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watson.fawkes
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An excerpt from the review in a 1921 journal:
<a href="http://books.google.com/books?id=-nMQAAAAIAAJ&pg=PA421&ci=56,726,856,410&source=bookclip"><img
src="http://books.google.com/books?id=-nMQAAAAIAAJ&pg=PA421&img=1&zoom=3&hl=en&sig=ACfU3U2KFo6kpQUGcZSZiL4jMEFKh1u9EQ&ci=56%2C
726%2C856%2C410&edge=1" border="0" alt="Text not available"/></a><br/><a
href="http://books.google.com/books?id=-nMQAAAAIAAJ&pg=PA421&ci=56,726,856,410&source=bookclip">Journal of the American Ceramic Society
By American Ceramic Society</a>
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Rosco Bodine
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Yeah I saw that reference along the way to requesting the book. Evidently it is the highly activated "nano-tube" or whisker form of the hydrated
alumina which looks like a mold growing at a visible rate from the surface of amalgamated aluminum in air. So this may well be the easy source for
the filamentary form of the precursor which may be useful for our purposes as a dopable catalyst or a reactive catalyst carrier, and thixotropic dip
precursor additive which serves as a bonding agent and reenforcement fiber in baked MMO coatings. Cobalt aluminate may even form by acid digestion of
the raw hydrated whiskers in percobaltous acid, followed by pyrolysis.....resulting in a kind of nano-structured spinel material which sets as a
sintered "fiberglass-like" mat
of a ceramic felt , that is conductive and is an active anode material. Some added Bi doping there might result in the closest thing to an
indestructible anode which we have contemplated.
[Edited on 28-11-2008 by Rosco Bodine]
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dann2
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Hello,
| Quote: | Originally posted by Swede
From a practical viewpoint, a durable LD coating over a substrate that will not passivate is all that is needed to make a good perchlorate anode.
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I'll second that!
Ti substrate (with one interface coat) LD anode will hopefully solve the Garage Perchlorate Makers quest for a durable and reasonably cheap anode
made by a repeatable method.
| Quote: | Originally posted by Swede
I am going to gather chemicals for some of the more "exotic" methods, but only if a reasonably simple means of LD plating simply cannot be achieved
over MMO. |
My own opinion (it's only one opinion, milage will vary and most folks are capable of making up their own minds) of the hugh volumous verbose amounts
of articulate 'scientific reasoning' regarding the more exotic (allegedly definate solutions or routes to solution of the problem) are in the fruit
cake category. Argueing long and hard (it's been quite a while now though) against (AGAINST) Ti as a substrate to possibly good solutions, is a
very tangible demonstration of my opinion. Sometimes I wonder are some folks taking the piss and having a good hearty laugh.
The one and only patent showing LD on MMO (US 4444642) plated the LD at a highish current density at the start (Alpha LD) then decreased the current
density after a bit (Beta starts to deposit). This method might save the bother of starting with a Tartrate bath for the Alpha.
The ability to plate Alpha then Beta from the same bath simply by changing the current density has been disputed in places.
My own opinion it that if you want a definite coat of Alpha then go with a Tartrate bath. Since the amount of Alpha plating is going to be small you
do not need a very big bath.
The crystal structure of Alpha is more close in nature to Tin Oxide, that is why it sticks better. Don't know about Alpha/MMO but since they appear to
use Alpha as a first layer in the patent above than it would appear that it does indeed adhere better to MMO that Beta.
Platinum or Platinized Ti, I don't know.
Magnetite I have been told has a crystal structure miles from Alpha or Beta and therefor is probably not a good substrate.
Graphite cannot be plated with Alpha I believe. You must start with a Beta.
Dann2
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watson.fawkes
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I was impressed with the large surface area indicate by water adsorbtion in that review. It contains a hint of a failure mode that might need to be
dealt with—a pinhole in an outer coating that leads to mechanical failure of the substrate.
Here's another old reference, this one with pictures. Click on the link at the bottom to a bit more than shown here.
