More on PbO2 electrodes

I am wondering now if a mixture of SnCl2 and SnCl4 might have better usefulness than SnCl4 alone , ( for the tin oxide precursor ) . SnCl3 anybody??? ( SnCl2 - SnCl4 )
I have also wondered about adding other materials like lead or zinc or iron as the chlorides or nitrates .


[Edited on 19-7-2007 by Rosco Bodine]

@Twospoons

The conductivity of undoped SnO2 is poor and it was
the effect of a mixed oxide of SnO and SnO2 ....maybe a suboxide O value of ~1.5 that I was thinking about there
as a scheme for increased conductivity aside from other doping . Anyway I am pretty sure I have seen Sn(II) compounds used in coating schemes and they tend to oxidize to Sn(IV) in the baking process via oxidation from the air and/or reaction with other materials that are present .

Many of the patents show examples using one tin compound like SnCl4 - 5 H2O , but they specify a list of other tin compounds which may also be used , neglecting to give any details concerning those alternatives .

Also there is the possibility of a substituted bimetal oxide
along with the possibility that some of those mentioned
can have a doping action on the titanium oxide diffusion layer , along with the reducing action of SnCl2 which could
compete with the complete oxidation of Ti to TiO2 .

In several articles I have seen the intermediate stage of formation for the doped tin oxide layer described as forming a transient sol - gel system which then dehydrates and the dispersed colloidal particles then sinter as a solid solution ...which is the mechanism which produces a tough vitreous like coating , and the conductivity and amount of doping possible to be in solid solution is directly dependant upon the smallness of the oxide particle size and homogeneity of dispersion .

These sols can even be produced externally by separate synthesis and then applied as a coating to shortcut and make more complete what occurs in situ . By such a strategy , a conductive doped tin oxide coating can be
cold applied to even a polyethylene substrate . If anyone has need of an electrically conductive soda pop bottle for example .....then that is a can do

BTW , this is another reference which shows an upper limit of Sb doping in the range of ~8-10% , before Sb oxide exceeds the capacity of a solid solution in SnO2 and appears as a separate phase with conductivity going down , and confirms other references reporting the same thing for Sb doped SnO2
prepared under the most ideal conditions . And in a usual
baking scheme the upper limit is something on the order of one third that amount before the same effect occurs . I am doubtful that the diffusion from a substrate of what would be an additional material trying to find room in the tin lattice would improve those figures . The SnO2 is something like a sponge that can only hold so much in the way of dopants ,
no matter where they originate .

What I conclude from all of the stuff I have read is that when you think of what are probably useful percentages of dopants ......
think small

With the higher levels of Sb , perhaps a spinel formation
comes into play ?

[Edited on 19-7-2007 by Rosco Bodine]

Attachment: Antimony doped Tin Oxide colloidal nano-sols.pdf (584kB)
This file has been downloaded 1390 times

Cold Deposition of Doped SnO2 , the "oxidative soak method"

That is true. I am going to use the Sn/Sb Oxide coat as an inbetween coat for Ti and LD.
In order to test the coatings I am simply putting the Ti coated strip into Chloride solution to see how well it stands up. It is far too much trouble to coat each with LD just to test the Sn/Sb Oxide coat.
Perhap this test is not appropriate.
I also give a small portion at the top end (only one small place the top) a rub of steel wool to see how well the coating has stuck or hard it is. A patent (one only!) did this and they were able to obtain a glossy black appearance. Sounds like a good coat to me.

Side Note

Mrs. Jones would need some elbo grease to remove that coating if it were on glass....but we are discussing anodes
End of Side Note!

Some of the Sn/Sb Oxide coatings were used on their own to electrolyze brine solutions in the patents for quite a period of time too.
I noted that any of the patents that give an example where by the Sn/Sb Oxide coat was used to electrolyse brine (no overcoat), the Sn/Sb Oxide coat was put on the Titanium using anhydrous SnCl4. They refluxed it with an alcohol for some hours first to obtain a compound for adding the Sb Chloride to.

Dann2

All the Anode patents have reported a black coat. Why do you thing that I should get a clear coating on Ti.
I agree you do get a clear coating on glass.

Regarding the rubbing bit, I only rub a small amount at the top of the Ti just to see how adherent the coat is.
The part that I rub with steel wool is not involved in the 'test' where I then put the DTO coated Ti into a solution of Na Chloride as an anode.
As I said before my 'test' may not be very illuminating but it is quick and handy.

