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Rosco Bodine
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@Swede
What kind of oxygen barrier interface are you contemplating for the Ti substrate ?
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Swede
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Rosco, I guess the idea is to have a brutally efficient and heavy plate job on bare Ti. Several patents claim they're doing it. I have no idea if it
would work. I've got a lot of chemicals, and it may be worth a try. For now, MMO.
I'm taking a break right now from plate #1. The bath is mixed and heating. I am going complex on the first attempt, with added Nickel salts,
surfactant, the whole 9 yards. But adding Bismuth hydroxide was a mistake. Being insoluble, the bath turned opaque. It was stupid to even consider
Bi.
The small MMO anode (8 X 4 cm) was soaked for 1 hour in acetone. It was then etched in dilute HNO3 for a few minutes, rinsed, and is now soaking in
300 ml of distilled water plus 1 ml Triton X-100 surfactant at 80 degrees. It will then get vacuumed, and plated.
The bath looks like an opaque, turquoise-colored body wash. Toxic as hell, NaF, lead salts, nickel salts. I'm dressed like an astronaut. There's
lots of pics that will hopefully turn out. I keep thinking "This is nuts" as I'm weighing out 700 grams of lead nitrate for a 2.25l bath.
If this doesn't work, attempt #2 will be "simple". I've got the litharge doses ready.
I could have purchased 5 good Pt anodes (or at least 100 pounds of perchlorate) for the $$ I've shelled out so far... but where's the fun in that?
Dann2, I understand the need for a simple process for the average garage chemist, and I'm headed in that direction, definitely. I'll be back in a few
hours with a report + pics.
Time to don the astronaut gear again. Here we go, into the void... 
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Swede
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What a PITA. It's been about 3 hours now. There is lead dioxide plating, but at a slower rate than I had anticipated.
Two catastrophic events... I hadn't even calculated current until I was ready to flip the switch, and found the intial current needed to be 9 amps!
The lab supply I was going to use is good only to 3. So I had to drag my 80 pound Sorensen supply that I use for chlorate and patch it into what had
been a very elegant system.
Initial pH seemed measurable at 0.5. I had added 10 ml of 68% nitric to 2.25 l to start. pH dropped RAPIDLY, indicating nitric buildup. Even worse
, my rotating shaft galled and seized. It took a bit of lube and some manipulation to free it; all the while, plating is still going on.
The vibrational system works TOO well. If turned up too high, it literally begins to toss bath outside of the container... AND the container begins
to move. Pretty soon I'm hearing BANG BANG BANG as the anode is hitting the wall of the container. The vibrational concept is excellent, and no
doubt works, but everything needs to be very secure.
I have babysat this thing for three hours now, and am getting fatigued. How long is a typical plating session? At a minimum, I want to fill the mesh
holes, and it looks like I'm a long way from that.
Nitric control... litharge works. 10g of litharge in the bath raises pH from 0.00 back to start, 0.05. Lead Carbonate seems to work even better,
sizzling CO2 as it contacts the liquor. Both seem to be doing what they are supposed to do.
I've got to go pick my kid up from school. I'm afraid to leave this setup for very long, but I cannot stop plating until it's done.
Oh yes, the opaquity, caused by the Bismuth, was not a factor... the insoluble Bi salts settled to the bottom where I assume they get dissolved slowly
by the acid.
There appears to be some smut building up on the Ti cathode. What it is, I cannot yet tell.
Wearing a respirator for hours sucks. I'm hungry, and I need a shower too. Better go check on the bitch.
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dann2
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Hello,
Do you have any patent numbers for patents that plated LD onto bare Ti?
I know of one where they plated LD onto bare Ta (Ti would do to I am sure) but they then went on to use the anode as a massive anode. Current
connection in Chlorate/Perchlorate cell was by putting Silver on the LD and ignoring the Ta.
There is an article that discussed plating butt naked Ti with LD. Will look it up. There was considerable debate as to what exactly was happening/not
happening, working/not working.
What are the dimensions of the anode that you are currently plating.
US 3,318,794 describes an LD anode made from LD powder and polymer/glue.
