What of it? Should we discuss some platinum anodes?
I can post a picture of some commonly seen platinum anodes and/or how to make them from wire?tentacles - 1-3-2008 at 19:52
The wear rates are both interesting, and alarming. The lowest wear rate was 5.3 g/ton of Na chlorate, and the highest (discounting the invalid data)
8.6g/t. At today's prices ($72/gram!) that's $381 per ton of perc, *if* we could replicate the lowest wear rate. I don't know if the chlorate to perc
wear rates would be lower, but I would expect that as amateurs, we can expect higher wear rates with our less controlled cells.
At 8.6g/t the wear rate comes up to $619/ton, which is actually $.3096/lb of perc. Not terrible, really, but probably the biggest running cost besides
the time.
Still, I'm interested in how 12AX7's cells are doing with his platinized Ti anodes. Chlorate is cheap to make, and a good working perc anode is worth
a bit of cost.
Edit: Read to the end of the paper, and they were running the cell at 110C! I wonder what effect that had on the efficiency?
[Edited on 1-3-2008 by tentacles]12AX7 - 2-3-2008 at 04:29
Quote:
Originally posted by tentacles
Still, I'm interested in how 12AX7's cells are doing with his platinized Ti anodes. Chlorate is cheap to make, and a good working perc anode is worth
a bit of cost.
They were going slowly until things went just too slowly, supply voltage rose and the platinum all but delaminated.
I'm still recovering wastes before I can replate anything.
Timgarage chemist - 2-3-2008 at 05:46
Brauer has a recipe for a bath for electrolytical platinizing of titanium and tantalum.
It consists of:
H2[Pt(OH)6] 20g/L
KOH 15g/L
The anode is stainless steel.
This special alkaline bath is for titanium and tantalum only.
It is operated at 70- 80°C, 0,8A/dm2 current density and almost 100% current efficiency.
The substrate has to be pretreated, though it is not mentioned how.
This bath is found on page 1708, in the third volume, which is not included in the english version, but in the german one.
I have only found out about this method of Ti platinization recently, I was only aware of the molten salt elctrolysis before.
There is also a preparation of this H2[Pt(OH)6] compound (as the potassium salt, which of course would form in the KOH solution anyway) in this
volume. I can translate this if needed.
[Edited on 2-3-2008 by garage chemist]not_important - 2-3-2008 at 07:56
Titanium and tantalum only, and not other valve metals?dann2 - 2-3-2008 at 08:00
Hello,
The temperature of the cell (110C) is crazy high. I though it was a misprint. One advantage of the very high temperatures is that the cell voltage
goes down and you will get power savings. This is important when using megawatts of power. Price of Pt was much less then than now, wonder what price
it will be in ten years????????????/
I would guess this type of cell/production setup never made it on an industrial scale, it was a study after all.
I think a way to make Ti plated anodes would be useful. The actual cost of the anode would not be too prohibitive, the problem is (IMHO), it will take
a bit of cash to get to a point where an amateur process is usable and repeatable. With LD or Manganese Dioxide etc etc you can do a lot of
experimentation with small finanical input.
Pt?.....
Did Tim's bath not cost $300, that's very bad news for a stingy gits pocket like myself (bad for the blood pressure too).
Would not mind seeing some plating solutions. Everyone seems to claim that not all the details are in the bath ingredients, as such. There always
seems to be one detail/step/secret left out.
Perhaps wire is the best way to go..........
Cheers,
Dann2
[Edited on 2-3-2008 by dann2]Fleaker - 2-3-2008 at 08:38
Mind you it wasn't his 300 dollar a gallon plating bath, and that was back in December, about 600 dollars an ounce ago :p The good thing about it
though, is that he can recover the platinum from failed attempts and reuse it.
I think the details are not in the bath ingredients but rather (as I keep repeating ad nauseum) in the preparation of your substrate!!! Proper
pretreatment will give a suitable anode. This is true for almost anything in electrochemistry.
[Edited on 2-3-2008 by Fleaker]12AX7 - 2-3-2008 at 10:50
Yeah, and I'd much rather have more like $1000 of Na2PtCl6, if not more, for the size of bath I started with. I suspect a higher concentration
(giving higher current efficiency and less hydrogen) may produce a better deposit. It's just the price you have to pay. Only one-time, if you
collect and process all your crud!
Brush plating may be more suitable, since it takes so much platinum in the bath. You still need to strike the titanium with something quickly though.
Timtentacles - 4-3-2008 at 10:02
12AX7: Have you tried plating platinum over ATO at all? A lot of these MMO patents mention using them as an interface layer with a noble metal or
metal oxide active layer over top. Unfortunately I haven't seen it specified anywhere how they plate platinum over the interface. It was mentioned in
the BTO patent as well.
[Edited on 4-3-2008 by tentacles]12AX7 - 4-3-2008 at 13:16
I don't have the pertinent nitrates or whatever on hand. Of course I have tin, but it's all alloyed with lead. Seems to me I was going to get
lead-free solder from the hardware store at some point...
I do have a mixture of transition metals which I leached (with HCl) from carbide cutter grindings (should be roughly 80% WC, 20% Co). At the moment
it has a yellow brown color similar to Fe(3+), but not nearly as orange as FeCl3. When reduced, it is green; when oxidized, it turns this color, and
over time a precipitate (I think dark olive green, but I haven't washed it yet) has formed.
Incidentially, said grindings burn white hot with a chlorate. CO2 and tungstate formation perhaps?
TimRosco Bodine - 4-3-2008 at 14:27
Yeah lead free solder simplifies things greatly . But it isn't absolutely essential .
You could separate your tin from the lead/tin alloy
using warm and medium strength HNO3 . On dilution the lead will remain in solution as lead nitrate while the tin will be dropped out as metastannic
acid . You could use that metastannic acid for reaction with oxalic acid and H2O2 to make a stannic anhydride / peroxalic acid sol . Or you can
peptize the metastannic acid to a sol using an organic amine . Or you can depolymerize the metastannic acid by fusion with NaOH , dissolve the product
in H2O and neutralize with HCl to precipitate alpha stannic oxidehydroxide which you can use then to make stannic chloride , stannic nitrate ,
ammonium stannate , ect.
[Edited on 4-3-2008 by Rosco Bodine]R.P.Wang - 13-3-2008 at 04:43
Quote:
Originally posted by tentacles
12AX7: Have you tried plating platinum over ATO at all? A lot of these MMO patents mention using them as an interface layer with a noble metal or
metal oxide active layer over top. Unfortunately I haven't seen it specified anywhere how they plate platinum over the interface. It was mentioned in
the BTO patent as well.
[Edited on 4-3-2008 by tentacles]
I attached a article which is about adding Pt between titanium substrate and Sb-SnO2 layer, service life is increased!
I've been considering scoring some myself. An ounce might make a decent sized anode, but how do you work it - we need to find a jeweler's suppy or
something. I thought I might speak with some jeweler's and see if they can't order me Pt in a sheet/foil. Isn't jewelry Pt usually a 90/10 Pt/Ir alloy
that lasts longer as anode?garage chemist - 29-9-2008 at 17:44
Pure platinum is soft and malleable. You should be able to beat it out on an anvil.
Pt/Ir, on the other hand, is hard and elastic, and much harder to work with, though more resistant against corrosion in a perchlorate cell.
