Any way to anodize a heatsink?

[Szech]

I was looking through my spare parts drawer, and besides an old SCSI card and a bunch of thin coax cables, I have some heatsinks that aren't doing anything productive. Thought I'd put them to some use. Long story short: is there any way to paint a heatsink black? Because it absorbs the heat better, right?

[Szech]

Why would they anodize heatsinks black then? Doesn't it cost more?

[Dave_H]

I think the reason they anodize them is because unprotected aluminum would oxodize and that would interfere with the heat transfer. I don't think the color matters, I have seen red and blue ones.
Dave
edit- anodizing also makes the surface of the metal harder and more durable-edit

[This message has been edited by Dave_H (edited 05-12-2000).]

[reddog4629]

Color doesn't matter unless it's out in the sun. http://sysopt.earthweb.com/forum/biggrin.gif

[thekingofpain]

If I remember back to my motorcycle racing days...bare UN anodized/painted aluminum released heat more efficiently...

[pickel]

Flat black high temp engine enamel works the best . I have my motor painted as such and it disapates heat better. My motorcycle engine is the same but glossy, for appearance but still disapates heat better. Shouldn't really make a difference inside a computer box, I wouldn't think (?).

the pickel

[tonym]

The rason a heatsink is anodized is to increase the surface durability and to prevent oxidation in the application.

Heat + Moisture + Crud = Oxidation and Pitting.

Also, the black anodization looks sexy! In an application where there's a fan blowing at the thing, it could be painted green for all that matters...the torrent of air passing over the fins swamps out any other thermal transfer.

So, use the sinks in the color that they are...unless they're unplated (over time you'll get intermetallic crud (normally acid-based pitting from free sulfur in the air and where you've touched it -- sweat!). If they're obviously unplated, ditch them!!!


Tony

[dkozloski]

Compared to conduction and convection, the amount of heat transferred by radiation is inconsequential so it doesn't matter what the finish is. Look at a Golden Orb for example.

[Missing the point]

I kinda wanna anodize the fan covers, but I dont know anyone areound me that can anodize http://sysopt.earthweb.com/forum/frown.gif

[tonym]

Any competent plater in your area should be able to anodize (black, hard, etc.) an object. Look in the yellow pages under "Plating".

It's probably going to cost you a few $$ for the setup charge, but it can be done!

Good luck...


Tony

[Axel]

I understand custom painting a CPU case - I understand painting a keyboard and a mouse, I even understand the little fuzzy animals people put around their monitors, but WHY bother painting a heat sink?

As far as oxidization goes, if you have fans in the unit, it should be hot enough in a CPU that's kept running to avoid oxidization for the life of the unit. best to leave it unanodized and DEFINITELY unpainted for best heat transfer..... The thing to look for in a good heat sink is surface area - buy the biggest one that will fit with the biggest vanes on it and then add a bunch of fans to the case to insure good air flow - also - make sure your ribbon cables for IDE, floppy and SCSI don't badly obstruct the airflow.

additionally - oxidization is mostly a problem for people who turn off their systems inbetween active use especially if they live in a humid climate like Florida or Washington State. They will want an anodized heat sink to avoid oxidization.

As for the color black - it doesn't "attract" heat or transmit heat better - the color black only reflects less light - so, a black brick in the sun would get hotter than a white brick in the sun as more light is reflected away from the white brick......

Anodizing a heat sink plates the aluminum material with another metal which is less prone to oxidization - (i.e. rust on iron - white powdery stuff on aluminum, green stuff on copper) - on engine parts and car bumpers this plating material is typically chrome. Aluminum is plated with different metals which come in different colors such as gold and metalic blue, etc. etc.

Paint actually insulates a metal which will slow oxidization, but also slows heat release, so paint is a bad idea for a heat sink.....and I don't care if bubba thinks painting his engine black makes it release heat faster - that's bunk..... It just keeps it from rusting as fast.....

next.....

[Axel]

additionally - the metal has an electrical lead attached to it and is dipped in a solution which has the plating material suspended into it. Current is applied to the container closing the circuit with the lead attached to the part to be plated. The electrical charge causes the suspended material to bond to the surface of the metal item to be plated in an even coat. - and thus the plating material sticks to the metal object in an electrolytic bond making for a tough oxidization resistant surface.

Don't do this at home folks - typically, the suspended plating material is toxic - fido won't survive a quick drink from your plating vat.