Sciencemadness Discussion Board - Multilayer Metal Oxide / Titanium Anodes for Chlorate/Perchlorate

Multilayer Metal Oxide / Titanium Anodes for Chlorate/Perchlorate

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Xenoid - 13-1-2008 at 14:31

Much as I dislike starting a NEW thread on this subject, I feel the various OLD thread titles are not really descriptive enough to cover what is presently being done by various members in this field. Some of the early ideas we had concerning oxide coatings were perhaps a little naive. It now appears extremely unlikely that a simple single coating of oxide over titanium will make a successful anode for amateur chlorate and/or perchlorate production.

I would like this thread to incorporate all titanium coating processes (baking, electroplating and perhaps plasma coating) which utilise oxides as working, interface or intermediate layers. As such we will be able to bring together the ideas which are now spread over several diverse threads on PbO2, MnO2, Co3O4, Fe3O4, SnO2/Sb etc. Many of the processes and techniques used in some of these oxide coatings are applicable to others. There is no reason to separate plating and baking procedures as both can be used on the same anode. Unfortunately they are being spread over several threads.

I feel this thread can be a natural successor to the following threads:

Cobalt Oxide Anodes.
More on PbO2 electrodes (as applied to coating titanium)
Magnetite Anode (as applied to coating titanium)
Tin Oxide + Antimony Oxide Anode
MnO2 Anode
Thoughts on Anodes
..... and several other minor and earlier threads

Hubert Lives!

Xenoid - 13-1-2008 at 14:34

After Hubert's unfortunate accident resulting from the power failure, the electrode assembly and container were cleaned up, refilled with fresh, saturated KCl and reborn as "Purple Haze 2". Hubert appears little changed, I am starting to think that most if not all the black/brown mess in the cell came from the cathode. When I started up "Purple Haze 2" the electrical parameters were identical to those previously. I have now increased Hubert's current to 3.6 amps, this corresponds to a current density of 100mA/cm^2.

Interestingly "Purple Haze 2" is neither purple or hazy, but crystal clear. It seems weird seeing a chlorate cell so clear, it has iridescent, platelet-like crystals of KClO3 floating around like snowflakes, before settling on the 3 cm high pile on the bottom of the container.

It would appear that some of our earlier ideas on the origin of the purple MnO4- were wrong. I now think it was coming from unconverted Mn++ in the pyrolitic coating. It may be possible to remove the pink colouration, if deemed necessary, by a quick electrolytic leaching, pretreatment in a brine solution!

Another possibility, really too awful to seriously contemplate, is that all the MnO2 coating was stripped of Hubert during the "accident" and that he is now running on the 4 Co3O4 interface layers, much like my earlier "4 coat anode" from the "Cobalt Oxide Anode" thread. I think this is unlikely though as both coating schemes were put on under the same conditions, and the "4 coat anode" started to shed oxide very early on! There is no sign off this happening with Hubert at the moment.

Hubert has now been in a chlorate cell for nearly 2 weeks and scarcely seems affected by his "ordeal". He has produced copious amounts of KClO3 (Na - free) which I am still extracting. He has been running most of this time at 50 mA/cm^2 and for the last few days at 100 mA/cm^2

[Edited on 13-1-2008 by Xenoid]

PurpleHaze2.jpg - 15kB

Meet Mathilda!

Xenoid - 13-1-2008 at 14:37

In a continuance of my Teutonic naming scheme, my latest anode is called Mathilda (brave little maid). Mathilda is destined for a perchlorate cell like her predecessor Gertrude. I have put together a 400 ml cell for this purpose, which closely matches Mathilda's length. About 10 cm of her is in electrolyte for a surface area of about 30 cm^2. She will be run at 3 amps, which is 100 mA/cm^2, my new "benchmark" for anodes of this type. Running at any higher current density will only cause the 400 ml cell to overheat.

Mathilda was pretreated for several hours in a saline solution at 100 mA/cm^2 to leach out any unconverted Mn++ from the coating. This produced a purple colouration similar to Hubert's first cell.

Mathilda's coating scheme closely follows that of Hubert. Major changes were:

1) Even higher temperature, 400 oC +/- 10 oC. versus 380 oC.

2) More MnO2 coats, 15 versus 10

3) The 4th Co3O4 interface coat was alternated with the 1st MnO2 coat. I did this on a whim, I thought perhaps it would produce a more "diffuse" boundary layer, with less stress. Who knows!

4) The final "baking" time was extended to 1 hour. I did this to hopefully make the pyrolysis of the outer layers more complete.

In addition, I made a major blunder with the MnO2 coating solution. I forgot to 50:50 dilute my ~2.4 molar "stock solution" manganese nitrate. I couldn't understand why I was getting MnO2 rubbing off each coat, when this had not happened with Hubert. It was not until after I had finished that I realised my mistake! The last 5 coats were somewhat experimental:

Coats 11,12, 13 used "stock solution" diluted 50:50 with isopropyl alcohol, and various schemes of controlled heating, eg. 100/200/300/400 oC.

Coats 14 and 15 used the previous solution diluted further 50:50 with water.

Mathilda has been running at 3 amps in the perchlorate cell for 15 hours. There has been a little brownish precipitate, the coating looks OK, although the electrolyte level line is visible. I have decided to filter the solution. and it is now perfectly clear. This will allow me to more easily monitor ongoing corrosion. The pH of the cell was measured after 3 hours and was 11.3, it was measured again after 15 hours and found to be 11.7.

Methylene Blue test indicates perchlorate is present, but only does this after making the test solution more alkaline with NaOH. This happened with Gertrude also, I just don't understand what is going on with this!

[Edited on 13-1-2008 by Xenoid]

Mathilda.jpg - 5kB

jpsmith123 - 13-1-2008 at 15:15

Some of the early ideas we had concerning oxide coatings were perhaps a little naive. It now appears extremely unlikely that a simple single coating of oxide over titanium will make a successful anode for amateur chlorate and/or perchlorate production.

That may be generally true, but I would consider Beer's MMO coatings to be relatively "simple". (BTW how is your pool chlorinator cell doing?)

At this point, after having read more patents and more papers on the subject, I see TiO2 as a "unique" oxide, and instead of MMO, I tend to think of these coatings as "doped TiO2".

Xenoid - 13-1-2008 at 15:37

Quote:

Originally posted by jpsmith123
(BTW how is your pool chlorinator cell doing?)

Hi, jp'

Actually, I'm a bit disappointed in it's performance.

I did a "runtime" calculation based on a 60% efficiency (yes, I know, a bit optimistic), and then let it run for about twice that length of time. I did one concentration and extraction of NaClO3, I tried concentrating the remaining liquor, but got quite alot of NaCl precipitating during the evaporation. Given the amounts involved, I didn't go any further, and it's now in my "recycling" tub. I'm still recrystallising the NaClO3 I did extract as it was pretty dirty from some cathode corrosion problems. There was also a certain amount of "black material" which could only have come from the anodes. I think I'll redesign it, but not at the moment as I have 3 cells running and it's quite a handfull. So basically they work OK, but will they last and be value for money.

Edit: If these pool chlorinator anodes are RuO2/TiO2 MMO they will not stable in alkaline brine solutions. Remember industrial set-ups are pH controlled (6.8 for chlorate production). The pH of my chlorinator electrode cell was 8.3 at the end of the run! pH control is an aspect of (per)chlorate production that industry takes for granted, whilst being difficult (if not impossible) for the amateur to master. Thus coatings which are used industrially may not necessarily be satisfactory for the amateur, where pH may rise to 12 in perchlorate cells.

[Edited on 14-1-2008 by Xenoid]

chloric1 - 13-1-2008 at 18:16

See Xenoid, I told Hubert was fine. I have seen stainless make some ugly messes. Especially in the presence of dichromate antireduction catalyst. I never told you what I did the very first time I hooked up my chlorate cell. My mind was in space somewhere and I put negative on the graphite and positive on the stainless steel

. In 5 seconds I noticed wisp of blackish material coming off the cathode and saying"Hum thats interesting". It still was so obvious yet I did not acknowledge. When I took my digital photos and posted to my website, I looked at my setup and said" What the hell?" I went outside immediately switched the power clips and lo and behold, chlorine started to evolve at the graphite anode. After some hours, the solution smelled of hypochlorite. So, what does this mean? Well, when you described your situation I new that your anode was OK and your Stainless cathode gave up the ghost. May it rest in pieces

.

It is interesting what came of the purple haze situation. I wonder if your pretreat brine can accumulate enough manganese for you to extract it as the carbonate. Hopefully these multilayer schemes prove to be durable as it might be cumbersome and difficult to reclaim metals from failed coating. Unless the metals have wide variations in there aqeuos chemistry. Still waiting on my thermocouple. I also ordered an aluminum tube 1 1/2" ID for the baking.

[Edited on 1/13/2008 by chloric1]

Xenoid - 13-1-2008 at 18:56

Quote:

Originally posted by chloric1
I wonder if your pretreat brine can accumulate enough manganese for you to extract it as the carbonate. Hopefully these multilayer schemes prove to be durable as it might be cumbersome and difficult to reclaim metals from failed coating. Unless the metals have wide variations in there aqeuos chemistry.

You would have to be desperate to attempt this, 10 coats of MnO2 would lower the level of the Mn nitrate solution in the dipping test tube by no more than 10 mm. The amount of Mn used is miniscule. Mn carbonate is dirt cheap at the pottery suppliers anyway! Manganese solutions are just not worth messing around with, believe me!

chloric1 - 13-1-2008 at 19:27

Yeh good point but after awhile the manganese would build up maybe after a year. I guess I like to reuse chems as long as it is reasonably easy and not overkill. I am sure 5 grams of MnCO3 over a few months is not going to make or break you. At least it is better than dumping though.

Your Pool MMO might be a good candidate for a recoat

Strip it down to bare Ti and put your coatings on it. It would be interesting to see how different shaped substrates work with this.

Rosco Bodine - 13-1-2008 at 20:25

There was a suspicion by me expressed earlier in the other thread that the catalytic component for perchlorate in combination with MnO2 was likely bismuth . That earlier idea
remains , and I have turned up a couple of more references
which describe a Bi and Mn mixed oxide compound which
forms in the temperature range which is operable for these
baked coatings . So it looks like a good bet , especially for
this one that forms from the mixed nitrates by thermal decomposition . It precisely fits the template of conditions
which seems to make it fit as a candidate dopant for the MnO2 to achieve the desired selectivity for perchlorate .

US5419986

Of course the chemistry involved here would have to be included in the coating scheme , but it looks like it would be an easy fit .

