| Pages:
1
2
3
4
5
..
14 |
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
| Quote: | Originally posted by jpsmith123
Xenoid the way you describe your baked on coating...well it sounds exactly like my best electrodeposited coatings...and I have to say I don't like it
 .
I think Rosco's right in his implication that the trick (if there is one) is in the interface layer.
|
jpsmith123 - Yes, I understand your scepticism, my description does not sound all that promising. But I have examined this a bit further. After
removing the upper "smudgey" layer and being left with the dark "stained" layer (which BTW cannot be removed by any force known to man or beast). I
put the anode back in the cell, the stained layer has been running at ~150mA/cm^2 for several hours.
This "stain" layer is very thin (comparable to oxide layer on Ti, I would imagine).
1) This stain layer is the "interface" layer, with a softer cobalt oxide coating on top!
or
2) This stain layer is the true cobalt oxide coating we are looking for, but is thin because I only applied one coating/baking cycle, and has a thick
overlayer of softer oxides because the coat I did apply was too concentrated. I think this is the more likely case.
Today I will try 3 coats of a more dilute Co nitrate solution and hopefully get a thicker stain layer!
Even if (1) was the case, I think it would still make a usable anode, although soft and smudgey, the coating doesn't exactly "just fall off" and it
may get harder with extra coats.
Xenoid
|
|
|
jpsmith123
National Hazard
Posts: 764
Registered: 24-6-2005
Member Is Offline
Mood: No Mood
|
|
Some Papers I'd Like To Look At
I wonder if anyone has access to the following papers? These sound like they may have some useful information.
###################################
A new cobalt oxide electrodeposit bath for solar absorbers
Solar Energy Materials and Solar Cells, Volume 51, Issue 1, 1 February 1998, Pages 69-82
Enrique Barrera, Ignacio González and Tomás Viveros
A study was carried out in a Hull cell in order to optimize the deposition conditions of cobalt xide (black cobalt) in an electrolytic bath, which
uses cobalt nitrate for direct
obtention of black cobalt. Thermal stability of the material was surveyed on several samples of black cobalt prepared on stainless-steel with a
thickness of approximately of 2.5 μm. It
was found that the optical properties change, in respect to the initial values, with time of treatment until an equlibrium is reached. This
equilibrium depends on the substrate and the
temperature of the treatment used.
##############################################################################
Black cobalt solar absorber coatings
Solar Energy Materials, Volume 22, Issue 4, August 1991, Pages 293-302
S. John, N. Nagarani and S. Rajendran
A new electrolyte has been proposed for the deposition of black cobalt selective absorber coatings. These coatings are used in solar collectors for
photothermal conversion of solar energy. We have studied the influence of electrolyte composition and operating parameters on the properties of the
black cobalt coatings including optical (α, ε and electcical properties.
Thermal stability and corrosion resistance tests showed good durability of black cobalt selective coatings for high temperature applications.
##################################################################################
Preparation of selective surfaces of black cobalt by the sol-gel process
Renewable Energy, Volume 9, Issues 1-4, September-December 1996, Pages 733-736
E. C. Barrera, T. G. Viveros and U. Morales
Black cobalt, Co3 O4, thin solid coatings on stainless steel and glass substrates have been prepared by the dip coating technique via the sol-gel
route using a CoCl2 precursor. The
coatings produced on substrates exhibit a blue to black colours as a function of the film thickness. Sols have been made from a cobalt acetate
precursor 0.1 M, and for such conditions, the dip coating process gives 0.08–0.25 μm thick uniform films per dipping, depending on the
viscocity of the sol.
###################################################################################
Cobalt oxide thin films prepared by chemical vapor deposition from cobalt (II) acetate
Solar Energy Materials, Volume 23, Issue 1, November 1991, Pages 25-29
Toshiro Maruyama and Tsuyoshi Nakai
Cobalt oxide thin films were prepared by a low-temperature atmospheric-pressure chemical vapor deposition method. The raw material was cobalt (II)
acetate which is non-toxic and easy to handle. Polycrystalline films were obtained at a reaction temperature above 300°C. From near-normal reflection
measurements it follows that the films have solar absorptance α = 0.73 and thermal emittance ε = 0.089.
##################################
Xeniod that so-called "stain layer" you refer to is exactly what's underneath my electrodeposited coatings as well.
As I mentioned, my coatings didn't actually passivate, but rather, I removed them from the brine and wiped them and the coating came off like slime,
all except for that blue, stained appearance, that is. At that point I sanded them and recycled them.