Dann2
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Swede
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I'll try to find it for you Dann2. I think it was the one where they scored the anodized Ti plates to prevent warpage. The lead dioxide plated on
those areas where the anodizing was removed.
Holy cow what an effort. Good news + bad news. With the rotating arm galling and seizing, I could not let it go overnight, which it would have
needed to so as to fill thye voids. As it is, it is heavily plated. As to the quality, I have no idea.
I worked hard this morning adding plastic bushes to the support arm, and prepped the 6.5 liter bath. 6.5 liters is TOO much, too much of everything.
I am going to plate the hell out of this anode. I'm boiling it in surfactant right now, after an acetone degrease. It'll go right into the plating
bath. I'm beat. Walking around with a near boiling 4 liter beaker full of lead nitrate is not fun. So far no catastrophic spills, but I pictured
that 4 liter beaker on the hotplate cracking and dumping it all into my shop.
Pics as promised are forthcoming.
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Rosco Bodine
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There has been some discussion in the patent literature and the scientific literature indicating that plating onto a naked Ti substrate requires a
special technique or the result is not a long life and good performing anode because of interface problems. I have an assortment of references that I
am trying to organize. Basically the plating baths which are optimal for a graphite substrate are not optimal for a bare Ti substrate, even though the
PbO2 is plated out beautifully, the Ti/PbO2 interface tends to be semi-passivated by the acidic electrolyte and it gets worse with aging in service,
even buried beneath the PbO2 it slowly passivates, so you don't really have a permanent conductivity there and it can delaminate also.
So a bare Ti substrate is a special animal, and may need an alpha PbO2 plating alone, built to a working thickeness,
or as a primer coating then followed by the beta PbO2.
I have found a reference or two which indicates that glycine may be a useful additive in both electrodeposition schemes and pyrolysis schemes for MMO,
as it reacts with
nitrate salts of the types we are interested forming soluble complexes that are easily decomposed in a controllable way for production of nano scale
particles of either the oxides or the free metals depending upon the conditions, and also forms the mixed oxides of spinel, perovskite, or ferrite
variety when mixed nitrate/glycine complexes are the precursor, so it should be interesting for that reason alone ....aside from it's possible value
as a surfactant in plating baths 
The glycine intermediate with an assortment of metal nitrates actually results in a sort of pyrotechnic composition
at certain balanced proportions, and the material can be ignited to produce the MMO material as the ash remaining
following ignition. Evidently the reaction is highly energetic
and at certain proportions may even partially sinter the resulting ceramic from its own heat of reaction. I have speculated before that it would be
great to come up with a sort of "self-casting" all ceramic anode where the powdered precursor is poured into a form and ignited and the heat of
reaction does the rest, similarly to a thermite reaction being used to make an "instant metal casting" ...and this glycine / nitrate complex is sort
of headed in that direction. But I anticipate it may have more applicability in less extreme applications where its usefulness could be its easy
decomposition and self-reaction to form MMO composites
in film coating schemes, it's value there being the homogenous distribution of the reacting oxides by the decomposable complex in which they are
contained. This could be desirable for producing very consistent doping of interfaces and intermediate layer films where the complex could be useful
as a carrier for the dopant ions.
Here is another sort of summary listing of some of the metals which are chelated / complexed by glycine and you can see that this probably incomplete
list , along with those listed in the patent, includes metals of interest whose oxides are useful as components in anode coatings.
http://cat.inist.fr/?aModele=afficheN&cpsidt=3532220
http://www.youtube.com/watch?v=oXCkEEWQxgg&fmt=18
http://www.youtube.com/watch?v=KKPBtZ0Zzok&feature=relat...
[Edited on 14-1-2009 by Rosco Bodine]
Attachment: US5114702 aqueous precursor for metal oxide ceramics.pdf (207kB)
This file has been downloaded 1380 times
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tentacles
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| Quote: | Originally posted by Swede
Holy cow what an effort. Good news + bad news. With the rotating arm galling and seizing, I could not let it go overnight, which it would have
needed to so as to fill thye voids. As it is, it is heavily plated. As to the quality, I have no idea.
