Black Heatsinks

Originally Posted by AAngel

I don't want to keep beating dead horse, but...from what I understand anodizing is a process by which aluminum is forced to oxidize, forming this layer of anodizing. If this is true, then black type II anodizing may actually promote the dissipation of heat, while type III may inhibit it.

I just know that type III is some pretty tough stuff. I had a tube that I turned out of 6061 aluminum, then knurled with some pretty aggressive knurling and then had type III anodized black. Although the anodizing did nothing for the tensile strength of the aluminum (it would dent if I slammed it again a brick), I was able to saw into a piece of wrought iron with the knurling without damaging the coating.

I'd bet the heatsinks from Mike are type II (for color only). Type III is expensive and it to improve hardness and wear mostly. Ususally limited to chassis plates and such. As far as heat transfer, any anodizing will improve Al's heat transfer (both radiant and convective), by increasing it's emissivity and etching the surface which improves convection. Polished Al is the worst possible (except for conducting).

Originally Posted by AAngel

All of this regarding the color is interesting. At the risk of sounding like an idiot, I just have to ask. Does all of this mean that I can get my aluminum heatsinks to work better just by "coloring" them with a Sharpie?

I'd use a layout dye normally used to dye metals for scribing marks on them.

Here's a link to an example (the dyes look pretty on metal)......

http://ami.thomasnet.com/viewitems/d...d-2?&forward=1

cadima, thanks. I didn't know that there was any such thing. I'm going to have to get some just to play around with.

Isn't it funny how involved a discussion can get about something as simple as anodizing? LOL