[Edited on by jpsmith123]
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
| Quote: | Originally posted by Xenoid
After removing the upper "smudgey" layer and being left with the dark "stained" layer (which BTW cannot be removed by any force known to man or
beast). I put the anode back in the cell, the stained layer has been running at ~150mA/cm^2 for several hours.
This "stain" layer is very thin (comparable to oxide layer on Ti, I would imagine).
1) This stain layer is the "interface" layer, with a softer cobalt oxide coating on top!
or
2) This stain layer is the true cobalt oxide coating we are looking for, but is thin because I only applied one coating/baking cycle, and has a thick
overlayer of softer oxides because the coat I did apply was too concentrated. I think this is the more likely case.
Today I will try 3 coats of a more dilute Co nitrate solution and hopefully get a thicker stain layer! |
Consider this , that the "stained" layer is indeed the conductive interface , and it isn't going to grow in thickness no matter what you do . It is a
substituted bimetal spinel with titanium , replacing the usual TiO2 which would otherwise be there . The softer outer layer is purely amorphous
unsubstituted monometal cobalt spinel which formed by decompsition of the excess precursor nitrate which didn't enter into reaction with titanium to
form the hard interface material . It may be better at this point to try to deposit a crystalline form of the monometal cobalt spinel as
a harder deposit , or perhaps to work with the cobalt and zinc bimetal spinel which should be a tougher coating . The second coating having zinc
would then actually tend to react
with the first ( outside layer of soft Co3O4 ) rather than simply being a second coat of the same thing applied on top . I think it might even be
good
to use slightly different bimetal compositions for each subsequent layer , encouraging an "equalization" of sorts
to force reaction in the boundary regions between layers ,
as this might improve the bonding having each layer react with the one before and the next . | Quote: |
Even if (1) was the case, I think it would still make a usable anode, although soft and smudgey, the coating doesn't exactly "just fall off" and it
may get harder with extra coats.
Xenoid |
You can even preform a specifically crystalline and hard form
of the cobalt spinel , as a separately fired material in a crucible , and mix this "grog" as a thickener with your
precursor , so that when it bakes it will cement the crystals
together .
| Quote: | Tricobalt tetroxide, C0304, is produced when the other oxides, or the nitrate, are heated in air.
By heating a mixture of cobalt oxalate and sal-ammoniac in air, it is obtained in the form of minute hard octahedra, which are not magnetic, and are
only soluble in concentrated sulphuric acid. |
excerpt from cobalt article
http://www.1911encyclopedia.org/Cobalt
@jpsmith123 , the following is the one to get 
| Quote: | Preparation of selective surfaces of black cobalt by the sol-gel process
Renewable Energy, Volume 9, Issues 1-4, September-December 1996, Pages 733-736
E. C. Barrera, T. G. Viveros and U. Morales
Black cobalt, Co3 O4, thin solid coatings on stainless steel and glass substrates have been prepared by the dip coating technique via the sol-gel
route using a CoCl2 precursor. The
coatings produced on substrates exhibit a blue to black colours as a function of the film thickness. Sols have been made from a cobalt acetate
precursor 0.1 M, and for such conditions, the dip coating process gives 0.08–0.25 μm thick uniform films per dipping, depending on the
viscocity of the sol.
|
[Edited on 6-12-2007 by Rosco Bodine]
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
The Real McCoy???
Firstly, I have checked the calibration of my thermocouple/multimeter using ice/water, boiling water and molten lead - amazingly it was within a
couple of degrees for all three.
1) Ti rod was spun in drill press and "sanded" with 100 grit garnet paper for 1 min.
2) Ti rod was immersed in hot concentrated (290g/L) HCl in a test tube sitting in a beaker on a hotplate for 30 mins. Vigourous bubbling ensued and
the HCl turned mauve. Actually, I think this is overkill, probably 5 or 10 mins would be fine!
3) Another test tube was filled to an appropriate level with a solution comprising approximately 20g cobalt nitrate hexahydrate and 20 mls of water.
4) The rod was dipped in the solution for 15 seconds, shaken several times and placed in the previously described heat-gun set-up for 10 mins at a
temperature of 370 oC. +/- ~ 10 oC. The rod was then allowed to cool to room temperature (about 8 mins).
5) This procedure was repeated 4 (four) times, with the 4th run lasting for 60 mins. (1 hour).
The main differences in this procedure as compared to my first attempt are;
1) More dilute and purer coating solution.