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I'm not sure you can plate beta directly over beta, you might be much better off plating a thin alpha intermediary layer over the beta, then
continuing the beta. It's just a thought, but I thought there was some info somewhere on this?
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Swede
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Actually, anode #1 is pretty heavy and may be quite useful as-is. I don't think I'm going to mess with it any more, mainly because of the stupidity
of using Bi in that bath. I went right to the 6.5 liter for anode 2. It's been plating since noon yesterday (it's 6:30 AM right now) and because of
work, I am probably going to pull it. Not being here to add the litharge periodically, I'm afraid the nitric will climb too high and ruin the job.
I'm hoping this anode is a good one. It's hard to tell, but the mesh voids may be filled on this one. It's looking good, from the surface of the
bath, anyhow.
My pH meter seemed to be a useful tool, with reliable measurements down to 0.0. When it got that low, about 20 grams of PbO brought it back to 0.5.
I'll say this, ANY future plating system I do is going to have a strong stirrer, of the motor + shaft + propeller variety. Constant hand stirring is
a PITA.
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Swede
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Got to get to work fast. Anode #2 pulled... VERY HEAVY! LOOKS GOOD! It actually has that "shiny, ceramic-like" finish described in the patents.
YES!!!!!!
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dann2
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Hello Swede,
Perhaps you should have exclaimed
<font size=+1>   yes </font>
    <font size=+2> yes </font>
     <font size=+3> yes
</font>
         <font size=+4> yes!!!!! </font><br>
Just wondering when you say that the pH is at 0.0, it may be below 0.0. Does you meter go into the minus region. Don't know a lot regarding pH meters
myself.
Also have you a buffer solution with a pH some where in the low pH's so that you can check/calibrate the meter, just so that you know it is not way
off.
Just for future reference could you measure the pH of the Lead Nitrate solution before you add any Nitric acid to see what pH it is?
Link below to stuff on Plating Lead Dioxide. It includes discussion on plating butt naked Ti with LD. Some of these anode have been used for years
,mainly in
electroflotation plants (whatever they are?), not in Chlorate/Perchlorate cells.
It is a scan and alot of the patents numbers do not seem to be scanned correctly.
http://www.geocities.com/lllwolly/further/sauce2.html
I think with naked Ti you will be back to all the problems of the Graphite substrate. No actual corrosion of the Ti substrate but if the coat of LD is
not perfect and
thick some solution will get in between Ti and LD and passivate the Ti.
They also state above that Ti mesh is great as starting substrate and that the idea of drilling lots of holes in flat plate (making mesh really)
originated from the
bureau of mines.
Dann2
[Edited on 15-1-2009 by dann2]
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tentacles
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Bah! All this talk of successful LD plating is giving me the itch. I'll filter off some of that copper nitrate crystals and then dunk some lead in
there, start making up some LN solution for plating.
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Rosco Bodine
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Word is that if you know the trick, good old 316 stainless perforated sheet ( and probably even better perforated tube ) can be used as a substrate
for a PbO2 anode which lasts for over a year in service 24/7. It could even last longer than a Ti substrate because the adhesion may be better.
The downside is that the substrate can't be recoated and reused after the coating reaches end of service life, because when the coating fails, the
substrate corrodes and dissolves away through the cracked coating rather than passivating. So it is a one shot, one use anode rather than a permanent
renewable anode. However, a year in service is a good long run for an anode, especially for an expendable anode which can be made much more cheaply
than the renewable variety.
See page 4 Example 3 of the patent US5545306 attached
Possibly the anode could be "refreshed" with a repair coating
at intervals less than it's predicted end of life, or perhaps
routinely removed from service and stripped and recoated
before the substrate is damaged. It would make sense that these strategies may be used, but the patent doesn't describe this....so this is
speculation.
