Sciencemadness Discussion Board

Stannous Chloride

dann2 - 23-4-2007 at 16:52

Hello,

I'm going around in circles.
Will Tin Chloride (Stannous Chloride, SnCl2) decompose with heat, in the presence of O, to Tin Oxide. I know Tin Tetrachloride (Stannic Chloride) will. Can Stannous Chloride be easily made. I can obtain Tin Oxide, Tin metal and HCl easily.
Also looking for Antimony Trichloride. I believe this is easy to make with Antimony Trioxide and HCl? Is it possible to start with Antimony Metal.

TIA,

DANN2

gsd - 23-4-2007 at 18:29

It is very easy to make SnO.

Gently boil tin chips in HCl till it dissolves completely. Filter the solution of suspended impurities. What you get is solution of SnCl2 in dilute HCl.

Now precipitate SnO by adding stoiciometric quantity of NaOH dissolved in water. In some patent literature it is mentioned that adding abut 5-10 % Na2CO3 to caustic lye, and carring the precipitation reaction at about 80 Deg C, gives good yields.

wash the precipitate 3/4 times with water to get black / grey SnO.

Please note dry SnO is pyrophoric!

gsd

Eclectic - 23-4-2007 at 19:01

Be aware that SbH3 is highly toxic...

Sb is supposed to dissolve in concentrated hydrochloric acid to produce SbCl3 solution, recoverable as anhydrous SbCl3 by distillation.

I wouldn't try this without using very good ventilation...

Don't use alloys as your Sb source, especially Sb/Zn :o

[Edited on 4-23-2007 by Eclectic]

dann2 - 24-4-2007 at 17:08

Quote:
Originally posted by gsd
It is very easy to make SnO.

Gently boil tin chips in HCl till it dissolves completely. Filter the solution of suspended impurities. What you get is solution of SnCl2 in dilute HCl.

Now precipitate SnO by adding stoiciometric quantity of NaOH dissolved in water. In some patent literature it is mentioned that adding abut 5-10 % Na2CO3 to caustic lye, and carring the precipitation reaction at about 80 Deg C, gives good yields.

wash the precipitate 3/4 times with water to get black / grey SnO.

Please note dry SnO is pyrophoric!

gsd


Hello,
Thanks for replys.
I need to make the Tin (IV) Oxide (SnO2) on Titanium Metal using a Tin compound. The Patent askes for Stannic Chloride to be decomposed with heat to Tin oxide. I am wondering if Stannous Chloride will do instead of the Stannic Chloride as I can obtain Stannous Chloride easily.
I can purchase lots of Tin Oxide at the ceramics store but that is no good to me.
The Tin Oxide on the Titanium must be doped with Antimony Oxide so I need a compound of Antimony that will decompose using heat to Antimony Oxide.
Both the decomposable by heat Antimony and Stannic (or hopefully Stannous) Chloride are applied in a alcohol solution to the Titanium and the Ti heated.

Quote from US Pat. 4,040,939:
A solution for the semi-conductive intermediate coating was prepared by mixing 30 milliliters of butyl alcohol, 5 milliliters of hydrochloric acid (HCl), 3.2 grams of antimony trichloride SbCl.sub.3), and 15.1 grams of stannic chloride pentahydrate (SnCl.sub.4.5H.sub.2 O).

A strip of clean titanium plate was immersed in hot HCl for 1/2 hours to etch the surface. It was then washed with water and dried. The titanium was then coated twice by brushing with the solution described above.
The surface of the plate was dried for ten minutes in an oven at 140.degree. C. after applying each coating. The titanium was then baked at 500.degree. C. for 7 .+-. 1 minutes.

The theoretical composition of the semi-conductive intermediate coating thus prepared was 81.7 percent SnO.sub.2 and 18.3 percent antimony oxides (calculated as Sb.sub.2 O.sub.3).

End quote:

Wondering if Stannous would do instead of the Stannic Chloride??
If yes, I guess I would need to use less of the Stannous to keep the molar ratio of Sn to Sb the same as the patent.
(excluding the water in the Stannic/Stannous)

As you explained above I can make SnCl2 easily enough but how do I extract the SnCl2 from the HCl?
I had not thought of looking up patents for to make chemicals! (embarrased face here)
Thank You,

Dann2

not_important - 24-4-2007 at 17:34

You need to keep tin chlorides in fairly acid solutions. The hydrates can be made by evaporating the solutions (NOT to dryness) until crystals form, then cooling and collecting the tin salt on a filter. In the case of SnCl2 you will need to evaporate it almost to dryness, as it is very soluble in water, although strong HCl may reduce the solubility. If you do take the solution all the way to dryness, especially without enough HCl around, you likely will get some hydrolysis to basic chlorides.

SnCl2 is a fairly strong reducing agent. If you expose a solution of it to air, more quickly be bubbling filter air through the solution, the solution will grow cloudy as hydrated oxide of Sn(IV) is formed. Adding concentrated HCl will dissolve that forming a solution of SnCl4 in HCl. Evaporate solution to get crystals of SnCl4.5H2O

SnCl2 will go to SnO unless oxidised by air. As you are making a semiconducting film, not getting too much deviation from the actual stoichiometries would seem to be a good idea. Try Sn(II), but if things don't work quite right then switch to Sn(IV).

