Thoughts On Anodes

Hello AF,

Sorry to hear about your troubles. You should inquire from the Ti suppliers if they will give you your money back

It looks as if Ti is not the mother of all Cathodes after all. Thick stuff definately stands up for a long time but you do see some corrosion in it (at least some to the stuff I have used). It would have been exposed to Fluorine if that made any difference.
Hydrogen embrittlement is probably your problem and since your Ti is so thin it effected it badly and fairly quickly.
I guess you could try SS.
I have ofter wondered would Lead make a workable Cathode? You could add some Sodium Sulpate to the solution at the end and see of there is any PPT from Lead that may be in the solution at the end of run, as Lead Sulphate is insoluble.

Dann2

Quote: Originally posted by dann2

Hello, The pH strips sound good. I am going to purchase a Nitrite test kit for aquarims from ebay. There are cheap enough. Hopefully they will work in a tank of poison. I had measured the density of the Lead Nitrate solution for to decide what type of beads would be of a similar density to the solution for stirring purposes. From this link: http://www.machinist-materials.com/comparison_table_for_plas... (divide by 0.036126 to convert lbs/inch^3 to g/cc) the best one is PEEK with a density of 1.3g/cc. Peek in not available but Perspex is available as Acrylic beads on ebay at a density of 1.218g/cc which will hopefully sink and 'mix' when stirring starts. They will add some nice colour to the plating tank if nothing else. PVC is 1.46g/cc which may do too. Anyone any other suggestions as to what could be used? The density of Lead Nitrate solution with 350g Lead Nitrate per liter is 1.28 grams per cc. @Hashashan (if your are still reading!!). What did you use? Dann2

A bit late with the answer
I used just ceramic debris ... I took a ceramic plate and shattered it to pieces of different size( I mean really different .. starting from 2mm diameter and ending with fine dust)
It did the work

Hello,

I have been holding my breath waiting for the answer Hashashan and I am rather blue in the face
I think Acrylic (Perspex or Methylmethacrylate) will do the job. They can be had on Ebay (necklace making brigade) for a few dollars for hundreds of them. Approx 2mm diameter. They are slightly less dense than the Lead Nitrate solution and stay around the plating Anode when stirring starts. This contrasts with other bead/plastic pieces I have tried that are slightly more dense that the Lead Nitrate solution where they go to the outside circumference of the plating tank when you start to stir. It's a bit like a Helium filled balloon in a car (if you ever drove a car with a Helium balloon in it). When you put the brakes on, the H balloon goes flying to the back. When you accelerate it comes to the front. Going around corners it goes the opposite way to everything else (including the air) in the interior of the car. It's a bit weird and you would think the thing is possessed.......

Dann2

What about titanium nitride?

Last time I was heating titanium, it was yellow hot, in air, stable.

Personally I'd rather blast the fuck out of it with an arc welder.

Tim

Damn, im actually working on Ti coated with TiN at these moments
I still claim the idea as mine because i started to work on it about a month ago however the setup in my lab broke and it is being fixed.
I hope that next week ill have my first baby running.
tools with TiN wont work because the smallest hole in the coating will degrade the whole anode.
you need to have either a perfect coating or a valve metal coated with TiN or TiC. (ZrN and ZrC are also accepted).

Im making my anodes using PVD. Vacuum arc deposition in very diluted nitrogen atmosphere(about 2 Torr)
so just wait and ill tell you about any progress

12AX I dont think that ull get proper TiN that way. I believe that it wont be as conductive and as protective as pure TiN. Im not sure how it is even possible to get direct Ti+N reaction in such a low temperature. an arc enchanced process would be plausible, but once again do it under nitrogen and not air. the TiO2 will absolutely ruin everything.

sintering at home????? i really dont think ull get anyhting close to workable that way.
and about getting ahead of ourselves ur not right. maybe the coating wont be perfect for an anode.
but I do believe that it will be really good as Ti->TiN->PbO2 buffer. if it is thin enough it will do great.
[Edited on 22-7-2009 by hashashan]

[Edited on 22-7-2009 by hashashan]

Quote:

