Multilayer Metal Oxide / Titanium Anodes for Chlorate/Perchlorate

Ok, while dann2 and Rosco start another cat fight, I decided to get to work. Although I admire the subtle blue hue of cobalt oxide baked on Ti, I am not going to do exactly what Xenoid did, I need to do different. First, I did my first ever anode with just (2) 10 minute Co3O4 coats follow by one nickel oxide coat then 1 hour bake. His name is Nicolas. The next anode I am in the process of working up is being temporarly called anode X. So far it has 3 coats of Co3O4 with no annealing 1 hour bake. Anode X is going to receive a SnO2 coat and then be annealed. This will hopefully close the debate between the madscience devas.

@Xenoid- I have provided pictures of my horizontal setup.

[Edited on 1/27/2008 by chloric1]

I wanted to show a picture of Nicolas also. You can tell the color is different. The blue hue of cobalt oxide is no longer seen instead you get more of a steel grey look but more refelctive. Of coarse the picture is misleading because of diminished lighting.

[Edited on 1/27/2008 by chloric1]

MadScience divas LOL .

I've had two red headed wives with some Scot and Irish
blood and buddy lemme tell ya , they mean business
and they know how the story goes ...when they get
Hot!!! like a tube furnace they will put a big smile on your anode

About that bimetal nickel spinel , or alternating Ni and Co ,
it goes back to the early part of the Cobalt Oxide Anode
thread where I posted a journal article about these spinels being compared and their mixture 50-50 was
reportedly even tougher than either spinel alone .

@chloric1 ,

That was probably not the best thing to do with the stannous chloride But don't toss it .

Do you have any left that you didn't neutralize ?

Do you have an accurate temperature controlled warmer or hotplate , if you do , you should take a shot at the oxidative soak deposition , as it should very evenly coat
the anode .

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

Yes I have a hotplate. I neutralize all the 28 grams of SnCl2 I measure out. I got a few hundred grams left. The milk does seem to put an uneven coat. I am doing a second coat with crem de leche right now. After this I wanted to try the 1 hour bake to seal it. For what its worth the tin oxide wants to coat everything and it seems to like being suspended in solution.

This oxidative soak. You have peaked my curiousity. So, what concentration do I use? I use only stannous chloride and boil I take it. I can use the anode as a stir stick since it would be in the way of a stir bar. I do not want to use a bunch of tin so I need to heat a graduated cylinder. Possibly the 25 ml one I am using for dips.

Rosco-One last thing, once I do the long bake, am I going to be abe to add to an anode?

Xenoid-I think the stannate only forms under the most grueling alkaline conditions. SnO2 is very persistent and wants to coat everything. I am having a time getting residues off glassware. The milk dip is not the best way to get the SnO2 coating. I did a REALLy hot bake for 30 minutes on a final thrid coat of stannic oxide. Incidently, I can no longer block three of the four baffles any more because the last two inches of the rod where glowing dull red. Also, I want to try zinc dopant on my next anode. If I can manage a alkali fusion with zirconium silicate, I would like to make zirconium nitrate to dope the cobalt spinel.

There is no white powder crust and my deposit is VERY tough although not as smooth as Nicolas is. Will test both soon. It appears my uneven SnO2 coat has reduced the streaking on the paper when wiped wet. I am thinking the cobalt spinnel absorbed most of the tin as no visible white coating is seen.

That tracks *exactly* with what I expected and predicted about the solid solution mutual solubility of cobalt spinel
and SnO2 , which was guessed from the electrical properties chart of US4369105 in early study of the Dow patents .
It was clear that plain SnO2 picks up doping from cobalt spinel quite easily by diffusion when the spinel is overcoated
onto the SnO2 , and diffusion should have occurred equally well in the reverse order as is being used here . Dow had the right idea , they just had the most desired order of application reversed I was reasonably certain that was the case.

Actually there is a mutual solid solution solubility that should be high for MnO2 as well with both the Co2O3 and SnO2
in binary or tertiary system , and I think Bi and also Fe
follow that same pattern at least with regards to SnO2 .
All of these should diffuse pretty well and form well adhering
boundaries of variable diffusion between layers , particularly when SnO2 is predominating as the major component .