There will be a lot of HCl coming off those solutions during evaporation, you'll want to trap it to keep all the metals around from corroding. Same goes for SbCl3.

Eclectic - 24-4-2007 at 18:26

Thanks for that patent number. I'd been looking for it.

Some of the earlier Diamond Shamrock patents:

US3865703, US3917518

Maybe with some additional useful experimental results using Sn/Sb mixed metal oxides to depassivate titanium electrodes.

As long as the Sn:Sb ratio is near 90:10, it may not be that critical.
Dissolve your metals or oxides in concentrated HCL, mix, maybe add some HNO3 or H2O2 to bring up the oxidation state, evaporate to syrup, add alcohol, paint, bake, and repeat.

(That's what I plan to try. Let me know if you get it working first.)

[Edited on 4-24-2007 by Eclectic]

Rosco Bodine - 24-4-2007 at 19:28

You probably shouldn't try to directly isolate these chlorides in pure form because they require the presence of some excess HCl to prevent hydrolysis . You don't actually need to isolate the chloride salts you have made .

For convenience , the equivalent mixture of the patent
would be made simply by working with strong solutions of the metal chlorides still residing in the solutions in which they were made , and having HCl in excess for their stability . You know how much metal or metal oxide was dissolved to make the chloride , so you can calculate the amount of the chloride contained per unit volume of the solution , and just measure out the volume of liquid which contains your required quantity of chloride .
Do that measurement for both the antimony and the tin
chloride strong solutions , and just add those quantities
to your butanol , letting the HCl component simply be that
HCl which is in excess as a stabilizer for the chloride solutions .

I didn't see any specific data for the lifetime of this electrode on a perchlorate cell , which would seem to be the real " acid test " for the performance , so I remain a bit dubious about the value this particular patents method . It would seem that if their testing did reveal
some suitability for use in a perchlorate cell , then that
data would be presented . It's not likely they forgot to test that capability or that it performed superbly in
perchlorate production and they neglected to disclose
that value .

Eclectic - 24-4-2007 at 19:37

One of the older patents uses 90:10:6 Sn:Sb:Ru for a hypochlorite electrode with a lifetime before passivation of 600+ hours at 1A/in^2 if I read it correctly. That's without PbO2 overplate. The Sn:Sb oxide seems to do a good job of preventing the formation of insulating TiO2 under strongly oxidizing conditions.

I suspect the Diamond Shamrock folks are more interested in hypochlorite and chlorate bleaching agents, and chlor/alkali process electrodes than perchlorate cells.


[Edited on 4-24-2007 by Eclectic]

Twospoons - 25-4-2007 at 14:26

You might also try doping the SnO2 with Indium, as in ITO glass. Source: indium/tin lead-free solder. Indium content is usually about 2%.

dann2 - 25-4-2007 at 14:57

Hello,

Thanks for replys. US Pat. No3940323 uses Molybdenium as the dopant (instead of Sb, Indium etc).

It also says that there are lots of salts that are ok for thermal decompositon to SbO2 + Dopant (Mo).
_______________________________
Stannic and Stannous Chlorides, Oxychlorides, Alkoxides, alkoxy halides,
resinates, amines and the like (to quote exactly)
_______________________________

Are any of these's compounds used anywhere that access to them is straightforward for the 'non chemist'.

Cheers,

Dann2

Edit = wrong Pat. No.

[Edited on 25-4-2007 by dann2]

Eclectic - 25-4-2007 at 15:16

There is a lead free solder 95/5 that is 5% antimony, balance tin.
Dissolve it in concentrated HCl (outside, good ventilation) and you are half way there.

Fluorine doped tin oxide is also conductive. Here is an abstract that seems to indicate that tin oxide doped with both fluorine and antimony may be more conductive than either alone:
Sb, F doped SnO2 (This paper indicates highest conductivity at ~5mol% Sb. F content is reduced by baking @500C on a glass substrate)

Fluorine concentations in F doped tin oxide films seem to run 3-4% and are obtained by adding a bit of NH5F2 (ammonium bifluoride) to the Sn chloride solution before spraying it on the substrate and baking.

You may be able to get everything you need for this OTC via 95/5 solder, brick cleaner, and aluminum cleaner :D



[Edited on 4-26-2007 by Eclectic]

Eclectic - 26-4-2007 at 08:19

(from "Industrial and Engineering Chemistry" Vol. 16, No. 4)

The following procedure is recommended for the treatment
of an alloy containing tin or antimony or both:

Treat 1 gram of the borings with 20 cc. of concentrated
nitric acid and 10 cc. of water. Evaporate to dryness over a
flame or a steam bath. Add 10 cc. of dilute nitric acid and
warm. Filter and wash with dilute nitric acid. The filtrate
will contain all the metals except the tin and antimony, which
are retained as oxides on the filter paper. Up to this point
this is a regular procedure for alloys. Wash the oxides into a
beaker with 50 cc. of a strong solution of sulfur dioxide and
digest from 3 to 5 minutes at 60" to 70" C. Heat to boiling,
add about 10 cc. of concentrated hydrochloric acid, and boil
until all sulfur dioxide is removed. If necessary to remove
traces of the oxides from the filter paper, this can be treated in
a similar manner. Tin and antimony will now be in solution
as chlorides of the higher valence in the presence of traces of
sulfate, which is a convenient form for further treatment.

dedalus - 26-4-2007 at 13:11

SnCl2 always makes a lot of white "metastannic acid" sludge even if you dissolve it in acid. Incredibly easy to oxidize.

alancj - 14-5-2007 at 18:50

Can stannous chloride (SnCl2) be made by disolving SnO2 in HCL acid? Or is the oxide inert to the acid?