<a
href="http://books.google.com/books?id=MF1AAAAAIAAJ&dq=fibrous%20alumina&num=100&client=firefox-a&pg=PA258&ci=154,307,789,951&
source=bookclip"><img
src="http://books.google.com/books?id=MF1AAAAAIAAJ&pg=PA258&img=1&zoom=3&hl=en&sig=ACfU3U1YidoffwZeipzdxhrgRXcMa-fqLA&ci=154%2
C307%2C789%2C951&edge=1" border="0" alt="Text not available"/></a><br/><a
href="http://books.google.com/books?id=MF1AAAAAIAAJ&dq=fibrous%20alumina&num=100&client=firefox-a&pg=PA258&ci=154,307,789,951&
source=bookclip">Colloids in Biology and Medicine By Heinrich Bechhold, Jesse Godfrey Moritz Bullowa</a>
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Rosco Bodine
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Yeah the nanostructured alumina whiskers are sort of an ultimate form of "activated" alumina, having an aerogel like matrix evidently, formed from
filamentary structures.
It is intriguing stuff on several different levels, anode coatings being only one of many potential uses. This material is what they use to filter
virus particles, or even molecules from their suspended state in gas or liquid,
so it truly is a nanoscale material.
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watson.fawkes
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There's a paper titled "Formation of Nanostructural Oxide Fibers" in the volume <i>Nano-Architectured and Nanostructured Materials</i>,
ed. Champion and Fecht. Hydrated cellulose was impregnated with aluminum oxychloride (also with other metals) and then dried and fired. The
scaffolding fiber burnt off. Oxide fibers formed in the same shape as the scaffolding fiber.
This seems worth investigating, as the process seems doable with a temperature-controlled furnace. I don't know about the availability or ease of
synthesis of oxychlorides.
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Rosco Bodine
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US3039849 Amalgam Derived Fibrous Alumina
I don't see that one sorry. It seems like a more complex route than working with the precursor which may come off by the tablespoonful as you watch it
growing like a white snake, from the surface of some scrap very pure aluminum electrical wire, which has been amalgamated.
But I do see the potential usefulness of a nanowhisker alumina used as a sort of structural reenforcement having serious bonding capability as an
ingredient in a dip and bake coating scheme, as a potential solution for any adhesion problems, and also to increase the thickness of build coatings
which are applied as a series. Having the added ability to function as a catalyst carrier is a bonus.
As for the porosity, well that can be plugged up with
sintered DTO, simultaneously in the precursor dip or subsequently as a followup coating by dips in precursor not containing the fibrous alumina
additive. What went before would soak it up, since the electropositivity is shifted to electronegativity after sintering. Kind of beautiful as a
strategy actually....if the physical chemistry goes as planned.
Something I have wondered about as an unexplored idea
is the use of magnetite nano crystals as a bi-electrode ,
embedded in the surface of a lake of DTO as tiny particulate islands. Something like the same way as palladium black or platimum might be used as
distributed micro-particles fused onto the surface of a conductive ceramic , but of course magnetite would be far less expensive. The bi-electrode
effect is sort of an unknown, like the elephant in the room.
It might be one of those undiscovered simple things that
has been overlooked. And just because there may be no ready reference spelling everything out 123 in a patent or a journal, doesn't necessarily mean
it isn't so, or isn't known,
so one should keep a certain reserve concerning possibilities
for further experimental work which could be worthwhile, especially for stuff which has not been examined and already ruled out by authoritative tests
and testers who know what they are doing.
Attached is a patent which I haven't had time to read thoroughly, but on first glance it may be what we are looking for as a fibrous alumina source of
least complexity.
US3039849 Amalgam Derived Fibrous Alumina
Hmmm this patent looks familiar to me and I think I may have looked at this patent before in connection with castable refractory cement applications,
although I don't recall posting it here. But it would make sense as it would serve the same purpose as reenforcement and bonding in thicker layer
refractory compositions.