Quote: Originally posted by hashashan   Damn, im actually working on Ti coated with TiN at these moments I still claim the idea as mine because i started to work on it about a month ago however the setup in my lab broke and it is being fixed. I hope that next week ill have my first baby running. tools with TiN wont work because the smallest hole in the coating will degrade the whole anode. Of course I didn't mean to imply that TiN coated tool bits would suffice for a practical anode; my suggestion was to use what's readily available as a quick test to merely get an idea if further effort is warranted. That's all. Did you read the "secret" research paper on the search for perchlorate anode materials to replace Pt and PbO2 (posted by Dann2)? In case you didn't, that's what the authors did; i.e., they did quick tests with variously oxidized surfaces of pieces of tool steel, IIRC. In any case, being that you claim to be investing some real effort into this, I assume you've already done some kind of test or have some favorable information? Or you're doing the whole thing on a hunch? Quote: you need to have either a perfect coating or a valve metal coated with TiN or TiC. (ZrN and ZrC are also accepted). Well of course. Quote: Im making my anodes using PVD. Vacuum arc deposition in very diluted nitrogen atmosphere(about 2 Torr) so just wait and ill tell you about any progress Why not just heat a Ti rod with an induction heater in a pure nitrogen atmosphere? Why wouldn't a layer of TiN form in nitrogen just like a layer of TiO2 forms when O2 is available? Quote: 12AX I dont think that ull get proper TiN that way. I believe that it wont be as conductive and as protective as pure TiN. Im not sure how it is even possible to get direct Ti+N reaction in such a low temperature. an arc enchanced process would be plausible, but once again do it under nitrogen and not air. the TiO2 will absolutely ruin everything. sintering at home????? i really dont think ull get anyhting close to workable that way. According to Wikipedia: "Bulk ceramic objects can be fabricated by packing powdered metallic titanium into the desired shape, compressing it to the proper density, then igniting it in an atmosphere of pure nitrogen. The heat released by the chemical reaction between the metal and gas is sufficient to sinter the nitride reaction product into a hard, finished item. See powder metallurgy." I realize nothing's ever easy, but it doesn't sound too awful daunting for some of the resourceful people on this forum. In fact, hasn't Dann2 done some sintering? Quote: and about getting ahead of ourselves ur not right. maybe the coating wont be perfect for an anode. but I do believe that it will be really good as Ti->TiN->PbO2 buffer. if it is thin enough it will do great. Well I'd like to see if a TiN coated tool bit will hold up for a little while in a cell without sliming off in an hour like the cobalt oxide did.

Im doint it by means of VAD just because I can. Im doing my thesis in a thin coatings lab and one of the students is doing his thesis on TiN coatings using VAD so all i need to do is to put my sample in the chamber. Thats why im not really investing too much effort in this. The information i got is just the one you got. TiN is a conductive material and it withstands some severe coroding conditions, thats it.

why not using just induction heating ... I just think that the heat will not be sufficient. It will be much more effective to do the heating with an arc because it will ionize the nitrogen and the reaction will flow much better.

about sintering .. i think that compressing will be the main problem, I believe that the pressure that is required will be much too high.

^^^ Follow up:

Thinking that the cleaned eBay MMO might spot weld adequately to commercially pure titanium without scraping the coating from the junction areas, I tried a spot weld without scraping.

It appeared to work, but a modest tug on the single spot broke the joint. The same piece, same weld, when properly scraped, is about 5X as strong, so scraping still appears to be necessary.

The easiest way to clean the spots in preparation for welding is with a dremel tool and a fine sanding drum. A few gentle passes of the drum over the triangular areas (where the weld takes place) works quickly. A dust mask is a good idea - you don't want to be breathing ruthenium oxide dust.

One last note on adapting MMO sheet in general to Ti straps - creating a leakproof, easy to use fit between the rectangular strap and your cell is a pain. Today, in another experiment, I took a section of CP titanium tube, slotted it, and attempted to crush it over some MMO mesh to flatten it in preparation for welding. This worked poorly... the Ti cracked and it was a mess.

A simpler method was to heat the plain tube end dull red, and flatten it thorought in an arbor or hydraulic press between two good pieces of steel. It came out very flat and even. This flattened portion was degreased and welded to a section of MMO mesh. I now have a cylindrical strap, which is infinitely easier to use. All you have to do is take an appropriately-sized compression fitting, preferably of PVDF plastic, and if your tube is 1/2" OD, drill the compression fitting entirely through 1/2". The tube is installed from the bottom, the ferrule and nut added, and it's tightened down. You now have a leakproof, threaded fitting that can be adapted to your cell.

Down with salt creep and chlorine gas!

Yey, the samples are ready. I hope that Ill start the experiment today or tomorrow.
However a professor from my lab told me some bad news, he said tht he recalls that TiN pits while doing electrolisys in the presence of ClO3 ions so im not too optimistic.
anyway im going to dry this.

These are the two anodes. one is Ti foil coated with TiN and the other one is a Ti rod with TiN coating. the coating is very thin, sub micron.