One last salvo on Sb %'s in DTO.
US 3,627,669 Examples 1, 2 and 3 are somewhat illuminating
with regard to making Anodes. They are not LD outer coat anodes but bare DTO Anodes, Ti substrate.
Very rough synopsis:
Example 1:: 10% Sb as I would calculate (10% Sb2O3 from Patent), ... OK after 5 days
Exmaple 2:: less than 10% Sb (1% Sb2O3), ...not so good at start, anode not tested for long.
Example 3:: more than 10% Sb (14.5% Sb2O3), ...same as Example one.

Patent here:

http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...

The patent is not directly relevant to obtaining a interface coat between Ti and LD but close enough IMHO.
This in not a 'dodgy' Diamond Shamrock patent either
The patent gives some info. on DTO in regard to Anode making. It also gives two
book refs. for anyone interested in some reading and can get them.
Controlled-Valency Semiconductors by E. J. W. Verwey et al., Philips Research Reports No. 5, 173-187, 1950.
Chemical Physics of Semiconductors by J. P. Suchet (D. Van Nostrand Company Ltd., 1965).


Dann2

[Edited on 19-7-2007 by dann2]

The oxidative soak method of cold deposition of adherent SnO2 and other oxides

This is a method which reportedly produces coatings
having excellent adherence to substrates and very even coatings via a cold process . The process uses a lower
valency salt of the metal oxide precursor , which is oxidized
to the higher valency and deposited as colloidal particles
of a hydrated oxide , then baked to dehydrate .

Reportedly the SnO2 film is so tough and adherent that
it cannot be scraped off with a knife

Since this method has been used to apply SnO2 to TiO2 ,
then it would seem very likely to work on Ti as well .

This oxidative soak method can also be used for the
cold deposition of Co3O4 and MnO2 and Mn3O4 ,
and likely also for other metal oxides .

Attachment: Preparation of SnO2 thin films by the oxidative-soak-coating method.pdf (324kB)
This file has been downloaded 930 times

Ok, thanks for the info. That's what I get for guessing when my main internet connection is down.

I like the oxidative-soak approach. I saw this sort of translucent film deposition on my glass bowl while evaporating and oxidizing my SnCl2 solutions. (Steel wool cleaned it off the bowl). Recall from some earlier posts that Na does not have beneficial effects on film conductivity though, so HNO2, H2O2, or just air may be a better oxidant for our application.

Regarding Rosco's idea of protecting the clean Ti surface from oxidation, again I suggest experimenting with HCl/SnCl2 solution as an etchant to lay down a thin flash coating of tin on bare titanium. Maybe etch and oxidative coating can be done in a one pot process with some development?

[Edited on 7-20-2007 by Eclectic]

I got my internet connection back, so I can use Google and not have to read and post through my cellphone.

The info I can find says steel wool is hardness 5.5. Titanium is 6?

Regarding titanium etching: reducing conditions seem to help. The etching seems to speed up once the acid gets a blue color from Ti 3+.

Quote:

Originally posted by dann2 Hello Hashashan, Quote: Originally posted by hashashan Correct me if I'm wrong' but isnt the Sb, Sn doping meant to be just a relaying layer between the Ti and PbO2? if so then why are you trying to run a chlorate cell with no coating? That is true. I am going to use the Sn/Sb Oxide coat as an inbetween coat for Ti and LD. In order to test the coatings I am simply putting the Ti coated strip into Chloride solution to see how well it stands up. It is far too much trouble to coat each with LD just to test the Sn/Sb Oxide coat. Perhap this test is not appropriate. I also give a small portion at the top end (only one small place the top) a rub of steel wool to see how well the coating has stuck or hard it is. A patent (one only!) did this and they were able to obtain a glossy black appearance. Sounds like a good coat to me. Side Note Mrs. Jones would need some elbo grease to remove that coating if it were on glass....but we are discussing anodes End of Side Note! Some of the Sn/Sb Oxide coatings were used on their own to electrolyze brine solutions in the patents for quite a period of time too. I noted that any of the patents that give an example where by the Sn/Sb Oxide coat was used to electrolyse brine (no overcoat), the Sn/Sb Oxide coat was put on the Titanium using anhydrous SnCl4. They refluxed it with an alcohol for some hours first to obtain a compound for adding the Sb Chloride to. Dann2

Hello,

Some of the layers I got were not 'too bad'. I don't know how to judge them. They were not clear and shiny by anymeans.
They were black (the better ones) but somewhat powdery. Perhaps they are good enough to use as in intermetiate layer for the Ti and LD. I don't really know.
You can doposit LD onto bare Ti once you start your bath with not too much acid. Connect the + of your supply to anode before you put it into plating tank so that plating will start IMMEDIEATLY. Then use anode as if it were a massive anode.