[Edited on 28-11-2008 by Rosco Bodine]
Attachment: US3039849 Amalgam Derived Fibrous Alumina.pdf (437kB)
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watson.fawkes
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| Quote: | Originally posted by Rosco Bodine
It seems like a more complex route than working with the precursor which may come off by the tablespoonful as you watch it growing like a white snake,
from the surface of some scrap very pure aluminum electrical wire, which has been amalgamated. |
There is one
significant advantage to the cellulose method: no need for mercury. I'll not deny that the method in the patent is useful. If you want bulk fibrous
alumina, it looks just fine. On the other hand, it's not a simpler method. It requires baking the raw fibrous product at 750 - 950° C to
remove (by vaporization) mercury-oxide compounds. And the initial reaction temperature is at 100 - 200° C, where the vapor pressure of mercury
is significant. Both of these processes would require (at least for me) construction of sealed reaction vessels with mercury vapor condensers. It's
not a construction effort I'd consider lightly. I'm not even going to say it's beyond the reach of a hobbyist, because I don't believe that. I do
believe, however, it would have to be a pretty dedicated hobbyist. | Quote: | As for the porosity, well that can be plugged up with
sintered DTO, simultaneously in the precursor dip or subsequently as a followup coating by dips in precursor not containing the fibrous alumina
additive. |
With a hexagonal close-packing structure, α-alumina doesn't have the crystal structure
needed to be an oxygen ion conductor. So it can be used in the metal-contact layer without problem. But tin dioxide (from what I can tell) is an ionic
conductor, or at least enough of one that you'd have to worry about passivation. You'd want an oxide material that was solely an electronic conductor
at this innermost layer | Quote: | Something I have wondered about as an unexplored idea is the use of magnetite nano crystals as a bi-electrode ,
embedded in the surface of a lake of DTO as tiny particulate islands. |
The problem with magnetite is that it
oxidizes to hematite fairly readily, and hematite isn't an ionic conductor. Magnetite was tried in SOFC's and failed by reason of short lifetimes. You
might hark back to ceria as your island material, since it's stable and both an electronic and ionic conductor, so it should have all the catalytic
effect you're after.
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Rosco Bodine
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Amalgamated Aluminum at ordinary conditions
Cobalt doping of the gamma alumina resulting after pyrolysis will result in cobalt aluminate spinel which is conductive, and anyway this fibrous
alumina material is not expected to be more than 5%-10% or so by weight of the coating overall oxides , so it's conductivity isn't so much any issue
anyway, even if it should be inert, which isn't very likely since the matrix of the fibrous alumina will be filled with conductive materials along
with some expected compounding being involved for the fibrous alumina itself.
As for the patent process , it is only illustrative of the general idea implemented on an industrial scale. For a lab scale I had more in mind simply
laying pieces of amalgamated 3mm solid Al wire on a fiberglass screen, and shaking the the fibrous alumina effluent through the screen occasionally
for its collection in a tray below, using something like one of those plastic boxes used for storage containers for sweaters for example.
thanks to solo for the attached article
Attachment: Synthesis of alumina nanofibers by a mercury-mediated method.pdf (1.3MB)
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watson.fawkes
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What you need at an innermost layer is electronic conductivity with the absence of ionic (oxygen) conductivity. Since that layer, in this discussion,
contains at least two substances, we have to ensure that at least one conducts electronically and has a continuous path and that none with a
continuous path conduct ionically. That was why I pointed out that the alumina isn't conductive. Also, the suggestion of a cobalt+aluminum spinel
seems workable.
Of the two steps in the patent process, the first is surely the lesser problematic. You could get some fibrous alumina, admittedly contaminated with a
bit of mercury, pretty easily and exhaust through a fume hood. The bake-out, though, that remains a problem.
It's an interesting article, although their earlier reference is from 1991, not 1904 when the original fibrous alumina work was done by Wislicenus.
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Rosco Bodine
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commercial availability
The fibrous alumina is commercially available since it is used as thickener for lubricants, cosmetics, ect. as well as being used in papermaking,
water purification, ceramic materials and assorted other uses.
http://www.sasoltechdata.com/alumina_group.asp
There is no technical difficulty in making the material as a sol by various schemes which involve hydrothermal decomposition under autoclave
conditions of solutions of various unstable hydrolyzable aluminum salts. Simply heating a solution of aluminum nitrate at 50 psi autogenous pressure
for several hours results in a sol of fibrous alumina. The patent US2915475 describes many different precursor solutions and hydrolysis conditions.