[Edited on 28-7-2009 by hashashan]

Well, I have some bad news. I fired up an electrolysis yesterday and I got very weired results. The Ti-TiN works like a diode, it does not conduct as an anode.
As a cathode the coating peels off

I guess that the only chance is an intermediate layer. Now well have to wait until Ill make a PbO2 coating.

very weired,
I had a chat with the professor again and he confirmed my results .. he said that it doesnt conduct as an anode and gets destroyed as cathode(not what he said last time but he is a weired dude)
anyway few volts over hundreds of mA is what I call not conducting 5V in a small cell should easily give you several amperes.
I did get some bubbling when using TiN as anode but it was extremely unefficient.
well I guess Ill have to do more experiments, maybe in a more controlled environement,
jpsmith are you sure you used it as an anode and not cathode?

New Spot Welder rig

I've tried both TIG welding and spot welding to create anodes and cathodes of CP Ti and MMO in various sizes, and it turned out spot welding was infinitely easier and more effective than TIG, unless you have a very high-end TIG machine that can create a stable arc of just a couple of amps. Anyway, my old spot welder had been made from a rewound transformer, coupled to a pair of clamp arms and a timer + foot pedal.

I was making up a bunch of MMO + Ti anodes, and my old homemade welder just wasn't hacking it... not enough current. I decided to try Harbor Freight's 115V spot welder. Not the cheapest, but the results are spectacular compared to my homemade welder.

I took the harbor freight welder and modified it extensively. As it came out of the box, it was a handheld clunker with a simple ON-OFF switch under the handle. I pulled the switch, found it was simply 115V for the primary of the transformer, and routed them instead to a timer-controlled solid state relay of 40 amps.

The handle was modified, and the welder itself clamped to the same aluminum plate used earlier.



This setup is AWESOME. If $$ is not a big object, and you want to do a bit of spot welding for technochemistry, this is a decent way to go. A 1/2 second weld time easily welds MMO mesh to Ti sheet of 1.3mm thickness, and I have no doubt it'd do several mm if needed.

The timer (red thing) is a "National Controls Corporation" model TMM-0999M-461, set to "1-shot" function on the control face.

Here is a basic diagram for this timer when coupled to a home-modified transformer. To adapt the HF welder, the 2 wires in the handle are simply attached to the SS relay output side.

Quote: Originally posted by dann2

What metals can you make the actual 'pincure tips' from. Does it have to be Copper. Wonder would very thick steel? do or perhaps use steel bars with Copper pieces on the ends where the welding actually takes place.

WF is correct. I've tried Copper, tungsten, and brass. The latter two did not work well. The brass did work, but left behind touches of zinc slag, and the tips tended to stick to the work.

Copper bar can be a pain to work with, let alone find. It usually has to be ordered. For this sort of work, the tips also need to have a cross section of maybe 1/8" or 3mm, and an included angle of 90 to 120 degrees.

Solid Ag would probably work very well! Whatever is used, the resistance needs to be as low as possible, or they will heat ferociously.

Edit: I also noted the AC voltage of the arms on this rig are 1.6 volts vs. 4 volts for my homemade job. In the transformer, fewer secondary winds = lower voltage = greater current. On my homemade rig, if I had taken a couple of the secondary winds off, I might have been able to jack the current up a bit, but the secondary, of #4 stranded copper, was already heating up too much. It couldn't have carried more current. The transformer was just too small.

Hacking the HF spot welder is not the cheapest way to go, but it does work very well indeed and will save a lot of time.

[Edited on 3-8-2009 by Swede]

I think movement of air through the solution would be a good way to go, at least as a start, being gentler than peroxide. I don't know if a peristaltic pump alone will provide adequate contact between the plating sol'n and atmospheric oxygen. You could always use a bubbler, but I would be very hesitant to use one outside of some sort of sealed chamber due to misting. I definitely need to get going some more.

I've continued my examination of the Laserred MMO mesh. I've got quite a bit, and overall, I am very pleased with it. There are some areas of contact where the Ti is slightly exposed, but you can easily create 6 3" X 5" MMO anodes from one sheet. I set up a jig on my bandsaw and ripped off that 90 degree "L" portion with little fuss on several sheets.

The brown smut is ever-present. Some sheets have more than others, but they all have it to some extent. I reported earlier that HCl cleans it up well. I did some more experimenting, especially with an ohmmeter. On an untreated sheet, the surface resistance can be high. I've measured it in the 20 to 30 kilohm range even on portions of the sheet with no smut. But an HCl pickle not only removes the smut, it apparently strips some other contaminant, not necessarily visible, and the pickled sheet shows near zero resistance, in contrast.