[Edited on 15-1-2009 by Rosco Bodine]
Attachment: US5545306 Lead plated titanium substrate PbO2 anode.pdf (148kB)
This file has been downloaded 757 times
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Swede
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Good stuff! RB, I like the idea of a one-shot 316SS anode. Picture this: 316 screw stock, say 3/8 X 16 pitch. You've got a nice, coarse surface to
plate. Sandblast the bugger, clean it like crazy, and plate away.
You've now got a (perhaps) 8" long rod, 7/8 PbO2, 1/8 SS. Screw the stainless into a PVC plastic lid until the lead dioxide bottoms; maybe use a
viton o-ring or two.
Dann2, thank you for all your encouragement and great info. IF (Big if) this anode works, I'll have learned a lot.
I made a monstrous blog entry. Rather than repeat all the info here, well, here's a link:
http://www.apcforum.net/forums/blog/swede/index.php?showentr...
Anode #1 is fugly and 90% estimate it will fail. It took up only 27 grams of lead dioxide (these are small 8 X 4 cm anodes). Anode #2 is hopeful,
and plated 182 grams of lead dioxide. While anode 1 leaves behind little flakes of PbO2, anode 2 seems solid.
Still wet:
Dried... crappy Anode #1 to the left
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Rosco Bodine
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I am pretty sure that DTO and PbO2 has been used successfully over several alternative substrates other than Ti, so long as the thermal expansion
parameter for the substrate is compatable, there is no physical reason why it shouldn't work. The use of Ti is based on a "fail-safe" scenario where
the Ti passivates when the anode fails instead of causing a mess where the substrate corrodes badly and contaminates the product of the cell. This
would be a greater concern in a commercial operation where tons of product could be contaminated and it would be economically infeasible to
decontaminate and purify the product. So Ti wins as the substrate of choice, even though other substrates may be operable. And it is probably
relevant also what is the intended end use for the perchlorate, how critical is its purity specification, which would have bearing on the required
choice of anode design also.
There is a correlation between the MMO anodes and the PbO2 working layer anodes, because the two can be combined to make the ultimate in a long
service life anode. The MMO is used to provide a conductive interface for the PbO2, to which it can adhere well,
and it serves to protect and seal the substrate from exposure to ionic oxygen or fluorine or electrolyte which
may migrate through the PbO2 via porosity or through any actual cracks. So everything learned about MMO is directly applicable also to the
overcoating of MMO with PbO2, and really the PbO2 lasts the longest and is renewable, without having to completely redo the MMO, which can itself be
renewed if the anode is stripped all the way down to the MMO before renewing with fresh PbO2. The shops of perchlorate factories probably do their
own routine "overhauling and reconditioning" of anodes so
that the factory there stays in continuous operation,
while older anodes are being swapped with renewed anodes. I'm sure that is probably the system they use commercially....regardless of what anode
substrate and
design they are using. Lead recovery is probably done also to recycle the material as opposed to the cost of disposal which otherwise might be even
more expensive.
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dann2
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Congrats
Good luck with the anode. 
You have definitely notched up a new mile stone on the humpy, potholed, crucked, twisting, winding, never ending, idea strewn, tear soaked highway
of the Lead Dioxide Anode.
The No. 2 Anode looks almost edible in the first photo! You can see the classic velvet sheen in the next photo where it has dried.
To stop nodules/warts appearing at the edges/points you could round them off as much as possible before plating. There will be no MMO on the cut ends.
Rounding off will not be too easy to do and you will rub off more of the MMO. You will end up with rounded ends that are bare Ti which may not plate
the same as the MMO, or may not plate at all if you leave the MMO lying around for a long time after the rounding/cutting operation before plating
(Oxide will appear on bare Ti and may stop plating). You could try bending each loose end inwards (if there are loose ends sticking out). Another
possible way to stop the warts would be to put a baffle, like blobs of glue, to insulate the sharp ends/corners so that you get a abrupt end to the
LD plating at the edges.
As you said yourself they are not really much of a problem anyways. Perhaps even an advantage, more surface area!
Lead Dioxide is impossible to get to plate into (inward) right angles or accross small hair-line cracks. In the picture below at B you have lots of
extra LD,(where you don't really want/need it). At A (where you would like extra LD for current distribution) there is less LD than the average coat
thickness, BAH!.