Tantalum can be coated easily from a LD bath. The oxide coat does not seem to form as quick (or something in that line) An anode has been made this way (discussed somewhere in this (short ) thrread. They then went on to use the anode as if it were a massive andoe. They ignored the substrate and connected 'Chlorate current' to LD.

Dann2

In my thoughts about this , there isn't any second fluxing or etching during the baking step of the very minimal oxide thickness on the already etched titanium required . The superficial oxide is modified while going preferentially into solid solution with an SnO2 layer . The idea which I am following is to modify the composition of the interface layer and limit its growth , by deliberately *avoiding* going through a Ti chloride byproduct intermediate which is then pyrolized .

What I am thinking is not to attempt to use the HCl evolving from decomposing Sn and Sb chlorides as
a means of fluxing away the existant TiO2 or TiO1.75 ,
which is of minimal thickness on a freshly etched Ti
substrate , but to seal and dope that interface layer before it grows in thickness which under usual exposed conditions would lead to formation of the passivating dielectric layer of dioxide . This also eliminates the further
pyrolysis of the chloride of titanium byproduct to an oxide of titanium , decreasing the loading of TiO2 into solid solution with the SnO2 layer . Using chloride precursors
for the SnO2 and Sb dopant , there is an etching of the
titanium proceeding from the HCl byproduct of decomposition of those precursors at the same time as
is occuring the formation of the doped tin oxide layer which is intended to blanket the Ti substrate from exactly
the sort of attack as the HCl is causing ....which seems to
be counterintuitive to me anyway It seems by the
brute corrosive force approach of the HCl being used to flux deeper and deeper into the titanium , that the result would be a growing thickness of an interface layer of Ti chlorides , later oxides , whose growing thickness is the very thing not desired to occur but to be prevented ...
this is counterproductive so why do it that way if there is any logical alternative ?

It would also seem possibly helpful to do a preliminary cold treatment of the freshly etched titanium , with chromic acid , cobaltic acid , or something else which
would apply a very superficial very thin , perhaps even not visible layer which would further retard any growth
of any TiO2 layer , and yet which would readily go into solid solution with the SnO2 layer on baking .

My thinking is that O2, Cl2, and HCl are able to migrate through the mixed oxides at 500 C, but that the metal atoms themselves are fairly static at that temperature. If the SnO2 is able to act as an O2 diffusion barrier, that facilitates the formation of conductive titanium oxides underneath, and prevents oxidation from PbO2 or other oxidants above. This is all the more likely if pre-etch or other titanium surface treatments load the Ti surface with H2.

In an acid etching bath, SnCl2 should plate out a very thin flash coating of tin on the metallic titanium surface as soon as the TiO2 dissolves...

[Edited on 7-22-2007 by Eclectic]

Aluminum IS a passivating metal.

Anyway, yeah, that's what I'm talking about.

But WHY would you want to do that if that's what the Sn/Sb chloride treatment does anyway once the process details are worked out?

K.I.S.S. Less variables, not MORE.

OK. As long as we are speculating, I wonder if SnO2 can be grown electrolytically from chlorides like PbO2 is from nitrates? Electrostrip with the polarity one way, then reverse and grow the protective conductive oxide layer. (I'm a bit unclear about anodes and cathodes, I haven't gotten that far yet.)

(BTW, when do I get to be an International Hazard too?)



[Edited on 7-22-2007 by Eclectic]

Rosco, I've got no problem with other coating methods. I just don't think there is anything wrong with using the chlorides. Very cheap and readily available from OTC materials. I like cobalt also, but that is a different process. I'd like to explore what can be done starting with 95/5 solder, and understand what's been going wrong with Dann's experiments using tin chlorides. I suspect cooking technique, rather than bad recipes. (How to make bread: Mix flour, water, and yeast, then bake. Simple, yes? But there is a bit of technique involved.)