[Edited on 13-1-2008 by Rosco Bodine]

Attachment: US5419986 Bismuth doped MnO2.pdf (615kB)
This file has been downloaded 1106 times

Rosco Bodine - 13-1-2008 at 20:28

Here's another method for formation of the Bi and Mn mixed oxide .

US4520005

Attachment: US4520005 Bismuth substituted Manganese Birnessite.pdf (250kB)
This file has been downloaded 1168 times

Xenoid - 13-1-2008 at 20:54

@ chloric1

Yes, I only used the two best anodes of the chlorinator assembly. There are another 4 to play around with. I'm not sure of the best way to strip off the remaining MMO coating. May have to be sandblasted. Also they are perforated plates, I'll need some sort of new baking system.

@ Rosco

I have sent an email to a metals company, here in NZ, ordering some Bi (min. quantity was 1Kg). They still haven't replied, so I'm still waiting. I didn't particularly want 1Kg, but it has interesting magnetic properties (repelled by magnets) so I can "play around" with that aspect as well! Yes, I'm very keen to dope the MnO2 with Bi, it definitely needs "something", but the MnO2 seems brilliant in the chlorate cell.

chloric1 - 14-1-2008 at 03:19

@Rosco-Fascinating patents indeed. From my general overview, it seems this synthetic Birnssite is made at much lower temperatures than our other coating schemes. Heck one might be compelled to use the kitchen stove when the wife is sleeping

Although NOx fumes in my kitchen are NOT cool. What I am wondering is, what is the highest temperature that can be used here for birnssite?
I tried to look but could not turn up any data on decomposition temperature etc.

@Xenoid-Yes a new baking set up would be needed. Possibly a metal box with suitable refractory and nichrome wire with an inlet for a small blower. Would not have to be too fancy as it is used at 400°C and only needs to max out at perhaps 600°C.

Rosco Bodine - 14-1-2008 at 05:07

It may seem somewhat tangential to the attached patent ,
whose use of Ru doped TiO2 is more parallel with the Beer patents , but the function of the bismuth doping in the attached patent is really pretty much the same in the scheme I am contemplating .

The attached Diamond Shamrock european patent is about the same year as the US4072586 patent related to MnO2
perchlorate anodes , and describes the use of Bi doping
for the same purpose . According to the MnO2 patent , there is only needed something in the range of 0.5% to 5%
of the Bi doping in the MnO2 for achieving the desired effect
in that differing composition , ( if indeed the dopant being referenced is Bi as I suspect , and not As or Sb which are the other two choices of dopants ) . I believe the lack of specificity on this choice was a deliberate ambiguity in the patent description , where the authors were being cryptic
for business reasons , and Bi seems to be the most likely suspect dopant which they try not to single out and declare .

I also have a suspicion that the ~20% " SnO2 component " may be the anomalous solubility Fe doped metastannic acid hydrosol . This would also fit within the boundaries of what is described in that US4072586 MnO2 perchlorate anode patent .

[Edited on 14-1-2008 by Rosco Bodine]

Attachment: WO-1979-000842 Diamond Shamrock Bi doped SnO2 perchlorate anode.pdf (637kB)
This file has been downloaded 1205 times

tentacles - 14-1-2008 at 07:53

I was making a CoO/MnO2 anode last night, got 5 coats CoO and 4 coats of MnO2 so far. I've read the previous two Bi patents (relating to batteries) and I happen to have a piece of crystallized Bi. I'm thinking about breaking a small chunk off and making a few ml of Bi dopes MnO2 tonight. If I get to it (and find the damned crystal) I'll let you guys know if it adheres. The Pb doping is also a possibility.

The anode I'm working on is another 15x2cm strip, baked in a tube attached to my heat gun. I don't have a thermocouple yet but the "high" setting is supposed to be 450C. Thermocouple is on it's way, though!

[Edited on 14-1-2008 by tentacles]

Xenoid - 14-1-2008 at 09:24

@ tentacles
You haven't told us the IMPORTANT information, what's the name of your anode? ...

Yeah, good point about the Bi crystals, there is someone locally who is selling them, might be the way for me to go! With the Bi doping, you could add say another 6 coats of MnO2, but with say an extra "drop" of Bi nitrate in each successive coat (depends on your solution concentrations off course) this would produce a range of doping levels in the outer layers.

If you are using thin metal strip it may be advantageous to "anneal" or slowly cool after an extended baking period at the end of the coating sequence.

I wouldn't take too much notice of what heat gun manufacturers claim as a maximum temperature ...

tentacles - 14-1-2008 at 10:34

Xenoid: Which is why I used a piece of my sheet lead to test the temperature at the end of the "plating barrel". The temp seems to hover right at the melting point of Pb, so it seems like it should be just about perfect. I can block some airflow for a bit more heat.

I think my Bi crystal is like 34g, and we gave like $17 for it, but all you really need is a few grams to dope with.

The strip is 1mm thick, my Mn(NO3)2 was initially far too strong, and bubbled some, I brushed and wiped the majority of that coating off and thinned out some. It seems to be adhering fairly well.

I have two more Ti strips, so I may try one with Pb doping and one with Bi doping. I've got another piece of Ti on the way (19"x2"x.063) for bigger cathodes and some longer anodes.

Oh, and I'm calling the anode... Ugly Betty

Rosco Bodine - 14-1-2008 at 10:40

Regarding heat guns , I have surveyed the thermocouple
controlled heat guns . The Steinels seem to be top of the line , but the Milwaukee 8988-20 seems to be about the same thing for less money and is Swiss and German made . The Makita HG1100 is another possibility . And the cheapest of the thermocouple guns which also seems to have gotten good reviews is the Wagner HT3500 , probably the best bargain .

There's a few others , NTE , Eddy , and Master which are
mid price range .....and there are some really high end
swiss made production line guns that are several hundred dollars .

The least expensive of the true incremental adjustment
digital temperature readout heat guns is the Milwaukee
8988-20 at about a hundred and forty dollars if you really need that sort of accuracy . I think it steps in 10F increments and regulates the temp regardless of airflow
while showing a real time sensed temp readout on an LCD display on the top of the housing .

chloric1 - 14-1-2008 at 14:14

Quote:

The least expensive of the true incremental adjustment
digital temperature readout heat guns is the Milwaukee
8988-20 at about a hundred and forty dollars if you really need that sort of accuracy . I think it steps in 10F increments and regulates the temp regardless of airflow
while showing a real time sensed temp readout on an LCD display on the top of the housing .

Are you kidding me? I like my chem hobby but I am not spenfing $140 on a heat gun. I have the entry level Milwaukee $29 special. With a maximum output of 538°C, the other end of my aluminum tube should be just right at 400-420°C.

@Xenoid-yeh I know you cannot take the advertised temperatures as gospel but when I held my 250°C rated thermocouple at 5 cm from the gun nozzle on low, it happily was reading over 300°C before the thermocouple sheathing turned brown and started to smoke

. Hence I ordered a different K-type thermocouple with the stainless probe rated at 700°C. Antisipating....is keeping me waiting..

Methylene Blue Testing

Xenoid - 14-1-2008 at 14:15

On page 11 of the "Cobalt Oxide Anodes" thread, I described some of the "inconsistant" problems I was having testing the "Gertrude" perchlorate cell for perchlorate production using 1% Methylene Blue (MB) solution. A similar situation has arisen testing the "Mathilda" perchlorate cell. I have now spent a couple of hours experimenting to try and work out what is wrong.

There is a problem with the Methylene Blue test at low perchlorate concentrations (ie. when testing a perchlorate cell in the early stages of it's operation). At low concentrations the test is remarkably TEMPERATURE SENSITIVE. The "Mathilda" cell is operating at 35 oC. at the moment, when tested with MB the solution remains blue, indicating no perchlorate. When a similar aliquot is cooled in a fridge for a few minutes, the same test gives a distinct violet precipitate.

To test this further, I made up a very dilute K perchlorate solution, and divided it equally between two test tubes. One was heated, and tested at 40 oC. the solution remained blue, no precipitate. The other was chilled to 15 oC. and produced an immediate violet precipitate.

To some extent, the reactions are reversible, when heated gently the violet precipitate will dissolve and the solution turns blue. Also chilling the blue solution does seem to bring about some violet colouration. The effect does not happen with high perchlorate concentrations, where a violet colouration occurs at very high temperatures.

Although I haven't determined the concentration and temperature limits in any formal way, suffice to say, ensure your sample is at less than 15 oC. if testing for low levels of perchlorate.

chloric1 - 14-1-2008 at 14:49

Ahha! I will note that

Well, IIRC from the "perchorates" book the MB actually forms a perchlorate salt and there might be a solubity product issue especially at 35°C or above. Or it is an abduct that is loosely bound and high perchlorate concentration favors the bond to the point where cooling is not needed.

Rosco Bodine - 14-1-2008 at 15:10

Quote:

Originally posted by chloric1
I have the entry level Milwaukee $29 special.

for want of an additional $2.29 this is what you missed

http://www.acehardwareoutlet.com/(gxqv5sb5x4lwi145md1rxuu1)/...

Xenoid - 14-1-2008 at 15:44

Quote:

Originally posted by chloric1
..... it happily was reading over 300°C before the thermocouple sheathing turned brown and started to smoke ....

Yes, I had this problem with a new thermocouple I bought, the end was finished with a bit of heatshrink tubing! I cut it off and used a length of plumbers teflon tape. I folded the end of the tape over itself a couple of times, then inserted it between the two wires, about 10mm back from the junction, then wrapped it around, back over the glass fibre sleeve for about 2 - 3 cm. I have two like that now, and have not had any problems up to 400 oC.

Edit: Also, having the soft tape over the end means I can "push fit" the thermocouple into the Al tube, and it stays there, with the junction in the airflow about 5 mm from the anode.

[Edited on 14-1-2008 by Xenoid]

chloric1 - 14-1-2008 at 15:46

Probaby has the same 1 1/2 inch nozze also. I will have to control heating by more mechanical means.

That international patent you posted was pretty blatant on stating the significance of bismuth doped tin oxide coating. In fact line #9 and #13 had the same word for word statement that the preferred undercoating is tin oxide doped with bismuth oxide. It was odd like it was jumping off my computer screen.

tentacles - 14-1-2008 at 16:13

I called a local rock shop, and he "knew a guy" with some Bi, so 25g for $10, he's supposed to have it saturday (damn I hate waiting!). It felt so damn shady, and all I wanted was some metal!

