I work in a (physics) lab in which an aluminum oxide coating is applied to the inner surface of a plasma confinement vessel (made of Cu) to provide an electrically insulating layer that can withstand high temperature environments. The product we use comes in a medium that allows it to be brushed or sprayed onto the metal surface (something like: http://www.zypcoatings.com/aluminum-oxide-coatings/ -- see the data sheets).
I'm wondering if a similar product might exist for black aluminum oxide. I've seen that black aluminum oxide powder exists, but cannot find information on a coating product that is black.
I'd like to understand what the difference is between the two: Does black aluminum oxide have the same physical properties as the white variant? Is it reasonable to expect that a similar suspension or solution of black aluminum oxide in water or a different solvent could be made? What makes one black and the other white? Any information on their differences would be helpful.