By all means, keep up the good work posting all those great patents and articles you've been finding.

It might be best to avoid oxidizing anions when trying to get a conductive coating on reactive metals that form an insulating, tenacious, and chemically impervious oxide surface coating.

[Edited on 7-23-2007 by Eclectic]

What were those Dow patent numbers again?



[Edited on 7-23-2007 by Eclectic]

Definitely not the cooking technique.
It's the dodgy recipes, I tell you

Dann2

That is to provide "surface roughening" to increase the
chances of something sticking to the surface and staying put . Not very encouraging about the adhesion when you
see that sort of treatment described . It reminds me of someone trying to reglue a rear view mirror mount to a windshield , and getting instructions to first sand the
surface of the glass very well , then plunge immediately
the puddle of melted wax on the mount against the surface , and thereafter to never park the vehicle in direct sun
It would seem like they haven't quite got things worked out in terms of materials which should be agressively adherent in the existing condition .....like they haven't quite discovered
the equivalent of a cyanoacrylate "super glue" which will marry the different materials inseparably and with a substantial permanency (like years and years to forever) .

The cold application of a colloidal particle sized SnO2 via the oxidative soak method is the "most likely to succeed" in terms of adhesion , which I have read about anyway , which seems easily attainable . I think that the most adherent coatings are likely to be achieved from the compositions which deposit in the smallest particle size since that is closer to the "solid solution" and requires the least heating for the shortest duration to develop .

Also perhaps possible is the electrodeposition of the substoichiometric cobaltic oxide , followed by baking .

Al would be useless

Hello,

A strange thing happened today. I noticed a piece of Ti that I had coated with DTO at some stage (about 9 days ago) and it looked extremely black.
Would time be a factor in getting an improved coat?
Sounds ridiculous.
I dunked it into a NaCl solution as an anode and it took about 10 minutes to passivate. I ran it at a small current density but this was the best yet and this particular anode had been tried before in a NaCl solution and had passivated (and was therefor condemmed).
I left the anode aside for about an hour, dunked in into the solution again as an anode and it seemed to have recovered, ie. it was not passivated. It did passivate after a few minutes. It seemed as if the anode (as I said) had 'recovered' from passivation.
WTF

Perhaps my 'test' for DTO is a load of Boalderdash. (rubbish if in USA )

Dann2

Quote:

Originally posted by dann2 Perhaps my 'test' for DTO is a load of Boalderdash. (rubbish if in USA ) Dann2

I am American and I understand this.

..but seriously dann I wonder if this is like the electrode plates in automotive batteries that improve with a few charge/discharge cycles. Next time don't show mercy just run the hell out of the anodes say 200mA per cm2. Even if it passivates in 60 seconds. Maybe you need to do this 10 timesor something?!?!?!
Maybe your DTO has captured the titanium in a lower oxidation state and letting it set in open air corrects this. Can you take pictures of these anodes or your DTO mixtures?

another idea

Getting a good interface at the titanium metal without growth of the oxide layer on the titanium is a bit tricky ,
and I have an idea how this might be done using SnCl2 ...
not as an HCl solution , because HCl attacks the Ti and/or
its oxide .....but rather to use *anhydrous* SnCl2 in an organic solvent with an abrasive , and scrub the titanium
with the mixture .

I wonder if it wouldn't be useful to just work with the completely anhydrous SnCl2 gotten from heating the
the SnCl2 first to drive off all the H2O @ 110C overnight ,
and then in a covered beaker continuing the heating to fusion ~250C . When the melt has cooled to ~200C and solidified , cover it with anhydrous glycerin , and on further cooling add some anhydrous isopropanol . Then break up
and dissolve as much as possible the SnCl2 in the combined solvent . Decant the SnCl2 solution and thicken it to a paste with diatomaceous earth or corrundum or pumice , and use it as an abrasive scrub on freshly etched , possibly hydrided titanium with a wire brush or a scotch brite pad , wearing gloves , and covering the titanium with the mixture in a shallow tray .

I believe this would get the surface plating of Sn at the interface which you have described , without an undesired growth of the oxide layer on the titanium . The vapor of the isopropanol would provide a shielding atmosphere from the oxygen and moisture of the air ....allowing the reactivity of the SnCl2 to prevail as the primary effect on the titanium .