idea for a tube furnace

After pricing of some industrial grade heating elements
and getting sticker shock , I remembered something about
an incoloy sheathed hot water heater element being made
for hardwater service , and a manufacturers note that the
elements could withstand dry firing . So basically what it is
is a folded hairpin "calrod" sort of tubular element that is a whole lot like the heating elements on an electric kitchen range cooktop , or the oven element , or the heating element
in an electric broiling grill , or an electric charcoal starter .....
it can be run actually glowing red hot ....probably even orange hot at the service limit . And best of all they are not
expensive . Here's what one looks like , and I think the element sheath is 3/8" diameter . The way I was thinking
of making use of the element involves splitting the mounting
plate with a saw , to separate the terminal ends of the hairpin so it can be spread apart slightly , and possibly also spreading apart the single U-bend slightly , so the whole
12" of the heated section is sprung slightly against the inside walls of a 13" length of square stainless tubing ,
2" square stainless tubing looks right , with the longer
legs of the element seated against the inside corners and the folded back portions sprung slightly against the inside walls and clamped down with small brackets or perhaps
with stainless lockwire through small drilled holes . The
tube furnace could be wrapped with rockwool or kaowool ,
and then fiberglass for added insulation , everything laced down with stainless lockwire or stainless zip ties like used for securing header wrap . A sensing thermocouple and
a digital PID furnace controller would be used for controlling
the element , and using half the rated voltage the actual
power would be only 25% of the rating , which would be
1375 Watts actual and very safe for the element .
From an economics standpoint , I like it The heating
would be very even due to the heatsinking by the tube .
I am thinking maybe about a 3/16" to 1/4" vent hole in top
and bottom to allow it to breathe by chimney effect ,
and orient it vertically with the unheated 2" terminal ends
exiting the bottom , and the thermocouple sensor near the top .

$16.42 for the 5500 Watt rated incoloy element isn't bad
http://www.homeandbeyond.com/prod-0114176.html


[Edited on 29-1-2008 by Rosco Bodine]

Yeh that might work but I think you are overengineering here. I am thinking Kanthal wire,which is not terribly expensive on ebay, wrapped around a stainless mesh with kaowool,variac and a thermocouple. Athough there are inherent problems with the heat gun approach, I do like to think the air flow is quite beneficial for what we are doing. It offers a constant fresh supply of oxygen. I just have to watch out and not block as many baffles.

Maybe over the top , but I already have the precision
digital programmable process controllers and sensors on hand ........besides , I love LED real time process monitoring
Takes the guesswork right out of the picture with regards to gradients and stuff , I can monitor not only the element
and air temperature inside the oven , but actually monitor
the substrate core temperature itself and watch the heating gradient and plateau , soak time ect .
I have some airhandling and flowmonitoring capability too but figure that is probably over the top for sure . But I like the other stuff . Using the parts I already have , I can
put it together without too much expense . I mainly like
going that way because I won't have to babysit the
process like a blacksmith at a forge ......but just do a
"run program" and come back later when the cake is ready to come out of the oven .

It's probably bakelite and was expected to be toast
I was going to torch it and crumble it away with a few taps with a hammer and chisel or try crunching it away with vise grips . The screw tabs are probably spot welded to the solid exit pins which are likely about 2 1/2" long .
Anyway I'll know soon enough cause I got one on the way .

When it arrives I will peform the "exploratory surgery"
and see what I've got after parting the plate , probably
bisecting the terminal block at the same cut , with a hacksaw . I'll probably leave the metal plates attached to the incoloy as heatsink flanges for that terminal area .

[Edited on 29-1-2008 by Rosco Bodine]

Please don't think I am dissing the heat gun furnace , no
not at all . I actually have some other need for a tube
furnace and have thought about building one for awhile ,
before the heat gun idea ever came up , so that's why
I already got the controllers before even knowing about the heat gun . There's nothing wrong with that so don't get me wrong . Some of the things I want to do other than
anodes is beyond the reach of the heat gun , and the furnace can do both . I have the heat gun too so I have it covered either way . Anyway having the readout data will
allow me to know exactly what the parameters are ,
if I should submit an article or go further .

Actually I have a variable speed linear actuator which I could use to duplicate dip coating withdrawal rates where
the precursor film is applied . But I probably won't use that either , not that it would be a bad thing for eliminating another variable . I'm an old production line
worker so I tend to think along those lines so I know I can reproduce nearly exactly whatever was done before that turned out right Clones , reproducibility ....you know.

BTW that group of Irish ladies , the MadScience divas
are in my area and I checked the cost of tickets and got another case of sticker shock ...about $200 each for general audience seating and it gets worse of course for premium seating ....so those girls are definitely upscale , there will
be a lot of valet limo parking at that concert . Well they may be high maintenance , but that's not really surprising .
I would definitely say those girls are some of Irelands national treasure .

[Edited on 29-1-2008 by Rosco Bodine]

No offense taken. Actually, I am taking note of your statements for future use. If I was in a pinch I would like a precise furnace so I may heat some potassium chlorate to EXACTLY 400°C so I can get perchlorate if I am unable to have an anode ready. At least with the heat gun, I can use it to remove paint when I am not cooking anodes.

How about cryogenic bakelite? A nice dip in dry ice & acetone.

Well, if you bad mouth the divas, your just jealous thats all!

ooops almost forgot , time for a diva fix

http://www.youtube.com/watch?v=KGpTkv713vQ&feature=relat...
or
http://www.youtube.com/watch?v=_H4TlDxXxVk

Just a bit of curiosity concerning the Bismuth explorations .
Anybody have any further developments with
Ti / Co2O3 / SnO2 / Bi2O3-SnO2 or
Ti / Co2O3 / SnO2 / MnO2-SnO2-Bi2O3 or perhaps
Ti / Co2O3-Ni2O3 (50/50) / SnO2 / SnO2-Bi2O3 (95/5) ?