Thanks
Alan

12AX7 - 14-5-2007 at 19:42

SnO2 has Sn(4+), how exactly does it get to Sn(2+) by dissolving in HCl?

Tim

alancj - 14-5-2007 at 19:51

would I just get a solution of stannic chloride then?

UnintentionalChaos - 14-5-2007 at 20:06

Stannic Chloride reacts quite violently with water releasing clouds of HCl, though it does form hydrates. I imagine that dissolving SnO2 in HCl would require a large excess of concentrated acid and would make nice plumes of Cl2 (analagous to MnO2 + HCl, which makes MnCl2 and used to be a means of producing Cl2 before the chlor-alkali process). Don't gas yourself. If your oxide is calcined, it will be hellishly difficult to dissolve it in the acid. I think the addition of small amounts of H2O2 helped the dissolution along in a discussion about MnO2 IIRC.

[Edited on 5-14-07 by UnintentionalChaos]

alancj - 14-5-2007 at 20:54

Quote:
Originally posted by UnintentionalChaos
Stannic Chloride reacts quite violently with water releasing clouds of HCl, though it does form hydrates. I imagine that dissolving SnO2 in HCl would require a large excess of concentrated acid and would make nice plumes of Cl2 (analagous to MnO2 + HCl, which makes MnCl2 and used to be a means of producing Cl2 before the chlor-alkali process). Don't gas yourself. If your oxide is calcined, it will be hellishly difficult to dissolve it in the acid. I think the addition of small amounts of H2O2 helped the dissolution along in a discussion about MnO2 IIRC.

[Edited on 5-14-07 by UnintentionalChaos]


Well, I know that PbO2 will dissolve in hot HCL, I never noticed any large amount of Cl. but then again I did it in a test tube in a small amnt. I thought SnO2 might do the same thing. I was wanting to make SnCl4 .5H2O. Following what not_important said:
Quote:
SnCl2 is a fairly strong reducing agent. If you expose a solution of it to air, more quickly be bubbling filter air through the solution, the solution will grow cloudy as hydrated oxide of Sn(IV) is formed. Adding concentrated HCl will dissolve that forming a solution of SnCl4 in HCl. Evaporate solution to get crystals of SnCl4.5H2O


Maybe hot/concentrated HCL in excess plus bubbling air into the solution would work to dissolve the SnO2. I haven’t bought any yet. Would I be better off just buying metallic tin? What do ya'll think?

Btw, why would calcined Sn02 be any different than something that was (say) precipitated? I have had trouble with getting calcined litharge to dissolve in acid (I ground it to a powder- with dust mask on) but precipitated litharge dissolves in nitric acid just fine.

Thanks for the help,
Alan

not_important - 14-5-2007 at 21:35

SnO2 isn't a strong enough oxidiser to form Cl2 from hydrochloric acid.

As SnO2 is already fully oxidised, there's nothing to be gained by bubbling air through SnO2 + HCl(aq), and you'll lose some HCl that way.

If you're after SnCl2, then buying tin or making it from SnO2, if you already have that, is the way to go. Reacting with hydrochloric acid and evaporation with the exclusion of oxygen will crystallise out SnCl2.2H2O.

Calcining something tends to increase the crystal size, fuse very find particles into larger ones, cause solids in metastable forms to release energy and change to the more stable form, and so on. All of these tend to reduce the reactivity of the solid, by reducing surface area and/or forming more inert forms.

In the case of tin, precipitated SnO2 is a hydrated form of the oxide, which is somewhat more reactive. Usually the hydrated form is calcined to get a product of fixed composition.

Heating SnO2 with strong alkali, or by fusing the oxide with an alkali, will given a stannate such as Na2SnO3 (+3H2O as a solid). Solutions of these precipitate 'metastannic acid' on treatment with CO2 (or exposure to air), one of the hydrated oxides. This dissolves in acids fairly easily.

alancj - 14-5-2007 at 22:39

So SnO2 will form a solution of SnCl2 with HCL, then?

If that's true, and I wanted to make SnCl4.5H20 by the above quoted procedure, then I would first dissolve my Sn02 in an excess of conc. HCl, and once dissolved, bubble air through the solution to oxidize it to SnCl4. Correct me if I'm wrong.

The metastannic acid info you mentioned is interesting, as well as that on calcined oxides. Thanks.

Alan

alancj - 14-5-2007 at 23:02

Quote:
Originally posted by Eclectic
Fluorine doped tin oxide is also conductive. Here is an abstract that seems to indicate that tin oxide doped with both fluorine and antimony may be more conductive than either alone:
Sb, F doped SnO2 (This paper indicates highest conductivity at ~5mol% Sb. F content is reduced by baking @500C on a glass substrate)
[Edited on 4-26-2007 by Eclectic]


Anyone have access to this paper?

woelen - 14-5-2007 at 23:08

No, SnO2 does not make a solution of SnCl2. Oxidation state does not change from +4 to +2! I think not_important made a typo by telling that SnO2 is needed for making SnCl2. What actually is needed is SnO, which also is available commercialy. Sometimes it is offered on eBay.