DON'T

chloric1 - 14-1-2008 at 16:55

It seemed shady because it is DEFINATELY shady. It is nothing less than a RIP OFF. You can find bismuth on ebay for about $20 per pound. I linked this auction:99.99% pure Bismuth 17 ounces

Rosco Bodine - 14-1-2008 at 17:52

Bismuth and tin are both used as lead substitute fishing sinkers , you can get 'em at WalMart .

Quote:

Originally posted by chloric1
That international patent you posted was pretty blatant on stating the significance of bismuth doped tin oxide coating. In fact line #9 and #13 had the same word for word statement that the preferred undercoating is tin oxide doped with bismuth oxide. It was odd like it was jumping off my computer screen.

Yeah that patent was almost like somebody at Diamond Shamrock got overexcited , ran to the patent office with the rough draft instead of going to the usual company law firm , and just spilled the beans.... before the technical mystery writers could work their special editing magic on it to make it more cryptic so the technology couldn't be easily understood or copied . I read this patent and thought it may be a nugget having dislodged and tumbled downstream from the usual mystery mountains .

The paragraph I found to be interesting was line 33 page 2 :

Quote:

In one preferred embodiment of the invention , the electrode coating consists essentially of the SnO2-Bi2O3 solid solution applied in one or more layers on a valve metal substrate. This type of coating is useful in particular for the electrolytic production of chlorates and perchlorates, but for other applications the coating may desirably be modified by the addition of a small quantity of one or more specific electrocatalytic agents .

The very next paragraph section (d) covers the case of the MnO2 coated anode , in my opinion reading down through line 29 of page 3 . This then skips to page 11 where the
first and last paragraphs of page 11 are pertinent .

Sooooo...

I'm looking over a four leaf clover that I overlooked before ...

Now everybody sing

Sing louder dann2 !

....I can't hear you

[Edited on 14-1-2008 by Rosco Bodine]

dann2 - 14-1-2008 at 18:05

ZZZZZZZZZZZZZZZZZZZZZzzzzzzzzzzzzzzzzzzzzZZZZZZZZzz
BUMP
Did someone mention my name?

oh Hello,

A yea, the old SnO2/Bi2O3 chestnut.
RongPeng mentioned it back about 40 posts ago.
It may be the way forward no doubt.
I'm still stuck with the Alembic anode and intend to stay stuck on it untill I have a reproducable HOLY GRAIL anode.
A lost cause or total glory? we'll have to wait and see.
Will have to leave the SnO2/Bi2O3 to someone more skilled in the art etc etc.

Dann2

and anyways I can't sing, krokes only.

JohnWW - 14-1-2008 at 18:14

Quote:

Originally posted by Rosco Bodine
Bismuth and tin are both used as lead substitute fishing sinkers , you can get 'em at WalMart .

At the prices they are asking, compared to the price of fish, you might as well use good old Fe, although to obtain the same weights the sinkers have to be about 45% larger in volume than Pb sinkers. Besides, Bi is too rare and valuable a metal to be used for sinkers or shot, and it is only about 25% denser than Fe anyway.

Rosco Bodine - 14-1-2008 at 18:17

@dann2

Heck listening to you , now I have a Kilo of reagent grade Sb2O3 , when I should've ordered Bi(NO3)2

Oh well , maybe it will be useful for something ....for sure for sunshading float glass , even if it isn't much good for perchlorates

The jar of Sb2O3 I can always use for a paper weight . I said I had a suspicion about the Bi ...
of course I would be more comfortable with the whole thing if it wasn't in a shamcrock patent

Could be
they are both wrong .....in which case I may become an international fugitive as opposed to an international hazard

BTW ..

Rong Peng has been challenged by Rite Pong to a friendly game of back and forth .....Rite ??? - Rong !!!
Peng ??? - Pong !!! This will be known as the
Rite-Rong Peng-Pong Tournament

[Edited on 14-1-2008 by Rosco Bodine]

tentacles - 14-1-2008 at 18:41

Guys, I'm not sure if the Bi sinkers are availible here in Canada. I know you can get a lb of 99.99% on ebay for $17 - plus about $20 shipping, and then customs will take their cut - minimum $7. There's also the fact that a lot of ebay sellers won't ship from USA to Canada, etc etc. It's not like I need a lot of it (I'll probably eat those words!). I WILL check walmart later tonight. Are they actually labeled as being Bi or Sn, or do I have to try and guess?

[Edited on 14-1-2008 by tentacles]

Also, an update on ugly betty: I wasn't getting good conductivity with the anode, so I sanded off the coatings - a much more difficult proposition than I had expected. The new coating - I'm up to 4 coats of MnO2 after 5 coats of Co - looks MUCH better. I added more ethanol to the solution and the coatings are sticking better. Conductivity is much better (as compared by reading with an ohm meter). I'm getting readings as low as .5k ohm vs megaohms with the original try.

On another note: after sanding most of the coating off, a dip in hot HCl removed the rest of the CoO/MnO2 as well as providing a fresh etch.

[Edited on 14-1-2008 by tentacles]

Checked Walmart, picked up some non-lead sinkers, they appear to be tin. I may try and hit a sporting goods store tommorow for the eagle claw brand sinkers.

Also, I tested out Less Ugly Betty after 6 coats of MnO2 - got the same low readings despite a much nicer coating. Turns out my PSU had burned up a couple caps (so THAT was the burning smell!). I stole some Rubycons out of my old PSX and it's cranking out power again. With one cathode (so only current from one side of the anode) it was drawing about 1.7A at 5V. That's about 110mA/cm2. Got a dash of pink permanganate coloring, same as Xenoid, but I prepared for that and am testing it in a throwaway NaCl beaker. If I can find Bi tommorow I will try a couple coats doped with Bi. If not, I will make up a splash of Pb doped MnO2.

I've filtered my gouging rod cell and now have 4L of urine water that I'll be boiling down tommorow. It was supposed to run another 3 or so days but the gouging rods "ran out" so I tossed the stubs and decided to collect the chlorate and reuse the liquor with Ugly Betty.

[Edited on 14-1-2008 by tentacles]

The_Davster - 14-1-2008 at 18:46

Go to a gun store that caters to those that reload their own ammunition. Can buy bismuth shot, nontoxic for waterfowl or something. I have never seen bismuth elsewhere in Canada.
EDIT: Mind you, I have never extensively looked through walmart.

[Edited on 14-1-2008 by The_Davster]

Rosco Bodine - 14-1-2008 at 18:50

Edit : Not Eagle Claw but Gremlin Green

The Bi or Sn fishing weights will definitely be labeled and the price will tell you something too . The brand name on the Bi egg sinkers is Gremlin Green , the split shot are Tin .
Water Gremlin is the tackle manufacturer name , but they also make lead weights so check the label for Gremlin Green
which is their environmentally friendly lead-free product line .

The big outdoor outfitters and tackle vendors probably have these too . Also some lead free solders are Bi-Sn alloys .

For a pound ingot of Bi or other metals

http://www.rotometals.com/_c_36.html?gclid=CKal3-2gr5ACFRAgQ...

IIRC the Bi shot for waterfowl is alloyed with Cd or something else , it isn't pure . But maybe easy enough
to use anyway if you could buy a few Bi duck shells and just
cut 'em open for a few ounces of shot , rather than having to buy a huge bag of shot .
On second thought a box of 10 Bi shotshells is more expensive than a pound ingot of Bi .
http://www.cheaperthandirt.com/21013-51145-2362.html
A box of 5 Bi shotshells is less and about the minimum
for this source of Bi .
http://www.cheaperthandirt.com/21031-16528-2445.html

Cabellas has some of the Bi fishing sinkers
http://www.cabelas.com/cabelas/en/templates/links/link.jsp?c...

Both pure Tin split shot and Bismuth sinkers are sold
under the Gremlin Green product line name of Water Gremlin
as the manufacturer name . Gremlin Green should bring up plenty of search hits .

http://cgi.ebay.com/WATER-GREMLIN-Non-Lead-Egg-Sinkers-1-2-O...

[Edited on 15-1-2008 by Rosco Bodine]

tentacles - 15-1-2008 at 18:03

I procured some Bi today - tried dissolving in ~30% nitric... It doesn't seem to work very well. CRS says that Bismuth Nitrate pentahydrate is reactive with water. JTBaker's MSDS says "Solubility: Slowly decomposes in water to form subnitrate." So I have a pile of subnitrate in the bottom of my beaker, it would seem, as the subnitrate is listed as being insoluble in water (and unfortunately, EtOH). I will try and dissolve a small piece in my 80% nitric.

I tried dissolving a small piece of Bi in my 80% nitric - at room temperature, there is no visible erosion, but the Bi does turn dark/black. I also tried a Cu(NO3)2 displacement - with success, in acetone. Bi(NO3)2 is listed as soluble in acetone (who knows to what degree!). I have a slow precipitate of clear/white crystals and the copper is confining itself (mostly) to simply replacing the bismuth metal.

I suppose the next question is - is Mn(NO3)2 soluble in acetone?

I am trying a solution using the white precipitate (subnitrate?) from my first attempt at dissolving the Bi - it's up to 4 coats. Making a total of 5/6/4 on Less Ugly Betty (but getting uglier all the time!)

[Edited on 15-1-2008 by tentacles]

Apparently the subnitrate is soluble in nitric acid, forming the nitrate. I don't really fancy drying out a high strength nitric acid solution to get crystallized nitrate. I attempted this and it does seem to be the case. I can't find any information on the decomposition temperature of the subnitrate. edit: The subnitrate decomposes at 260C, so it should be suitable for our uses - it may be possible to simply use it in suspension. It is soluble in "mild HNO3 and HCl solutions" so it may just need a splash of the good stuff in the plating solution.

ref: http://www.sciencelab.com/xMSDS-Bismuth_subnitrate-9927341

[Edited on 15-1-2008 by tentacles]

[Edited on 15-1-2008 by tentacles]

chloric1 - 15-1-2008 at 19:04

Oh yes. Last time I dissolved bismuth in nitric acid was 2003. IIRC I used nitric acid full strength and applied some heat. The subnitrate is soluble in HNO3 and it is available from pottery suppliers. The property of bismuth nitrate hydrolysis should be of no major concern. Manganese nitrate needs a slight excess HNO3 to ensure stability so manganese and bismuth in the right ratios should go together hand in hand. Suspensions of subnitrate may not give even distribution unless some serious stirring and super fine particles of subnitrate are used.

tentacles - 15-1-2008 at 19:37

By full strength you mean 68%?

Xenoid - 15-1-2008 at 20:42

I did not forsee any problems with bismuth dissolving in nitric acid!

My Mellors states; "... is readily attacked by dilute and concentrated nitric acid, forming the corresponding salts."