I took 6 sections of the "L" I removed, and pickled them all for various amounts of time in 16% HCl. I took a seventh piece, and pickled it for 6 hours in 32% HCl. None of the strips in the 16% HCl cleaned up nearly as well as the one in 32%, and as far as I can tell, even the 32% cannot touch the actual MMO; it simply cleans it very well.

On the left is a piece pickled for an hour in 16%... the one on the right, 6 hours in 32%.



The 32% actually only needed about 15 minutes to clean, but I left it in for a long time to verify that no actual damage will occur. The surface resistance of the 32% piece was nil, and it spot-welded instantly with no scraping needed. Conclusion - pickle away in 32% hardware store muriatic all day if you want. It definitely does a good job.

The HCl will become brilliant yellow. Use caution - I have no idea what this contaminant is, and it would be wise to treat it as possibly toxic. Handle uncleaned sheets with gloves, and dispose of the used HCl in a responsible manner.

dann2, I realized I didn't really address your nitrite question very well. My problem now is that my workspace is about 130 degrees F, literally. Every operation that requires a decent clear space, or is potentially hazardous, such as working with the Lead Nitrate plating bath, is on hold until the weather changes. I cannot describe how hideous it is. The best I can do is putter until my shop cools down.

If nitrite is a short-lived species that is created during the actual plating process, any serious experiments for me will have to wait a bit. The best I can do right now is see if the aquarium kit can detect added nitrite to used plating bath liquor.

Since nitrite is exceptionally poisonous to fish, the kit is designed to be fairly sensitive. The kit I bought is by "Aquarium Pharmaceuticals" and is designed to detect as low as 1/4 ppm. Interestingly, the base color (0 ppm) is an aqua color that is identical to the color of my particular plating bath, which contains nickel nitrate. In other words, even before the reagent is added to the sample, the sample starts with the same color as the "0" scale. Adding the test reagent doesn't appreciably darken the color. What I'm trying to say (badly) is that even with nickel nitrate (added as a grain refiner) I am hopeful the kit will work. But given the acidity, the strong lead nitrate presence, it will be hard to say if it will work until additional tests are done.

I need to scour the web and my own book resources a bit and see if I can find the basis behind the test kit. If we know what the test reagent is, we can determine if it will be effective. If it's not, we can possibly find one that is. I have a college text named "Quantitative Analysis". I'll see if there's anything in there on nitrite.




[Edited on 8-8-2009 by Swede]

Hi Swede,
The test kit I have is exactly the same as yours!
There is a test at this link using Sulphuric acid and Ferrous Sulphate.
http://en.wikipedia.org/wiki/Nitrite_test
but I reckon it would be useless as when you add Sulphuric acid, Lead Sulphate will ppt. I think the Nitrate ion will not interfer as per reading on the next link below at where it says: 'Parameter Overview'
Hach do a Nitrite test at this link:
http://www.hach.com/hc/browse.parameter.list/PAR114/NewLinkL...

Another test kit here says:
______________________________
CHEMISTRY OF COLOR REACTIONS
Nitrite reacts with two acids in the Nitrite Powder Pillow Reagent (sulfanilic and then chromotropic) to form a red complex whose concentration is directly proportional to the amount of nitrite originally present. By measuring the intensity of the reddish complex with the color comparator, the concentration of the nitrite is easily determined.
______________________________

Perhaps that's what is in all Aquarium kits?

Another test (attached picture) from link below:
http://www.springerlink.com/content/p425v73427852116/


Test strip below:
http://www.sigmaaldrich.com/catalog/ProductDetail.do?D7=0&am...

You can make Sodium Nitrite using Lead Metal and Sodium Nitrate. Melt Lead and stir in Sodium Nitrate. Other product is Lead Monoxide (Litharge). Now let me see, where did I see a useful idea for using that stuff...............

If you read patent US 5558772 it says that Nitrobacker Agilis (the little bugger ) which in present in air converts Nitrite to Nitrate but that bacteria is hardly able to operate in a plating solution.

This post is becoming a bit of a ramble..........

Regarding the pump I was setting up to pump plating solution from one beaker into another beaker, I have given up on the air driven type. Apart from the splattering that was occuring (it could be controlled using a cover) the air pipe is inclined to plug with crystals from small amounts of solution what would make it's way into the air pipe and then dry off with the stream of air going past (and deposit the crystals). This type of pums is not suitable for pumping solutions IMO. Only simple liquids. So I am onto the Peristaltic and timer set up. A syphon returns the fluid back to the original beaker. I am using a conc. solution of Ammonium Nitrate, density about 1.3.