Hard to know about the first anode. You may be surprised how long it will work. It won't fail suddenly but will go on working untill all LD has gone
off it, and will continue to 'work', (as in current will still flow into solution) but if making Perchlorate nothing useful will be happening. Then
plate again hopefully of use as regular MMO. It's a win win substrate.
Try doing that with (the substrate from hell if ya ask me) Graphite.
4 my 8cm Anode are not to be sneezed at, it sounds better if you describe them as a '15 amp' anode. (approx. 200mA+ per square cm). If making
Perchlorate you can get quite a lot at 15 amps over a period (coming from Chlorate).
Hope it does not erode like the one I made. It had a total weigh of LD = 31 grams from 800ml tank with 360 grams Lead Nitrate dissolved in it with no
addition of any Lead compounds. That's 0.129 moles LD, giving 0.129 X 2 moles Nitric = 16 grams (+ what was in the tank at the start, a few mls)
Nitric acid per 800ml. Nitric conc. getting high. Perhaps thats a major disadvantage from the, shall I call it, in service erosion perspective.
Perhaps pH controll of Chlorate cell would help with regard to anode erosion. Perhaps the same for a Perchlorate cell too.
TENTACLES...............get your (goddamm) skates on
Dann2
[Edited on 17-1-2009 by dann2]
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Rosco Bodine
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Back in the PbO2 anode thread I posted a series of references and the first two are really keepers to keep in mind, but especially the second one
which details the role of the fluoride in reducing the grain size by a factor of 10 and improving the adhesion of beta PbO2 in scenarios where your
initial coating of PbO2 is going to be beta PbO2.
http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...
This also goes into some explanation about the use of Bi doping.
The use of dopants complicates things greatly because of the pH conditions required, even beyond the usual pH sensitivity which plays a huge role
ordinarily anyway.
To achieve stable coatings of substantial thickness, pH control is essential, where the allowable swing is tenths of a pH not several pH , meaning
like for example holding plus or minus a tenth around 5.5 if that is the target ....not letting the pH wander from 0.5 to 6.5 That kind of control isn't going to happen unless a pumped electrolyte having a
pretty good reserve volume and some sort of "filter bed" neutralization scheme is in effect. Otherwise you will need a huge volume plating cell
....like gallons of electrolyte for plating something the size of a pencil , to keep the pH from wandering all over the place.
There is some indication in the references that if you are going to use an uncirculated one-vat kind of setup as the plating cell, you may be better
off plating alpha PbO2, if it
is a fairly thick PbO2 coating which you are desiring via a one stage plating process.
An issue which can arise with the beta PbO2 coatings which are plated at too low a pH is that the coatings can look beautiful and be perfectly
sealing, and yet have low activity
and low efficiency in operation. Evidently there is a "surface active" catalytic kind of property for the PbO2 coating and
if the pH isn't just right, then that desired structure to the PbO2 doesn't form and you can end up with a beautiful looking anode coating which
doesn't work properly when
put into service in the perchlorate cell. There is a sort of
controlled porosity required for the PbO2 on the nanoscale
of things which makes the surface active. And it is related to the electrodeposition strain also, the more of these tiny voids
which convey the surface activity, the lower is the strain in the material, sort of like air entrained concrete, it has a lowered density there for
the surface active coating which does have an open cellular structure of interlocked crystals.
Too low a pH and you get something like a solid glasslike coating very dense which loses its desired surface activity.
So there is a "happy medium" where the ceramic like hardcoating appearance and strength is there, but if you
zoom in for a closer look at electron microscope resolution,
you want to see something like you would want to see with silica gel, swiss cheese sort of structure where the volume
surface area of all the inside walls of the exposed "tunnels and caves" is perhaps 20 times the exposed surface area of the 2 dimensional outer
surface, or more. That porosity is one parameter that is affected by pH, and why it is important.
I'm not trying to foretell doom or anything, so don't get me wrong, I'm just saying that you won't really know what you've got is good as an "active
anode" until you test it in a perchlorate cell and see what the efficiency is for what you have made, because it can look really pretty, but not all
that glitters is gold. Don't count the chickens before they hatch.