"Bismuth nitrate can be made by the action of nitric acid on the metal itself, or on the trioxide or carbonate. It is a colourless, crystalline, deliquescent substance, soluble in water. With a large excess of water it forms bismuth subnitrate."

Bi(NO3)3 + H2O ---> BiO.NO3 + 2HNO3

tentacles - 15-1-2008 at 21:05

It's probable, then, that I should have used an excess of HNO3 rather than an excess of Bi!

Rosco Bodine - 15-1-2008 at 23:08

Bismuth nitrate should be straightforward , using five times the weight of granulated Bi as d 1.2 HNO3 to dissolve .

Attachment: Bismuth Nitrate.pdf (125kB)
This file has been downloaded 970 times

Rosco Bodine - 15-1-2008 at 23:11

Here's some more concerning Bi nitrate and subnitrate ,
as well as Bi(OH)3 Milk of Bismuth from an old pharmacy text .

BTW I have a half kilo of Bi in transit .

Attachment: Bismuth Nitrate Bismuth Hydroxide related.pdf (206kB)
This file has been downloaded 1917 times

Xenoid - 15-1-2008 at 23:44

Quote:

Originally posted by Rosco Bodine
BTW I have a half kilo of Bi in transit .

Half a kilo, half a kilo..... I laugh at your half kilo! I have ONE kilo in transit ....

Aaaand one kilo of antimony, aaaand one kilo of tin.

They were the minimum amounts I could purchase, actually the antimony was dirt cheap only NZ$14 a kilo. The bismuth was NZ$40 a kilo, luckily I have other uses for these metals, and should be able to offload the excess online at prices high enough to cover my costs.

I guess the antimony was so cheap because the bottom has fallen out of the tin oxide doping market ...

JohnWW - 16-1-2008 at 00:40

Let me know when it arrives, Xenoid, - I might want some. I am thinking of experimenting with alloys of Bi, for example, as in types of solder which do not contain Pb. However, Sb is comparable with As in toxicity.

BTW Other uses for Bi are:
(a) Oxidized to the +5 oxidation state, which is done electrolytically, results in, among other things, sodium bismuthate, NaBiO3. It is an extremely powerful oxidant, and is used in the colorimetric method of analysis for Mn in water by oxidation to MnO4- and spectrophotometric measurement of that; although because it also oxidizes Fe(III) to FeO4--, which has a very similar color, Fe interferes with the analysis.
(b) The Russians use Bi-209, the only stable isotope, to make, via Bi-210 by irradiation with neutrons and beta-emission, Po-210, an intense alpha-emitter with a half-life of 183 days. They use it for murdering defected KGB agents, by slipping it into their food or drink.

Xenoid - 16-1-2008 at 01:14

Yeah, bismuth is kind of interesting, I've never had any before. What I'm interested in, is it's strong diamagnetism (repelled by magnets). I have a bunch of RE magnets so the effect will be very noticeable.

It also forms various sub-100 oC. melting point alloys, Newton's (94.5), Rose's (93.75) and of course Wood's (60.5).

chloric1 - 16-1-2008 at 16:11

Let us not forget about Bismuth's legendary crystallizing behavoir and the irridescent interference type oxide coating. "OOOO look at all the pretty colors!"

One thing I remember from my bismuth nitrate endeavor was that the solid pentahydrate began decomposition REAL easy on heating. IIRC it starts NOx evolution at 30°!

So a slight HNO3 excess is highly recommended especially if you leave the solution to dry and you need to redissolve it to add to other oxide precursors.

@Xenoid-The antimony should be of some use for making alloys or as a fuel with some of the perchlorate you'll soon be making.

I believe it is brittle enough that you could grind it pretty fine or maybe freeze in dry ice/acetone mix and grind. I would think it could be part of some blue flame compositions.

[Edited on 1/16/2008 by chloric1]

Rosco Bodine - 16-1-2008 at 16:33

Bismuth Subnitrate ,

Bi(NO3)(OH)2 ,

is stable in contact with H2O plus HNO3 at a concentration of one-half molar . At lower acidity hydrolysis to the hydroxide Bi(OH)3 occurs .

[Edited on 16-1-2008 by Rosco Bodine]

Attachment: Bismuth Subnitrate.pdf (60kB)
This file has been downloaded 983 times

Rosco Bodine - 16-1-2008 at 17:37

Bismuth Nitrate , Bi(NO3)3

Preventing first stage hydrolysis of Bi(NO3)3 requires the presence of 9 molar HNO3 .

Attachment: Bismuth Nitrate Hydrolysis Reactions.pdf (118kB)
This file has been downloaded 2136 times

Xenoid - 17-1-2008 at 01:03

@ tentacles (or anybody else)

We seem to be following the same lines of reasoning. I am also going to try plating some LDO over a Co3O4 and/or MnO2 coated Ti rod.

I have a small quantity of Pb nitrate made using nitric acid, and some Pb acetate made from the Pb/Cu vinegar process. I would like to make larger quantities using your Pb/Cu nitrate process. I made a bulk amount of Cu nitrate (no problems, I am familiar with this technique).

The problems started when I put the Pb in the Cu nitrate. I've tried 3 times now with all sorts of strange reactions going on!

My last try was with about 400 mls of Cu nitrate. I hung 4 large strips of brushed Pb sheet over the edge of the glass container. Immediately Cu plated out, there were a few bubbles and some insoluble Pb compound ppt. out (may be Pb sulphate from residual Ca sulphate in the solution). Cu and other "crud" fell to the bottom. More bubbles, smell of nitrogen oxides (nitric acid). Left it for a few hours when I returned, Pb strips all encrusted with white "stuff", solution was greenish. Filtered the whole lot, solution now blue! Solution pH=4.2 Hung cleaned up Pb strips from side of container, immediately coated in choco-brown (?PbO2). Brushed Pb strips again, shiny Pb underneath, hung in container again, immediately coated again, repeated a couple of times more and gave up! Solution had turned greenish again.
I heated some of the ?PbO2, on a SS strip, it swelled up and then melted, the melted product (when powdered) was yellowish brown ?PbO (massicot).

What the hell is going on here! Why am I getting nitric acid forming! Why is PbO2 plating out! Why doesn't it work.... :mad:

JohnWW - 17-1-2008 at 02:55

I wonder why, though, nature intended that Bi-209, having as it does one proton outside the "doubly-magic" filled shells of 82 protons and 126 neutrons in Pb-208, the most common Pb isotope of its stable four, should be the heaviest known completely stable isotope (not counting the very long lived Th-232 and U-238, which owe their half-lives to a filled sub-shells effect). However, it has been suspected that Bi may decay with a half-life of about 10^17 years, many times longer than the universe is old. This is in spite of the fact that even-numbered elements usually have more, and more stable, isotopes, due to spin-pairing of protons, making it surprising that something like Po-210 or Po-212 should not be the heaviest stable isotope. But then, if it were stable, for what could Po be used chemically or metallurgically that Te or Bi could not be used?

chloric1 - 17-1-2008 at 03:21

Xenoid-I am not sure what is going on here. I know that lead is only a couple levels up from copper on the electromotive force scale so I am not sure if this is even efficient way to make lead nitrate. If you can sacrifice some 35% nitric acid then I would heat this and put your lead strips into this. Tne nitric readily digest this and lead nitrate,being low solubility in HNO3, will settle as very fine glistening crystaline granuals. THe process needs to be as sulfate free as possible. By the way lead sulfate is soluble in strong alkali if that helps in cleaning.

Xenoid - 17-1-2008 at 04:41

@ chloric1

Yeah, I know about making it with nitric, it's just that I didn't want to sacrifice my valuable, limited supply. I have heaps of cheap Ca nitrate and Cu sulphate is readily available.

Tentacles claims this procedure works well!

Possible variations from his procedure are;

1) It's summer here in NZ, so solution temperature may be 5 - 10 oC. warmer
2) I used molar quantities for the Ca nitrate / Cu sulphate reaction and ended up with somewhat less than a mole of Cu nitrate in about 400 mls. So Cu nitrate solution was roughly 2 Molar, this may have been stronger than tentacles used.

It's as though some sort of nitric acid producing electrochemical cell is operating at first and then PbO2 forms on the Pb plates (but not where there is still some plated Cu adhering). I'll have to experiment further with this, I really want it to work!

Patent #6777477

jpsmith123 - 17-1-2008 at 06:49

A while ago Rosco uploaded patent #6777477.

http://www.sciencemadness.org/talk/viewthread.php?tid=8592&a...

Supposedly bismuth can be used in this process as well as antimony.

Has anyone tried anything with this?

I'm curious about the chemistry of what's going on here. Anyone know what would be the precipitates described in Example 1 that apparently subsequently dissolve in the ammonia solution?

Rosco Bodine - 17-1-2008 at 09:19

Quote:

Originally posted by jpsmith123
A while ago Rosco uploaded patent #6777477.

http://www.sciencemadness.org/talk/viewthread.php?tid=8592&a...

Supposedly bismuth can be used in this process as well as antimony.

Has anyone tried anything with this?

I'm curious about the chemistry of what's going on here. Anyone know what would be the precipitates described in Example 1 that apparently subsequently dissolve in the ammonia solution?

Thanks for reminding us of that patent . I had forgotten which one of the many patents had described a soft process for the Bi precursor for use as a dopant .

I'll have a go at explaining the chemistry which appears likely . Evidently Bi is similar to Sn and Sb in the formation
of amphoteric hydroxides whose character is dependant upon the level of hydration .

Tin salts neutralized in solution at mild temperature form a hydrate Sn(OH)4 , hydrated stannic acid or stannic hydroxide which is amphoteric , that is it can either function as an acid or a base . For example
as an acid it will react with a stronger base to form a stannate , like ammonium stannate .

Evidently Bismuth likewise forms a hydroxide when a
Bi salt is neutralized in solution at mild temperature ,
forming a hydrated bismuthic acid , Bi(OH)3 , (milk of bismuth) which is likewise amphoteric and forms
with ammonia , an ammonium bismuthate .

These sorts of compounds would probably exist only
in solutions having excess base and they are likely unstable . When heated , the system that allows for their
solubility will be disrupted and the lower hydrated
oxide , less soluble form will be precipitated especially
from a system kept basic by ammonia where the ammonia is lost on heating due to volatility .

BTW , with regards to preparation of Bi nitrate , curiously
Bi metal will dissolve in fused ammonium nitrate to form
Bi(NO3)3 . It seems likely that any of the oxides or hydroxides or carbonates would likewise react .

There is some indication that Antimony or perhaps its oxides may do the same .

