Anodizing Question

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Ripthorn

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I have some small aluminum parts that will see a small amount of wear, and I would like to prevent surface scratches and the like as much as possible. I thought about powder coating using a clear powder, but I have not powder coating setup and would like to see if I can do something with what I have. I have read about home anodizing, but my big question is whether it hardens the surface at all, and if so, to what extent? The parts are 6061 and all I want is a clear finish. I have a large 12V power supply from an old electronics something or other that could be used for this, as well as buckets. The parts are no larger than 3"x3"x.5", so I don't think I would need tons of solution. If it will harden the surface, I may go this route. Any other thoughts would be greatly appreciated.
 
I don't think the home proses will hold up to much wear. You would need hard anodize for wear.
 
The anodized coating is very hard - it is alumina, Al2O3. So I guess it would be resistant to scratches. But beneath the surface it is still aluminum. I mean the commercially done process - I don't know anything about the home brew method.

Electroless nickel also produces a hard, nice looking surface on aluminum and is not too expensive. I don't know if it can be done at home.
 
it will still scratch unless you get a good hard anodize or ceramic coat..

for general purposes i throw my parts in the dishwasher
 
There are 2 common "classes" and 3 common "types" of anodizing. The hardest (and thickest) is a Type III and either Class 1( not colored - dyed) or Class 2 (colored - dyed).

The hard anodizing is a rather involved process compared to normal Type I or II that people do at home. Yes, regular home anodizing is hard, but bear in mind that it is a very thin layer, in the 10 micron range. Even being hard, it will scratch easily. Things like hand wear, it will do fair.

Austin should have quite a few anodize shops, so it might be worth a call or two.
 
There is anodizing, which seems to be had in a multitude of colors, and there is hard anodizing. I only recall seeing hard anodizing in black and it is very hard. IMO regular anodizing does little for wear resistance where it rubs. Hard is pretty impressive resistance wise.
 
Thanks for all the info. I only have a few small parts, so maybe I'll see what it would cost locally. Otherwise, I may go the powder coat route and just get myself a cheap gun and some powder.
 
Ripthorn said:
I have some small aluminum parts that will see a small amount of wear, and I would like to prevent surface scratches and the like as much as possible. I thought about powder coating using a clear powder, but I have not powder coating setup and would like to see if I can do something with what I have. I have read about home anodizing, but my big question is whether it hardens the surface at all, and if so, to what extent? The parts are 6061 and all I want is a clear finish. I have a large 12V power supply from an old electronics something or other that could be used for this, as well as buckets. The parts are no larger than 3"x3"x.5", so I don't think I would need tons of solution. If it will harden the surface, I may go this route. Any other thoughts would be greatly appreciated.
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You should be able to create a durable anodized surface with a home process. All aluminum anodizing involves the formation of an aluminum oxide coat on the surface. The degree of resistance to scratching is determined by the depth of the coat. A thicker coat tends to turn a yellowish hue and for that reason is not used for dyed surfaces. Even a thin coat will provide a fair degree of resistance to scratching though.

IMO, an anodized coat will be more resistant to scratching than any paint process, including powder coating. A urethane finish will be very durable but will show scratch marks.
On one project, we used a spray urethane coat over an anodized finish. We did this for chemical resistance as anodizing is attacked by both acid and alkali. The combination proved to be very hard to remove.

I had anodized a multitude of parts for a prototype. I used a 13% H2SO4 solution and ran between 6 and 10 amps/sq. ft. I used a constant current power supply and voltages were up in the 16 volt range. The depth of the coat will depend upon how long you run the process. I ran to 300 - 500 amp- min./sq. ft.

If you are interested in trying it, I would suggest that you experiment with some scrap pieces first. I would strongly advise using a constant current power supply. You are talking about a maximum of 24 sq. in. so a supply capable of 2- 3 amps should do it.
 
I don't believe that my power supply is constant current. Perhaps I will have to see if I can find one. Are car battery charges constant current, or just current limited?
 
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