I think the presence of HCl as solvent for the SnCl2 is going
to interfere with what you are trying to accomplish and this is possibly the way around that problem .

After the titanium is treated as above decribed , rinsed with isopropanol and dried , the next step IMO would be to apply the dip coated alkaline sol of combined stannic and antimonic acids , as their ammonium stannate and ammonium antimonate precursors , that I have mentioned before in regards to US6777477 . Then the substrate is baked .

Anyway .....that's my theory and proposed experiment .
Call it the star trek approach ....to go where none has gone before

[Edited on 27-7-2007 by Rosco Bodine]

12N HCl isn't really that corrosive to titanium. Dann did an experiment for me with 25% SnCl2 in 10-12N HCl with a piece of Ti half submerged overnight. The solution turned blue indicating SOME attack on the Ti, but there was no apparent surface corrosion, only a slight change in color, which I suspect is due to a thin flash coat of tin.

Rosco, How did you get stuck on the idea that acidic chloride solutions are BAD in this application? Your insistance on using alkaline coatings seems completely counterintuitive when you look at the chemistry of titanium. Dunk a piece of Ti in HCl and see for yourself how slowly it reacts.

'Course, classical physics says bee's can't fly, but they do anyway.

[Edited on 7-27-2007 by Eclectic]

You can't "see" what is going on in these nano scale layer chemistry reactions ....only detect it with instruments and then make an educated guess . Maybe I have the dots connected wrong from what I have read and how I interpreted it ... but then what are experiments for ?

In other words ..at least we agree on something

The capacitor patent US3454473 is attached

BTW .....I know what you are meaning to happen with the Sn deposition in the etching scheme ...I just don't think it will happen in the presence of the HCl , as the Ti will preferentially react with the HCl and the H2O also present , instead of reacting only with the SnCl2 .
What I was suggesting was a way of getting past that likely problem ......by having no HCl and no H2O present along with the SnCl2 .

You see then , there is only one reaction route and no competing reaction .

What I am describing does not seem to me at all to be counterintuitive . I am proposing something which steers the natural inclination of the materials ( as I understand it anyway ) to produce the layer structure and chemistry that is desired , instead of trying to force formation of a layer structure and chemistry that goes against the way I suppose the materials will react . One theory on which I am operating is that titanium doesn't just go directly to an oxide but probably first forms a transient hydroxide which then dehydrates .....and this mechanism will predominate in anything other than anhydrous reaction condition .

[Edited on 27-7-2007 by Rosco Bodine]

Attachment: US3454473 Titanium film capacitors.pdf (178kB)
This file has been downloaded 673 times

Some pictures for some light entertainment

Two more attempts

Hello,

I returned to solution No. 5 and attempted to evaporate some of the liquid off by heating.

Reminder if needed__________________________
[Solution No. 5]
0.2 grams Ammonium Moly.
1.5 grams SnCl2:2H20 +H202 (min. amount added, had Ti indicator added)
+ HCl. Total volume of Paint made was 7.6cc
Orange coloured paint. When baked did not turn black.
______________________________________________
(The above solution No. 5 was posted before up the thread BTW.)

The solution changed colour from Orange (Ti Oxide indicator) to light yellow.
Oxide started to PPT. I stopped heating. A very small amount (~0.4 cc from 7.3cc)
of solvent was evaporated.
Painted and baked with the solution.
As soon as I pointed the heat gun at the painted Ti, the coating turned black.
After baking, the coating was less black but blacker that the first time I had
used this paint (before I had attempted to evaporate some solvent away).
I coated again and the same thing happened. As soon as I pointed the Heat Gun
at the painted Ti the coating went black. It is a bluish black. It may be the Ti
indicator in the paint turning blue again??

When baked the the coating was less black than when it went into oven. It looked better than first time I use the paint (up the thread) but does not look good enough for it's intended purpose.
Did not 'test' in Chlorate cell, and probable will not.

----------------------------

New paint!!!!!!!!!

Solution No. 6

1.5 grams SnCl2:2H2O dissolved in 2cc Iso Proply Alcohol
2cc HCl (12%)added.
0.2 grams Ammonium Molybdate added to solution and the lot mixed.
Solution turned deep green/yellow with some (very little) solid at bottom.