Manganese carbonate also reacts , but forms a double salt
nitrate , which is however anhydrous , and the Mn(NO3)2
may possibly be isolatable via some subsequent scheme ,
or the mixed nitrate might be useful in nitrate salt plus acid nitration schemes as a combination dehydrating / nitrating
precursor .

Anyway this scheme may have usefulness as an alternative
for aqua regia or concentrated nitric acid when working with
Bi or Sb metals to form soluble intermediates for further workup .

[Edited on 17-1-2008 by Rosco Bodine]

Attachment: Fused Ammonium Salts as Acids Reactions in Fused Ammonium Nitrate.pdf (540kB)
This file has been downloaded 985 times

tentacles - 17-1-2008 at 10:27

Xenoid: I believe the Pb precipitate is Pb(OH)2 - I filter this off. The greenish tint to the solution does not seem to affect the PbO2 plating, my guess is that this is unconverted Cu(NO3) - or Cu(OH)2. Given that Pb is not a strong reducer for Cu, it's possible the reaction reaches a point where the Pb doesn't reduce any more Cu out of solution. The HNO3 smell seems to be normal, at least for the Pb(NO3)2 that I have made, both from Ca/Cu(NO3) and from dissolving in nitric acid - I recrystallized some in the past and it still had the odor. You can also recrystallize the Pb(NO3)2 from the solution.

Is your lead fairly pure? My wheel weight (3% tin) lead had a white ppt that was actually metastannic acid, even when using the Cu(NO3) reduction method. Does the white ppct dissolve readily in water? I seem to recall the metastannic acid dissolved without coloring or clouding the solution.

Regarding the brown crud, I've never had this happen but I don't usually brush the copper off. I just leave the lead strips hanging until the Pb dissolves. Is it possible that it is very finely precipitated copper? Is your calcium nitrate the real Ca(NO3)2 or is it the ammonium complex of Ca nitrate? I believe mine was not the complexed salt.

[Edited on 17-1-2008 by tentacles]

Rosco Bodine - 17-1-2008 at 13:12

With regards to the Bi doped baked coating on the MnO2
perchlorate anode , my inclination would be to preform the Bi as the finely divided hydroxide , Bi(OH)3 , perhaps by simultaneously running streams of neutralization equivalents of Bi(NO3)3 in 9 molar HNO3 and NH4OH together with vigorous stirring at a mild or cool temperature , crashing out the hydroxide , settling and decanting , rinsing the precipitate with distilled H2O .
The pH of this can be adjusted with HNO3 to match the
pH of the Mn(NO3)2 solution , and a mixture then made
which should be okay for use as a dip coating .

Sn(NO3)4 could be made up the same way as the Bi
is handled and added to the coating mixture .

I would save out a portion of this tin nitrate
and use it alone or very lightly doped as as sealing layer
over the spinel interface , before or in alternating fashion
with the MnO2 layers , before getting to the Bi doped
SnO2-MnO2 catalytic outer coating(s) .

What would be the optimum composition for the mixture
I am not sure but my *guess* about a good starting point
would be precursors in mixture resulting in proportions
of the oxides based on the metals on a molar basis
Mn 73% Sn 24% Bi 3% .....up to a mixture having about double that amount of Sn and Bi in the same proportions ,
such as Mn 46% Sn 48% Bi 6% . There is something of a contradiction between the two Shamrock patents here and it may be that the final coating would be better having MnO2 as a relatively minor ingredient in the final coating which could be more like Sn 85% Bi 10% Mn 5% ,
or even a final coating having no Mn at all , such as
Sn 90% and Bi 10% .

Xenoid - 17-1-2008 at 13:28

@ tentacles

MagicJigPipe is right, I am a silly goose ...

Things appear to be working well now!

The initial problems may have been due to residual sulphate in the Cu nitrate solution, this is always a problem with the Ca sulphate metathesis reaction. Much of the ppt. was probably Pb sulphate.

Today, I boiled the greenish 400 mls of solution this produced some orangy-brown ppt. When the solution was filtered it had turned, a beautiful turquoise blue again! I put 20 mls in a small beaker and put a small strip of brushed lead in the solution, after about a minute I pulled it out, it was dark brown , but there was a hint of "copper colour" in a few places. I put it back and left it longer, another min. or so, and it was covered in "bubbly" copper, when I pulled it out, within a few seconds it turned dark brown (?oxidation). After leaving it in for several mins a lasting distinct copper coat apppeared. This started to flake off and eroded Pb was visible underneath.

The "choco-brown" material from last night was actually finely divided Cu/CuO if I'd left it a few more mins, the "copper appearance" would have become obvious. It dissolved in nitric to give a blue solution.

Sherlock and Shamrock part deux

Rosco Bodine - 17-1-2008 at 14:22

Back before Christmas on Dec. 15 , in the cobalt oxide anode thread I mentioned this patent US4272354 .....
http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...
....which regards Bi doped SnO2 as a perchlorate anode coating . I don't think I made the connection before , but this patent looks to be the exact same information in a better formatted form , as is the earlier european patent that was posted earlier which appears to be sort of the original draft for this patent .

Anyway this US4272354 is easier reading and the charts
are more complete .

Attachment: US4272354 Bismuth DTO perchlorate anode.pdf (253kB)
This file has been downloaded 839 times

Great

chloric1 - 17-1-2008 at 18:44

@Xenoid-Well I am glad your single displacement is working. I am not fond of replacing one metal with another as it rarely results in a clean 100% displacement. In this case you actually want a little cupric ion anyways

@Rosco-Thank you for the "onium salt" document! I have 1Kg of Lab grade ammonium nitrate not sure what to do with it aside from the more obvious uses. Now I know I got some experimental studies to do. :cool:

[Edited on 1/17/2008 by chloric1]

Xenoid - 17-1-2008 at 23:57

Hubert and the KClO3 cell.

After a few calculations, I have figured out Hubert has now been running for 422.5 hours (nearly 18 days) for a total of 912 Ah. After I increased the current to 3.6 Amps a slight pink colouration appeared in "Purple Haze 2". I have since dropped the current back to 3 Amps, mainly because the power supply was overheating. I have done 3 or 4 extractions of KClO3 crystals, (it is amazing how 3 - 4 cm of crystals in the cell ends up as 1 cm in the filter). The cell has been recharged with KCl and continues to operate well, it is still perfectly clear, there is another couple of cm of crystals accumulated. There is very little change in the electrical parameters since day one. Hubert should continue for a while yet, obviously MnO2 performs quite well in a chlorate cell.

Mathilda and the perchlorate cell.

Mathilda has completed 118 hours, for a total of 251.5 Ah. Most of this was in the one perchlorate cell, but when the run finished I put her in a second cell, unfortunately the voltage has now risen to about 5.6 Volts and I am stopping this experiment. Mathilda has performed much better than Gertrude (mainly because of the higher temperature MnO2 baking). But the performance in a perchlorate cell is by no means satisfactory. Mathilda has continued to produce brown/black hydrated MnO2 particles in the high pH (11.6) environment of a perchlorate cell. I have done a single extraction of KClO4 from the 400 ml cell, it's not worth the trouble getting out more. Unless the addition of say Bi, improves the attrition rate, I don't see much future in MnO2 as a perchlorate coating. I guess if Bi were to increase the oxygen potential, there might be less attrition caused by the aggressive evolution of this gas.

Perhaps Bi doped SnO2 will prove more satisfactory in the perchlorate environment ...

Rosco Bodine - 18-1-2008 at 08:34

The alkalinity is high and you are still getting chlorine loss
so the current density is also high .

For the desired operating condition IIRC it is needed to
be near neutral and the current density just below what
produces chlorine evolution at near neutral , very slightly basic pH .

You may also need some additive to the electrolyte like
a soluble phosphate , dichromate , and/or MnCl2 at
low levels maybe a tenth to a few tenths gram per liter .
A persulphate additive might help too .

Another thing that could create a voltage gradient problem
particularly in the perchlorate cell is interelectrode spacing , the gap between the working anode surface and the cathode is much too wide for my comfort on these experimental cells . For the coaxial arrangement it
would be good to try for a relatively narrow gap there , on the order of one half inch to 3/4 inch at the outside limit ,
and get some pumped flow through the assembly using
a small mag drive aquarium circulator for example to keep the electrolyte flowing past the electrodes at a pretty good rate . The wider is the interelectrode gap , the harder it tends to be on electrodes and particularly on coatings that
are challenged already and barely good enough for the reaction even under the most ideal conditions .

[Edited on 18-1-2008 by Rosco Bodine]

tentacles - 18-1-2008 at 10:31

Rosco: that's good to know, I haven't seen a lot of information on electrode spacing.

Rosco Bodine - 18-1-2008 at 12:23

I think I have seen spacing of 3/8 inch for coaxial
flow-through anode core - cathode housing type assemblies
using PbO2 coated anodes . I know I posted that way back
in the other thread concerning PbO2 anodes . I'll look for that patent again .

Anyway I came across another Bismuth anode coating related patent , US4353790 , which is interesting even though it is not specific to being a perchlorate anode , but rather as an oxygen anode . This patent is interesting because an oxygen anode having a titanium substrate is something of a torture test with regards to its likelihood of passivating the substrate , which is precisely the mechanism which is believed also to ultimately cause perchlorate anodes to fail .

There is some food for thought here with regards then to
the usefulness of Bismuth in the interface or near interface
layering on a titanium substrate , regardless of whatever
eventual outer coatings for specific electrolysis products may
be used for producing things other than oxygen . There is
indication here that Bi doped tin oxide is a superior protective
layer for a titanium substrate as well as having possible catalytic value in the outermost coatings , where that would be specific and selective for perchorate . So some percentage of Bi doping could be useful for different reasons
in all of the coating layers , from the substrate interface itself
all the way to the outside coating .

[Edited on 18-1-2008 by Rosco Bodine]

Attachment: US4353790 Bismuth Oxide Ti Substrate Oxygen Anode.pdf (409kB)
This file has been downloaded 904 times

Xenoid - 18-1-2008 at 13:01

@ tentacles

Pb nitrate method works so well, I am doing a second batch. First batch has run to completion and solution is palest-green. The second batch seemed to work better from the start, and 8 hours after starting, there were Pb nitrate crystals encrusting the Pb "electrodes" in the cool of the early morning. When you mentioned Cu contamination, am I right in assuming you used the solution "as is" for plating! I intend to crystallise out the Pb nitrate.