130F THAT'S hot.

Dann2

I have a problem with my mmo anode. I bought it 10 month latter from north star pyro, and the anode is already dead...

Last time i go see my chlorate cell, it was full of rust (i use high quality stailless stell and sometime is can make black stuff, but this time it was really the orange color rust). When i pull out the electrodes from the mess, the anode has a line of gray color just at the level of water when the anode was in the cell. The gray line is 0,5 cm wide. I am pready sure that it is TiO.

Cell specs:

- 7,5 volt
- 3,25 amp
- 2L
- mmo anode
- stainlless stell cathode
- no ph control
- no temperature control

p.s.: The anode was running for 8 month in those condition. But in the last 3 month, i let the cell run up to the end ( well under the 100g/L of KCl). beffore that, i was getting the kclo3 out and refressing the cell all week.

Now, I have 2 question. First, can this anode can always be turn to a lead dioxide anode, and can i use this anode as a cathode???
I pay 80$ with shipping for this anode, it is why it should be nice to reuse it


thx

[Edited on 12-8-2009 by Bikemaster]

Hello,

@Bikemaster
I presume it's 2 cm by 6 cm. Thats a surface area of 2 x 6 x 2 = 24cm squared assuming a flat plate.
Looking at the picture of the Anode I am going to guess that the Anode has approximately one third (it may be less) of this area = 8 cm squared.
Running the Anode at 3.25 Ampers gives a current density of 400 mA per square cm.
That's considered high for MMO. Just goes to show how tough the stuff is.
I presume you have one Cathode and it is to one side of the Anode.
You could cut you Cathode in half and put each half on either side of the Anode so that current distribution on the Anode is more even. It is hard to guess how uneven current distribution on the Anode is when the Cathode is on one side only. The Anode will be inclined to wear more on the side nearest the Cathode because of the higher CE on that side.

@ User Try Googling for Corrosion control companys, Cathodic protection companies, or of course the water chlorination people (swimming pool supplies).

............there's always Graphite with acid dripping into cell............

Dann2

What a fine day for the PMMMO this is!!!

Hello,

There is definately a conspiracy going on on the board to keep the dimensions of that Anode from me!!
I attach a screen capture of you last post Bikemaster. Whatever character you put in for inches? or centimeters? has come out my end as the word 'Text' in bold (to boot!)
Did you mean inches or did you actually mean to write 'Text'. If so I don't understand what you are saying.
Cheers,
Dann2

Hello,

Going back to the topic of making Perchlorate with a Graphite rod in a cell with a divider...
It was suggested to use a 'Lambskin' condom. I took this to be (literally) a piece of Lambs* skin around the Graphite (like a condom).
Granitstaterecovery (name of poster) was referring to a 'Lambskin' rubber (as in, how would I put it, a dick cover... LOL).
From a reputable publication, page 18, from here:
http://www.thevespiary.org/Naf1/Fester/AdvTech.pdf
I quote:


"netic stirrer. Clip a well scrubbed Kling-Tite Naturalamb rubber
in one side of the beaker, and put a piece of lead about viinch
in diameter, and a few inches long, inside the rubber. On
the opposite side of the beaker, stand up a one ounce ingot of
palladium Using alligator clips, make contact with the ingot,
and with the piece of lead. Next pour most of the dilute sulfuric"

The Author is not making Perchlorate etc btw but he mentions the divider. Will have to try it for Perk. Perhaps the cell conditions will be too harse in a Perk. cell.

Will any condom do or does it have to be a 'lambskin'. Not too well up in condom varieties. I find it hard to belived they will allow electricity through.

edit:
FFS, I Googled 'Lambskin' and it come up first with the word Condom after it, with a hits rating of 30,000.
It appears that they are made from Lambs intestines.
Brings a whole new meaning to the threat, 'I'll have your guts for garters'........
Now where can I get a dead sheep. Hope, when and if I do find one, that it does not ravish me. It's happened before you know......
Good Night

Dann2


*(an in: meaa, meaa, bleat, bleat, four legs good, two legs better. four legs good, two legs better. four legs good, two legs better, four legs good, two legs better.)

[Edited on 3-9-2009 by dann2]

I guess modern science has produced better membranes since the use of lambskin but the use of what’s at hand (lamb skin intestines??) is what we are all about. Pig intestine skins are widely used as sausage outers and may have the same characteristics.


I find it no surprise that such material conducts electricity/permits ion mobility after all didn't life evolve intestines for the diffusion of water and ions out of the poop shoot into the blood stream?