2) More coats, 4 vs. 1
3) Slightly higher temperature 370 vs. 350 oC.
4) Last coat was baked for extended time, (this is in the patent, I had forgotten about it)
This has produced the anode shown below;
In retrospect I think that an even more dilute soln. may be called for, it is amazing how black the initial coat is, given how little soln. appears to
be clinging to the surface. This may produce an even more homogenous coat.
@jpsmith123 - Note this coating is tough, it cannot be wiped off, there is just a slight grey smear on ones finger after it is repeatedly rubbed up
and down. The first anode used too strong a soln. and produced a thick, "fluffy" coating. This looks like the real thing.
I've put it in a new cell and ramped the current up to 50mA/cm^2 (1.65 Amps) the voltage was about 3.2 (very low). I've turned it down to about
5mA/cm^2 to "run it in" for an hour.
I will report back with initial perfomance figures in a short while!
|
|
|
dann2
International Hazard
Posts: 1523
Registered: 31-1-2007
Member Is Offline
Mood: No Mood
|
|
Hello Folks,
Anode looks good.!
I purchased some Cobalt Carbonate, Zr Oxide and Antimony Oxide in ceramcis store so hopefully will get some thing done in near future. I have Zinc
powder + Nitric acid.
Got a bit bogged down with other work last few days.
The DTO coat on Ti still going strong. (Approx. 120 hours) I put up the current density to hurry up it's destruction. The damm thing will still be
going at Christmas at this rate.
It is making Perchlorate.
Following thread with interest.
Has Spinel Cobalt Oxide 'Holy Grail' status? Now THERE is a question.
@JP
You could try asking in the reference section for the paters. I Solo cannot do it, nobody can do it.
|
|
|
jpsmith123
National Hazard
Posts: 764
Registered: 24-6-2005
Member Is Offline
Mood: No Mood
|
|
Dann2 maybe with your DTO coatings you've already got the answer.
Could you explain the details of how you prepared it?
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
| Quote: | Originally posted by Xenoid
Firstly, I have checked the calibration of my thermocouple/multimeter using ice/water, boiling water and molten lead - amazingly it was within a
couple of degrees for all three. |
Ha! Xenoid busted Rosco  I got one of those Fluke digital multimeters too that
has the thermocouple input plugs ....
and now I know a good use for it . Heat gun here I come Need to
make a little trip to the building supply tool department . Got money
burning a hole in my pocket right now for parts and such .
| Quote: |
1) Ti rod was spun in drill press and "sanded" with 100 grit garnet paper for 1 min. |
Got drill press Ever used that cloth backed emery ribbon
they sell by the foot ? It's just like the sheet stuff but is about an inch and a half wide ribbon . Plumbers use it on copper pipe to scuff it for
soldering . Makes quick work
for polishing a rod in a drill press when you see saw it back and forth . The filings fall right out of it as it goes so it doesnt load up the grit
and keeps cutting , doesn't get hot in
one spot either .
| Quote: |
2) Ti rod was immersed in hot concentrated (290g/L) HCl in a test tube sitting in a beaker on a hotplate for 30 mins. Vigourous bubbling ensued and
the HCl turned mauve. Actually, I think this is overkill, probably 5 or 10 mins would be fine! |
Yeah with a freshly emery polished rod , you maybe just need
to rinse in acetone , if it is going straight into the nitrate .
BTW ,
I am pretty sure you can dissolve the nitrate hexahydrate
in denatured alcohol and gradually azeotrope the water
off from the hexahydrate , might have to simmer it overnight .
This might be handy if you are experimenting with some sort
of anhydrous coatings or solvents , and need to get the water out of the hexahydrate .
| Quote: |
3) Another test tube was filled to an appropriate level with a solution comprising approximately 20g cobalt nitrate hexahydrate and 20 mls of water.
4) The rod was dipped in the solution for 15 seconds, shaken several times and placed in the previously described heat-gun set-up for 10 mins at a
temperature of 370 oC. +/- ~ 10 oC. The rod was then allowed to cool to room temperature (about 8 mins).
5) This procedure was repeated 4 (four) times, with the 4th run lasting for 60 mins. (1 hour).
The main differences in this procedure as compared to my first attempt are;
1) More dilute and purer coating solution.
2) More coats, 4 vs. 1
3) Slightly higher temperature 370 vs. 350 oC.