@ Rosco

Industrial manufacturers run both chlorate and perchlorate cells slightly acid, with pH control in both cases. This has implications for the type of anodes suitable for "amateur" use. For example, I am thinking that MMO pool chlorinator anodes may not be stable in the pH = 8.5 environment of an amateur chlorate cell.
I am reminded of P.C.S.Hayfield's comments in his review of coated Ti electrodes, where he mentions alkaline hypochlorite was accidently fed into a Ru based MMO electrode cell. The electrodes lost 25% of their coating in a few hours ...

Interestingly he then goes on to say they were still used for another 5 years ...

I ain't addin' no stinkin' additives to any of my cells.... !

With regard to electrode spacing, I think I did a check on this about 6 months ago, when I was messing with the MnO2 treated gouging rods, you had mentioned the same thing. From memory I measured the voltage at different distances for a constant current, and over the few cm involved in a home cell there wasn't much difference. For an industrial setup with thousands of electrodes, a .05 volt change would be economically important, at home it isn't. I'll recheck it, but I assume the results were not startling enough to make me change my ways! My chlorinator electrode assembly had 10mm electrode spacing and I have not been impressed with it's performance.

I've been toying with the idea of pumping solution around. In particular with regard to a KClO3 cell like "Purple Haze". It's a drag having to remove all those KClO3 crystals, I was thinking of a continuous filtration setup, and adding KCl back at the same time! All the tiny pumps I have looked at are the "submersible" type, and are not readily modified. They also have exposed metal in the impellor drive (?rotor). I'm still looking at this, trying to find something suitable. A peristaltic pump would be suitable, with silicone tubing. I actually have one, I picked up for a few dollars, but it would be overkill in this situation.

Rosco Bodine - 18-1-2008 at 14:57

It would make sense that the pH is neutral or very close from a reaction standpoint and byproduct chlorine evolution indicator observability. With regards to the additives , you may well be eschewing success whilst chewing the cud of dead and dying anode crud to forsake these parameters

I think you will find the additives
are necessary when running higher current densities
because their purpose is to interfere with the chlorine byproduct by emulating a membrane cell with a slime
layer on the cathode and perhaps on the anode also .
The additives tend to broaden the useful operating range
of pH and current density and increase efficiency while
protecting the electrodes .

On the spacing , if it doesn't make much difference in the measured voltage at a fixed current ....well okay then maybe it's no big deal .

The Resun King pump that I posted a link and image for in the PbO2 plating scheme was a mag drive hermetically sealed circulator pump which could be run unsubmerged
and had no metal wetted parts . I think the impeller spindle in those is a ceramic shaft in a teflon journal
and the pump body and impeller is glass filled polypropylene IIRC .

[Edited on 18-1-2008 by Rosco Bodine]

tentacles - 18-1-2008 at 20:41

Many of the small aquarium mag drive pumps ("powerheads") use a ceramic shaft and molded in magnet - they are frequently subjected to seawater The aquarium systems brand is quality stuff, as are the Danner/"Mag Drive" brands.

chloric1 - 19-1-2008 at 05:22

Xenoid-Been thinking about Mitilda and her perchorate endeavor. I believe , as you stated somewhere in the Co3O4 thread, you start a perchlorate cell with twice recrystallized chorate? About 600gms/L? I am trying to figure out how and why you are running so alkaline. IIRC perchlorate production is practically nil in alkaline cells. What is the pH of your solution before electroylsis? If I where to guess chlorine loss probably occurs during the dispropiation of the chlorate via: 4ClO3>3ClO4 +Cl. Analgous to what one might see in a potassium chlorate melt at 400°C. Correct me if I am in error.
I believe a persulfate would be quite helpfull here. It can oxidize chlorate as well as be acidic and lower pH. Problem is shelf life and low consumption. Residual sulfates will probably be removed via recyrstallizations.

12AX7 - 19-1-2008 at 05:41

Quote:

Originally posted by Rosco Bodine
by emulating a membrane cell with a slime
layer on the cathode and perhaps on the anode also .

Say, that reminds me: when running chlorate or perchlorate (with dichromate), my platinized anodes get a yellow slime on them! This is something I would've never noticed with a graphite anode, if it even ocurred. I don't know about the cathode, it looks normal.

Tim

chloric1 - 19-1-2008 at 05:58

Heat gun apparatus update. OK here is what I have so far:

My heat gun has three settings: High,Low, and Off.
I am using a 1 1/2" diameter, 11" long 6061 aluminum tube with OD of 2" so I have a substantial wall thickness

Running for 10 minutes at Low I get a max of 205°C.
When I switch to high the inside glows with hellish glow but only elevates me to 330°C

I put my fingers over the ALL the baffles to get it up to 380°C but I don't think this is healthy for my gun. So obviously I need a 70°C increase so I need suggestions as what material to wrap around my monster tube and where to buy them. Some I can find but I am curious what novel suggestions I know I will get.

tentacles - 19-1-2008 at 06:25

Sounds very similar to my setup - my tube is a bit thinner, also Al, 3/16" wall. But mine gets just hot enough to melt sheet lead (99+%), so should be about 330C. I have covered the outlet somewhat with some steel bits to get a bit more heat, this should not be a problem for the gun if you don't go too overboard. It sounds like we may have the same gun. Mine is rated at 1200W, also has H/L/O. I have a thermocouple on it's way to properly determine temp.

chloric1 - 19-1-2008 at 06:49

Yes mine is a Miwaukee 1220HS. Or as I stated to Rosco the $29 special

. So I see you have baked at this temperature how have you been running?
I have read most of the patents that Rosco posted and I definately feel 400-420°C is the idea baking temp for durability. Going to look into ebay for some heat resistant fabric. Probaby cheaper there.

Rosco Bodine - 19-1-2008 at 09:01

Aluminum or copper would be the worst choices of material for the tube as they are excellent heatsinks .

The Wagner HT3500 which I have , without the nozzle concentrator restrictor reads 570C free air temperature directly at the exit of the nozzle , and that is using a long extension cord which is dropping it down a bit from where it could be . So the one I showed may do the job if there isn't too much heat loss in the chamber it is trying to heat . The heat drops very rapidly after exiting the gun .
Some sort of insulated chamber is definitely going to be needed for the target temperature range to be achieved .

chloric1 - 19-1-2008 at 17:43

I understand about the heatsink affect quite well. But I did not find anything with the right ID measurements. Besides, this was quite affordabe. The heat can be trapped in. I am thinking of wrapping in ceramic blanket.

Rosco Bodine - 19-1-2008 at 17:54

One thing I have been considering doing is getting some
rigid insulating board and cutting it into 6 inch squares ,
drilling holes on a diagonal 4 inch pattern near each corner , and a hole saw bored hole about 1 and 3/4 in the middle .......stack the pieces and snug the foot long stack
together with small threaded rods through the holes
near the corners . Maybe a piece of that inch thick or two inch thick mineral wool rigid board or fiberglass rigid board
or even fire rated suspended ceiling tile boards would work for this .

chloric1 - 19-1-2008 at 18:19

Yes I understand what you trying to accomplish here. With just two settings though I might want a little heatsink affect. Without a slight loss, our improvised tube furnaces would run maybe 470 or 480°C risking damaging the coatings. But, we will need hotter temps for uses not related to MMO anodes so being versatile is best.

So in summary, a heatsinked furnace with slight insulation to run from 350 to 420° and an option to go to a completely insulated furnace for hotter work. I am entertaining a stainless wire mess rolled to correct dimensions then perhaps an inch or two of mineral wool wired around the support.

Rosco Bodine - 19-1-2008 at 18:32

I don't think you will need to worry about getting too much heat using a heat gun , getting enough is going to
be the problem .

Catalyst in the coating!

chloric1 - 20-1-2008 at 08:32

Rosco if you already mentioned this I am sorry.

I am messing around online today because it is too damn cold to do much. Also, I caused this thread to go offtrack so I found something to put it back on.

Given Xenoids difficulty in obtaining sufficient yields of perchlorate, I think this patent offers an intriguing possibility. A fluoride doped cobalt spinel!

It stated that a max of 2% by weight of fluoride though. But thats OK because how much NaF would you put in a NaClO4 cell anyways? Could this keep alkalinity under control?

Attachment: US4514518 Fluoride-substituted Cobalt Spinels.pdf (135kB)
This file has been downloaded 819 times

Rosco Bodine - 20-1-2008 at 16:38

Hmmm I'm not sure how much good F doping might have
with regards to perchlorate selectivity , but it seems likely it could toughen a coating and act as a sort of grain modifier . It would probably not be good to use a
sodium salt as the precursor fluoride , but rather an ammonium salt which would tend to having the ammonium
volatalize on baking and not contribute unwanted Na
as a byproduct .

Really my thinking on this baked anode scheme is that
some barium doping and tin oxide are going to be the
most helpful additives , but F could be useful too , there just isn't as much information to suggest its value in
comparison with those other two .

chloric1 - 20-1-2008 at 16:52

Yes I know well back to sleuthing. No I did not intend to suggest using sodium fluoride in the doping of baked coatings. I made a reference to the addition of 1 or 2 grams of sodium fluoride to the sodium chloride to be electrolyzed with lead dioxide anodes.
No, I would add the 2% by weight by adding ammonium bifluoride to one of the nitrate solutions. I have 8 ounce of this fluoride I plan to use for etching, fluxing, or glass etching.

Xenoid - 22-1-2008 at 16:24

Well, my antimony, tin and bismuth finally arrived today. They were rattling around in the bottom of a cardboard box, with balls of paper on top, they weren't labelled so I hope I can identify them correctly ...

They took sooo looong, I think they went by mule train via Outer Mongolia. Should be enough here for at least 5x10^4 anodes, should I choose to make them ...

There is about 1 Kg of each, the Bi at the bottom of the image is about 10 cm across, it sure is heavy!

[Edited on 22-1-2008 by Xenoid]

SbSnBi.jpg - 15kB

JohnWW - 23-1-2008 at 04:52

You should be able to differentiate them by their densities, Bi being much denser than the others although still only about 25% denser than Fe. Also, Bi has an orange tinge, and Sn is softer than Sb and Bi.

dann2 - 23-1-2008 at 10:28

Hello,

@ Xenoid: Mind your toes.

Don't know what thread you mentioned the problem with Methylene blue and warm test solution but I will stick this here.
Took two test tubes and put a solution of Perchlorate that was giving a fairly positive test for Perchlorate. Heated one to about 40C. It will not give an indication for Perchlorate when Methylene blue dropped in.
Put in some more perchlorate to solution. Filled two new test tubes. This time the test for Perchlorate was very very positive in the cold tube. The one heated to approx. 40C did not give a good positive indication.
Lesson: (as pointed out by Xenoid) Make sure your Perchlorate solution is cold when testing for Perchlorate with Methylene blue.