The commercial SnO2 does not dissolve at all in any acid, no matter what concentration and what temperature. It simply is inert. The only reasonable solvent for SnO2 is molten NaOH or molten KOH, not something you want to play with if you don't have the experience and the right equipment (remember, molten NaOH/KOH dissolves glass and also attacks many metals).

So, go for SnO instead of SnO2.

not_important - 14-5-2007 at 23:13

Ahh - meant make tin metal from SnO2, as opposed to buying the metal. Do not try to speak in one language while typing in another.

alancj - 15-5-2007 at 00:14

Quote:
Originally posted by not_important
Ahh - meant make tin metal from SnO2, as opposed to buying the metal. Do not try to speak in one language while typing in another.


I understand… I guess I misunderstood what the "it" was referring to. Would I just heat SnO2 with carbon in air to reduce it to metallic tin? Are there different ways to do it?
Quote:
Originally posted by woelen
No, SnO2 does not make a solution of SnCl2. Oxidation state does not change from +4 to +2! I think not_important made a typo by telling that SnO2 is needed for making SnCl2. What actually is needed is SnO, which also is available commercialy. Sometimes it is offered on eBay.

The commercial SnO2 does not dissolve at all in any acid, no matter what concentration and what temperature. It simply is inert. The only reasonable solvent for SnO2 is molten NaOH or molten KOH, not something you want to play with if you don't have the experience and the right equipment (remember, molten NaOH/KOH dissolves glass and also attacks many metals).

So, go for SnO instead of SnO2.


You say commercial SnO2, is that to say that a non-calcined form of SnO2 would dissolve in acid? Just out of curiosity…

From my reading of the sodium metal thread I was under the impression that NaOH doesn’t really attack steel, or stainless steel. Could a porcelain dish or crucible be used as well? I have both porcelain and a very nice 18/8 stainless steel cup I found (it’s wider than it is tall and probably is about 400ml). I would think it would work quite well. But what do I know, I’m just “harmless.” ;)

Thanks for the clarification guys,
Alan

not_important - 15-5-2007 at 00:48

porcelain gets chewed up by strong base just about as much as glass, it's the SiO2 content that does it.

Non-calcined SnO2 is generally one of the hydrated form, which dissolve in acids to a greater or lesser extent. That precipitated by bases from SnCl4 solutions, or by or acids or CO2 from stannate solutions, tends to me more soluble in acids than that made from the action of strong HNO3 on tin metal.

Eclectic - 15-5-2007 at 02:45

Look up thread and see that there is a procedure for dissolving the normally unreactive oxide you get from dissolving tin in nitric acid. It involves digesting the oxide for some time in boiling SO2 solution before adding hydrochloric acid.

12AX7 - 15-5-2007 at 14:13

Quote:
Originally posted by woelen
The commercial SnO2 does not dissolve at all in any acid, no matter what concentration and what temperature. It simply is inert.


Not even any reaction with HF? I would expect SnF6(2-) or something to exist.

If it's so inert, why don't they make SnO2 crucibles? Do they? :shock:

Tim

alancj - 16-5-2007 at 00:18

Thanks, guys. I ended up just buying some tin shot on eBay instead. Digesting SnO2 with SO2 sounds like a royal pain (though interesting)... as well as fusing with a hydroxide. Considering that more round-about ways are just more likely to introduce unwanted impurities, I'm going with easier and more direct methods. So, Tin metal it is!

-Alan

woelen - 16-5-2007 at 01:19

Be aware that the tin from eBay probably is VERY pure, something like 99.9+ % or better. This sounds good, but it actually isn't. Such pure metal dissolves in HCl, but VERY VERY slowly. Dissolving a single granule of the shot (2 mm diameter or so) takes days at least in 25% HCl. When there is some impurity in the metal, then it dissolves much faster. You could cast the shot to rods (or buy some rods off eBay, they are available frequently very cheaply) and use these as anode in a HCl-electrolysis setup.

alancj - 16-5-2007 at 03:19

The stuff I bought was technical grade shot and is supposed to be 99.96% so I thought "well, kinda impure, but at 17 bucks for a pound and for my use it's probably ok." I also bought 30g of antimony shot 99.999% for about the same $. I might treat my metal with Cl gas and go for anhydrous... or put it in a flask and be patient, or do as you say and pass a current through it. Will pure antimony be as slow as Tin in HCL?

-Alan

woelen - 16-5-2007 at 05:47

IIRC antimony does not dissolve in HCl, you need an oxidizing acid like concentrated HNO3, or a concentrated mix of HCl and H2O2.

You are calling 99.96% impure :o ?? Most chemicals you have will probably be less than 99% and many of them probably less than 95%!

alancj - 16-5-2007 at 18:53

Quote:
Originally posted by Eclectic
As long as the Sn:Sb ratio is near 90:10, it may not be that critical.
Dissolve your metals or oxides in concentrated HCL, mix, maybe add some HNO3 or H2O2 to bring up the oxidation state, evaporate to syrup, add alcohol, paint, bake, and repeat.

(That's what I plan to try. Let me know if you get it working first.)

[Edited on 4-24-2007 by Eclectic]


Would the HNO3 react (or for that matter, the HCL) with isopropyl alcohol? Also, does HNO3 just help form the chlorides but doesn’t create nitrates? That is... if you were to evaporate the solution, would you get a mix of nitrates and chlorides or what?

