Posted by C(G) on February 09, 2004 at 02:28:00:
In Reply to: Offbeat plating question posted by Frank Rosenau on February 09, 2004 at 00:20:57:
I think you're thinking about titanium nitride. Titanium (di)oxide is very white and is used as a paint pigment base (if your can of housepaint has lots of this stuff, you've got some good paint).
Titanium nitride, on the other hand, is deposited on items using a process called Physical Vapor Deposition or PVD. There are several variations to the process, but basically, the item to be coated is placed in a partial vacuum (various gasses may be introduced to aid in the process), the material to be deposited is converted to a vapor (by sputtering, ion bombardment or arc vaporization) and deposited on the item.
For the typical drill bit, only a few microns of coating are deposited. A popular application would be bathroom "gold" fixtures, cabinet and door hardware, etc. Coating a tuba might be a problem, since the item has to be perfectly clean and non-outgassing. Coating something more-or-less monolithic like a faucet or drill bit, however, is pretty simple. Cost of the process is also related to the number of items that can be processed simultaneously. A one-off like a tuba would be pretty expensive.
I'd love to see a mouthpiece coated via PVD, though.