Anyway, *all* of this "fibrous alumina" discussion seems to point back favorably to the Pytlewski polymers based upon tin, which are formed more
easily under less extreme conditons of hydrolysis, and should result in a conductive material after pyrolysis. There has not been any followup on
this which can be cited for reference, but the described properties of the sols gotten by Pytlewski are similar in many ways to the properties of sols
of fibrous alumina, and it seems highly probable to be a similar nanowhisker material that is produced there by Pytlewski. IIRC there are several of
the hydrous metal oxides which will polymerize under various extremes of conditions, and hydrogen peroxide has been used as a catalyst to facilitate
some of these polymerizations. In the making of some of the stannic chloride precursor solutions which have been experiments by forum members, where
H2O2 has been used to oxidize Sn II+ to Sn IV+ , there have been reported observations of "syrupy" liquid products and these are very probably the
result of stannic oxide polymers having some fibrous structure of the colloidal SnO2 which is present to enough extent to have a thixotropic effect
for the sol. The thickening effect would be pronounced even for the presence of the fibrous colloid at extremely small percentages of the total
weight of the liquid, only hundredths to tenths of a percent would be needed to completely gel the liquid....so it doesn't take much fibrous colloid
to produce the desired thickening. All of these aqueous precursor mixtures which are prone to hydrolysis are also likely under certain "notch
conditions" of pH and temperature to undergo polymerization to some extent resulting in the formation of sols and the particles would be expected to
be fibrous ....for *all* of them 
Perhaps I am going a long way around the block here, using the better documented description of "fibrous alumina" and its implications for MMO anode
coatings, to try to make folks understand why I was pointing out the significance of Professor van Leent's anomalously "soluble" stannic oxide gotten
from dissolution of tin in nitric acid when in the presence of iron, chromium AND *aluminum* ( hehehe there's that metal !!! ) and say Hey Folks !! ,
do you maybe see the analogy, the nexus here ??? Do you see why old Rosco is turning somersaults about this "sol" stuff which van Leent was writing
about a hundred years ago, and later Pytlewski was decribing as "polymers" ??????? These things are all related to our "fibrous alumina" ....they are
all cousins in the same family of materials in terms of their physical chemistry. And van Leent and Pytlewski are absolutely both relevant to these
MMO precursor schemes, if not as the precursor itself , then at the very least as "modifier oxides"
and thickening, viscosity modification of the precursor liquids used in the coating schemes. And van Leent's aluminum stannate or stannous aluminate
sol should be especially intriguing, if you can connect the dots here. It is very likely fibrous and very likely conductive and requires no autoclave
conditions to produce.
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Swede
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Don't get me wrong, I would truly love to experiment a bit with boehmite aluminum. The problem for the garage chemist is the sourcing. Yes, it can
certainly be made, but I would much - MUCH - rather find some outfit that has a "2.5 kg Boehmite ----- Add To Cart " setup. I'd rather spend the
time on the doping and testing of the resultant anode than in the preparation of the boehmite itself. I requested a sample from one of the companies
(BASF) but they haven't even emailed back. I doubt I'll ever hear from them.
The entire micro-fiber aspect of it reminds me of anodizing... it is the hollow tubules of aluminum oxide on a freshly anodized Al surface that take
the dyes so well.
I need to educate myself a bit more on this phenomenon.
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Rosco Bodine
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Here is another possible supplier
http://www.wesbond.com/colloidal_alumina.htm
and another
http://www.nyacol.com/information.htm
I have wondered if fibrous alumina or colloidal silica (cab-o-sil) is the thickener used in 20% HCl toilet bowl cleaner. It is probably one or the
other. Little else could withstand the acidity.
Yeah the materials chemistry, the physical chemistry on the "closeup view" of this stuff is amazing, it is the ultimate kind of nano scale
scaffolding, open framework
sponge-like material. And it is within this structure where
the chemical reactions occur that transforms and gives birth to all the little ions of chlorate or perchlorate that
we are wanting to be happening. On the surface visibly it may look like a sheet of glasslike ceramic, while it actually will be a labrynth cellular
matrix where the current flows, with a whole lot of ion traffic descending as one thing and jumping back out as something else But don't get tunnel vision for boehmite, it is simply an example that is better
described, and the other materials are similar. Even MnO2 can do these structural tricks, and SnO2 certainly can also. Understanding what is actually
going on with these materials is not any waste of time when an effort is being made to improve the integrity of baked MMO coatings. Commercial
manufacturers who make the MMO anodes which are near indestructable have covered this same ground. These mixed ceramic coating materials are a
specialized scientific art to themselves.