I will watch the development of this perchlorate route with interest

Enjoy catching your lamb -ask one of the ozzy members if they have any spare Velcro gloves (couldn't resist!!!)

I finally figured out a way to adapt a round Ti tube as an electrode shank, which gives one the huge advantage in a secure (yet maintainable) setup using a stock PVDF compression fitting.

In a nutshell: Flatten the tube at one end, weld to the electrode. At the other end, install a plastic plug inside the tube, then hammer in a brass or similar threaded fitting for the electrical connection.

Flat straps are a pain - here is a way to use a round shank for many electrochemical processes.

The MMO pictured is the "Laserred" material after pickling in HCl. Laserred is not currently offering any more on eBay. It was a tremendous bargain... maybe he'll be back.

Quote: Originally posted by dann2

I often wondered would a few Ti bolts do instead of the welds to connect the Anode to the Anode shank? Would the junction between the Anode and the shank form an Oxide coating that would stop current flowing?

Quote: Originally posted by 12AX7

I bolted copper to titanium anodes. The copper corroded and the bolts rusted but it kept on dumping amperes just fine.

Hello,

Welding is definately the best job. It is probably the only way to do the job properly.

When you say that you "bolted Copper to Ti Anodes" I presume you meant it was all above solution surface (obviously). When you go under, things get difficult and the Ti passivation (at contact point) now makes the whole idea unworkable.
When joined by a bolt (under the solution surface) the Anode shank at the point of contact is an Anodic surface (bare Ti remember) where you DO NOT want it to be Anodic. The MMO, at the point of contact with the shank is a Cathodic surface.
My own opinion is that the Ti shank will passivate at the point of contact BUT perhaps it will not? I would be inclined to put my money on the fact that it will but not my bottom Dollar. You could seal the joint but this would be very difficult to do and you would be back to square one messing with sealents etc which never seem to work medium to long term anyways.

Dann2




[Edited on 5-9-2009 by dann2]

Quote: Originally posted by Swede

I have committed myself to potassium, which forces a two-step process (Cl to chlorate, harvest/clean, chlorate to perchlorate) due to the crappy solubilities.

Quote: Originally posted by hissingnoise

Quote: Originally posted by Swede   I have committed myself to potassium, which forces a two-step process (Cl to chlorate, harvest/clean, chlorate to perchlorate) due to the crappy solubilities. Why not NaCl Swede? It has advantages over KCl besides better solubility. . .

that nice guy is me!!! Thanks swede
The smell went away after about 2 weeks. I think the smell was due to the anodes being cut with the abrasive wheel probably immediately before being put into the bag for postage. I could cut a bit of anode to test this.

Since then I have cleaned a piece in HCl and used about 6" submerged in a KCl cell at 30A with a PC power supply. It works well.

I'll look into it. I'll bet there are companies or universities that would do it at a decent cost.

On the tubular electrode shank concept - one thing that concerned me was heating. At 60+ amps, pure Ti heats pretty badly at typical cross sections of 25 mm^2. A 1/2" dia (12mm) OD Ti tube with an average wall has a similar x-section, and will heat up in much the same manner, with the tubular section being more difficult to affix to a heat sink vs. a strap, making it more difficult, and with the very real possibility that the Ti tube will melt or deform the compression fitting that carries it.

I had a thought, and perhaps a solution. #2 or #4 Cu welding cable has an OD, when stripped of its jacket, such that the Cu bundle can be inserted into the tubing to carry the current. With the bottom flattened and welded shut, similar to this picture:



It should be leakproof. From the top, open end, insert the Cu bundle with some force, creating a chisel-shaped deformation at the bottom where the Cu is near the anode. Now, you cap the Ti tube with brass, bronze, or Ti, and the Cu bundle is internally filling the hollow void, with vigorous contact on the walls and cap. You have instantly created a Ti tubular shank capable of carrying a couple hundred amps with little heating.

Of course, the Cu will be 100% protected. Another option - use Cu round bar as an insert for 90% of the length of the Ti tube. At the bottom, fill it with stripped Cu cable, or even jam in some Cu or bronze wool, very tightly. You'd get the same effect. Think of the Ti tube as simply an insulator jacket for the Cu, rather than as a primary means to carry current.

Quote: Originally posted by Swede

Another option - use Cu round bar as an insert for 90% of the length of the Ti tube. At the bottom, fill it with stripped Cu cable, or even jam in some Cu or bronze wool, very tightly.