I found some semiconductor manufacturing surplus
new old stock components which are furnace related bargains and I couldn't resist So I have some more components in shipment now for making a larger tube furnace as well as making the smaller furnace using the hot water heater incoloy element . I got some strip heaters that are incoloy too , and some 40A solid state relays arrived yesterday that are way more than adequate for the heating element control . More parts are coming in over the next week . Still tooling .

[Edited on 6-2-2008 by Rosco Bodine]

Well, I have not been able to venture to the hardware store lately and my daughter has chicken pox. So homelife is rather demanding. Just enough time to look into this forum a little here and there. Not to menton weather problems. Tornados n Jan/Feb? Whaaaat the hell?!

I have the current density calculation for my first SnO2 attempt figured out. Unfortunately, I do not have the precision power supply with current and voltage limiting like Xenoid has. I will fill everyone ASAP! I need to get on this because I know Xenoid is dying to know about nickel-cobalt spinel mix.

[Edited on 2/5/2008 by chloric1]

elementary wattsome

On the preceding page I proposed that possibly an incoloy
sheathed hot water heater element might be modified as
an inexpensive heating element for a 2" square tube tube furnace .
I ordered one and have gradually gently opened the original bends
to reshape the element to a larger dimension .
Still have some final cambering of the element
to finalize the fit , but it looks like it may work out okay .
The calrod is 5/16" diameter instead of the 3/8" I was guessing before having the part in hand .

Here's the before modding Camco #04963 , 240V 5500W


and here's after modding



The length between the outside of the single hairpin to the
outside of the double hairpin is 11 1/2 inches . At 120 V
the element should produce something in slight excess of 1375W , which in an outside insulated 2 inch square tube
should get plenty hot enough for baking any anodes and
will probably go fine to 650C - 1200F as a comfortable limit .

The terminal block turned out to be polypropylene and a heat gun softened it up
enough that it pulled away in a couple of chunks easily .

The next step was opening up the double hairpin bend at the extreme end gradually until there was about 3 inches clearance at the single hairpin tip where it was folded close to the parallels near the mounting plate as manufactured .

The mounting plate was separated using a vise and three separate cuts with a hacksaw , the first a straight cut with the blade at normal angle making a cut from the backside of the folded section , the cut about a third of the distance through the plate . Then the plate was flipped over and
the blade was placed at the 60 degree side angle position
in the hacksaw frame , and a similar depth cut was made
from the folded hair pin side . Then the element was flipped
vertical and rotated 90 degrees in the vise , the blade was loosened and put between the elements where they enter
the mounting plate on the hot side , and with the blade still
at that side position used in the cut before , the middle third
remaining was cut completely through , intersecting the two
previous cuts to form a single cut , separating the plate .
Where there's a will there's a way

I haven't yet tested the element to see if it has withstood the very gradual reshaping ,
but supposedly calrods can be bent okay before they are put into service . After they have been fired up , the heating element inside embrittles so after firing they cannot be reformed . Therefore I am not going to energize the element until it is finished mounting in the tube whereafter it will not be moved , except by its own thermal expansion and contraction within mountings which will allow that slight free movement .


[Edited on 9-2-2008 by Rosco Bodine]

BTW , nice to know that somebody is listening about the
sol-gel deposition and baking technology which I have been trying to reveal has applicability here for coating anodes .
It hasn't been stated openly as such in any of the literature
that doped tin oxide is a clathrate , but take my word for it , that is precisely what doped tin oxide is . And I have tried to break that news somewhat gently in another thread with a reference to the hundred year old discovery of this clathrate structure by a Dutch chemist ,
http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...
It seems van Leent , like some other scientists of that era before the mechanism of inclusion compounds had been elucidated , were creating clathrates and puzzled by them ,
for not really understanding what they had , other than it was a genuine curiosity , an anomalous material which
seemed to be a compound of some sort but didn't behave
like usual compounds in every way .

The intermediate hydrosol gel formation which is thermally unstable and forms a mixed matrix with the included , or caged dopant material , in an expanded water containing lattice structure , which collapses on dehydration by heating ,
is a *classic* clathrate formation mechanism which I certainly do recognize for what it is . And the polycrystalline inclusion compound which results is a "solid solution" , but likely at the point of saturation with dopant , it is also more precisely an inclusion compound or in other words a clathrate .

It's time for a diva break
http://www.youtube.com/watch?v=faKFcfytlxU

[Edited on 10-2-2008 by Rosco Bodine]

Yeah! I haven't quite worked that out yet! Adding a small quantity of Bi(NO3)3 or BiCl3 to the soak solution will result in bismuth subnitrate and oxychloride respectively forming, which is undesireable. I may try multiple oxidative soak/ pyrolysis for the SnO2 with some Bi(NO3)3 pyrolysis layers interspersed.