4) Last coat was baked for extended time, (this is in the patent, I had forgotten about it)
This has produced the anode shown below; |
How about three or four Halleluiahs ! It looks like the real deal . I bet this thing's right .
| Quote: |
In retrospect I think that an even more dilute soln. may be called for, it is amazing how black the initial coat is, given how little soln. appears to
be clinging to the surface. This may produce an even more homogenous coat. |
You could be right , most of these sorts of coatings will have an optimum concentration for a particular solvent , optimum viscosity and pH also , or
certain other additives like wetting agents ( the same spreader sticker as mentioned for electroplating ) small details that can enhance the finish
quality . But those tweaks can be worked out later if
the main process goes okay . No worries there .
| Quote: |
@jpsmith123 - Note this coating is tough, it cannot be wiped off, there is just a slight grey smear on ones finger after it is repeatedly rubbed up
and down. The first anode used too strong a soln. and produced a thick, "fluffy" coating. This looks like the real thing.
I've put it in a new cell and ramped the current up to 50mA/cm^2 (1.65 Amps) the voltage was about 3.2 (very low). I've turned it down to about
5mA/cm^2 to "run it in" for an hour.
I will report back with initial perfomance figures in a short while! |
Yeah I think Xenoid just nailed it . ( Knock on wood )
[Edited on 6-12-2007 by Rosco Bodine]
|
|
|
jpsmith123
National Hazard
Posts: 764
Registered: 24-6-2005
Member Is Offline
Mood: No Mood
|
|
Well I hope Xenoid gets back soon with an update as I'm getting nervous...
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
| Quote: | Originally posted by jpsmith123
Well I hope Xenoid gets back soon with an update as I'm getting nervous... |
Sorry to take a while getting back but I've been coating another anode using different conditions.
The anode has been running for 3 hours now and everything looks fine, the voltage even dropped slightly as the cell warmed up!
I didn't bother with the conditioning, that only lasted for 15 mins. The anode is running at ~50mA/cm^2 its somewhat longer than the previous one, the
active area is about 33 cm^2 and I'm running it at 1.66 Amps. Cell volume is about 400 mls, anode - cathode distance ~4.5 cm.
I'm limiting the current a bit, because it's running in my "electronics lab" which is totally enclosed with no ventilation. There is a little bit of
black scum on the surface of the electrolyte, but I don't think it's anything to worry about!
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
If my guess is right , because of the electrocatalytic effect
of the cobalt , no additives like fluorides or persulfates
will be required for the perchlorate production , and the
cell efficiency will be higher , lower operating voltage
for the cobalt spinel anode than other anode materials . No need either to make the chlorate first , separate and then make perchlorate , it should
go all the way from the plain chloride to the perchlorate , to a high degree of completion .
Might be interesting to put a bit of lithium chloride
into the cell to test earlier speculations about it possibly
being catalytic via continual metathesis for a KCl starting solution .
Of course you would need some cell depth below the
electrodes so the rising layer of KClO4 crystals doesn't short out the cell . Probably a circulating pump having an intake tube near the bottom could
be used to keep the crystals suctioned out and trapped on a filter or in a settling tank in the return stream . You could run a
smallish sized cell like a gallon jar , and keep replenishing the pumped electrolyte water and chloride , while the KClO4 accumulates in a picnic
cooler where you scoop it out occasionally with a snow shovel and deposit it in
a nearby wheelbarrow to drain and dry
[Edited on 6-12-2007 by Rosco Bodine]
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
Steady on, Rosco, lets not get too carried away...
For anyone out there...... is there anyone out there, other than we intrepid four, and the honourable Mr Wang!
Here is my primitive heat gun set up! The rod just sits at an angle, upright at the bottom of the Al tube. I hold the rod in place on the heat gun and
lower the tube over it so only one part of the rod touches at the top and one at the bottom.
Whilst making my latest anode I dropped it and it rolled across the concrete floor, there wasn't a mark on it!
This is not the ideal set up by any means, I'm still looking at toaster ovens. I will report back when I've done a bit of construction/destruction.
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
That's a good setup , but you could drill a 1/16" hole through the rod very close to the top and then put a wire
through the hole and bend it aound and back to itself to make suspension loop , hanging the rod like a wind chime
inside the furnace tube . I have some kaowool that I think I will line the inside of a fireplace duct with to
make a chamber about the size of one of those terra cotta
wine coolers , or maybe just take a 1" Remgrit holesaw and bore a hole in the bottom of one of those wine coolers and use it for a furnace chamber .
The clay will hold heat better than a metal tube . I actually have an old Weston process thermometer that reads up to 1200 F , and will probably use
that for temp monitoring .
