Anodizing niobium-what am I doing wrong?

[cheesehead]

I'm currently trying to anodize niobium in order to get the nifty colors obtained in this way. I've got a 20-200vdc power supply, an electrolyte (diet pepsi), a cathode (aluminum), and the niobium.
I've tried running everything between 20 and 140 volts DC through it, for up to fifteen minutes. Why don't I see any results? Am I just not waiting long enough?

 

[promotheus]

Im not sure, but i dont think pepsi is acidic enogh. Where i live it is illegal to throw coke into a chem labs sink because its so corrosive. but yeah, try something more acidic , if you cant get nething else, use coke. sides, coke is the better drink
. Btw, wtf is niobium?

 

[f95toli]

Voltage is irrelevant in this case. What matters is the current.
So, how much current are you pushing through the circuit?

 

[dkozloski]

I anodized aluminum motorcycle parts 30 years ago adding a few drops of battery electrolyte at a time until I got some current to flow. When you get through just add a lot of water to dilute it and run it down the sink. It isn't any worse than vinegar under those conditions. For dye I used "Rit" clothes dye that you can buy at some grocery and department stores.

 

[pm]

Yeah, I agree with dkozloski - use diluted sulfuric acid from a lead-acid car battery (should be a clear heavy liquid). About 10% concentration should work... maybe a little less. Be careful not to get it on your clothing or your skin.

 

[JSSheridan]

Niobium is also called columbium. It's atomic number 41. There's plenty of info on it on Wiki.

 

[cheesehead]

Thanks!

I'd like to clarify something about niobium; it's actually the voltage (and NOT the current) that's super-important. Varying the voltage leads to different colors.

 

[f95toli]

Hmm, yes I are right and I was wrong.
The voltage determines the thickness of the oxide layer which in turns determines the color.
However, the current should still be important since it determines the rate of transport thorught the electrolyte; hence without current nothing will happen.

 

[kevinthenerd]

Originally posted by: f95toli
Voltage is irrelevant in this case. What matters is the current.
So, how much current are you pushing through the circuit?

Almost irrelevant. V=IR

Edit: I need to figure out some cheap way to electroplate a stainless-steel-like coating on steel. That would be cool to have a chromed-out finish on strong steel.

 

[f95toli]

No, V=IR does not really work in this case.
The relationship between voltage and current is usually not a linear in cases like this (V=IR is strickly speaking only valid for an ideal resistor).

 

[dkozloski]

kevinthenerd, electroplating is an extremely environmentaly unfriendly process involving poisonous metals and poisonous liquids best left to the experts. Go to your local bumper repair shop.

 

[kevinthenerd]

Originally posted by: dkozloski
kevinthenerd, electroplating is an extremely environmentaly unfriendly process involving poisonous metals and poisonous liquids best left to the experts. Go to your local bumper repair shop.

Oh, come on... where's your sense of fun? Danger makes doing stuff that much better. :wink;

 

[kevinthenerd]

Originally posted by: f95toli
No, V=IR does not really work in this case.
The relationship between voltage and current is usually not a linear in cases like this (V=IR is strickly speaking only valid for an ideal resistor).

True.

 

[dkozloski]

kevinthenerd, the cadmium plating setup that I used while overhauling aircraft engines killed two people. One was an accident and the other was a suicide. The people involved had one thing in common, they were both dead before they hit the floor. Cyanide is final.

 

[kevinthenerd]

ouch. Whelp, sounds like I have some reading to do on OSHA standards before I mess with that crap.

 

[patentman]

 

[patentman]

Originally posted by: kevinthenerd

Originally posted by: f95toli
Voltage is irrelevant in this case. What matters is the current.
So, how much current are you pushing through the circuit?

Almost irrelevant. V=IR

Edit: I need to figure out some cheap way to electroplate a stainless-steel-like coating on steel. That would be cool to have a chromed-out finish on strong steel.