BTW Hubert is still running in the KClO3 cell, I will have to call it a day soon though, as I'm getting a bit sick of it. It's been running continuously for 42 days (1008 hours) now. Every few days I scoop out KClO3 and add some more KCl (a bit like running a ginger beer plant). The electrical characteristics are very, very slowly degrading. I think if you put on 20 coats of MnO2 and kept the current density to 50 mA/cm^2 it would just about run forever ...

Quote:

Originally posted by Xenoid BTW Hubert is still running in the KClO3 cell, I will have to call it a day soon though, as I'm getting a bit sick of it. It's been running continuously for 42 days (1008 hours) now. Every few days I scoop out KClO3 and add some more KCl (a bit like running a ginger beer plant). The electrical characteristics are very, very slowly degrading. I think if you put on 20 coats of MnO2 and kept the current density to 50 mA/cm^2 it would just about run forever ...

There's simply some more evidence there that dopant addition can be done by diffusion on baking .
It would seem likely that BiCl3 could be used identically as is SbCl3 .
And Bi(NO3)3 can be applied as a 10% solution to form the oxide on baking , but the solution of Bi(NO3)3 must be dissolved in and kept acidic with dilute HNO3 as it begins to hydrolyze immediately .

BTW , jpsmith123 had first posted one of the Bi related patents which I later found independently , I just ran across it while doing a search
http://www.sciencemadness.org/talk/viewthread.php?goto=lastp...

US4353790 indicates that Bi is useful as an interface on Ti substrate anodes , either plated on as the metal and oxidized on baking , or applied as a 10% solution of the nitrate directly to a Ti substrate and then baked to the oxide . In the patent , the Bi interface is used in conjunction with an overcoating of Iridium and Iridium Oxide to produce anodes having twenty times the durability of Pt plated Ti anodes . Of course Bi in other patents reportedly also performs well as a dopant for SnO2 and MnO2 .

CRC reports Bi(NO3)3-5H2O (mol.wt. 485.07) solubility as
42 grams in 100 ml acetone at room temperature , which would seem to make acetone
the solvent of choice for any dip coating scheme .

Bi(NO3)3 is reportedly unstable to heating even slightly warm , CRC says decomposition at 30C
with loss of 5 H2O at 80C which I assume is for the neutral salt in the absence of any stabilizing excess of HNO3 .

I would presume from this that neutral Bi(NO3)3 would be something then which you would want to crystallize out from dilute HNO3 ( maybe .5 to 1.5 molar ? ) in the cold and dry without any warming in the cold , looks like a refrigerator storage item . How stable is the acetone solution , I have no idea . Interesting chart below also are double salts of
Bi(NO3)3 which might also be soluble in acetone , particularly
interesting is the Mn(NO3)2 , and the juxtaposition with some
other materials of interest like Co and Ni . It makes me curious about stannic nitrate as well .


The above chart was excerpted from a book downloaded from here http://books.google.com/books?id=G5BLAAAAMAAJ&pg=PA151&a...

[Edited on 12-2-2008 by Rosco Bodine]

Oxidative Soak

@Rosco - this is for you!

I've just started another anode, this one is destined for a perchlorate cell. I have put on 4 coats of Co3O4 using the same procedures as outlined in earlier posts. I am following this with an oxidative-soak-coat of SnO2. Over the top of all this I plan to do several coats of Bi doped MnO2. If this coating scheme shows no improvement over the earlier MnO2 coated perchlorate anodes, I think I will give up on MnO2.

I have used the solution concentrations suggested in the paper; .01M SnCl2 and .05M KNO3. The soak solution was made up by pippeting .5 mls of 2M SnCl2 stock solution and 5 mls of 1M KNO3 stock solution into a 100 ml volumetric flask. About half this quantity is being used for the soak.

My setup is shown in the attached image. The Co3O4 coated Ti rod is resting in a 25 mm diameter test tube containing the soak solution,which in turn is supported in a large beaker of water on a hotplate. The temperature is coming up to 60 oC at the lowest hotplate setting. I will probably let the soak run for 48 hours.

I think I will call this anode Gunther (brave warrior).

Update: Temperature has stabilised at 59 oC. Unfortunately, after only an hour a little whitish floc has formed in the test tube, and the solution is a little hazy. This is not supposed to happen!

Edit: Hmmm.. after 2 hours some of the floc has settled out, it's a dirty grey brown colour, may be just due to impurities in the water.

[Edited on 12-2-2008 by Xenoid]

Putting some theory to the test huh ?

How was the wetability of the spinel without a mixed valency polymer pretreatment ,
did it seem to wet out fine by the SnCl2 oxidative soak solution ?