Quote: Originally posted by dann2

Another option might be to jam in some pieces of Copper at the bottom of the tube and fill up with melted Lead or melted solder. About the yellow color in HCl. The yellow color that is sometimes in hardware store HCl is Iron contamination (I have read). Dann2

Good deal Tentacles. Because Ti is slow to transmit heat, a lot like stainless, you can get a nice localized heating that definitely helps with the welds. I've been using an area of slightly greater than 1 square inch for attachment of the mesh to the shank, and I think that should be adequate for anything up to 100 amps.

Got any pics?

For the people who miss the really cheap mmo!!! laserred is now alive

http://cgi.ebay.com/EXPANDED-TITANIUM-MESH-STRETCHED-SCREEN-...

Quote: Originally posted by bbartlog

Of course it's possible that the surfactants, fluidizers and so on would be too vulnerable to chemical oxidation in this situation.

Quote: Originally posted by hissingnoise

Magnetite was used, and may be still, as anodes for the production of perchlorates. It's rate of disintegration is higher than that for LD and its conductivity is on the low side but it was, at one time found to be fairly economical on the large scale. . .

All you need is Magnetite (me foot)!!!!!!

Hello,

Tutt Tutt!!
Terrible language.

Have you any references that show Magnetite was ever used "fairly economically on a large scale" to make Perchlorate, as you stated?
The refs. you give are a verbatim copy of the Geocities site (no mention of making Perchlorate in any sensible fashion with Magnetite), and the other ref. is a verbatim copy of Wouter Vissers site on Chlorates/Perchlorates. He simply states that you can make Perchlorate with Magnetite. As we all know you can make the stuff (Perchlorate) with DSA, Graphite, IRON!, Lead metal, Cobalt Oxide, Tin Oxide, ............but in a fashion that is of little or no use to us.


Some info. here if anyone is interested in Magnetite Anodes.
See also GB 850,380 where it states that Magnetite will make Perchlorate at a current efficiency of 4 to 5%. Not very economical me thinks!!!!!!!!!




Primary refs. would be nice, in fact they would be fecken great. I think I speak for lots of folks in here when I say that we are all very interested in making Perchlorate, with Magnetite, in a fashion that could be described as economical (thats economical for us, a much easier target to hit than what industry would demand).

You need to calm down Hissing noise. If you continue to yield that sword Seaside Windmill in your usual wild and frothing-at-the-mouth manner, y'll put yer own eye out.
Stop sending me U2U's as I don't read them (when coming from the 'Hissingnoise' instance anyways) as they are inclined to be a bit rude

Dann2

Quote: Originally posted by hissingnoise

Ok! You really think that every manufacturer went out and bought sheets of polished platinum every time they wanted perchlorate?

Quote: Originally posted by hissingnoise

And I apologise dann2, for the rudeness---next time I'll be less rude. And Xenoid (strange name for a silly goose?), consider my puff-adder behaviour under reconstruction. . .

You don't actually think I take it seriously? It IS noisy though. If you could make an effort at being less pre-teen so as to lessen said noise.

Where are the ref's, or do we take the statement, "Perchlorate's were made fairly economically on a large scale with Magnetite", as just some more Hogwash.

Dann2

Quote: Originally posted by hissingnoise

Magnetite was used, and may be still, as anodes for the production of perchlorates. It's rate of disintegration is higher than that for LD and its conductivity is on the low side but it was, at one time found to be fairly economical on the large scale. . .

Have you any refs. to back up the claim above irrespective of the interpretation put on it.
Refs. please (ie. get a move on).
How big were the Anodes, who/where were they made and used. Where did you find out or learn of these 'facts'. If you don't have any refs. to back up the claim (irrespective of the interpretation) I, (and I suspect others too!) will be presuming that both the claims that:
1)Perchlorate was made on a large scale with small scale Magnetite Anodes and found to be fairly economic or
2)Perchlorate was made on a small scale with large scale Magnetite Anodes and found to be fairly economic
(ROFL)
are indeed more Hogwash.

If you have no independent refs. you can always simply state that you have no independent refs. to back up the claim. I don't believe you, your taking the piss.