Would electrolysis help the antimony get into solution of HCL without the use of HNO3? I have some, but my retort broke, and don't have much left to go around.
Edit: HA! I managed to fix it. I welded a piece of broken flask over the hole in the bottom. It hasn't cracked yet, now that I've been distilling water in it for a few hours.

-Alan

[Edited on 16-5-2007 by alancj]

[Edited on 16-5-2007 by alancj]

not_important - 16-5-2007 at 21:14

You'll want an excess of HCl. When starting with elemental Sb you'd cover it with an excess of concentrated hydrochloric acid, warm it, and slowly add HNO3 until most or all of the Sb had dissolved - but don't overdo the HNO3 as you're just wasting the excess. Boil the solution briefly to finish decomposing any excess of HNO3 and drive off Cl2 and NOCl. So long as there is an excess of HCl no nitrates are going to stay around.

H2O2 might work, but it should be fairly concentrated. Too dilute of H2O2 will result in the formation of oxychlorides and oxides, which will slow do the reaction of the elemental Sb. If you do get white ppt, you'll have to add more HCl, possibly evaportating down the reaction mix first.

Eclectic - 17-5-2007 at 09:51

If you start with 95/5 solder, you can just dissolve it in concentrated HCl solution, maybe with a dash of H2O2 to prevent SbH3 formation. (OUTSIDE or with good ventilation!) There was a paper referenced upthread that said highest conductivity is at ~5%Sb.

Too much HNO3 will make insoluble oxides.

[Edited on 5-17-2007 by Eclectic]

alancj - 17-5-2007 at 13:18

Isn't that just with 3-4% fluoride ion (?) You said that ammonium bifluoride is available as aluminum cleaner. Who might sell that do you think? I have 500g of sodium fluoride; I don't suppose there is anyway to convert some into the ammonium salt without sodium contamination?
If anyone has access to the paper that Eclectic mentions, feel fee to post it :)

Thanks
-Alan

Eclectic - 17-5-2007 at 13:59

I think that's 5%Sb with or without F-, but lower resistance if the F- is in there too.

Ammonium bifluoride is in aluminum wheel cleaners and refrigeration coil cleaners. I don't think it's really vital to the coat and bake process, but could help to strip residual surface TiO2.

conductivity data for doped tin oxides

Rosco Bodine - 3-7-2007 at 19:25

This data is from a Corning patent US2564707 concerning conductive tin oxides baked on a glass substrate , such as might be used for heating elements and other purposes . This patent was posted in another thread but the information is so pertinent also to this thread that I am attaching it here where it will be more easily found .

Attachment: US2564707 Sb2O3 doped SnO2 and tertiary compositions.pdf (479kB)
This file has been downloaded 1216 times

state of the art coating from 95/5

Rosco Bodine - 4-7-2007 at 22:04

This is the most advanced reference which I have found
that is directly applicable to the mixed chlorides gotten from
95/5 .

A transparent , pore and crack free optical quality coating
having four to eight times the usual single baked coat thickness and superior conductivity and adhesion results from the use of polyvinyl alcohol as a thickener .

US6777477

http://www.sciencemadness.org/talk/viewthread.php?action=att...

The best ratio

dann2 - 10-7-2007 at 17:46

Hello,
Reading the patents that use Doped Tin oxide (With antimony) the perchantage of Sb used is variable.
Two patents that are doing what we want to do are

US 4040939 Example 1

US 4028215 Example 1

They use a ratio of SnCl4 to SbCl3 of 3.5.
This equated to a ratio of Sn to Sb in a starting alloy (assuming you are making your Chlorides from metals) of around 24% Sb the rest Tin. The solder at 5% Sb is very far from that percentage.

I am currently making my own solder from Sb and Tin from EBAY.
The conductive coatings on glass patent(s) may not be directly applicable to putting the DTO on Ti. They use lower amounts of Sb.

Can I make SnCl4 by dissolving SnCl2 in HCl and adding H2O2?

Cheers,
Dann2

[Edited on 11-7-2007 by dann2]

Rosco Bodine - 10-7-2007 at 19:37

The baked coating technology of 30 years ago is very likely not better than the newer technology of 3 years ago for the same type of conductive coating .

Eclectic - 11-7-2007 at 05:28

SnCl2+2HCl+H2O2-->SnCl4+2H2O

Of course it's a lot more complicated than that, but that is the net result. The reaction makes a lot of heat. Some of the H2O2 will be lost as H2O and O2. Premixing 2 parts 10-12N HCl with one part 30% H2O2 can reduce the localized heating and spatter. (Don't try to keep the mix, and the glassware must be very clean to avoid catalytic decomposition of the H2O2 and foam up)

A few drops of Ti dissolved in HCl can serve as an indicator of the endpoint. Blue until all the SnCl2 is converted, orange when there is an excess of H2O2.

Unless you are planning a series of tests with different concentrations of Sb, I'm fairly confident that anywhere between 3 and 10% Sb in the final coating solution will be "good enough", and in the same range as "best".

[Edited on 7-11-2007 by Eclectic]

dann2 - 11-7-2007 at 06:13

Quote:
Originally posted by Rosco Bodine
The baked coating technology of 30 years ago is very likely not better than the newer technology of 3 years ago for the same type of conductive coating .