I'm thinking all you should see as a result is a change
in the sheen and color, like a clear coat or perhaps a
slightly hazy clear coat , and a more visible glassy appearance to the coating after baking .
With four coats of spinel there , it may soak up the SnO2 like
a sponge , so it may take a couple of repetitions .
It may not even take four coats of spinel for the interface
before the SnO2 , but only one or two may do it .

The SnO2 should be followed by Bi2O3 doped SnO2 .
A great time to try stannic nitrate there , or even here
if the oxidative soak doesn't seal and build thickness
rapidly . IIRC there is a point where the thickness
of the hard deposited material limits out , per coat ,
and thereafter a bulk precipitation rather than a controlled
deposition just deposits the usual slime .

Don't get in too big a hurry with the Bi2O3 - MnO2 ,
save that for last .

BTW , in the article it was reported that slight turbidity was
normal in the first prepared solutions even using reagent grade materials and distilled H2O ,
so they held the solutions at 80C for three hours and then filtered them before use .

Looks like you should prop open that watchglass cover slightly ,
to allow the solution to have a very limited access to air so it can breathe a little .

Something which has been an idea for awhile concerns the
stannous nitrate which was described in the antimony and tin nitrate thread
http://www.sciencemadness.org/talk/viewthread.php?goto=lastp... .
Evidently the stannous nitrate solution is only stable at
lower temperatures and at higher temperatures it hydrolyzes and precipitates
a hydrated stannous or stannic oxide .
This has made me wonder what might happen
if a relatively warm anode say at 95C , like would be for
the case of an anode having a baked spinel , then dipped
and blow dried mixed valency polymer , was plunged into
a cool solution of stannous nitrate . I wonder if the the
heat loss there at the anode surface would result in a flash deposit of an adherent film
of hydrated SnO2 , derived from local thermal decomposition of the stannous nitrate solution
immediately adjacent the hot surface . If it was adherent ,
then it would be simple to build thickness . You could have
a beaker of stannous nitrate sitting in an ice bath , and
a heat gun handy for drying and warming up the anode
and just do sequential dips to build a thickness , and then bake at a higher temperature
to sinter the material . This might be thought of as an oxidative quench deposition method
with the Ti blacksmith dipping the "not so hot but pretty warm anode" into the "special water" ,
to flash coat an oxide .

Also stannous nitrate might work as an oxidative soak deposition material
which could operate at room temperature as opposed to the 60C for the SnCl2 .
The stannous nitrate might set about an auto deposition simply by removing it from the refrigerator ,
diluting it and exposing it to air . And it would also likely be compatable with Bi(NO3)3 .
Anyway this is all purely hypothetical but might be worth experimenting at some point .

[Edited on 13-2-2008 by Rosco Bodine]

I just did a melt test on my reputedly "bismuth" non-lead fishing sinkers , expecting to get a pool of metallic bismuth
separating from molten plastic , but that didn't happen ....
so WTF is this black powdery crap , maybe Bi2O3 ???

The smell indicates a polyethylene thermoplastic binder ,
smells like paraffin burning after you blow out a candle
and the wick ember is smoking . I have just heated
the stuff till melting and then let the plastic vapors ignite and burn off . After I ash this grungy garbage down to
carbon and whatever is left , I will see what some nitric acid does to the residue . Just hope the manufacturer
hasn't sold us iron oxide filled plastic at bismuth prices .

Iron or magnetite is precisely what it is a magnet test just told me that much ......those sorry ass low down dirty
pieces of dog shit ......there's no bismuth in these no lead sinkers , they substituted iron when bismuth got expensive

Now I am going to have to order some for real bismuth from a metals dealer .......no OTC fishing sinker bismuth anymore .
pass the word , check with a magnet to see what you got .

[Edited on 13-2-2008 by Rosco Bodine]

LMAO! Xenoid you are soo silly! If it is from China then it should be magnite with a little lead. I guess 5% lead would be considered non-lead by Chinese standards.

Accept no substitutes !

Be careful where you dip your rod isn't Madame Butterfly

http://www.youtube.com/watch?v=IMsnqQHOwFg

Evidently there was at one time a real bismuth fishing sinker sold under that same brand name as I got , but they phased out the bismuth when it became expensive
and what I got was shit , instead of bismuth .

Anyway , I ordered some genuine reagent grade metal shot .

Some Good News and Some Bad News

Yes it's a brain strainer to follow the complex chemistry and hydrolytic reactions , of these polyvalent and amphoteric metal oxides / salts / oxy-salts / basic salts / hydroxy oxides / ect . on and on it seems till a good baking simplifies everything and makes a well behaved SnO2 from all the misbehaving precursor mixtures . And pH is very important
not only to adhesion , but it also affects the decomposition
temperature curve , and what is good for one isn't necessarily good for the other .

One thing about the Pytlewski polymer as a precursor for baked coatings is that all the patents either run from it completely or mention it as if it was the elephant in the room . The deepening color with increased polymerization
is what we want to see there . Possibly even hybrid polymer
having both nitrate and chloride anions , or nitrate and acetate could be a good precursor for baked coatings .

