Anodizing diy led Heatsinks

[vanished88]

I have been looking into ways to coat the heatsinks so that corrosion is not an issue. Anodizing them seems to not interfere with heat disapation, but does anyone know if it will hinder thermal conductivity (between the led and the base of the heatsink, if the heatsink is anodized on the bottom aswell)? If this is doable; i believe i can build a module that looks as nice as the AI module, but at half the cost.

 

[cr500_af]

Pretty sure it won't. Anodizing is purely a surface hardening process (done with electricity in an acid medium). The anode I'm pretty positive doesn't deposit any material on the aluminum, but is only present to electrically charge the acid. Even if it did, the anode used is copper which is a good thermal conductor by itself.
The color you see is done after the actual anodizing, by boiling in a dye mixture. There is a really good DIY site (the guy makes telescope parts and sells the chemicals for anodizing) but the link is on my desktop which is dead at the moment.

Edit: found the link.

 

[bruce 1]

I would like to see your LEDs when you get finished.

 

[rbredding]

cr500_af;629191 wrote: Pretty sure it won't. Anodizing is purely a surface hardening process (done with electricity in an acid medium).

I'm pretty sure that B's right..


could you be thinking of Powder Coating (maybe)?


on a side note... the heatsink is probably aluminum (or an alloy)... shouldn't be too much corrosion as long as it doesn't actually come into contact with the water..

and it should be high enough above the tank so that if it does come into contact with water, it'll probably mess up the LEDs first...

 

[ichthyoid]

First-
FYI- To anodize aluminum, it must be the correct grade, as all aluminum does not lend itself to this process. It is an oxidizing process of the surface. There are many different methods to give different properties, colors, etc. Black anodizing is a softer surface, than untreated aluminum.

There is a reduction in thermal conductivity as well, to answer the OP's original question. However it will not likely be enought to cause any problems with the relatively low amount of heat dissipated by some LED's.

Check the grade of aluminum required first, then find heatsinks with that alloy. There are several local businesses that will do this for you, and may even help with sourcing. You can even DIY, if you are competent with caustic chemicals and electrical equipment. If you are not, leave it to professionals-IMO.

 

[rjrgroup]

Ah, I knew this tube of heat-sink compound would come in handy one day...
The anodizing won't interefere with heat transfer but could possibly leach in to the water if it's not completely cured. Take the heat-sink up to a temp above 180+f. Then cool to below 50f. The heat flux will cure and harden the anodizing. Oven and fridge are 2 easiest ways to achieve this. Oh, don't do black or other dark colors, they're more difficult to cure properly. Gold or silver is probably best, IMO.

 

[vanished88]

Rbredding;629212 wrote: I'm pretty sure that B's right..


could you be thinking of Powder Coating (maybe)?


on a side note... the heatsink is probably aluminum (or an alloy)... shouldn't be too much corrosion as long as it doesn't actually come into contact with the water..

and it should be high enough above the tank so that if it does come into contact with water, it'll probably mess up the LEDs first...

I realize i cant powder coat them, I just wanted other opinions on mounting the led to an anodized surface instead of bare metal. I am getting pricing on the anodizing, i may or may not have this done depending on the cost. I am planning on getting some acrylic from homedepot and building some enclosures that will cover the leds so I do not have to worry about water splashing.

Edit:

bruce 1;629200 wrote: I would like to see your LEDs when you get finished.

you are more than welcome to come see them. I am just in the researching/pricing stage at them moment. I was planning on building these over the summer but I ended up registering for summer classes so I will have to see how time/money goes. I am still waiting on my tank to show up (will probably be here in about 4 weeks) so I can get some final measurements on the inside of the canopy and start welding up a lighting rack.