Painted and baked.
6 coats total, 2 coats per bake, 3 bakes total.
There was no visable crystals on surface of Ti when drying with Head Gun.
The paint covered and wetted the surface well.
The baked paint was a black colour and looked good.
Electic please skip one line
Steel wool could remove coating.
Piece of plastic does not remove coating.
Have yet to 'test' in a Chlorate cell.
This looks the best coat yet.
US 3940323 uses Mo though it is an Ru based anode.
_____--------------------------------------____________


'Water based' paints seem not too good at covering surface of Ti. They do
not wet the surface and are inclined to form puddles when drying. The dissolved
solids are inclined to migrate to theses puddles and you get too much solid
when the puddles eventually dry. Hard to get even coating.
The HCl in last in puddles too where it may be etching holes in the Ti ( perhaps this does not matter) as I have seen lots of pits where the puddles have been.
If you use small amonts of paint to stop puddles from happening it is then hard to get the smaller amount of used paint to wet the surface successfully.

Dann2

[Edited on 29-7-2007 by dann2]

"shake and bake" ......LOL



Oxidative soak should be looking pretty good about now

[Edited on 29-7-2007 by Rosco Bodine]

Dann, this is about the 3rd time you've asked these questions going down this path...

Are we being Punked? A good game of rile up the old codgers, eh?

Hard headed tunnel vision younguns are a real pain 'eh

I used to be a regalar Einstein too 'fore I grew out of it

Rosco, I read through the Ti capacitor patent, and found some good info in there about alcohols facilitating the wetting of titanium surfaces. The idea of strongly acidic solutions chewing through the TiO2 seems to be correct too. I think I'll be happily studying the interaction of titanium surfaces and various tin chlorides for a while, not that there might not be a better way to make an anode, but because I've gotten a LOT of the stuff, really cheap, made from a $12 1lb roll of 95/5 solder, and a $10 roll of 97% Sn leadfree solder, balance Cu, which does not seem to dissolve in plain 31% muriatic acid and settles out as a gray colored powder.

I'm more into the chemistry than the final product.

Quote:

Originally posted by Eclectic Dann, this is about the 3rd time you've asked these questions going down this path... Are we being Punked? A good game of rile up the old codgers, eh?

?? Greetings old codgers, (thanks for the compliment )

Apologys about the post, I was rather tired and not thinking too straight. Is it only the 3rd time....

The latest coating (solution/paint No. 6) on Titanium passivated soon after placing coated Ti into Chlorate.


Same goes for Solution/paint No. 5 that was heated in an attempt to evaporate off some solvent.

Dann2

I can get a heater, the heater is not a problem, i can buy a wire, use some primitive type of a stove or anything like those, oh yeah i can use a thing i once used... placing a candle under the tank (the candle does keep it in a good temp at night but at day it gets too hot.
The main tank is just a chemical glass (600ml) i think it is a good tank, no need for anything else.
The problem with all those heaters is that i cant sit by the electrode for 2 days and watch it getting plated, and it does get really hot here at daytime.

You mean to tell me that a DTO precursor which is *alkaline* in nature can actually be used instead of a chlorides precursor , where the chloride is there to flux and etch the
titanium ???? Well imagine that ...must be a misprint or something , huh ???: Actually you will likely find the alkoxide based coatings in the earlier patents , where it was probably used first as a butoxide , later as an ethylene glycolate , or a glycerylate . The theory was probably that the molten organic material afforded some blanketing of the titanium at up to ~200C , whereupon the precipitation of SnO2 would begin , and the formation of a solid solution of TiO2 in the SnO2 would commence ....limiting the growth thickness of the TiO2 layer and modifying its chemistry . What a novel idea ! There might even be other better ways of going about that

Your test may not have validity since the ATO is not really a working anode coating , but an intermediate layer . Still it would seem that days would be more expected than minutes for the coating to fail . I'd try baking on some
cobalt spinel over the outside . Everything you have described sounds like porosity is what you are getting rather than a sealed vitrified continuous coating of ATO . I really think that is what you will continue to get with any chlorides based precursor system applied alone in a coat and bake sequence like you are doing ...believing you are following a "recipe" which is likely a greatly abbreviated description from what was actually done . I think you are pursuing an exercise in futility where hope springs eternal for solving a puzzle for which you do not have the missing pieces , particulary in regards to any one patent . There is no
single "magic anode patent" , but you may learn the elements required from several different patents , and then
put them together to accomplish what you want to do .