Anyway , I still believe the alternating scheme makes sense .
And with the oxidative cold soak , that could still work with
a slight anodic polarization to protect the spinel . Or one of the sol-gel deposition methods which works similarly as oxidative soak , sans the oxidation for working from a solution of the Sn+IV salt originally . Stannic nitrate solution
diluted to 4.75 grams per liter tin content as the metal might deposit the same sort of film spontaneously at room temperature , and gradually precipitate the gel going to completion just sitting there .

Attached is a paper concerning the hydrated oxide of tin(+IV)
and the pyrolysis curves for the material gotten at different pH .

Of course no discussion of tin would be complete without mention of this variety
http://en.wikipedia.org/wiki/Rin_Tin_Tin

[Edited on 19-2-2008 by Rosco Bodine]

Attachment: Stannic Oxide Hydrate.pdf (661kB)
This file has been downloaded 753 times

No pain , no gain Really it is a bit convoluted with regards to the steps required in working up any tin based reagents
in any sort of solution , since most of them are unstable .
Even pure tin metal itself is unstable and its compounds tend to inherit instability . Many tin reagents will have to be made
and used fresh , that is just the nature of the compounds .
You can alternately make your alpha stannic acid precursor via sodium stannate , neutralized with HCl and rinsed well ,
and then reacted with nitric acid . There are several different
synthetic routes .

Yeah , by well below ...about 50C below there would probably be about right , I would do that neutralization
in an ice bath , and probably keep the stuff under 10C ,
never even go close to 50C .

Well lemme think here a minute . If you took tin and dissolved it in concentrated nitric acid with heating ,
you would get metastannic acid precipitated and that's a
a Sn(+IV) compound , which on fusion with NaOH would
depolymerize and form alpha stannate of sodium . On
neutralizing that with HCl , then alpha stannic oxyhydroxide
would precipitate and after rinsing could then be neutralized
in the cold with HNO3 to give a solution of Sn(NO3)4 .

But it would be a lot easier probably to just dissolve tin
in aqua regia to get SnCl4 in solution and then neutralize
that with ammonium hydroxide to precipitate alpha stannic
oxyhydroxide ( alpha stannic "acid" ) and then rinse that ,
and neutralize in the cold with HNO3 to get a solution of
Sn(NO3)4 .

Both routes use HNO3 and HCl , but the second is probably
easiest .

Tin dissolved in HCl plus potassium nitrate reportedly works also , and it would be my guess that NaNO3 or NH4NO3 would possibly work too for producing an aqueous solution of SnCl4 suitable for use as precursor for alpha stannic oxyhydroxide , gotten after neutralization by ammonia and
rinsing the precipitate free of byproducts .

All this stuff about the natural polymerization tendency
of tin compounds makes old Pytlewski seem like one
much smarter pollock all of a sudden

There's a bit more general tin chemistry in the attachment
which is a more general description. Sometimes seeing the same thing in different words , or an added bit here and there completes the picture when no one text seems to cover it all .

[Edited on 20-2-2008 by Rosco Bodine]

Attachment: Tin chemistry summary.pdf (204kB)
This file has been downloaded 1457 times

something very interesting

Two posts above I posted a chapter from an old inorganic chemistry textbook . On page 6 (417) in the middle of the page is a reaction for stannic chloride with sodium sulfate , and very possibly a similar reaction occurs with ammonium nitrate , the product being a precipitate of alpha stannic oxyhydroxide .

There is another old text circa 1876 which refers to this .
I am attaching the page here which shows what I believe
is a mangled and incorrectly written reaction equation .
There is some confusion in the naming of compounds in
that era as well as mistaken or misprinted identification on the number of chlorines held by stannous versus stannic salts , so this brings uncertainty when referencing these ancient texts . Trying to reference this from the original
german journal article may or may not clarify the matter as the reference is from the year 1852

http://www3.interscience.wiley.com/cgi-bin/abstract/10975695...

J. Löwenthal , Journal für Praktische Chemie , Volume 56, Issue 1 , Pages 366 - 374

However , this parallel reaction for ammonium nitrate with
stannic chloride , if that is what it turns out to be , could
lead to a shortcut method for conversion of tin metal
to a precipitated alpha stannic oxyhydroxide , simply
by dissolving tin metal in a mixture of hydrochloric acid
and ammonium nitrate , or perhaps in a ternary mixture
of HCl + KNO3 + NH4NO3 .

The original german article is going to need to be translated
to get at the possibility of clarifying this reaction , if by chance
the reaction is identified correctly by the good german chemist of that era . If it's true , this could be a very good find , since it would greatly simplify the making of *any*
Sn(+IV) compounds desired via two easy steps from the metal using mundane materials and mild conditions .

[Edited on 21-2-2008 by Rosco Bodine]

Attachment: p 279 from Quantitative_Chemical_Analysis 1876.pdf (168kB)
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Well, I have given up on oxidative soak for the moment.

