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Re: Rubber toroids
From: Wes A Brzozowski[SMTP:wesb-at-blue.spectra-dot-net]
Sent: Tuesday, October 28, 1997 3:59 AM
To: Tesla List
Subject: Re: Rubber toroids
On Fri, 24 Oct 1997, Tesla List wrote:
>
> From: Harri Suomalainen[SMTP:haba-at-cc.hut.fi]
> Sent: Friday, October 24, 1997 5:27 PM
> To: Tesla List
> Subject: Re: Rubber toroids
>
> On Wed, 22 Oct 1997, Tesla List wrote:
> > The laquer is made easily conductive by the addition of powdered graphite
> > (I've experimented with mixes of graphite and conductive lampblack, which
>
> Commersially available sprayable graphite (used on tv's for example) is
> quite reliable and not too expencive. It should be considered as well
> as a choise. Making something similar your self may or may not be worth
> the trouble.
It most certainly is worth the trouble. To see why, you'd have to reread
the portion of my message that you clipped off. My methods involved
building up polystyrene parts, layer by layer (it's really not too hard).
The laquer used to build it up already exists as part of the manufacturing
process; the only new requirement is to make up a batch of the stuff
that's also conductive, so that the plastic itself is platable. There's no
worry about wether the plastic sticks to itself; ordinary cohesion is all
you need. The conductive layers are also an integral part of the solid
structure of the workpeice. The result is that the conductive layers add
strength to the part (they can be quite thick with little effort) and
do not have the liability of flaking off from flexing or temperature
cycling, do to uneven coefficients of expansion. The method works very
well, indeed when combined with my original plastic forming method, and is
actually much less bother than having to add new materials to the process.
> Also remember the order of mixing: pour sulfuric acid to water. Never ever
> do pour water into the acid. It will generate quite a lot of heat and it
> may (probably will) be spilled/spached all over. If poured in the right
> order it is ok. This is just too easy mistake to make if you just won't
> happen to know it.
A good reminder. Some of the readers trying to experiment with the process
may have never have handled sulfuric acid before, and should take this
as a dire warning, rather than a friendly suggestion.
> > The original posts also contained some severe warnings about using nickel
> > plating for something like a toroid, but which some people are suggesting
> > now. The discharge from a toroid may vaporize small amounts of metal. While
> > copper can be ingested in small amounts (hey, we actually need it in trace
> > amounts; perhaps coiling can be healthy? ;-) nickel can do really nasty
> > things to you. Worse are some of the incredibly toxic organometallics it
> > can form. Given sufficient energy and ordinary atmospheric components,
> > nickel can form nickel-carbonyl, a toxin that makes the cyanides
> > everyone's been worrying about look like candy. The stuff is vaporized at
>
> I'd like to hear more about the nickel subject. I guess I ought to do some
> quick checks at the library too. Any idea of LD50 and ED50?
My references on toxic substances are more centered on living with
hazardous materials than killing with them, and the commonly reported
numbers center more around the mass per cubic meter of air that may
be breathed in an 8 hour workday. By those numbers, nickel-carbonyl is
around 15 times more toxic than hydrogen cyanide. If you consider that
the nickel-carbonyl molecule is about six times as heavy as HCN, we might
say that on a molecule-per-molecule basis, it's 6x15 = 90 times as
toxic as HCN. (Organometallics can be truly nasty things!)
> However, I'm still not very convinced of the dangers of nickel until
> further info has been dug up. That would be too common stuff you know..
> I'll still look more into it, just to be on the safe side. Nickel would
> be a nice lookin plating you know..
Hari, I don't think you've been paying attention, here. We're not talking
about the dangers of nickel (though you may be surprised to find out just
what nickel can do to your body) but of a particular nickel compound.
Heavy metals, when combined properly with carbon groups, can produce
classes of toxins that are radically more toxic than the metals,
themselves. That said, we still have to be much more careful with nickel
plating solutions than with copper solutions. Our bodies will use copper
in trace amounts, but nickel ions can be rather harmful (though not
anywhere near the toxicity class of nickel-carbonyl!)
> I'd assume the risk much more commonly known if it did happen. However,
> avoiding the possible risk makes sense too.
Known to whom, Hari? The toxicologists? They've documented the hazards
quite well. You just have to read them. People who produce and
professionally use large discharge terminals? They'll use either
aluminum, or, if they want a plated surface for some reason, will
more likely go with copper, with a hard chrome plate. The very idea of
using nickel is pretty much relegated to people who'll settle for an
inferior plate, providing they can apply it with a low-tech approach
in their garages. But just as many scientists in decades and centuries
past have died from exposure to new things they've created, the basement
experimenter can also suffer injury or death from working witout
understanding the hazards. We're investigating a possibility here; mine
based on having read up on the matter, and yours on the promise that
you'll read up on it later on. Now, I sincerely hope that my concerns
prove groundless. But it's also my feeling that any minimizing of the
possible dangers should be based on documented evidence, rather than
speculation. Let's err on the side of caution...
There are several other fields where there's also concern about formation
of nickel-carbonyl. Once again, there's nothing definite, but there's
hesitancy to do anything without real evidence. One is in the field of
pyrotechnics. There have been some reports of interesting effects using
nickel compounds, but there's also the concern that the residues left
behind will be contaminated with traces of nickel-carbonyl. So even
though every year, in the PGI convention, there are displayed new and
amazing pyrotechnic effects that will probably never be done in public
displays, there are no effects using nickel. Period. That's not due to
any safety rule; it's just due to concern because those who do the more
exotic research tend to be chemists who are aware of the kinds of
problems that may occur.