If it works fine ....then you got lucky
[Edited on 17-1-2009 by Rosco Bodine]
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Swede
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Well, you guys have been a real inspiration, and I thank you with real sincerity. These are baby steps, certainly.
First, I think we can conclude safely that "size matters" and a bigger bath is a better one. But beyond a certain size, it becomes unwieldy for the
home chemist. As I mentioned earlier, manipulating 3 to 6L in giant beakers, hot, is unpleasant. For anode 2, I had almost 3 kg of lead nitrate in 3
liters of water, near boil, on that hot plate, and in my mind I could imagine the CRACK as the beaker gives up the ghost, and now I've got 3 kg of
boiling lead nitrate everywhere. Scary. In the future, I am going to dissolve the Lead Nitrate IN THE BATH after bringing the bath up to temp.
pH... I've got a relatively cheap meter (actually it is a controller) and the probe was a $40 Milwaukee brand. The bath started with 5 ml / liter of
70% nitric, and the measured pH was 0.5, a reasonable value to measure with a pH probe. So I attempted to keep it there with litharge, and it wasn't
too hard. About every two hours, I'd check the bath, and if it was below 0.2, I'd add about 20 grams PbO; sirred a bit, and 5 minutes later it was at
0.6. Again, the size of the bath keeps the swings a bit lower than they otherwise might be.
I don't think it will be possible to plate a mesh and have it be anything but warty and unattractive. Dann2, I believe in the case of anode 2 that
the edge warts actually improve the structural integrity overall. They are thicker than the remainder of the anode, and in their ugly way, make it
stronger. But only because they "grew" into each other. If they are separate warts, I suspect they'd be fragile and not help.
Rosco, the dried anode appears to have a surface that is NOT glasslike... it is satiny. I'll see if I can get some photomicrographs. All of this is
moot if the anode does not make perc, but regardless, it has been an invaluable learning experience. I'll say this, I really like your idea of
plating a 316 SS round, starting with threaded rod, giving a surface that the LD can bite into, then building the coating up until it is near round.
But I do need to learn more about what happens at the surface of the substrate, and how to possibly prevent problems there. Hell, a simple anode that
would last a year in industry would last a hobbyist a lot longer. All of these anodes are for perc only cells; I am not going to risk them in a
chlorate cell, and in all cases, I've got to minimize chloride ion presence, probably by recrystallizing raw chlorate before it goes into a perc cell.
One last thought, a recommendation - US Platics sells plating tanks of all shapes and sizes, quite a few of them are 1 or 2 gallons, about right for a bath. The polypropylene tanks
handle heat better than polyethylene, and the tank was thick and sturdy. If someone invests in one, a deep rectangle, I think, is the best shape,
rather than a shallow square.
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Rosco Bodine
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Satiny is good Kind of a semigloss sort of sheen as opposed to a "high gloss
lacquer effect" which would probably be too compact and dense. It would last forever in service, and it would make perchlorate, but the efficiency
would be way down below what it ought to be.
I'm going to suggest again that you think about using large "crock pot" containers *instead* of plastic tanks.
I have about four different ones which were gotten over the years cheap as "closeout specials" and have never seen kitchen use but have strictly been
used as very handy laboratory appliances. All of them have removable
liners and a couple of them are even thermostatically
controlled. They are great for evaporations, drying crystals or even dehydrating hydrated crystals, or for
use as hot water baths, or in this case they could be used
as heated reservoirs for electrolyte. The ones I use have
"corningware" removable liners that are either white pyrex glass or "corelle" and the liners are very heavy
with molded handles. Some of the more recent manufactured crock pots have digital programmable controllers and a few of those even have ported lids
through which a thermocouple probe can be inserted as a meat thermometer like into a roasting turkey to sense when a target temperature is reached.
It seems like
these crock pots are very close already to what is needed and could probably be adapted if some alteration is needed to refine their control scheme.