Just plate with Zinc or NIckel, that avoids the cyanide issue mentioned above and also the problem with hexavalent chromium, plus with the right bath you can get a nice bright finish....check out this site: http://dalmarplating.com/tankplating.htm One thing you should note is that once you are done with the bath you will need to dispose of it, and pouring it down the drain or in your back yard is not an option. You should have a company that speciallizes in the disposal of heavy metals take care of it!

 

[kevinthenerd]

Originally posted by: patentman

Originally posted by: kevinthenerd

Originally posted by: f95toli
Voltage is irrelevant in this case. What matters is the current.
So, how much current are you pushing through the circuit?

Almost irrelevant. V=IR

Edit: I need to figure out some cheap way to electroplate a stainless-steel-like coating on steel. That would be cool to have a chromed-out finish on strong steel.

Just plate with Zinc or NIckel, that avoids the cyanide issue mentioned above and also the problem with hexavalent chromium, plus with the right bath you can get a nice bright finish....check out this site: http://dalmarplating.com/tankplating.htm One thing you should note is that once you are done with the bath you will need to dispose of it, and pouring it down the drain or in your back yard is not an option. You should have a company that speciallizes in the disposal of heavy metals take care of it!

When you mentioned disposal procedures, it reminded me of the time I worked at Walgreens. It makes me wonder whether you could use photo processing chemicals to do silver plating.

 

[patentman]

Originally posted by: kevinthenerd

When you mentioned disposal procedures, it reminded me of the time I worked at Walgreens. It makes me wonder whether you could use photo processing chemicals to do silver plating.

You "can" plate usuing just about any bath that has a metal salt dissolved in it with enough work and energy, but it is much easier if you use a bath that is specially formulated for this purpose. Plating is not rocket science, but it is by no means something that is easy or predictable. As someone already mentioned, the compositions of most commercial plating baths are either trade secrets or patented. Its easy for someone to make a bath of say a silver salt or nickel salt and precipitate some metal from it....Its quite another thing to have that metal strongly adhere to a substrate and have a bright (desmutted) finish. Most of the guesswork in plating baths is in the additives to the basic metal salt solutions....

 

[kevinthenerd]

I was trying to extract oxygen and hydrogen from water one time when I think I discovered my probes we being covered in sodium. It was cool, but it wasn't efficient or repeatable for a nice finish by any stretch. (Sodium is volatile anyway.)

 

[patentman]

Originally posted by: kevinthenerd
I was trying to extract oxygen and hydrogen from water one time when I think I discovered my probes we being covered in sodium. It was cool, but it wasn't efficient or repeatable for a nice finish by any stretch. (Sodium is volatile anyway.)

Umm, how in the world did you get sodium (I'm assuming you mean sodium metal and not sodium chloride) to plate out on your electrodes when trying to get hydrogen and oxygen from water? Why didn't you just use electrolysis?

Also, given that sodium metal is highly volatile when it comes into contact with water, and given that most plating baths are aqueous, that must have been quite an experience you had.

 

[kevinthenerd]

Originally posted by: patentman

Originally posted by: kevinthenerd
I was trying to extract oxygen and hydrogen from water one time when I think I discovered my probes we being covered in sodium. It was cool, but it wasn't efficient or repeatable for a nice finish by any stretch. (Sodium is volatile anyway.)

Umm, how in the world did you get sodium (I'm assuming you mean sodium metal and not sodium chloride) to plate out on your electrodes when trying to get hydrogen and oxygen from water? Why didn't you just use electrolysis?

Also, given that sodium metal is highly volatile when it comes into contact with water, and given that most plating baths are aqueous, that must have been quite an experience you had.

I know... it was fvcked up.

 

[GalvanizedYankee]

I happened upon this while doing some research/study on electrolytic capacitors. Hope it offers some assistance.

http://electrochem.cwru.edu/ed/encycl/art-a02-anodizing.htm


...Galvanized