"Steve W." wrote in message ...
Ed Huntress wrote:
Right, and now black. The black ceramic knives are sinister looking.
Very cool.

Are you sure they're zirconia? Black is usually aluminum oxide. In
high-performance engineering applications, black may be silicon nitride.

I'll bet they're aluminum oxide (alumina).

--
Ed Huntress

--
Latin: It's not just for geniuses any more.



Nope, It is Zirconium Carbide.
They press the blades from Zirconium Oxide powder, Then they fire them at
14-1500 degrees for a few hours. These blades will be white at this
time,if you wanted a white ceramic this is what you would get. If you
wanted a black blade they run it through a second process called hot
isostatic pressing. During this process the zirconium oxide changes to
zirconium carbide, and you now have a black blade.

Wow, HIPping is pretty fancy for a knife blade. That used to be reserved for
things like jet turbine blades.

Where does the carbon come from to react with the zirconium oxide?

--
Ed Huntress