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High Temp Coating for Aluminum?

I have a 6061 aluminum heat plate which sees temperatures as high as 450 °C. After extended heat cycling in a low pressure environment (vacuum) the surface of the plate begins to change color and hence its emissivity changes. It is desirable to have the color of this plate remain stable due to the resulting changes radiative heat transfer effects.

I am considering some form of ceramic or other high temperature coating. My concern is with delamination, debonding, cracking, etc due to the mismatch in CTE. A material with TC similar to that of Al along with a relatively low emissivity (i.e., light and/or shiny) is also desirable.

I would appreciate any recommendations for coatings and/or experts which whom I can speak about this.

Sincerely

Brian Severson
product designer - Phoenix, Arizona USA
October 23, 2009