So to end a long response to a short comment, the risk is commonly known.
or at least the concern is commonly known. To determine the risk may
take time and facilities that aren't readily available. (The concern
in the pyrotechnic community has stalled work on nickel compositions for
years so far...)
> > ingesting in any trace amounts, and I'm not particularly worried about
> > handling cyanide solutions (though I am particularly cautious when doing
> > so). In any case, it might be worthwhile to hold off on the nickel plating
>
> Funny. Most of my co-workers *are* worried even professionals. At least
> a non-professional should worry a lot.
Hmmmm... If English were your first language, I'd have expected a little
smiley-face after that last comment. Maybe that was a good natured rib
anyway, and that's fine. If not, I'll point out that a statement that I'm
not particularly worried though I am particularly cautious (at least in
the American perversion of the English language) would probably put me in
the same category as your co-workers. We may have a deep respect for the
hazards inherent in a material, though not be so paralyzed with fear that
we can't work with it. Sorry if there was any confusion here.
> > One other item; the use of copper chloride as an electrolyte has been
> > mentioned, and while it seems that it should be able to deposit a layer
> > of copper just like copper sulfate can, I can also see some problems,
>
> Good point. Anyway, I think suphate is more common,
Not just more common. As I'd pointed out in the original post (the part
just below here, in fact!) the sulfate *is* what's used commercially.
(Well, you snipped out another part; I was really saying that the chloride
is not used commercially, and the mention of sulfate was snipped away
earlier.)
> > which may be the reason it's not used commercially. First, there's the
> > problem of using an acid-copper bath to improve adhesion. If we need
> > to add acid to get a decent plate for a surface that's punished the way a
> > toroid is, the addition of acid to a chloride solution will evolve
> > hydrochloric acid fumes, which are quite unpleasant to breathe. The
> > second is the fact that a class of chemicals called chlorates are produced
> > commercially by the electrolysis of chloride solutions. If any copper
> > chlorate is being produced in the process, you could be producing a very
> > unstable vat of liquid. I'm not sure how it acts in solution, but solid
> > copper chlorate has been known to explode without provocation. Now, I'm
>
> It would make a lot of clorine gas (not too healthy!) if chlorates were
> made. They're fairly toxic too and won't feel too good. In a
> large-scale production (like a huge toroid) the amount of
> chlorine involved could be quite a huge.
Not quite. You would *not* be making chlorine if chlorates were produced;
at least you wouldn't notice it. The chlorate radicals are produced by the
action of free chlorine on OH- radicals. This produces a soup of
hypochlorites, chlorites, and chlorates. (And of all these, the chlorates
are the *most* stable.) So if chlorates are being efficiently produced,
and this would be reasonably likely in some plating setups where the
anode and cathode are in close proximity, you wouldn't detect much
chlorine, if any.
> Chlorates sure can be unstable. They can be insoluable in the solution too
> so they will perticipate out. Quite a few chlorates do that. However, you
> can prevent chlorate making by controlling the voltage. I think around
> 4V or so would be needed for chlorate making. (From the memory, not
> checked!) However, everyone with 5V PSU's around can be in risk.
You might want to recheck this. Keeping the voltage low will prevent the
formation of perchlorates, but they're not the problem. If this comment is
a reference to the posts of those kids on rec.pyrotechnics, who
were making their own oxidizers, starting with table salt, you should
also be aware that you need much more than a voltage measurement to
determine what products are forming. The cell voltage will be a
combination of the electrode potentials needed to form the products and
the voltage across the electrolyte due to ohm's law, which will depend
both on current and the electrolyte concentration. This electrolyte
voltage is of no concern in determining reaction products, and must be
eliminated from the measurement. If you'll recall how those kids had
so much uncertainty over what they were producing, consider that they
seemed to have no clue as to the additional electrolyte voltage.
> I'd go for sulfates instead of chlorides too. Chlorides can work faster
> (or should at least in my opinion) in a non agitating solution. Still,
> usually time is no consern. Making better electrodes makes a lot more
> change anyway.
If you want a faster plate with CuSO4/H2SO4, you can just crank up the
current -- an advantage that is limited in the cyanide/copper plating
baths that have no advantage in this situation, anyway. Acid/copper baths
can be run quite heavily and still produce a solid plate, though the
effervescence at the electrodes can put a lot of tiny droplets into the
air if the bath isn't covered; very irritating and probably very bad for
the nasal passages...
> > Anyway, anyone interested in this subject might want to look for those old
> > postings from a year ago or thereabouts. I think there might be some
> > useful information there. In any case, I'm personally very interested in
> > seeing people work on this problem again, so keep tossing out those
>
> Me too. I think making nice toroids yourself should be something every
> coiler or hv electrician should be able to do!
Agreed. Actually, I'm more interested in cheap production of some
non-toroidal shapes. I've been playing for some time with computer
simulations that determine the capacitance matrix between various bodies,
and may eventually be playing with plated polystyrene shapes to check out
the validity of the models. This stuff has lots of uses!
Wes B.
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