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dann2
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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
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hashashan
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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
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Gamal
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About the beads.
I haven't been using a magnetic stirrer before, but my though is to cut them open, put some lead sheet in and glue them together again. Maybe u could
cover the magnet in the bead and the lead with epoxy of some kind. I don't know if it's possible, just a though. it can't be that hard to make the
bead sink.
/Gamal
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dann2
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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
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uchiacon
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Hey guys,
I was interested in making chlorate and maybe a small amount of perchlorate. I'm tasked with finding a suitable anode for both of these tasks. The two
options are Pt plated niobium mesh OR MMO anode.
Choices are for Pt anode
http://www.anometproducts.com//App_Themes/anometproducts/PtC... @ $5USD a square inch.
Or
MMO pool chlorinator - http://www.directpoolsupplies.com.au/prod733.htm
So I might be making a small amount of perchlorate in the futute, it'd be nice to have that option open. But is Pt still as good as MMO in a chlorate
cell? Could I just get two Pt anodes and use those for perchlorate and chlorate? Will it still be pretty tough in the chlorate cell?
I'm still unsure on this, can somebody just point me in the right direction? I can only get on type of anode.
Cheers
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Swede
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MMO cannot make perchlorate, so if you can only have one anode (??) it'd have to be platinum, unless you want to attempt a lead dioxide anode.
MMO is becoming more and more common as a surplus item. A lot of the guys here bought some excellent MMO over Ti for the equivalent of $5 for a
decent sized anode. Pt ALWAYS erodes, slowly, but it happens, so any platinum I have is reserved for perchlorate production.
Yes Pt is as good as MMO at making chlorate. Far more important in terms of efficiency is control of your cell parameters like temperature, pH,
stirring, etc.
Look around a bit, you'll find the MMO. Good luck.
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jpsmith123
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What about titanium nitride?
I just got a sales flyer from "Harbor Freight", and among other things the front page features some TiN coated step drill bits...so that made me
wonder: Has anyone here ever tried TiN coated anything as an anode?
TiN is a hard, chemically stable, highly electrically conductive ceramic material that's commonly found as a coating on drill bits, end mills, etc.
Of course high speed steel likely isn't a good substrate, but from what I've read, it seems it may not be too hard to make sintered TiN pieces or to
coat a piece of titanium with it.
I'm going to look and see if I have any expendable old TiN coated bits here somewhere and if not, I may stop by Harbor Freight and see what I can get
cheap, just for a quick experiment.
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12AX7
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One absurd way to make TiN is burn titanium in air. I've done this before, point a carbon arc torch at a hunk of titanium, it melts, boils and
combusts, leaving a brittle, spongy mess that used to be metal, and a haze of deposited yellow smoke around: nitride. I didn't check if it was
conductive...
Quality TiN is probably made by CVD... not really an accessible method unfortunately.
Tim
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jpsmith123
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What about taking a piece of Ti rod and heating it (a job for your induction heater) in a pure nitrogen atmosphere? Also, I read where sintered TiN
pieces are made from powdered Ti burnt in a pure nitrogen atmosphere.
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12AX7
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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
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jpsmith123
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Well I think we're getting ahead of ourselves a little bit. Maybe TiN is completely useless as an anode coating. Being that TiN coated tool bits are
relatively common and inexpensive (at places like Harbor Freight at least), I thought maybe a quick test in NaCl solution would be in order.
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hashashan
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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]
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jpsmith123
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| 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.
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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).
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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
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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.
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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.
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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.
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hashashan
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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.
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JohnWW
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TiN, although very hard and used to coat drill bits etc. as the result, is also very brittle, which poses a major problem in the fabrication of
articles made from solid Ti, such as the hulls of supersonic fighter jets/bombers able to withstand higher temperatures than Al alloys, as well as
anodes. Casting and welding of Ti articles thus has to be done under argon.
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Swede
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Notes on laserred's "eBay" MMO mesh
Quite a few guys purchased mmo sheet from a guy on eBay. The material is about 3" wide, with a 90 degree bend at one end. This material is very
effective, and produces chlorate as efficiently as my large commercial sheet. But...
A goodly portion of the MMO is coated with a red/brown smut. What this material is, I have no idea. It doesn't seem to harm the process, and appears
benign. My guess has always been that these MMO sheets were clamped into some sort of cell for a chlor-alkali process, perhaps even a chlorine
generator? I don't know.
The differences between it, and the commercial sheet, beyond the smut, is that the coating needs to be scraped off where any spot welds are placed.
Further, if you apply an ohmmeter along 6 inches or so of the sheet, with the probes on the coating, the resistance is fairly high.
I don't know why I decided to try this, but I took a scrap, and soaked it in 32% HCl for about 3 hours. The brown smut was completely removed; the
HCl took on a bright yellow tint. When I measured the resistance, it was 1/10th of the value along a similar, unsoaked piece. It is still higher
than the commercial sheet, but the removed smut was definitely inhibiting electron flow a bit.
With a decent lab, I could figure out what the yellow tint is from. I don't think it is ruthenium oxides in HCl. As far as I can tell, little to no
actual MMO was stripped, just the brown stuff. So if you feel the need to clean this material, 32% HCl works. I wouldn't go longer than 30
minutes... I don't think there is a need to, as the yellow appeared within 1 minute, and did not get appreciably darker. Even more interesting, I
tried Caro's acid on a piece a while back, and even that didn't touch the smut, but plain old HCl does.
Do you need to clean it? No, I don't think so. It may allow welding without scraping spots, but overall I don't think it's necessary.
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Swede
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^^^ 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!
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Bikemaster
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I buy 3 of those "electrode" and i was suspicious too about the red/brown color. I d'ont even test the electrode but i buy it to make lead dioxide
anode ... so i was d'ont really care about the quality of the mmo coating.
Your theorie seem to be plausible, maybe they are old anode... that may explaine the low price of the mesh.
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Swede
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The brown smut does not seem to harm anything when they are used for chlorate, but in the future, if I attempt further LD coatings on this material, I
will absolutely pickle it for a decent time period in HCl prior toplating.
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hashashan
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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]
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jpsmith123
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Well, nothing ventured, nothing gained I suppose.
Can the professor point you to any literature on the subject?
I haven't been able to find much at all on it. The only relevant thing I could find was a 35 yr old patent (US#3788968) which suggests usint TiN as an
intermediate layer on an anode.
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hashashan
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He told me that he once did an experiment like this on his own, however he is quite sure he did it with HClO3, and HClO3 is much more agressive then a
NaClO3 solution.
an an intermediate layer, well yes; if it wont work as an anode it will be a perfect intermediate layer, much better then the MMO, for me it is easier
to get TiN then MnOx or SbOy/SnOx
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hashashan
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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.
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jpsmith123
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Sorry to hear about your discouraging results.
I just borrowed a TiN coated drill bit from a neighbor and electrolyzed brine with it for about 30 seconds (I didn't want to risk ruining it on him)
in a stainless steel cup, and it seemed to work fine; i.e., a few volts gave a constant few hundred mA.
Then I took the bit out and looked at it and I couldn't see any obvious signs of damage...of course 30 seconds isn't long enough to say anything about
it except that it seems to have good conduction.
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hashashan
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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?
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