I have personally done a lot of experiments which have been inspired by patented processes .....and usually find ways of improving , refining process examples where they don't tell you the whole story ... as they may leave that for them to know and for you to figure out

Personally I think the chlorides based precursor strategy
is useful in a limited context , not fully described and not as simple as following any single patent example as a good stand alone recipe . What I am getting at is step one may come from one patent , step two from another , step three from yet another ....and so on . That's the *only* way you will put the pieces of the puzzle together .

[Edited on 31-7-2007 by Rosco Bodine]

Why mixed valence oxide precursors may be useful

more specifics concerning oxidation of titanium

To provide a more detailed look at the pH and electrical parameters which define the reactivity of titanium , these Pourbaix Diagrams are helpful . This data is useful in predicting what conditions may be helpful not only in plating schemes for titanium , but also in preparation of and coating
and doping schemes for titanium .

The first diagram is generalized and does not account for higher concentrations of dissolved hydrogen , for which titanium exhibits a very strong adsorption . The second diagram accounts for and shows the effects of the hydrogen .
These diagrams are important so I have saved them locally on the forum server .
Pourbaix diagrams for titanium below were found here
http://www.engr.sjsu.edu/WofMatE/projects/srproject/srproj5....






There are cathodic etching / hydriding schemes which are applicable to plating and also preparation for other coatings for titanium and other metals . It is possible to do this in a plating bath by first applying a low cathodic voltage to etch and hydride the metal , and then increasing the voltage to quickly deposit the metal plating so that a good metal to metal interface is produced .

Patents of possible interest concerning this technique are
US5368719 , US5456819 , US2801213 , US4153742 .

I posted this in response to electroplating of iron on titanium
in another thread , but this is also highly relevant here .

[Edited on 9-8-2007 by Rosco Bodine]

Oxalic acid related

There is a patent US3650861 which directly relates to the usefulness of oxalic acid for etching titanium in a controlled way which improves the adhesion of coatings or platings as compared with other methods .

Also it reportedly is possible to use the mixed oxalates of tin and antimony as non-volatile precursors for baked ATO coatings of high quality on a titanium substrate , by a simple
dip , dry , and bake method . See US5431798 attached .
Eclectic has mentioned the possible usefulness of an initial
plating of metallic tin directly on the etched metallic titanium substrate , and this is described in the attached patent .
However ...there may be easier or better ways of obtaining
such an initial plating , as the oxalate of tin will itself plate
out tin at an appropriate pH , if the substrate is made cathodic . There are patents which relate specifically to plating of tin from tin oxalate electrolytes .....and I will have to dig them up to see if there is an example for the conditions for titanium . It may be possible to perform the titanium etching , tin strike plating , and dip coating for baking ATO , all in one pot using an oxalate / oxalic acid system . Anyway , for an example of the plating of tin
from an oxalate bath .....there is a brief description of this
tin plating in a rectifier patent US2368749 , see last page .

Also a variant of these mixed oxalates reportedly produces transparent optical quality coatings . No examples are given for titanium substrates in these further patents , but the chemistry is described in some detail and the conductivity
of various levels of antimony doping in the finished oxides is charted .....the ~5% figure for antimony oxide agrees nicely with most other sources which report an antimony percentage range from a minimum of 2% to a maximum of 8% , IIRC . See US4873352 and US4924017 .

Edit :
I just found a later version of the same patent attached below , apparently a parallel application , same inventors , same company , same subject material ... US5683567 .


[Edited on 17-8-2007 by Rosco Bodine]

Attachment: US5431798 Oxalate Precursors for ATO coated Ti substrate anodes.pdf (130kB)
This file has been downloaded 840 times

Tin Oxalate, where/how to obtain?????

Yeah you know me ...I occasionally look at a patent or two
trying to find anything interesting

Sn(II) oxalate is poorly soluble, Sn(IV) soluble. H2S bubbled through a solution of Sn(IV) and some Sn(IV) oxalate precipitates antimony sulfide, but not tin.

(I'm still experimenting with 95/5 solder as a source of tin)

[Edited on 8-24-2007 by Eclectic]