Question about anodizing

[duster]

Hi guys!

Sorry for the dumb question but I was always wondering...


While anodizing on a heatsink could be a good idea for its electrical insulation property, I'm wondering if it's really a good idea according that it also induces thermal insulation...?

I mean...maybe not a real concern for a P4 if the heatsink is big enough but I think it could be a problem with a power angry P7.

Any input about this? Am I wrong?


Thanks!

 

[Oznog]

Actually anodized heatsinks have HIGHER dissipation.

It doesn't affect the convection part, but it has a strong affect on IR emissivity. Oddly enough, shiny polished metal is terrible at emitting IR. Emissivity of polished surface is like 20x lower than black anodized.

If you paint it black, the paint improves the surface emissivity but the paint acts as an insulator keeping heat from that surface. But anodizing is so thin, and creates metal columns, that this doesn't happen.

http://www.aavidthermalloy.com/products/extrusion/anodize.shtml

Overall significance of this depends on how much convection cooling vs radiation. On a flashlight with no force air cooling, convection is kinda low and radiation part is more significant.

 

[KowShak]

Actually anodized heatsinks have HIGHER dissipation.

I would dispute that.

A matte black coating on the outside of a torch might make the torch able to radiate more energy but the question (if I understand it correctly) was about a heatsink, inside a torch body. Any heat-sink contained inside a torch relies upon conduction for the most part to disipate its heat into the torch body, any gains in radiation caused by the anodisation will be insignificant compared to the loss in conduction caused by insulating the heatsink with a thin layer of non-conductive aluminium oxide.