Hello,

But they are on glass, not Ti. This may make a difference.
Don't know myself.

Dann2

dann2 - 11-7-2007 at 06:49

Quote:
Originally posted by Eclectic
SnCl2+2HCl+H2O2-->SnCl4+2H2O

Of course it's a lot more complicated than that, but that is the net result. The reaction makes a lot of heat. Some of the H2O2 will be lost as H2O and O2. Premixing 2 parts 10-12N HCl with one part 30% H2O2 can reduce the localized heating and spatter. (Don't try to keep the mix, and the glassware must be very clean to avoid catalytic decomposition of the H2O2 and foam up)

A few drops of Ti dissolved in HCl can serve as an indicator of the endpoint. Blue until all the SnCl2 is converted, orange when there is an excess of H2O2.

Unless you are planning a series of tests with different concentrations of Sb, I'm fairly confident that anywhere between 3 and 10% Sb in the final coating solution will be "good enough", and in the same range as "best".

[Edited on 7-11-2007 by Eclectic]


Hello,

I added some of my 'Ti dissolved in HCl (blue)' indicator. It turned orange (or at least the blue colour went away) after fairly small addition of H202. I am using 10 grams Tin. The H2O2 is 30%.

The 10 grams Tin dissolved in HCl was yellow to start with. I mean it was yellow after all the Tin had dissolved in the HCl.
I refluxed the HCl and Tin to get it to dissolve.
This yellow remained as far as I could see after the addition of H2O2. The orange of the Ti was hard to see along with the yellow colour of Tin in HCl.

I need to start with alloy though.
Thanks for help.

What do you get if you feed Chlorine gas to Tin/Antimony Alloy. The Tin goes to SnCl4 (anhydrous). Will the Antimony go to SbCl3?

Dann2

Eclectic - 11-7-2007 at 07:13

My solder dissolved in hardware store muriatic acid was water white before adding any H2O2. Are you sure your acid is pure? No dissolved Fe? Mine was a very pure grade also used to adjust swimming pool pH.

Cl2 should react directly with the dry alloy to make SnCl4 and SbCl3, but then you have to get it hydrated. You could also bubble Cl2 into the alloy dissolved in HCl solution, but I see no advantage over using HCl/H2O2, and much greater hazard.

[Edited on 7-11-2007 by Eclectic]

Rosco Bodine - 11-7-2007 at 08:12

Quote:
Originally posted by dann2
Quote:
Originally posted by Rosco Bodine
The baked coating technology of 30 years ago is very likely not better than the newer technology of 3 years ago for the same type of conductive coating .


Hello,

But they are on glass, not Ti. This may make a difference.
Don't know myself.

Dann2


Technically , the interface is SiO2 for glass (or silicon) and TiO2 for the titanium , which shouldn't be any problem . There is a similar diffusion layer that will be there in either case , and a better solution of the dopant will increase the adhesion and increase the conductivity for either interface .
Whatever produces a more homogeneous solution of the
antimony oxide in the tin oxide will benefit the interface ,
and the solution of the antimony dopant is increased in
the fusion product of precursors derived from the ammonium salts , as compared with the solubility of the antimony oxide
in the fusion product of precursors that are the chlorides .

Think of it as epoxy part A and part B , the better the two
are mixed and dispersed .....the more complete will be the
reaction .....no matter what materials are being glued together by the mixture .

It shouldn't make any difference because of the mechanism for the way these coatings work .....they are solid solutions ,
essentially a tin oxide based glass in which is dissolved the
antimony oxide . When the antimony content gets very large like the proportions you are referencing , not all of the
antimony dopant is dissolved in the tin oxide , but exists as a separate distinct phase which disrupts the continuous glass with pores and cracks and islands of particles of undissolved antimony oxide which makes the coating full of bumps and ridges , not as adherent nor strong , and certainly not as electrically conductive nor chemically resistant as a smooth and even layer of homogeneous glass .

The antimony oxide is the thing that dissolves in the tin oxide
and it is highly unlikely that increasing the amount of the thing difficult to be dissolved and decreasing its potential for being dissolved can be better for the integrity of the end resulting coating .

The substrate is vulnerable to undesired oxidation during the baking , so whatever melts soonest and most completely to a coating that seals it .....is going to be better than something which requires numerous coats to fill in all the
cracks and pores of the coatings which preceded .

So my bet is that the optical grade coatings that form a perfect coating in one bake from the first coat are going to
perform better .....no matter what the substrate .

If anything , the TiO2 layer will be more porous and thicker
than the SiO2 layer , and a more fluid , better dispersed fusion coating is more likely to be soaked into the TiO2 to produce a good diffusion layer ....as it will more easily wet that porous surface , than will a less dispersed coating .

dann2 - 11-7-2007 at 11:55

Quote:
Originally posted by Eclectic
My solder dissolved in hardware store muriatic acid was water white before adding any H2O2. Are you sure your acid is pure? No dissolved Fe? Mine was a very pure grade also used to adjust swimming pool pH.

Cl2 should react directly with the dry alloy to make SnCl4 and SbCl3, but then you have to get it hydrated. You could also bubble Cl2 into the alloy dissolved in HCl solution, but I see no advantage over using HCl/H2O2, and much greater hazard.