I oxidised some SnCl2 solution with H2O2 (dropwise) and to this clear solution I have added some Bi(NO3)3 solution (with nitric acid), the solution is still clear and I am using this as a pyrolytic coating directly on to etched Ti. The coating is being baked at about 470 oC. using the hot air gun with another vent taped over. It is producing a satin grey white coating. It's sort of like the Bi equivalent of Dann2's ATO precursor coating, perhaps we could call it BTO ...

It is not really an attempt at a serious anode, I just wanted to see how the solutions behaved and how the pyrolysis went. I'll try it in a perchlorate cell, though, as Dann2 reported that a plain ATO anode lasted a while.

@ tentacles

I thought you said in an earlier post that the Co3O4 layer had been stripped off, as happened with mine. Are you having success with the oxidative soak now, or was your earlier assessment incorrect. I also tried oxidative soak directly on Ti and still nothing seemed to happen, just a bit of precipitate.

My recent (half-arsed, admittedly) attempt at a doped SnO2 coating, I mentioned in a recent post was a failure. I used H2O2 oxidised SnCl2 and added some Bi (BTO). I put it on fairly thickly, directly on to etched Ti. In a perchlorate cell, I couldn't get any current until about 5 volts. To get 1.8 amps (50 mA/cm^2) I had to bump the voltage up to 8 or 9 volts. The current was continuously dropping so I guess it was passivating, and I didn't continue the experiment. I would imagine it had too high a resistance.
I guess these types of coatings vary by several orders of magnitude in resistance, unless the doping is spot on.The coating looked OK, it was like a thin white glaze on a teacup, but also clear in places. I did 5 dips each dried at 110 oC. and then baked at 470 oC. This was repeated 5 times. The coating was really hard, and nothing smudged off. There was no sign of any "free" yellow Bi2O3 forming, so it must all have gone into solid solution with the SnO2.

Hmmmm... I just read the electrodeposition paper a few posts above and THEIR thermally deposited anode only lasted for 10 mins. at 100 mA/cm^2. If these doped tin oxide coatings are so good, how come they don't last. Why are they being used as precursors for LDO? Even the cobalt spinel lasts much longer in a (per)chlorate environment especially if 20 coats were applied. Tin oxide is crap, judging from the results of that paper!

[Edited on 24-2-2008 by Xenoid]

[Edited on 24-2-2008 by Xenoid]

Hello,

I agree that if we can get a 'frozen lake' as opposed to 'cracked mud' it will be much better.
But since we are using a valve metal the cracks will be 'looked after' by the valve metal. (TiO2 will form if O gets into the cracks).
If using an attackable substrate then the 'frozen lake' would be ABSOLUTELY NECESSARY, 'craked mud' a disaster.............but we are using Ti.

Is not all our debate coming from the fact that SnCl4:5H20 is not OTC, therefor we are trying to use SnCl2 or 'homemade' SnCl4 (H2O2 + Stannous) (or something else that is 'gettable').
If SnCl4 were easily available we would all be quite happy with the 'cracked mud'.....I presume?
Lots and lots of articles etc use the 'cracked mud' as anodes both bare and with overcoats.
I must conceed without a doubt that Sol-Gel, and others have been shown to work for ANODES . I will have to withdraw the shaking head from way back.

For LD anode on Ti the function of the SnO2 is not to seal the substrate from electrolyte, it is to seal the Ti from the LD so that the LD does not Oxidize the Ti. (more like saving the anode from itself!!) If it succeeds in doing this in places only that will be OK, so long as there is enough of SnO2 links to the LD to carry the current. Let the other places on the Ti form a coating of TiO2 (to hell with them) .
Going off topic......

Perhaps it would be more wise to try making SnCl4:5H20 as per the S. C. Whack book (posted by Roscoe) and going the old tried and (successful dare I say) coldron stirring drones route of shake and bake.
The H202 + Stannous Chloride way does not (alas) seem to work.
Dann2

[Edited on 25-2-2008 by dann2]

@ Rosco

I'm getting very confused with all this ...

For example, in the case of Hubert I put on 10 coats of MnO2. Hubert did not directly die from "passivation", he died because the MnO2 (and the Co3O4) coating basically physically wore away over a period of 6 weeks or so. In fact when I removed the anode, the lower half still had a black coating, because it was thicker here due to the "dip solution" running down the hanging anode during pyrolysis.

If I had put a DTO layer between the Co3O4 and the MnO2 the anode would have lasted for 10 minutes longer .... according to the results in the paper above!

If I had simply put on 5 dip coats of MnO2 (with drying at 100 oC.) then baking at say 400 oC. and repeated this 10 times ( for a total of 50 coats) the anode would have lasted for at least 30 weeks as it is a simple physical wear effect. This coating scheme is only slightly more arduous than what I did initially.

In fact 50 coats of Co3O4 (may be with Ni or Zn) may last just as long (remember my 4 coat anode lasted for a couple of weeks in chlorate).

