Has anyone ever tried this?

[Caravan]

I don't even know if it's possible.

OK... You take a Cak which is all copper and electroplate aluminum on to the outside. Then you lap the bottom until you get to the copper.

Sinse copper conducts heat better, the heat will get to the fins, then the aluminum will radiate the heat to the air better.

I know nothing about electroplating, but perhaps someone does and has the means to try it.

 

[klosters64a]

Heat transferred to the air via radiation is only a very small percentage of the total heat that heatsinks dissipate. Conduction and convection are responsible for the majority of heat that HS's get rid of.

Your idea does make sense, in that copper oxidizes. That green patina looks stylish on church steeples, but it's not wanted on heatsinks!

As aluminum is the only metal that forms an oxide that prevents further oxidation, copper heatsinks with an aluminum skin won't oxidise. Shame to lose that expensive copper gleam. It's always something!

 

[Hoot]

Copper conducts heat almost 100% better than Aluminum, buts doesn't want to give it up as easily to airflow because of the increased density. With thin fins, the density is not nearly as big a limiting factor on giving up the heat. If you add aluminum to the fins, nothing positive would probably be accomplished.

Hoot