Dann2

Lord help us all if the Perskovites appear

[Edited on 22-11-2009 by dann2]

Hello,

@Swede. There is a Bi Oxide + SnO2 Anode in the patent below (example three). It claims that it is useful for Chlorate and Perchlorate production. It has not been tried before (patent was posted elsewhere on the board at some time or other). It would definately be worth a try. It's a no Lead, baked only, possible Perchlorate Anode.
You will need hot HCl to etch Ti, SnCl4 (liquid) and Bismuth Nitrate.
You could probably use SnCl4:5H2O (a solid) and dissolve it in Alcohol + some conc. HCl. You could perhaps use Bismuth Chloride if you cannot get the Nitrate.
You just brush on the solution to the Ti and bake. Put on about 6 coats (or whatever you wish).
Might be a break through!
SnCl4 (liquid) or SnCl4:5H2O (solid) can be had easily enough on ebay.com. You only need small amounts.
I tried using a Tin Oxide + Antimony Oxide Anode in a Perchlorate cell (pure Na Chlorate dissolved in water) for approx. 19 days. The solid extracted after that time contained 69% Chlorate the rest was Perchlorate. Not a useful Anode but the Tin Oxide held up well for the 19 days. It would have lasted much longer IMO but I put it into a Lithium cell and the Lithium cell seemed to erode it rapidly in approx. 24 hours. I was not really trying to make a Perchlorate Anode from Tin Oxide + Antimony Oxide Anode just testing my coating/coating method to see how well it held up in a Perchlorate cell as I was going to use it as an undercoat between Ti and LD.
There is a thread here on the Anode I was testing: Tin Oxide + Antimony Oxide Anode.
If you have an oven (you have) it is quite simple to do.
Keep it KISS. Don't be tempted to go down the 'Johnny Fortycoats + half the elements in the Perodic Table' road! (sorry about that )

Good Luck
Dann2




[Edited on 16-12-2009 by dann2]

Attachment: US 4272354 Bismuth_DTO perchlorate anode.pdf (253kB)
This file has been downloaded 798 times

DuPont Elvanol 71-30 100% hydrolyzed PVA thickener

http://www.chemicalstore.com/navigation/detail.asp?id=PVOH2

You could actually use a very small amount of the antimonate
for example 1 or 2% of the total weight of the principally Bi doped DTO composition. Sb reportedly functions to decrease the grain size and densify and toughen the coating as well as to increase the oxygen overvoltage, which are desirable and should enhance the anode coating durability. The hydrosol precursor should yield a much higher quality DTO baked film than what is gotten from other precursor schemes, and it should build thickness faster for a series of baked coats. For the first several coats it would probably be best to stick to the lower ~10% doping levels which result in an optical quality pore free sealing film, in order to create a dense barrier layer protecting the substrate. A higher doped but less mechanically perfect, yet more catalytically active coating can subsequently be applied as the working coating. The additional doping could be achieved by using the higher levels of needed Bi in the form of a soluble complex of Bi added to the hydrosol, if indeed it is not practical to simply raise the percentage of Bi in the described hydrosol.

This is a higher art for producing tougher baked coatings
than is likely to be achieved using chlorides precursors.

Oxalic acid is going to be a superior etchant for bare Ti.
There are a couple of reasons why oxalic acid is the preferred etchant. The surface effect has a physical property which enhances adhesion of coatings. And there is a trace residue of Ti oxalate at the interface which on baking supplies carbon from charring and has a reducing effect upon the TiO2 formed at high temperature, resulting in a conductive mixed Ti oxide at the interface which is also more capable of adsorption of dopants. For these reasons, it is
justified to prefer oxalic acid as the etchant.

And a Co spinel or a mixed Co/Ni spinel would probably make a superior interface coat as the first baked primer coat,
one or two coats only, followed by the DTO.

In the famous words of Yogi Berra,
"This is like deja vu all over again"
Attachment: US6777477 Bi2O3 doped SnO2 via ammonia soluble derivative.pdf (67kB)
This file has been downloaded 679 times

[Edited on 17-12-2009 by Rosco Bodine]

Here's a neat pool chlorinator MMO electrode assembly I recently acquired. It is notable for its unusual design which I haven't come across before.

Firstly it uses solid plate electrodes (140 mm x 47.5 mm) these comprise two monopolar anodes and two monopolar cathodes. Each set of these is connected by a strap at the bottom of the assembly. Between each anode and cathode there are two unconnected bipolar electrodes. There are ten electrodes in total and the total thickness is about 3.5 cm giving an inter-electrode distance of less than 3.5 mm.

All the electrodes are MMO coated and there is no polarity marked on the connectors, this suggests it was run in an automatic polarity switching "bipolar" chlorinator. I thought the design was perhaps quite old but in fact it is date marked 11 - 1 - 2005.

There is a little erosion of the MMO around the edges, but it still appears quite serviceable, I think I will pop it in a chlorate cell and see how it performs. That's about 660 cm^2 of MMO anode in a very compact unit

Quote: Originally posted by tentacles

Looks like it may have been removed from service because of that short or near short from one of the plates warping?