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Natures Natrium
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I think I see where you are coming from with the 555, it does sound doable.
As for power transistors, I was thinking of getting a 2N5684 (80V, 50A, 300W), that ought to be overkill enough that even if my circuit is running
improperly the transistor wont fry.
Which, actually, brings me to my next question (I got a million of 'em! ;-) ), do you suppose that an extra winding or two on the feedback coil might
alleviate my problems? I was thinking initially that too much feedback was what was frying the transitor, but if the transistor is staying in a
partially on state too much of the time and resistively heating, that would explain why I have been frying transistors left and right.
As for diodes for absorbing the reverse inductive of the flyback, any model numbers jump to mind? Wouldnt plain ole' resistors do this job as well?
-NN
[Edited on 20-2-2007 by Natures Natrium]
[Edited on 20-2-2007 by Natures Natrium]
\"The man who does not read good books has no advantage over the man who cannot read them.\" - Mark Twain (1835-1910)
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Natures Natrium
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I tried adding an extra winding on the feedback coil, and got the following results:
On the 12V PC PS: the arcs were significantly longer, a darker purple in color, and the frequency was so high I couldnt hear it unless I brought the
two arcing electrodes so close they were almost touching each other. Hmm, I thought, this is promising. Also, the transistor seemed to be heating up
a lot slower.
On the 18.5v laptop PS: The instant I connected the power the transistor fried, without a sound or smell. It didnt even get hot or anything, it just
instantly stopped working, even when I reconnected the 12V supply.
While I have sourced some much beefier transistors, I am not sure they would do much good at this point. There seems to be something fundamentally
flawed going on here, and my guess is that it somehow is related to the laptop PS. Not really sure what I can do about, except buy yet another PS,
and I dont have the budget for that right now.
On the other hand, I was reading through the DIY particle accelerator thread, and I got to wondering how effect a Van de Graaf generator would be in
powering an ozone producing system. Obviously the current would be DC, but I have to wonder if using a quater million volts would be detrimental or
helpful in the production of ozone. Certainly the ultra-low current would be nice, as just a few microamps would produce relatively little in the way
of heat.
I havent had much luck in producing a model which would be good for continous operation, but I will be damned before I give up on this idea. 
Despite all the difficulties, I cannot help but feel that getting this flyback circuit working properly would be the way to go. Anyone got any
suggestions, other than building solid state timers or buying tougher transistors? Can anyone imagine why the laptop PS keeps frying the transistor?
-NN
\"The man who does not read good books has no advantage over the man who cannot read them.\" - Mark Twain (1835-1910)
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Twospoons
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I've built a self-resonant inverter like this, but it was the two transistor push-pull version. Works flawlessly and I can pull an arc an inch long.
The single transistor circuit on powerlabs has some rather fundamental flaws mostly in terms of there being no protection for the transistor for
excess volts on the collector, or excess negative volts on the base, or excess current when the transformer core saturates or an arc "shorts out" the
secondary. I'd guess your transistor died because your extra feedback winding put too much reverse voltage on the base. especially given the extra
boost from the 18V supply.
Have a look for the two-transistor circuit.
Helicopter: "helico" -> spiral, "pter" -> with wings
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S.C. Wack
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FWIW, back to the topic of electrochemical ozone generation, and another article from someone who seemed pleased with it, after taking some trouble to
get it right. From Recueil des Travaux Chimiques des Pays-Bas.
Attachment: rec_trav_67_217_1948.djvu (219kB)
This file has been downloaded 765 times
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franklyn
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A good overview of what's involved for production
http://www.scielo.br/pdf/qn/v26n6/a17v26n6.pdf
Simple enough to make yourself
http://www.emanator.demon.co.uk/bigclive/ozone.htm
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Bander
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Interested in low frequency atmospheric ozone production by glow discharge around 20kV? These guys have a novel barrier discharge setup using flowing
deionized water as the dielectric; http://www.center.bg.ac.yu/plasma/DBD.htm
An example of usage, Removal of phenol and chlorophenols from water by new ozone generator | Quote: | | Depending on the experimental conditions, the new ozonizer after approximately 1 h of work provided the concentration of dissolved ozone in water of
7–40 mg/L. These values were onsiderably higher than 0.2mg/L obtained by authors using the reactor based on corona needle-toplate discharge.
