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-----Golden yellow finish on aluminum
Q. I would like to know what is needed to have a yellow gold finish for aluminum. The current density and voltage required for this bath with the basic chemicals that are needed to get the finish.
Suresh VenkataramanVallabha - Vadodara, Gujarat, India
2002
A. Your question is vague to me, Mr. Venkataraman. A yellow gold finish can be achieved with paint, with tinted lacquer, with electrophoretic coatings, with a chromate conversion coating, with a dyed anodized finish, with brass electroplating, with gold plating, with titanium nitride sputtering, and probably a number of other ways as well. A few of these finishes (electrophoretic lacquer, anodizing, and electroplating) would involve electricity applied in a bath. What are the components in question, and what is required of the finish besides looking "yellow gold" in color?
Thanks.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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2002
Q. Mr Ted Mooney,
For aluminium that is used in aircrafts / helicopters for fuel tanks they give a yellowish coat for protection, can you kindly guide what this coat is -- is it simple chromate finish
Thanks for the focus provided, gentlemen.
- vadidara, gujarat, India
April 8, 2012
A. Hi, Suresh.
Yes, a simple chromate conversion coating (which does not use electricity) can be applied to aluminum for corrosion resistance and conductivity, and it is often a yellowish color. The steps usually involve alkaline non-etch cleaning, alkaline etching, and desmutting (to remove non-aluminum alloy materials) before the conversion coating.
These days many finishes must be RoHS compatible, and that yellow color comes from hexavalent chromium, so it is not used as much as formerly. There are trivalent chromate conversion coatings, but they are often colorless. You can see MIL-DTL-5541 [⇦ this spec on DLA] for more information, or contact the major vendors of chromate conversion processes like Macdermid for the Iridite trade name, Henkel for the Alodine trade name, or Chemetall.
Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
April, 2012
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