The MnO2 Anode (chlroate electrodes in gerneral)

[blindreeper]

I have read in chlorate documents that MnO2 is resistant to oxidation and promising for amature use. All it says about preparation is "It is made by thermal decomposition of manganese nitrate pasted onto a substrate."
I was wondering is there anyway to use the MnO2 out of batteries to make such an anode. I am very interested in this as I plan on making Kg amounts of chlorate in 10L buckets.
Also their is some talk about using PbO2 anodes and they can be found in car batteries so there some thing to do tomorrow. But on a more serious note, when ever I am casting lead for whatever reason it is very shiny when molten and about 1 day after casting then it tarnishes. Is this tarnish not an oxide of lead? If so what would it be?

Another thing on the subject of electrodes has anyone used titanium or know where to get it? It seems to be perfect for per/chlorate cells.
Any other information on cell electrodes and experiences would be nice to hear

(Hope I don't get busted for starting a new topic :( )

[IPN]

I don't know about that "thermal decomposition of manganese nitrate pasted onto a substrate." but I have tried to make MnO2 anodes/cathodes by melting MnO2 in to a mold. I haven't had any good results with them...yet
I haven't thought of using PbO2..I might try it someday.

Titanium would be the Holy Grail cathode for someone doing electrolysis in large scale.
You could order them from Acros although the price is quite high,
"Titanium rod, 6.35 mm diameter, 99.97% 10 GR 129.65€"

[Anthony]

Is Ti metal stock of insufficient purity to use?

As a metal supplier would be *FAR* cheaper than that!

[IPN]

Well I think that if the titanium is very pure it will corrode very slowly, but because of the price the commercial titanium would probably be just good. Although I haven’t found any titanium suppliers around here..
Do you know any important uses for titanium?

[zaibatsu]

IPN, sorry if this sounds daft, as I know you are intelligent, but have you just tried searching for model engineering suppliers? Or just find a company directory for your country and search that. Look for specialist metal suppliers, as general ones may just sell Al, brass, Mild Steel, Cast Iron etc.

[Tuatara]

From what I've read about chlorate anodes, titanium by itself is no good. It is simply used as a substrate for platinum or other materials, as it has desirable physical properties in this role. This would mean that high purity is a waste of money - just use standard stock from a metal merchant.

A good source for MnO2 is ceramic and pottery supply stores. Its used as a coloring in glaze recipes (brown - naturally). I would expect this source to be simpler to use as there will be no other shit mixed with it, as in batteries.

The grey coating on your lead castings will be PbO.

One really interesting potential anode material is Boron doped diamond film. Making CVD diamond films at home should not be beyond some of us enthusiasts.
Have a look at this paper
Diamond films (http://www.chm.bris.ac.uk/pt/diamond/mattthesis/title.htm)

There's even a company out there (didn't bookmark it, sorry) that makes diamond electrodes for electrochemistry.

[blindreeper]

I guess the PbO isn't very good at resisting corrosion because now that I remeber I tried a small 150ml cell with 2 lead cast electrodes. I still have the electrolyte left and there is a very fine white solid at the bottom. It was running for about 1 hour then I decided the lead was crap. Any ideas on what the white stuff is?(in the cell ;))

Tuatara: http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/anodcath.html

Titanium is the supposibly the best for amature work :p

Has any one found "gouging rods" in welding places. They are supposed to be large and cheap? Does anyone know of any other sources of graphite electrodes, like BIG ones. Cause ATM i am having to epoxy 2 battery electrodes from a 6v end on end to get them 16cm long and 8mm dia.

[Tuatara]

Blindreeper: Regarding the titanium - as a cathode I see what you mean, as an anode its used as the substrate (see DSA on the same link)

[IPN]

Zaibatsu:

Well I took the local yellow pages and went trough the list of metal suppliers. After a while I made few phone calls and voila! I might have found my self some titanium plates (witch I can melt and cast into rods). And the price wasn’t even so bad
You were right. I didn't search from the most obvious:( :o

[Anthony]

Melting point of Ti is 1660*C, so casting may be difficult!

If it's plate, I'd simply cut it into strips.

[IPN]

Yes, it would be easier but I like a little challenge ;)

I think my oxy-acetylene torch can reach 1660C.. (or so I think)

[rikkitikkitavi]

to bad then that molten Ti ignites in open air. It also reacts with CO2 and N2 forming carbides and nitrides. It is not the scarcity of Ti-ore that makes the metal so expensive. It is the extraction and the handling of such an reactive metal (at high temps)




/rickard

[xyz]

Oxy/Acetylene torches can reach over 3000°C at the hottest part of the flame so heat isn't a problem. Good luck making an inert atmosphere though.