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(after thinking about this for a while it occured to me that this would make a kickass pre-ionization system for atmospheric pressure nitrogen lasers)
[Edited on by Bander]
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Dr.3vil
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ozone generator for ozonolysis
would something like the device linked below be suitable for the production of ozone used in ozonolysis reactions
http://cgi.ebay.com/High-Power-Water-Ozonator-300-mg-hr-Ozon...
- dr.3vil
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franklyn
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dr.3vil
While I researched this some and posted about it , I have not used
such a method myself. Note that 300mg is just a third of a gram
assuming you get good yield from your reactions , obtaining just
a few grams of product will be an all night affair , any meaningful
amount would take a week. This may well try your patience.
Ozonolysis also must be done using pure dichloromethane solvent
also available and known as methylene chloride, at the temperature
of dry ice if ozonides are being produced ,since these will decompose
over 20° C and are hazardously explosive.
.
[Edited on 19-4-2007 by franklyn]
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seb
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The Metropolitan water District of Southern California is building several 5 MW ozonators at water treatment plants as well as other units, such as
coal removal and water treatment (one facility is called Lake Skinner), and these will have liquid O2 tank farms. The plants already have Cl2 gas in
tanker trailers onsite. Chlorine treatment is supposed to be phased out. The project cost was originally $680 million.
Obtaining some ozone is admirable, but I mention this because a different focus might be what happens in theory when heretofore unheard-of
quantiies become available. I am not saying we can get our hands on any, which is too bad. A technician will get his job handling all that material
and never be allowed to conduct any experiments with it. Of course, the Chernobyl accident was supposedly the result of experimentation, but the full
story is that this design of reactor can have a runaway power buildup. I read about it in a "Dictionary of Scientific Ethics". All the
"experimentation" had to do with was how you do a low-power startup, since a no-power startup takes days to get going. In the ozone case, if you
ozonate water, you have to have an ozone destructor downstream. It would be nice to position objects in the stream just to develop the chemistry of
rubber that could resist ozone damage, maybe to make rubber hoses to use in biodiesel engines. I feel that MWD should be encouraged to to do research
with some of that cheap ozone.
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Matchheads
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Let's change our thinking and get rid of this kind of science. Isn't school a game? Okay, "300 mg is a third of a gram" (Franklyn). I was thinking
that if you are trying something with independent events, like answering test questions, even if you get two out of three, that is only 66%, not
passing. I think back in the day, they noticed this and said, "we are not letting ppl get away with competence. We are setting passing ABOVE the
best two out of three. I am only doing something 3 times, maximum. I am not going to get it all three times. Let's have school be just three test
questions and only promote those who get them all.
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franklyn
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In scientific notation rounded off to one one significant digit
how do you write one third of a matchhead
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Matchheads
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I am still unamused. The Nineties were a washout as far as Mars exploration went, a) The coloring books you men grew up on had no recent data on
Mars, therefore our trips to the library were heavily influenced by the likes of Dr. Martin Luther King, b) Oh, wasn't that a question of mere UNITS,
on the order of "Let's assume everone is using the metric system". c) That was "Mars Observer" failing an orbit insertion. Funny?
1/3 (mh), mh/3, 0.33333... x (mh), and 33.333...% of a matchhead, or a pinch.
Why would you go from something you can write in two figures, and w/o splitting a line, and's correct, to something you exaggerated a skosh?
Franklyn, you didn't even go "Franklin", so we could be talking about Benjamin Franklin. Aw.
Benjamin Franklin never gave up. That's why we have heard of him, see?
Note that we want to see all big numerals and zero plus the decimal point (because there's no 'Q'), unless you want to be a slave to a computer
screen and not really work in labs, and use a bar to offset information, then you'll get an "ADEQUATE" in NOTES, what we call, "legible". Also, use
superimposition to condense double letters. Thus, "Matchheads" or "mh" will come out like this: ,|,,.
[Edited on 11-5-2007 by Matchheads]
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Pulverulescent
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Hi anyone, My first post, and I'm putting it here because I have a "thing" about ozone.