Ultimately you *are* going to need a pumped electrolyte
when you are plating any serious "production scale" anodes, so you may as well view the "one vat" cells
as sort of "test cells" for short duration plating runs where
you are wishing to observe short term plating effects, rather than long runs for heavy and thick deposits.
The same 6-8 liters of electrolyte being pumped for recirculation through a filter bed neutralizer will be
better than having fifty gallons in a single cell. The
Gibson patents and even earlier patents show the
industrial setup and something a bit less complicated
can be improvised to accomplish the same thing.
And the same equipment can be used later for perchlorate production, where you add a "cooling tank" in the loop,
where perchlorate should drop out of the cooling solution
and accumulate as a bed of crystals, while the spent effluent is reheated and run through a salt bed filter
to replenish. Basically all of the requirements for a
home setup which works well are going to be a miniature scale model copying of the larger industrial scale factory.
Something I observed fairly early in reviewing the literature is that using a Ti substrate certainly doesn't simplify the requirements for a plating
bath to less than what control would be needed for plating a massive anode, you have the same headaches either way for the plating bath requirements,
plus you have the added complication of the interface at the Ti to PbO2. So using
a Ti substrate actually doesn't simply things with regards to the PbO2 bath requirements, if a thick PbO2 coating is intended to be applied .....in
which case you are probably not really better off using a Ti substrate than simply going ahead with a massive PbO2 anode, because the added
technical complexity for the Ti substrate offsets its value.
So really for a Ti substrate you shouldn't set a goal of getting a "heavy thick coat of PbO2", but more like getting a millimeter or two maximum
thickness of a very specific quality of coating, and even at that thickness it is still well into the area where a pumped electrolyte is probably
needed if the anode is of significant size in relation to the plating cell. Additionally when the design is evolved it is near certainly going to a
coaxial electrode assembly, and
when that occurs, the recirculating pump will be unavoidable. So ....you probably know where this is eventually headed is away from a one-pot batch
process
towards a continuous process scheme.
[Edited on 17-1-2009 by Rosco Bodine]
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tentacles
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| Quote: | .in which case you are probably not really better off using a Ti substrate than simply going ahead with a massive PbO2 anode, because the added
technical complexity for the Ti substrate offsets its value. |
Not to be a dick, Rosco, but that *TOTALLY* discounts the difficulty inherent in connecting a massive PbO2 to the power source, and sealing that
connection through a lid, etc. 6 of one, half a dozen of the other, as it were.. The MMO substrate, if it works, could simplify this by a staggeringly
large degree - eliminating the interface problem and providing an easy means of connection.
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Rosco Bodine
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Hmmm, about silver / PbO2 connection, that's no problem.
It's less technically difficult to make an external connection using silver leaf or a silver plated clamp to PbO2 than it is to engineer and implement
a durable interface on a Ti substrate as an internal anode structure. But yeah I agree that MMO is the probable solution, either as an interface or as
a working coating. You don't need a heavy plating of PbO2 when MMO is under it. Anyway I'm not trying to discourage any efforts or experiments, by
anticipating possible complications, which may or may not appear as
being an issue. I am sort of thinking out loud, when my
silent introspection would probably be more welcome.
I should probably go busy myself with contemplation of anomalously soluble Bi complexes which may be useful in varying pH scenarios as pyrolytic or
electrolytic precursors for achieving Bi doping in higher pH ranges.
Before I get busy on that theory, I found an interesting
metallic Tin plating patent about an alloy material I haven't seen before, and it could have some usefulness
in anode construction, where a thin flash plating of metal
is then oxidized on baking. This one caught my notice
because it is a strongly adherent 80-20 Tin / Cobalt alloy
which is a bright white faux silverplate appearing kind of material, sort of like a bright chrome plating....but on baking
to oxidize a flash plating of this alloy, for example if it was overcoated with nickel nitrate or manganese nitrate or other nitrate of interest and
pyrolyzed.....a DTO / MMO should result which I have not seen described anywhere before.
Example #3 is one I supposed would likely stick well to Ti.