What kind and rating of heat gun are you using ?
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
| Quote: | Originally posted by Rosco Bodine
.... but you could drill a 1/16" hole through the rod very close to the top.... |
Oh Yeah! Good luck!
It's a 2000 Watt model.
Something I forgot to mention! I have been putting the dipped, wet anode directly in the gun and turning the heat upto full. I did this because in the
patent they said to put the anode straight into an oven. The two new anodes I have made today are a bit streaky and patchy, I think it would be best
to gently dry them first in warm air whilst rotating, this should produce a more even coat.
I was thinking if these work out, and last for a run or two, the cost is negligible! Once you have purchased your Ti, this coating only costs about 20
cents in chemicals and electricity and the Ti will last a lifetime...
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
Won't drill huh ? How about a carbide or diamond bit ?
The stuff can't be that damn hard . I bet even a cobalt bit
would do it .
|
|
|
dann2
International Hazard
Posts: 1523
Registered: 31-1-2007
Member Is Offline
Mood: No Mood
|
|
Hello,
Can't see the bottom of the Heat gun but have you it a bit off the ground. It will burn out if there is not a good flow of air through it. (Hope I am
not stating the obvious.)
The DTO was done the way of the Diamond Shamrock patents using the same amounts of SnCl4:5H20, Antimony,
HCl, and Methanol.
Will right up exactly what I did but I do not think my exact procedure is important.
It is interesting to note that all patents use SnCl4:5H2O when making DTO as an undercoat for something (let it be LD or CO) but there is a procudure
in pat No. 3627669
C:\Documents and Settings\me\Desktop\Page download\top\Top\chlorate\leaddiox\us3627669.html
for an actual DTO only anode.
This uses SnCl4 (anhydrous) refluxed with Amyl Alcohol.
It must be better than the stuff (not really an anode, but just an undercoat) produced via SnCl4:5H2O but the DTO produced usins hydrated SnCl4 must
be better as an undercoat. Just guessing, reading between the lines.
Perhaps we need a DTO thread
My cell, the one testing the DTO, is now giving a 'yougart' product (lots of K. Perchlorate) when a sample it taken out and some KCl added to it.
Dann2
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
Something I have never seen mentioned as a possible anode substrate or possibly even directly used as an anode is stellite . It's a nickel cobalt
alloy used to make
car engine exhaust valves and seats , and jet turbine combustion chamber parts .
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
| Quote: | Originally posted by dann2
Can't see the bottom of the Heat gun but have you it a bit off the ground. It will burn out if there is not a good flow of air through it. (Hope I am
not stating the obvious.)
|
It's designed to sit on the ground, it has a built in stand, the air inlets are on the side!
Here is the anode I coated this afternoon, I made the cardinal sin and changed 3 variables simultaneously, otherwise same as above:
1) Etching was carried out for only 15 mins.
2) Solution concentration was halved.
3) Doubled the coatings to 8
It doesn't look all that different to the previous anode. I'm going to put it in a perchlorate cell and see how it performs. The coating may be
slightly harder ie. no force in the known universe is capable of removing it -
You know what it reminds me of - that black (antirust) coating on structural steel. I assume it's magnetite (another spinel). Might be worth trying
iron nitrate solution and giving the Ti a magnetite coat!
|
|
|
jpsmith123
National Hazard
Posts: 764
Registered: 24-6-2005
Member Is Offline
Mood: No Mood
|
|
Xenoid do I take you to mean that if you rub the coating with a piece of paper towel, for example, you will see no color on the towel? Is it really
that adherent?
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
| Quote: | Originally posted by jpsmith123
Xenoid do I take you to mean that if you rub the coating with a piece of paper towel, for example, you will see no color on the towel? Is it really
that adherent? |
Pretty much yeh! I think with these type of coatings there will always be a little "dust" on the surface. I have actually wiped this one quite
vigourously with a wet paper towel, virtually nothing came off. I thought I'd give it a good clean, so I wouldn't get any black scum on the surface
like the previous anode.
To free up my lab power supply for testing the perchlorate cell, I have moved the chlorate cell over to a 5 volt (constant voltage) computer supply.
I've put a 0.8 ohm 20 watt resistor in series. It is now running at 3.22 volts and 1.86 Amps. Still looks fine!