Some time ago, I produced ozone (apparently?) by passing unsmoothed dc through a plat/ir wire. The wire was to be used as anode for perchlorate synth
and I'd been checking its conductivity the lazy way.
The idea had been to pass currents of increasing density through the alloy to see how many watts I could get without burning the bakelite cell-cover.
The psu was two battery chargers in parallel and all switches were out of their housings. The alloy wire was 500mm in length and 0.5mm thick.
Intending to begin with the lowest density current, I connected the wire to the terminals which were fairly thick copper wires twisted round the ends
of the alloy wire so that the wire was stretched horizontally between them. Because of the confused arrangement of the switches I inadvertently
selected max power, and swiched on.
The wire instantly went whitely incandescent and sagged visibly so I dived for the off-switch. I reset the psu for min density and again switched on.
No glowing this time but visible convection currents were seen rising from the wire.
Suddenly there was a strong smell of ozone and it seemed as intense as that from a generator I'd made years before from an nst, small window-panes and
ulufoil.
On smelling ozone, my heart sank, thinking I'd got an arcing short in a primary coil.
On not finding any arcing, I put my facial ozone-detection sensor close to the alloy wire and found that the smell was coming off the wire itself. My
reaction then was, "this is interesting but there's a rocket waiting for nh4clo4 and you can get back to this ozone thing later. I had to turn it off
quickly anyway,because the rectifiers were at, near or above their operating limits. Setting up the e-cell required cutting the alloy wire into short
lengths and so, the ozone thing went on the back-burner for yonks.
When, later, I got to thinking about the anomaly I realised I might have stumbled on something useful. I purchased a new (expensive) alloy wire to
reproduce the "effect". If I'd succeeded you'd've heard all about it, already.
Basically, my lack of knowledge destroyed the second wire. I used steel croc-clips on the alloy and this caused fe ions to migrate onto the alloy
surface, causing extensive black staining, and poisoning the catalyst. I'd figured that ozone was produced by electron-induced desorption of oxygen
adlayers as 0, forming ozone by recombination.
The only other way ozone could have been produced would be by reduction of mixed oxides of plat/ir, formed by the high temps, but in that case only
traces of ozone would be expected and I remember the smell being quite intense, and sustained. Around this time, while browsing, I found a paper,
titled, "Electron-induced Synthesis of Ozone in a Dioxygen Matrix" by Lacombe, et al. The abstract is still available under that title.
The inferences in that paper seemed to suggest that ozone *can* be produced efficiently by a form of electro-catalysis---on platinum crystals. The
work had been done under uhv and low temp conditions to investigate the occurrence of ozone in spectra from some asteroid or satellite.
I haven't, yet, been able to reproduce the effect, but I'm not done trying.
I'll have another alloy wire sometime this year, but a variac is also needed.
Any similarities to junk-science are unwelcome and unavoidable.
Ozone synthesis by e-catalysis would be efficient (c/d generators are inherently inefficient), use low voltges (<10v), eliminate the nox problem in
air and allow the production of any concentration of ozone.
The entire thing may hinge on the fact that dioxygen is paramagnetic.
So, have I "sparked" interest in any cranial receptacles out there?
After this, thoughts of patents are well and truly out-the-door! But, C'est la vie!
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12AX7
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"Dioxygen matrix" means, they put something inside of frozen crystalline O2 (a matrix, bound by dispersion forces -- brr cold!), then did some sort of
reaction to it. Matrix reactions are done in a suitable medium (e.g., Ar, Kr, N2, etc.), frozen solid. Not amenable to producing things.
Ozone can be produced by the decomposition of permanganate in acidic solution, electrolysis of a nonreactive or, more commonly, strongly oxidizing
solution (e.g., peroxydisulfate, perchlorate, etc.), and I think fluorine and various compounds of it (CoF3?).
Tim
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Pulverulescent
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Thanks for the insights,12AX7. 'At risk here of stating the fairly bleeding obvious, but, all electrical discharges in air or oxygen produce some
ozone. Ozone is produced when atomic oxygen interacts with dioxygen by forming weak bonds---the resulting triatomic form owing its thermal instability
to the weak bonding of the third atom. Atomic oxygen can be produced by chemical and electrochemical action, electron bombardment, thermal desorption
of chemisorbed oxygen or by high temperatures.
