electroless nickel bath containing 23 gm of NiSO4 and 10 gm of sodium hypophosphite and 10 ml of acetic acid ⇦ this on eBay or Amazon [affil links] for a few minutes until the surface becomes coated with nickel. Then do copper strike in bath containing 20 gm copper sulphate ⇦ this on eBay or Amazon [affil links] and 100 ml sulfuric acid.

The ceramic part is ready now for usual plating like any other metal, electrically with conventional nickel electrodeposition and then chromium plating in the usual bath for chromium plating.

A. Hi, Shrikant Nigade.
You can use sodium hydroxide solution with concentration of 250-350 g/L at 75-88 °C. Immerse the part until the gassing stops. It could take 30-60 minutes. Be careful, if you immerse a lot of parts at the same time, the gassing will be very intensive.