The anodization / cathodization strategy for anchoring an interface coating into a columnar welled mesa of TiO2 is something which was brought up in
discussion in one of these threads before, and yes it has an analogous use in color anodizing of aluminum, whereas our purpose would be focused on
conductivity and coating adherence rather than colorfastness, but indeed the technology there may be adaptable. This fibrous alumina would add a
subsequent layer of horizontally oriented fiber structure
to the vertically oriented structures gotten by anodization.
[Edited on 30-11-2008 by Rosco Bodine]
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Swede
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Well, I went a bit wild and bought enough stuff to create a really deluxe plating rig... plenty of lead nitrate, bismuth salts, litharge, a
polypropylene tank of sufficient capacity, and an immersion heater + temp controller. A bit of NaF and nickel nitrate too to play with, if needed.
The tank, heater, and controller will also see use with anodizing and other processes requiring a good, stable heat source.
Maybe my "sample" of boehmite will arrive today! More likely, it got kicked out of the system because it wasn't an order from MIT, 3M, the U.S.
military, or some other gigantic corporate conglomerate. On the other hand, I've gotten product samples before that have exceeded my wildest
expectations, like pressure sensing film and other useful goodies. I'm hoping for at least 25 pounds. 
RB, I know what you're saying about "tunnel vision." I've been looking at tin salts as well. Both tin (II) and tin (IV) chlorides are available
commercially, but they are pricey, no doubt. Manganese, not so bad. I just need to take this stuff in order, and priority 1 for me right now is
investigation of PbO2.
Esteemed assembly - question on immersion heaters. For a two gallon bath, the wattage requirement comes in at several hundred watts minimum, unless
you insulate very well and don't mind waiting 4 hours to heat the bath to 60 or 70 degrees. The best heaters have a PTFE/PFA coating on them, but
expen$ive doesn't begin to describe them. 316SS would normally be suitable, but stray Fe ions in the bath = bad juju. I found that certain heaters
sheathed in an inconel alloy will shrug off nitric with ease, especially at these concentrations, and I am going to try and adapt an inconel-sheathed
cartridge heater for immersion duties.
The question is this... how would any of you heat a plastic 2 gallon plating bath to 80 degrees C, and hold it there for hours if needed? No iron
allowed. It sounds simple, but it's not! I like the idea of cobbling relatively cheap surplus heater elements into immersible constructs, and save a
lot of $$. Thoughts?
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tentacles
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You could sheathe a heating element (like a hot water heater element or similar) in a piece of copper pipe and use the pipe as part of your cathode
arrangement. Fill the pipe with antifreeze or similar, cap the bottom (use lead solder) good to go. Most are even pipe fitting threaded.
My latest plating attempt rather spectacularly failed when I went to put the beta PbO2 over. I think this bath needs to be reconstituted, I've had
problems plating from the same bath too soon before. So anyways, I filtered the hot solution, and now I'm going to evaporate it down, chill and
salvage the lead nitrate crystals. I'm thinking of either buying the chemsavers 10kg lead nitrate package, or buying some calcium nitrate and a bunch
of copper sulfate. Both are about the same price, but the lead nitrate is disctinctly less versatile.
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watson.fawkes
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| Quote: | Originally posted by Swede
The question is this... how would any of you heat a plastic 2 gallon plating bath to 80 degrees C, and hold it there for hours if needed?
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Glass. For the very cheap, use an aquarium heater. You can find them easily in 300W capacities. You'll have
to modify it, since their internal thermostats limit them not to kill fish. The one I've got on the bench right now also appears to have a thermal
cutout fuse (I doubt it's resettable) at 70° C. So take out all those guts and just use the heating element and its ceramic support. For the
initial heat-up, should you become impatient, get a second one and put it on a timer.