Dann2

My Fixture

chloric1 - 24-1-2008 at 16:31

Well, I finally got my act together and put a decent tube furnace fixture in action. As you can see I found four fire bricks that PERFECTLY fit around my aluminum tube. It is almost that I planned the bricks to work except I purchased them 9 years ago!

I played with the four baffles in the gun and if I blocked 2 I could get 350°C and if I block 3 I get 427°C at the end of the tube!

And that is at an outdoor reading of -9°C

My toes are frozen!! :mad:

I am doing my first cobalt coating as I write this on the lower temp. I will use the 427°C for the 1 hour bake. Heres the pick, Enjoy!

Improvised tube furnace.JPG - 138kB

Xenoid - 24-1-2008 at 16:37

@ chloric1

That looks pretty damn hot in there ...

How are you mounting the rod(s) with a horizontal baking arrangement?

Christ! Is that snow/ice on the bench!

[Edited on 24-1-2008 by Xenoid]

chloric1 - 24-1-2008 at 16:48

Yes there is snow and ice everywhere! A sunny day at 5°C would be very balmy to me right now.

The hell glow is a deceiver. Illumination from the heating element makes it look 800°C but the tube is 6061 aluminum

. Now I am running a second 10 minute coat.

I might run out of time here

I think I'll try a third coat with nickel nitrate and then on to the 1 hour bake cycle. The other anode I plan on making I will do the 7 coats if I can find the time.

Yes it is horizontal. Basically, I support the rod on a ring stand using a clamp that allows you to mount shafted devices perpendicular to the support shaft. Pictures will explain far better.

Let me put more pictures on here tomorrow.

[Edited on 1/24/2008 by chloric1]

tentacles - 26-1-2008 at 09:26

I scoured my Ti strip clean today, gave it a nice warm bath in HCl, and 3 coats of a more dilute Co(NO3)2 than I had been using - less excess to rub off after each coat. I made up a new solution for ATO, when I've done this, I let the HCl dissolve ALL the tin, leaving the SbO at the bottom, then add a splash of H2O2, the whole solution foams up like beer, and everything is dissolved, happy, and presumably the SnCl2 is now SnCl4 - assuming there is enough HCl in solution to permit this. Given the level of foaming, I think there is at least a good percentage of SnCl4.

Once I've completed baking this crap on, I will be attempting the PbO2 plating again. I may do another strip with Co spinel and ATO while the solution is still fresh.

I've been reusing my Ti etching solution, I happen to have 6 250ml graduated cylinders so I just left ~180ml in one of them, cover it with plastic wrap and a rubber band. I just set it in my sink, resting at an angle, and run hot water over it to heat it up, uncover a bit and slide in the Ti, recover.

Chloric: 5C is like, tropical! It's been around -35C here for the last few weeks, sometimes colder with the wind chill.

Xenoid: after 2 coats of Co spinel the weight was 13.9g and the thickness 1.01mm - see! I remembered this time. I'll weigh after the DTO coats and see if there is any difference.

[Edited on 26-1-2008 by tentacles]

dann2 - 26-1-2008 at 10:23

Hello,

Do you intend to test the DTO coatings to see what they are capable of withstanding?
I have feeling that they will fail (Ti will passivate) very quickly in a Chlorate or Perchlorate cell.
You would need to test a DTO only on Ti to see as the Co Oxide will stand up for a few hours in a Perchlorate cell and some days in a Chlorate cell.
I would be interested to see if you are getting 'good' DTO coatings from the method you are using. By 'good' I mean a coat that will last for say 10 hours (or even days) in a Chlorate or Perchlorate cell.
Perhaps there is no need for such a good coat when all we are asking it to do is be an undercoat?

Dann2

tentacles - 26-1-2008 at 14:17

I ended up making 3 anodes today, the first one (that I spoke of above) is getting it's plating of PbO2 now. The other two I sanded, etched, and hydrided. Then applied 4 coats of Co spinel, and one coat of DTO over the Co spinel. I'm not sure if I am going to put another on as the DTO is getting kind of dirty. The anode getting plated now has 5 coats of DTO on it, and I did notice that very little rubbed off after each baking.

Xenoid - 26-1-2008 at 15:27

Quote:

Originally posted by tentacles
.... then add a splash of H2O2, the whole solution foams up like beer, and everything is dissolved, happy, and presumably the SnCl2 is now SnCl4 - assuming there is enough HCl in solution to permit this. Given the level of foaming, I think there is at least a good percentage of SnCl4.

Do we know for sure that this actually works? I have scoured the internet and various chemistry books, I have found several procedures for SnCl4, but I have not been able to find this method described.

I recall seeing the original post, around the middle of last year, I wasn't interested in anodes at that stage, so I didn't follow it very closely! Can someone point me to the original post. Otherwise, I will have to UTFSE.

Rosco Bodine - 26-1-2008 at 15:51

From *everything* which I have read , the indications
are that except as an intermediate along the way to something else , chlorides are *not* the best choice
of a direct pre-bake precursor for DTO . In those schemes where the chloride was used there was more elaborate methods employed which put the *actual* intermediate beyond being a scenario where it was simply " dip substrate in chloride solution precursor and bake " .
Spray pyrolysis yes , dip and bake ......no way .
That is an oversimplification which does not square with
the chemistry required .

Where the chlorides have been used in any dip and bake schemes , the "digestion" of that chlorides precursor with
alcohol or simply it's keeping for some time , produces a
conversion from any "clear solution" of chlorides into a
dispersion colloid , a hydrosol , with loss of HCl and oxidation
to a dispersed form of probably metastannic acid . And the pH of that dispersion has great bearing on how well or poorly it adheres when it is baked , what quality of coating
it produces .

[Edited on 26-1-2008 by Rosco Bodine]

dann2 - 26-1-2008 at 18:03

Hello,

Xenoid, Xenoid, Xenoid. I am absolutely, completely and totally disgusted with you not reading (and forever remembering) the original post on converting SnCl2 to SnCl4.
It was a mere 2 months ago (though it was far longer meself).

http://www.sciencemadness.org/talk/viewthread.php?tid=2465&a...

Some here too:
http://www.sciencemadness.org/talk/viewthread.php?tid=9569

All attemps at making ATO coatings using SnCl2 or 'SnCl4' (from SnCl2 + H2O2) [+ Sb liquid] failed for me. I was testing coatings in a Chlorate cell.

Got ATO coating to work OK (as an anode, did not get around to plating PbO2 yet) using SnCl4:5H20 (out of a jar) + Shake and Bake :cool:

As per the Diamond Shamrock pats.

Dann2

dann2 - 26-1-2008 at 18:19

Hello,

Quote:

Originally posted by Rosco Bodine
........... for DTO . In those schemes where the chloride was used there was more elaborate methods employed which put the *actual* intermediate beyond being a scenario where it was simply " dip substrate in chloride solution precursor and bake " .
Spray pyrolysis yes , dip and bake ......no way .
That is an oversimplification which does not square with
the chemistry required .

What do you mean by this?
It has been stated to work OK in lots of the patents.
ALL my failures were using SnCl2 (SnCl2 is used in none of the patents, it is available on ebay though).
I got ATO to work OK (not as a productive anode as such) for some weeks in both Chlorate and Perchlorate cells. Seems like a 'not too bad' undercoat between LD and Ti to me.

Quote:

Where the chlorides have been used in any dip and bake schemes , the "digestion" of that chlorides precursor with
alcohol or simply it's keeping for some time , produces a
conversion from any "clear solution" of chlorides into a
dispersion colloid , a hydrosol , with loss of HCl and oxidation
to a dispersed form of probably metastannic acid . And the pH of that dispersion has great bearing on how well or poorly it adheres when it is baked , what quality of coating
it produces .

[Edited on 26-1-2008 by Rosco Bodine]

All solutions that I have been made using SnCl4 (solid) + Sb + HCl + Alcohol have remained clear. SnCl2 is another story.

Anyways I have moving away from the pathetic Shake and Bake (Sorry Eclectic) and going on to the lofty hights of spray pyrolylis as can be seen by the exotic apparatus below.
It's a cillit Bang (or is it flash) sprayer with the spring removed and a string substituted. You must both push and squeeze to get it to work. It will make mass production a reality...............

Dann2

sprayer.jpg - 28kB

Rosco Bodine - 26-1-2008 at 18:51

It would have disappointed me if what I said didn't get a rise out of dann2

. The chemistry is more complex than it might seem when SnCl4 is being used as part of a baked coatings precursor mixture , because it is unstable
both in the pot and on the substrate , it's composition is changing by the minute from when it is made . It is
so variable in composition and behavior that it produces
inconsistent and unrepeatable results unless you are
monitoring the variables in real time and following some
prescribed plan which realizes and specifies those variables .

The way to get past those variables is to use higher precursors for the SnO2 or indeed used the SnO2 itself
in the form of a stannic oxide sol or a stannate . Those
and the nitrate already contain the oxygen of SnO2 so
they don't have to lose chlorine and go looking for oxygen
from the air , as they brought their O2 lunch with them .
A hydrosol only has to lose water for example to leave an SnO2 layer , and there's no HCl coming off it to eat at any
spinel interface which it may be intended to seal , rather than to compromise .

As for SnCl2 not being used , well that's simply not true , but I'm not going back through a hundred references looking for the examples where it was used just to prove it . But now that you have brought it up , SnCl2 is a fine precursor for
the kinder gentler oxidative soak deposition method which
I have recommended as an easy no brainer sort of method
of applying an SnO2 sealing layer onto a baked spinel interface . SnCl2 hydrolyzes and oxidizes simultaneously
to a hydrosol of SnO2 on exposure to air and this can alternately be done using dilute solutions and NaNO3 as the oxidant to deposit a tough film of SnO2 onto a substrate ,
in a very slightly hydrated form which easily bakes out to
a tough and adherent film . Wait a minute , this isn't the way Diamond Shamrock said to do things is it ? You are right about that .....think of it as a whole new state of the art .

[Edited on 26-1-2008 by Rosco Bodine]

Xenoid - 26-1-2008 at 19:06

Quote:

Originally posted by dann2
...... It will make mass production a reality...............
Dann2

Yes Dann2, all you need now is my 3 Kgs of assorted anode coating metals....

Hey!... What was that! Out the window! I thought I saw a pig flying past...

tentacles - 26-1-2008 at 19:07

dann2: My "SnCl4" solution remained clear, with a slight yellow tinge, when I added alcohol to it.