Basically, I don't see the point of a DTO layer if the "working" coating is going to PHYSICALLY wear away!

Quote:

Lots and lots of articles etc use the 'cracked mud' as anodes both bare and with overcoats. I must conceed without a doubt that Sol-Gel, and others have been shown to work for ANODES . I will have to withdraw the shaking head from way back.

The SnO2 is an oxygen barrier for the conductive interface ,
wherever the oxygen may come from . Dopants are used
to do two things , make the SnO2 conductive , and to fill
the lattice with something which will act as a barrier to
migration of atomic oxygen through that SnO2 lattice to
the interface . Bismuth evidently works best , Cobalt and
Iron are about next best , and Antimony is about fourth down the list in effectiveness as that oxygen barrier
Know you gotta love hearing that

Oh the SnCl4-5H2O works true enough if you get your
alcoholate derivative pH just right , and it would work even better using Co doping than Sb doping , if you simply must
use SnCl4 like there is something holy about it , even though there isn't . SnCl4 is just one of the *two* conveniently soluble stannic salts from which we may choose , and it's
awkward use and variable results are well described , since it was the most convenient reagent for researchers to use .
But the nitrate is the other soluble reagent which may be useful , as the patents acknowledged , and which from a theoretical standpoint is a "cleaner" and higher precursor with respect to the reactions through which it must pass in depositing the desired SnO2 . There is nothing illogical about
trying an alternative or alternatives which may shorten the work of building coatings thickness via chemical reactions
and physical chemistry which is more favorable to the desired end result . Some of the things I have proposed
may seem ridiculous to you , but are never the less supported by theory and also by individual references whose
pertinence I have recognized is knit together towards getting
the alternate scheme to work . The analogy between the
Pytlewski polymer and subsequent coating with colloidal silica
is good basis for my hypothesis that sol-gel SnO2 will very probably likewise adhere , has a high probability of being true .....even though I challenge you to find that stated in any textbook or patent , I'll put fifty dollars US on it right now . You see it can be a safe bet because colloidal SnO2
and colloidal SiO2 are remarkably similar in their chemical and physical properties . Therefore it is no far reach to
hypothesize that alternating coats of things which are by nature film formers , and attractive to each other by their
differing electrostatic charges , would stick like hell to each other in adjacent layers , and build thickness quickly of
dense high quality films . What seems to square with theory
and what jumps off the pages in that regard as pertinent
is not something I can pass over as insignificant or irrelevant . It may seem like I have gone off on a tangent ,
because you don't connect the dots I am seeing in these
references I have been sleuthing . And you seem to have some preconceptions about the chemistry involved , or
maybe about chemistry in general .....which causes you
to disregard any justifications I may give about dopants
or whatever other detail .....so beyond that I don't know what else to say .

How about a song from an old accordion player ?
It all started the first time I snatched up a piano
and just squeezed it Noooo ??? How about
some gospel music ? Okay , time for a diva break

http://www.youtube.com/watch?v=jWk8TwaqXBI&feature=relat...

@Xenoid , remember the "modifier oxides" which were mentioned being added to the working coatings ?
SnO2 was one of those and serves as a binder and hardener
and toughener for the working coatings .

[Edited on 24-2-2008 by Rosco Bodine]

@Xenoid

Go back and look at US4072586 page 3 column 3 line 56 .


Notice what's the first thermically decomposable compound
listed as an up to 20% addition to the Mn(NO3)2 .

Haven't you wondered why that is the *only* tin compound listed ,
instead of the usual list of assorted tin compounds ?

Since there is only one choice listed , maybe the others
don't work . And for what reason would the one which
doesn't work be the only one example listed of what
does work ? Hmmmm ?

It looks to me like they are saying something interesting there without elaborating on it .

Also if you look at example 6 , test anodes 4 and 5 which
included some (2%) cobalt doping of the manganese dioxide
had *triple* the endurance of the manganese dioxide alone .
So it is evident that modifying the MnO2 can toughen it significantly .
And the patent makes it clear that the MnO2
alone won't hold up which is precisely why the modifiers
were used and tested . If the MnO2 alone was good enough
then they wouldn't have bothered trying to improve it , as
they successfully were able to do .
http://www.youtube.com/watch?v=eKfDB9Osa88

Essentially the tin nitrate would serve the same purpose
as the silicon ethylate and should bring down the wear rate
to nil for the MnO2 . The 2% Co might be included , but
the Bi would probably be better substituted or possibly in addition with the Co . And all of this over a sealed spinel interface should give you a bona fide perchlorate anode
baked system . If the chemistry of the coatings is correct
and the film integrity good on the near substrate sealing layers , then having a low wear rate on the working coatings
won't take so many coats , probably a dozen or less from
the spinel interface to completion of the anode , not twenty or thirty .

[Edited on 25-2-2008 by Rosco Bodine]

'Struth!... dann2 - your memory is going, it's in the above mentioned Patent - US4444642 ...