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Swede
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| Quote: | Originally posted by tentacles
You could sheathe a heating element (like a hot water heater element or similar) in a piece of copper pipe and use the pipe as part of your cathode
arrangement. Fill the pipe with antifreeze or similar, cap the bottom (use lead solder) good to go. Most are even pipe fitting threaded.
My latest plating attempt rather spectacularly failed when I went to put the beta PbO2 over. I think this bath needs to be reconstituted, I've had
problems plating from the same bath too soon before. So anyways, I filtered the hot solution, and now I'm going to evaporate it down, chill and
salvage the lead nitrate crystals. I'm thinking of either buying the chemsavers 10kg lead nitrate package, or buying some calcium nitrate and a bunch
of copper sulfate. Both are about the same price, but the lead nitrate is disctinctly less versatile. |
Sorry to hear the follow-up beta plating went bad on you.
As for your heater suggestion - that is an excellent idea. How about an oil (mineral oil) to transfer the heat? MgO powder, or some other refractory
powder (like a very fine grog), carefully packed around the element, would be even better, and incapable of boiling, expanding, etc.
WF, I've thought about messing with a 300W or so fish heater, but it seems all they sell these days are the submersibles, and the ones I've examined
look very well sealed. Just how do you get them open without damage?
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watson.fawkes
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| Quote: | Originally posted by Swede
I've thought about messing with a 300W or so fish heater, but it seems all they sell these days are the submersibles, and the ones I've examined look
very well sealed. Just how do you get them open without damage? |
The one I've got (bought retail) had the
molded-plastic equivalent of a rubber stopper. There are seven (yes, 7) sealing flanges, so it's in there pretty sturdily, but it's just a press-fit,
not glued. A couple of minutes of twisting and wiggling got it out. If you're planning on rewiring the thing anyway, I'd imagine an old-fashioned
corkscrew would make a fine handle. I took the long way the first time because I didn't know what was in it.
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Swede
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WF and others, thank you for your excellent suggestions on how to heat this plating bath.
I've done a bit more reading on industrial-type heaters in general. One of the more promising is a variety called a "cartridge heater" which are
inserted into bored holes in molds... they come in a wide variety of wattages and voltages.
Cartridge heaters come in two flavors, low watt density, and high watt density. The low watt density types are sheathed in 304SS, not good for this
process due to Fe ions. The high watt density types have the incoloy sheath, and come in a huge variety of sizes, voltages, and wattages, and aren't
that expensive, maybe $30 for a 500 watt heater, 120V. Incoloy is a metal acknowledged as compatible with nitric acid processes.
I bought one from MSC...
http://www1.mscdirect.com/CGI/GSDRVSM?PACACHE=00000007753612...
That link should bring up what I bought... item #00364281 It says "backordered" because I got the last one, but there are dozens just like it. When
it arrives, I'll inspect it and if it is readily submersible, then it's good to go as-is. If this style of heater is NOT readily submersible
(obviously to a point; wire end remains dry) then I'll encase it in Cu as Tentacles suggested, and then we could go with SS-sheathed cartridge
heaters. You could have several wattages on hand, but one Cu pipe; drop in whatever heater is appropriate for the process bath, and fire it up.
Circulation will definitely be necessary for a truly accurate system, but for now I'm hoping my spinning anode will do the job.
My order from Omega arrived, got the temp controller, SS relay, and PT-100 RTD's encased in PTFE. I'll put it all together today and see how it
works. I hate programming those process controllers... they're usually pretty cryptic and hard to use.
[Edited on 5-12-2008 by Swede]
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Rosco Bodine
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Omega ..Oh man ...grab your wallet before they do ....
sheesh
On those cartridge heaters, if you get those in a standard size diameter which corresponds to the tubing sizes used
with plumbing compression fittings, then you can stick them
right through the compression fitting for mounting. Those
fittings available in some plastics would probably work fine
or you could simply spiral wrap with teflon tape and forcibly
twist it as an interference fit in a teflon bushing.
[Edited on 5-12-2008 by Rosco Bodine]
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Swede
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Omega wasn't too bad this time. I think they are loading up a bit more with the Taiwanese/Chinese goods. The temp controller was something like $70.