Rosco: I used excess H2O2, could this possibly extend the usable lifetime of the SnCl4 solution by keeping the oxidation state high?

I haven't inspected the new anode, I haven't decided how thick I want this coating to be. Probably will wait til morning, so I can have ~.5mm thickness.

dann2 - 26-1-2008 at 19:17

Hello.

Quote:

Originally posted by Rosco Bodine
It would have disappointed me if what I said didn't get a rise out of dann2

Have you any examples of this being actioned in any patent, article etc etc.
All others may believe that the SnCl4 is not the way forward but I do not.
All patents, papers use SnCl4. None that I am aware of use other methods that you speak of.
Have read about Tin Sulphate on one patent and Oxalates in other patent (but Tin Oxalate as a pain to make)
Have you any pointers that show theses methods working for anodes, (ANODES) or intermediate coats for anodes (ANODES).
The only other conclusion I can come to is that there is a hugh coordinated and planned effort to by the scientific community to suppress the fact that theses methods (that you speak of) work far far better than SnCl4 route.
Dann2

Rosco Bodine - 26-1-2008 at 19:18

tentacles , see my edit above . You don't need SnCl4
for the sealing layer over the spinel , SnCl2 is just fine
since you are going from there to SnO2 using NaNO3 ,
if you want the easiest route .

@dann2

Trust me .

There are better uses for your SnCl4 .
It can be neutralized with ammonia to form
hydrated stannic acid , stannic hydroxide ,
which can then be neutralized with nitric acid
to form stannic nitrate , highly soluble and a
very much better candidate for a "dip and bake"
sort of coating .

Dissolved in excess ammonia it forms ammonum stannate ,
also highly soluble and when thickened a bit with PVA
or possibly with other things as well , it will also work
as a dip and bake .

Thirdly the SnCl4 can be used in making a mixed valency
Pytlewski polymer for use as a between baked coats wetting agent .

And antimony is a minor ingredient or not used at all ,
if all the references are correct in indicating that Bi is
the better dopant for SnO2 in DTO schemes .

[Edited on 26-1-2008 by Rosco Bodine]

dann2 - 26-1-2008 at 19:41

Hello,

@Tentacles
While I do not want to be 'running down' your efforts I suggest you test A DTO coat(s) if you want to see if you have a coating that could be described as viable. You will have to put a coat on Ti alone as the Spinel will only confuse the DTO test.
Spinel coats as you are doing have been shown to be OK as per Xenoid and others.
The spinel alone with or without the (existant?) DTO may be fine as a percoat for the LD.

@at Rosco
No way!!!!!!!!!!!!!!!!!!!!!!!
Examples (or even a vague ref.) please.

Dann2

Waiting anxiously

Rosco Bodine - 26-1-2008 at 20:38

Quote:

Originally posted by dann2
Hello,

@Tentacles
While I do not want to be 'running down' your efforts I suggest you test A DTO coat(s) if you want to see if you have a coating that could be described as viable. You will have to put a coat on Ti alone as the Spinel will only confuse the DTO test.

Hmmmm. Pardon me but you don't know what you are talking about . These layers have different functions ,
but when they are baked diffusion occurs , so no one layer is a single quantity unto itself . That includes DTO onto a
titanium substrate where no spinel is the interface but a solid solution of the SnO2 and TiO-TiO2 suboxide . All the spinel does is produce a good interface more easily and reliably than any chlorides concoction ever could . It's crisp and consistent in its formative reactions , not variable and muddy and fickle and unpredictable .

Quote:

Spinel coats as you are doing have been shown to be OK as per Xenoid and others.
The spinel alone with or without the (existant?) DTO may be fine as a percoat for the LD.

Nope it's going to need a sealing layer of DTO , just like I have said all along .

Quote:

@at Rosco
No way!!!!!!!!!!!!!!!!!!!!!!!
Examples (or even a vague ref.) please.

Dann2

Waiting anxiously

So schools back in session ....again ???? I'll swear you are
a stubborn hardhead about making the connection here .
But okay , I'll have at it one more time , I think this is three or maybe four ?? Anyway I lost track , but just for you dann2

Oxidative soak deposition using SnCl2 , ( yes that is stannous chloride , the stuff you get using no peroxide , just good old HCl + Sn ) + KNO3 and a little extra oxidation from limited air exposure . This produced a thin film deposit
of exceptional quality and uniformity , deposited on a polished glass substrate , which was so tough and adherent
that it could not be scraped from the surface being raked with the edge of a stainless steel knife . So the SnO2 is on there quite nicely from an SnCl2 precursor . You argued with me about whether this would work on Ti substrate
ect. and no I don't have an article that shows it will stick
to spinel either , as it is simply a *deposition method* for
the SnO2 . Take my word for it , the SnO2 doesn't care
what it is precipitating onto and it will damn sure film onto anything and everything , particularly anything that is
hydrophyllic , such as anything having been treated with
a Pytlewski polymer in particular would be hydrophyllic , even if the substrate was teflon . In short , you can bet your ass
it will stick to Ti or spinel or any damn thing else . And when
it is baked , it's there forever when it sinters and diffuses .
And as to whether or not the thus originating coating has
usefulness as a coating for anodes , well the second attachment in the next post will clear that up , showing
definitely it does make an anode coating , with that coating
also derived from a stannous +II valency precursor as well ,
and a sol precursor derived therefrom , which is a variation
on the same oxidative process involved as described here in this attachment , the exception being that no additional oxidant other than air is used for the second referenced method for arrival at the Sn +IV oxide .

Attachment: Preparation of SnO2 thin films by the oxidative-soak-coating method.pdf (324kB)
This file has been downloaded 1252 times

Rosco Bodine - 26-1-2008 at 20:39

And here's the second SnCl2 related reference

I think there's more in the ATO thread concerning
the same topic , another article referencing SnCl2
as precursor in sol-gel deposition processes and I know there have been other examples referenced for Ti and
TiO2 substrates , even for depositions onto PET substrates .
You simply don't want to accept the valid scientific basis
for proposing there is a higher state of the art available
and published in the literature already , than what is
represented in some particular patent which you favor .
We are trying to go beyond what any one inadequate patent
has to offer and come up with something better .
At least that is what I have been doing anyway .
And I stand by the logical basis for what things I have submitted are pertinent to that task . I won't labor
with a deficient method , copying what somebody else has done , when I see the promise of a clearly better way ,
which shows no good reason evident why it should not work . Do you have some problem with suggestions
which may advance the state of the art ?????

Anyway , after you Oxidative soak deposit that first sealing layer of plain SnO2 onto the spinel and bake it , it will dope itself by diffusion from the spinel below .

At this point the anode will be pretty well protected ,
and it's simply a matter of building thickness of coatings of whatever composition you like . Bi doped SnO2 would be
the type of coating to follow that seems to be the best
for sealing the substrate against oxygen diffusion which
ultimately leads to passivation . The Bi also has catalytic properties for perchlorate , so whatever Bi diffuses upwards
into any outer working coating such as MnO2 would be no problem .

Example 3 of US4272354 describes the use of SnCl4 +
Bi(NO3)3 as a baked coating precursor which forms a
working anode coating specific for chlorate and perchlorate
production .

[Edited on 27-1-2008 by Rosco Bodine]

Attachment: Sol–gel preparation and characterisation of mixed metal tin oxide thin films.pdf (428kB)
This file has been downloaded 4075 times

Hubert Update

Xenoid - 26-1-2008 at 22:44

Hubert and "Purple Haze" are still running well and producing KClO3 for me. Hubert has been running continuously for about 26 days (617 hours, exactly) for a total of 1349 Ahrs. About a week ago, I dismantled Purple Haze, chilled it and extracted the KClO3. I replaced the small stirrer bar with a bigger one and this keeps all the KClO3 in suspension. This seems to result in denser sand-sized crystallites forming. These can be scooped out of the cell at about 3 - 4 day intervals, when the stirrer is switched off.

The colour/manganese dissolution is a bit problematical. I'm not at all sure what is going on. Purple Haze is actually colourless at the moment. When I did the chilling-extraction a week ago the cell was slightly pink, it turned brownish and precipitated MnO2.H2O for a couple of days, now it is clear. Needless to say it is losing Mn from the anode slowly, but the mechanism is anyone's guess. The period when Hubert was running at 3.6 amps (100 mA/cm^2) seemed to result in a loss of Mn and a marked deterioration in electrical parameters.

Hubert is now running at 4.0 volts / 2 amps versus 3.6 volts / 2 amps on the second day of operation. I think perhaps if I had kept the current density at say 50 mA/cm^2 and the anode had not suffered during the electricity shutdown, it may have been capable of running for several months. I guess now though, I'll let it run it for another week, then call it quits, I've collected about 600g of KClO3 so far.

Woah...! I'm now an International Hazard, better watch out ...

[Edited on 26-1-2008 by Xenoid]

dann2 - 27-1-2008 at 09:55

Hello,

I am not argueing that you cannot deposit SnO2 films using Sol-gel, Hydrosol.
You can.
Theses methods have never been used for anodes. Do you know any refs. that show theses methods being uses as working anodes (ANODES) in (Per)Chlorate cells? (or waste water treatment tests/applications or brine electrolysis).

First paper mentions nothing regarding anodes.

Second paper mentions anodes by referencing Anodes that are made by the Pyrolysis technique (not sol-gel, hydrosol) using SnCl4 + HCl + brushing on with a soft brush + Pryolysis.

There is nothing to support your claims that I have seen or have been shown (apart from the large volume of argument that you are generating).
I wish anyone here who wants to try the Sol-gel etc methods the best of luck. Be aware that they have never been used or studied as (Per)Chlorate, waste water, brine/Chlorine anodes. This is a fact.
These's methods are being put forward here as being superior, far better, etc etc to the SnCl4 +HCl + Pyrolysis route. Nobody anywhere has shown this to be the case.

The SnCl4 + HCl + dip and bake + Pyrolysis route is being condemed as not workable ('dip and bake..... no way').
This is untrue.
No amount of words will change this fact.

The best way to educate your wee humble student of anodes is to show him some examples of your wise words of wisdom being actioned.
If there are no examples to be had, that is just the way the stuff works. ie. The sol-gel hydrosol etc does not work for anodes in (Per)Chlorate/brine/Chlorine etc applications.
The dip/brush + SnCl4 + HCl + Pyrolysis does work and has been shown to work.

Dann2

dann2 - 27-1-2008 at 13:50

Deary me Rosco you are moving your posts around???????????

Hello,
Calm down.
Refs please.
Dann2

[Edited on 28-1-2008 by dann2]

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