The new anode I made this afternoon is now in a small perchlorate cell (250 mls) near saturated NaClO3, no additives. I've got more adventurous with
this and upped the current to ~100mA/cm^2. It is running at 4.7 volts and 2.2 amps. I hope its making perchlorate, its certainly making some ozone!
Well what a day! I'm gobsmacked...
I just hope its all going in the morning!
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
nickel cobalt spinel versus zinc cobalt spinel
Spinel oxide coated titanium anodes-preparation and characterization
S. Kulandaisamy, , J. Prabhakar Rethinaraj, S. C. Chockalingam, K. V. Venkateswaran and S. Visvanathan
Electrohydrometallurgy Division, Central Electrochemical Research Institute, Karaikudi, Tamil Nadu 630-006, India
Received 21 April 1999; revised 13 December 1999. Available online 23 June 2000.
Abstract
Cobalt oxide based spinel anodes containing NiO or ZnO as
the secondary component have been coated over titanium substrate by pyrolysis technique. The conditions of preparation were optimised. Electrochemical
and structural properties were studied using X-ray diffraction (XRD), cyclic voltammetry (CV) and galvanostatic polarisation techniques and the
results are discussed.
Attachment: Spinel oxide coated titanium anodes-preparation and characterization.pdf (133kB)
This file has been downloaded 1328 times
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
Good grief Rosco, do you never sleep..?
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
Cobalt sol spontaneous from acetate solution
Preparation of selective surfaces of black cobalt by the sol-gel process
Renewable Energy, Volume 9, Issues 1-4, September-December 1996, Pages 733-736
E. C. Barrera, T. G. Viveros and U. Morales
Black cobalt, Co3 O4, thin solid coatings on stainless steel and glass substrates have been prepared by the dip coating technique via the sol-gel
route using a CoCl2 precursor. The
coatings produced on substrates exhibit a blue to black colours as a function of the film thickness. Sols have been made from a cobalt acetate
precursor 0.1 M, and for such conditions, the dip coating process gives 0.08–0.25 μm thick uniform films per dipping, depending on the
viscocity of the sol.
Attachment: Preparation of selective surfaces of black cobalt by the sol-gel process.pdf (311kB)
This file has been downloaded 1539 times
|
|
|
Rosco Bodine
Banned
Posts: 6370
Registered: 29-9-2004
Member Is Offline
Mood: analytical
|
|
| Quote: | Originally posted by Xenoid
Good grief Rosco, do you never sleep..? |
Look who's talking
Hard for kids to sleep around Christmas
It looks like the spinel is for damn sure a good interface ,
but how it will endure in the long run as an actual
wearing coating in perchlorate cell service is another matter .
It may be that PbO2 perhaps hardened with Bi will
need to be overplated to make a more permanent anode .
Just can't find any good data on perchlorate cell longevity
for the spinel , but seems like I have seen it once somewhere
that one combination did hold up well in perchlorate service .
Anyway the interface is the hard part , and it looks like that is at least one big headache and really core component that
very likely now has a solution .
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
Humble Pie!
Oh dear!...
The last anode doesn't appear to be holding up too well in a perchlorate cell. There is a lot of black crap floating around, although the anode is
still coated and producing from the whole surface!
Maybe I overdid it at 100mA/cm^2, I think I'll turn it down to 50mA/cm^2.
|
|
|
Xenoid
National Hazard
Posts: 775
Registered: 14-6-2007
Location: Springs Junction, New Zealand
Member Is Offline
Mood: Comfortably Numb
|
|
| Quote: | Originally posted by Rosco Bodine
Spinel oxide coated titanium anodes-preparation and characterization
S. Kulandaisamy, , J. Prabhakar Rethinaraj, S. C. Chockalingam, K. V. Venkateswaran and S. Visvanathan
Electrohydrometallurgy Division, Central Electrochemical Research Institute, Karaikudi, Tamil Nadu 630-006, India
Received 21 April 1999; revised 13 December 1999. Available online 23 June 2000.
Abstract
Cobalt oxide based spinel anodes containing NiO or ZnO as
the secondary component have been coated over titanium substrate by pyrolysis technique. The conditions of preparation were optimised. Electrochemical
and structural properties were studied using X-ray diffraction (XRD), cyclic voltammetry (CV) and galvanostatic polarisation techniques and the
results are discussed. |
Note: On the second page, in the part 2 Experimental section:
........baked in air at 200 oC - 400 oC for 5 MONTHS.....
I surely hope this is a typo, poor proof reading!
I think they mean 5 minutes....
|
|
|
| Pages:
1
2
3
4
5
..
14 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