US3914160 Bright White 80-20 Tin-Cobalt Alloy Electroplating Method
[Edited on 18-1-2009 by Rosco Bodine]
Attachment: US3914160 Bright White 80-20 Tin-Cobalt alloy electroplating method.pdf (146kB)
This file has been downloaded 1757 times
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Rosco Bodine
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electroless deposition of Tin-Bismuth solder alloy
This additional patent would possibly also be of interest.
What I was contemplating here is first plating the 80-20
Tin-Cobalt alloy flash onto an oxalic acid freshly etched Ti,
possibly hydrided, and then following that 80-20 Sn-Co
with an electroless flash plating 70-30 Tin-Bismuth .....and then applying a nitrate and pyrolyzing the intermetallics to an MMO layer. The well
adhering films of the metallic precursors on a Ti substrate *possibly* may result in a more compact and denser harder interface layer of MMO than the
use of nitrate precursors alone, as in the simpler "dip and bake" scenario. As a finishing touch, the baked coating could be dipped in ammonium
fluoride and baked again and the fluoride doping should really toughen up the MMO even further.
US5391402 Electroless deposition of Tin-Bismuth solder alloy
Of course you wouldn't necessarily be limited to applying this sort of strategy to only a Ti substrate, you could use say
stainless steel or copper or maybe even aluminum or ordinary low carbon steel perhaps phosphated or chromated first. The thermal expansion properties
there would probably be the compatability determinant.
[Edited on 18-1-2009 by Rosco Bodine]
Attachment: US5391402 Electroless deposition of tin_bismuth_solder alloy.pdf (174kB)
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Sedit
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I cant say that i have read through this whole threed but i do know for perclorite production that this threed started about I have read about alot of
gold electrodes being used.
I have always had very good success with gold electrodes which are cheep and dont fall apart like carbon and others always do over time.
Before you shrug it off as an expensive ass way of doing it let me tell you that gold electrodes are cheep as can be.
If you go to a craft store you will find gold foil that is extreamly thin and good for about nothing but you can take this foil and using it to coat
pieces of carbon rod or plate.
Iv used these type of electrodes for many differnt uses and found very few things that will react and destroy them.
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y2kbugger
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Hey guys, I started my own thread, but I was told it was better to keep in a related thread, so here it goes:
Currently I am running a miniature NaCl cell test run in a mason jar and graphite anode. Will test ppt a yield with KCl when i get some
I am ready to try something a little more real. I purchased a $20 30''x4'' MMO coated Ti.
I was given a 13.7V @ 30A PS so I will need to regulate it so I won't burn it out.
My question is whether or not a regular cooler would work as a cell container, or do I need to use a 5 Gal. Bucket?
Also, what do you guys think of the Anode? To good to be true? I will be getting one of those soon. When I get it how can i tell if it is good
(actually MMO not just Ti), I hope so because the guy has a bunch more and you guys may be able to use them.
Those lead anodes are beautiful BTW, you guys are awesome!
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tentacles
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That's awesome, at least he's getting better money for those sheets since I told him what the coating was.. I paid him $25 for three of those sheets..
They appear identical to every other MMO anode I've seen, but there's no telling what formulation they are - more than likely they are pool
chlorinator type material or for waste water treatment. I haven't tried mine for making chlorate yet as I've still got to make a spot welder to put
shanks on.
You're going to need to cut that voltage in half or more - there are other options but it gets complex to say the least.
What's the cooler made out of? Polystyrene? Is it even marked?
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Rosco Bodine
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You could have gotten them for half what you paid in mid-November when they were three for $30
If it is MMO it will have a flat black look to it.
For electrolysis you are probably going to have a cell voltage requirement in the 2.5 to 3.5 or max 4 volt range . If that is a linear supply you will
want to use a variac in front of it or at least a fixed stepdown transformer like maybe a 36 or 48V 10A so that you don't have to "burn off" the other
10 volts at 30 A which you don't need . With that supply, assuming it is a straight linear without an SCR voltage adjustable input which compensates,
at full output your supply will be consuming three times as much power as your cell.
[Edited on 21-1-2009 by Rosco Bodine]
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