[Edited on 7-11-2007 by Eclectic]


Hello,
My HCl is lab grade (Analar, same as AR I think)
The Tin is 'very pure' from ebay. It was purchased from the element collector people.

The Ti oxide(s) indicator will not turn back to blue (from orange) when you add SnCl2 into the Tin dissolved in HCl + H2O2. When you add some more indicator (blue) it will remain blue as the H2O2 has been knocked out by the added SnCl2.
What I am trying to say is: the indicator seems to only go from blue to orange when all SnCl2 is converted by H2O2. If you then add SnCl2 (solid) the solution will go back to having no H2O2 but the indicator will not indicate this. You have to add fresh indicator(blue) which remains blue. Add more H2O2 and it will go orange...........

The SnCl2 (solid) I have is ebay stuff sold as Tin Mortant. I presume it is hydrated as I added some to HCl and it did not fume or warm just dissolved (as suggested by Eclectic).
The HCl I am using is 35% AR grade.

Dann2

Eclectic - 11-7-2007 at 12:46

That's good to know about the Ti indicator. I was thinking the SnCl2 would reduce TiCl4 (colorless) and the Ti peroxide complex (bright orange-red) back to TiCl3 (intense blue). Still it seems usable in this application to determine when enough H2O2 has been added. With the SbCl3 also in solution, there is a color change to bright yellow-green when enough H2O2 is added, also the brown-black precipitate dissolves .

Rosco Bodine - 11-7-2007 at 13:10

The agony and the ecstacy of conductive enamelware:D

To ammoniate or not to ammoniate ?
*That* is the question :P

[Edited on 11-7-2007 by Rosco Bodine]

Eclectic - 11-7-2007 at 13:29

Nah. It's just reducing effect of SnCl2, easy to cure with H2O2. :D

I don't think ammonium chloride is going to have much of a fluxing effect in this system compared to all the other stuff, especially before it evaporates at baking temps. :P

[Edited on 7-11-2007 by Eclectic]

Rosco Bodine - 11-7-2007 at 13:39

One thing I like about the idea of a cobalt spinel over a glass clear type of intermediate over a titanium substrate .....the color could possibly be very striking ,
and even a thin layer would probably look ten feet deep ,
something like a sapphire , jewel like finish instead of
a dull black . A pretty anode is certain to be superior :P Many of the spinels are likely to be highly colored materials having that gem like flashy effect you might see on fancy custom auto paint jobs .

Anyway , I was thinking about the ammonium stannate and ammonium antimonate precursors absent chloride .

[Edited on 11-7-2007 by Rosco Bodine]

Eclectic - 11-7-2007 at 13:45

OHHH! Cobalt blue coated Ti electrodes you can wear as jewelry when not electrolysing!

I really like the blue synthetic spinel faceting rough :D

Rosco Bodine - 11-7-2007 at 14:07

I still think I'd try a cold depassivation of titanium via a titanium cobaltate (? exist ) surface treatment before doing the doped tin oxide baked coating . My bet is that would be blue colored also .

In another thread I posted a little note about the highly acidic H2CoO3 formation reported from H2O2 plus
Co(OH)2 , and this would seem like a natural for a
cold coating that would protect the Ti from oxidation ,
and then nicely diffuse at the baking temperature to
form a good conductive interface .

Anyway I bet it would be a striking color finish for some of these combinations . IIRC they actually use some of these fired ceramic materials finely ground as pigments in fancy paints because they have colors and reflectivity which are extraordinary .

12AX7 - 11-7-2007 at 15:18

More likely, CoTiO3, analogous to CaTiO3, though Co being in the same class as Mg, Fe(II) and so on, would probably only be stable at high pressure ("enstatite (MgSiO3) is a perovskite-structured polymorph which may be the most common mineral in the Earth", from Wikipedia). Co(III) or Co(IV) might work in different perovskite type structures though.

Tim

Rosco Bodine - 11-7-2007 at 18:25

@12AX7

What I was thinking was for a low temperature reaction

Ti + H2CoO3 -----> TiCoO3 + H2

And next on baking

3 TiCoO3 -----> Co3O4 + ( 3 TiO1.67 ) conductive suboxide

It would be sweet if it worked :D

I don't think the temperatures would ever get high enough
for the titanate .

dann2 - 12-7-2007 at 06:53

Hello,

I now have SnCl4 in HCl by dissolving Tin in HCl and adding H202. Used 10 grams Tin metal.

I (some days ago) attempted to dissolve some Antimony in HCl. I refluxed overnight but it was not dissolved. I added some Nitric acid and it dissolved. I evaporated to dryness and got a white powder.

What oxide do I have here??
Sb2O3? or is there anything else?

I attempted to dissolve the powder in HCl (in a heated beaker) but it did not dissolve.
I refluxed some, 3.4g, of the powder in HCl overnight and it did dissolve. :)

I now have SnCl4 and SbCl3!......I hope.

I will be mixing the "3.4 grams of Sb Oxide dissolved in HCl" with the "10 grams Tin metal dissolved in HCl + H2O2" to give myself a 24% (approx) Tin + Antimony mixture.

How do I get rid of the HCl?

I do not want to paint on a mixture contining HCl as I think it will react with the Ti substrate.
I will be using Methanol or Ethanol (+hic#~*!) as a solvent for theses Chlorides.