I could have saved some on ebay, but I'm sick of eBay a bit, mainly because when you are putting a project together like this, and you need many items
from several different sellers, there is ALWAYS one seller who is sloooooow, and the whole thing drags to a halt. At least with Omega, I get the
stuff in two days.
Learned something... wattage density is important. You don't want the watt density to be too high. But the LOW watt density models have the less
desireable 304SS sheath, not the incoloy. Solution: Order 240V high-density heaters, that come with an incoloy sheath, and run them on 120V. Watt
density cut in half.
They look good. The ones I have are a decent fit in a 1/2" copper pipe. I bought enough fittings and such to create a copper "L" shape. Pics to
follow of the deluxe plating rig at roughly 75% complete.
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Rosco Bodine
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Registered: 29-9-2004
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Mood: analytical
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Actually the watts drops to 25% at half voltage because the amperage also halves ....I favor incoloy also , the original calrod material you can go to
an orange heat
with it no problem, and self oxidizes to that nickle black
finish. Accept no substitutes when it somes heater elements, or refreshing the barrel on your well used machine gun, use incoloy , the proven
performer
As for Omega, I was recently the proud recipient of a
few quartz sheathed dual element type K thermocouples,
which I got surplus for cheap, but I checked the list price and they are over two hundred smackers each.
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Swede
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Registered: 4-9-2008
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The thermocouples and RTD's that Omega sells are definitely not cheap, but from what I have seen, they are top shelf items, quality-wise. I know that
Omega doesn't manufacture the stuff, they simply gather product lines from other makers and slap an "omega" label on them, but I have never failed to
be pleased with what I've purchased from them. I could have assembled the components for a temperature controller bath from eBay for probably 60% of
the cost, but the convenience was worth it... plus, the stuff is new. I am always leery of controllers and other electronics off eBay unless listed
as NIB.
Odd, I thought I knew my Ohm's law, but you are correct, the wattage decreases by a factor of 4 when the voltage is cut in half. Here's a handy calculator page.
A lower watt density is quite desireable in a plating bath from what I've read. Think of it this way... you can have 1000 watts distributed along a
heater line in a long coil at the bottom of a tank, giving you a nice, even heat. Or, you can package that same kilowatt in a unit the size of a pen,
and you'll have a localized boiling spot, while the rest of the bath received little heat, unless the circulation is very aggressive.
A very simple heating rig (uncontrolled) can be set up with a Variac and one of these cartridge heaters encased in Cu. Dial the voltage needed to
bring the bath to the temp desired. A little trial and error, and you can simply place a small tick on the variac dial for a given bath setup. Just
be sure your variac can handle the wattage output of the heater.
[Edited on 6-12-2008 by Swede]
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dann2
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Hello
If you decide to operate the tanks temperature control 'open loop' then lamp dimmers can sometimes substitute instead of Variacs as the load is
resistive and not too high of a wattage. Available OTC and not expensive. Insulation wrapped around tank will help a small heater to heat tank hot
enough and keep it insulated from external temp. fluctuations.
I attach a document I came accross on possible Perchlorate anodes from long time ago. Not much use to us I don't think.
(BTW, If anyone asks you did not get it from me)
Dannn2
[Edited on 8-12-2008 by dann2]
Attachment: Anodes for Perchlorate.pdf (2MB)
This file has been downloaded 655 times
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Swede
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Registered: 4-9-2008
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After a couple days of work, using the surplus cartridge heaters, and the stuff from Omega, the heater controller is finished. Programming the stupid
thing was typical Chinglish, but I managed to get through it.
The heater chosen was a 240V 1 kilowatt, running at 120V, encased in Cu. 4 liter beaker, cold water. I was tempted to set it up for a simple
"on/off" control, but instead went for the full PID cotrol, and I'm glad I did. Fired up, the 250 watt heater brought the 4 liters to temp inside of
an hour. Best of all, it NAILED the selected temp, and held +/- 0.1 degree C all day long. it turned out nice... I'm happy with it.
For more info than you'd otherwise care about, in a simple language:
http://www.apcforum.net/forums/blog/swede/index.php?showentr...
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