I am plugging in the oven as you read this>>>>>>>>>



Dann2

Eclectic - 12-7-2007 at 11:17

You can't get rid of the HCl, or your chlorides will hydrolyze and precipitate. Some etching of the Ti is GOOD!. That's exactly what you want to happen, as the SnO2 will form in intimate contact with Ti metal, and the dissolved TiO2 will mix in as well, forming an adherent, conductive, chemically resistant, mixed metal oxide coating. Ti is VERY slow to dissolve in HCl.

dann2 - 12-7-2007 at 11:31

Hello,

I will go ahead and paint and bake with what I have. I though getting rid of some of the HCl might be a good thing as it would be reacting with the Ti as I am painting which may be a bad (or good as you say) thing. It is another unknown into the mix.
The Ti I reacted with HCl to make the Oxidizing indicator reacted quick enough. The Ti was hack saw Ti dust. The HCl was hot.

It will get hot when I am drying the 'paint'.

I made myself a Tin/Antimony alloy, 77% Tin, 23% Sb. Placed into HCl and refluxed for about 7 hours. The HCl is getting it very hard to dissolve this stuff.
I will let it run for another 14 hours or so. Might try some H2O2 or Nitric acid if it does not dissolve.

Dann2

Eclectic - 12-7-2007 at 12:54

Did you granulate the alloy by pouring it into cold water? More surface area/smaller particles is better. Use H2O2 after the tin has dissolved, leaving the Sb as a fine precipitate. Nitric acid may make unreactive oxides.

You can evaporate the excess water and HCl until your chloride mixture starts to crystallize, then cool and redissolve with alcohols, concentrated HCl, whatever you want for a more concentrated coating solution.

[Edited on 7-12-2007 by Eclectic]

dann2 - 13-7-2007 at 10:02

Hello,

I added the Tin Sb Alloy into the HCl as four pieces about 3 grams each.
The Tin has all dissolved leaving behind a powder of Sb (I presume) I will continue to reflux for some more time.
Does HCl gas escape or does the condenser trap everything?
If the Antimony refuses to dissolve after a long reflux I will add some H2O2 or HNO3. The HNO3 seems to work better at dissolving Sb. Which would you recommend.?
In another part of this thread someone said the Nitrates (if there are any) would all go away when the stuff if boiled/refluxed.

My SnCl4 + SbCl3 coating that I have already made did not work as a coating for the Ti anode. When baked it did not turn black, as the patents said it should.
You can rub the coating off.
I put it into a Chlorate cell just to see what would it do and the Ti quickly passivated.

I will start again with new Tin and Antimony (or if the alloy I have refluxing dissolves I will use that) as I have done a lot of toing and frowing with the stuff I tried on the anode.
With the stuff I have (that did not work) I boiled off some of the HCl but I boiled off too much and got some ppt. I added the HCl back in and refluxed and got most of the ppt back into solution. I added a tiny amount of H2O2 (+ blue Ti indicator) to make sure everything was oxidixed OK.

Will check oven thermocouple too, to make sure oven is hot enough.

Dann2

Eclectic - 13-7-2007 at 10:40

Pour off the clear SnCl2 solution. Add HCl and some H2O2 to the precipitate and heat for about an hour to dissolve. Mix the solutions back together and convert the SnCl2 to SnCl4 with H2O2 to avoid a brown-black precipitate.

HNO3 may make insoluble oxides.

dann2 - 14-7-2007 at 17:04

Hello,

I got all of the Sb to dissolve my adding a small amount of H202 (down the condenser) without seperating out the SnCl2. Converted to SnCl4. Painted and baked.
It did not work.
Posted report in Technochem.
Will try homemake SbCl3 + SnCl2 (solid purchased).

Dann2

Rosco Bodine - 10-12-2007 at 11:19

Quote:
Originally posted by dann2
Hello,

I now have SnCl4 in HCl by dissolving Tin in HCl and adding H202. Used 10 grams Tin metal.

I (some days ago) attempted to dissolve some Antimony in HCl. I refluxed overnight but it was not dissolved. I added some Nitric acid and it dissolved.


Sounds like a plan . Best to add the HNO3 in small portions
to the HCl . Once you have the antimony in solution ,
leave it in solution :D

IIRC it takes about 5 parts HCl to 1 part HNO3 .

I'll dig up more and post it later .
Quote:

I evaporated to dryness and got a white powder.

What oxide do I have here??
Sb2O3? or is there anything else?

I attempted to dissolve the powder in HCl (in a heated beaker) but it did not dissolve.
I refluxed some, 3.4g, of the powder in HCl overnight and it did dissolve. :)

I now have SnCl4 and SbCl3!......I hope.

I will be mixing the "3.4 grams of Sb Oxide dissolved in HCl" with the "10 grams Tin metal dissolved in HCl + H2O2" to give myself a 24% (approx) Tin + Antimony mixture.

How do I get rid of the HCl?

I do not want to paint on a mixture contining HCl as I think it will react with the Ti substrate.
I will be using Methanol or Ethanol (+hic#~*!) as a solvent for theses Chlorides.

I am plugging in the oven as you read this>>>>>>>>>

Dann2

tin chapter from Gmelin

Rosco Bodine - 17-12-2007 at 02:05

Here's an oldie but a goodie


http://www.sciencemadness.org/scipics/Tin%20chapter%20from%2...