Oxidation of S02 at PGMs relies on the formation of ozone as a transient intermediate.
Ammonia is oxidised catalytically by a somewhat different mechanism because hydrogen reacts directly with adsorbed oxygen on the PGM surface.
A recent process generates ozone by bubbling air or oxygen through a water/phosphorus slurry; oxidation processes within the mass produce atomic
oxygen but the ozone formed is heavily contaminated by various oxides of phosphorus.
Corona-discharge generators produce ozone more efficiently than electrochemical methods but they themselves have efficiencies of only around 5%.
I don't know if my "observed process" is reproducible, but if it is it would produce ozone without most of the losses that occur with other processes.
Lacomb's process used ultra high vacuum as well as cryogenic temperatures. Atomic oxygen was produced in his experiment by electron-beam bombardment
of condensed oxygen layers on platinum crystals. Desorption occurred at electron energies of around 7.5 ev which coincidentally is roughly the output
in volts of a 6v battery charger. The extra 1.5v is there to overcome the cell-resistance.
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Pulverulescent
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Tim, asking pertinent questions won't make you look gullible as you might think!
I could have made the entire thing up, obviously, but I didn't; there's a possibility I'm terminally delusional, though.
Ozone, like its stable allotrope is odourless; it has *no* smell whatsoever. When inhaled, ozone attacks nasal mucus, producing odourous volatiles.
In a nut-shell, or matrix, you smell burning snot(ugh!)when ozone's around.
That Lacombe paper is now pay-per-view, unfortunately, and the abstract skimpy.
If you find a chink in your scepticism anytime soon and you've excess cash, you could check it out.
Ozone used to be made by a lab-curiosity by dipping a red-hot platinum wire into lox, withdrawing it and allowing the residue to evaporate. It would
seem that desorption of O produced ozone and the low temperature prevented its decomposition. If oxygen is blown though heated porous platinum ozone
is formed by the same mechanism in the interstices. In confined spaces it cannot decay thermally at its normal rate because of the limited number of
molecules available for reaction.
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-jeffB
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| Quote: | Originally posted by Pulverulescent
Ozone, like its stable allotrope is odourless; it has *no* smell whatsoever. When inhaled, ozone attacks nasal mucus, producing odourous volatiles.
In a nut-shell, or matrix, you smell burning snot(ugh!)when ozone's around.
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No offense, but this seems like a silly distinction. One could argue on the same grounds that chlorine is odorless, because when inhaled it
chemically combines with mucus (and water) to make odorous HCl and HOCl. The fact that it chemically attacks tissue does not mean it "has no smell"
of its own.
I remember long ago seeing a claim that ozone doesn't actually have any odor, and that what people think of as the "ozone smell" is actually the
oxides of nitrogen formed in electric discharges through air. This claim is easy enough to debunk; pass a discharge through a stream of pure oxygen,
and see what the product smells like.
I do see a number of Google matches claiming that ozone is a "colorless, odorless gas". They're wrong on both counts, unless they really mean it's
colorless and odorless in sufficiently low concentrations. By that definition, iodine is colorless, and hydrogen sulfide is odorless. 
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Pulverulescent
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None taken, jB, but dioxygen is determined to be odourless because our first breaths at birth are all too easily forgotten and we're breathing a
mixture, anyway.
On a more serious note, you must have noticed the similarities in smell between ozone, nitric acid and chlorine. The smell of ozone is that of a pure
oxidiser, but the other two have nitrogen and chlorine along with their reactive oxygen.
When I made a simple ozoniser, on switch-on the smell was all ozone, but running it for a time caused an extra pungency as the condensing moisture
within the discharge-gap caused increasingly hotter discharges bringing nitrogen in on the act.
At the time it got me thinking that an ozoniser running on air could be fine-tuned to produce n2o5 from ozone and no2. Bubbling it through water could
lead to hno3 of almost any concentration or the n2o5 could be condensed using dry ice.
As far as as semantics goes one *can* say that since oxygen has no odour, being oxygen ozone has none either.
Back to angels on pin-heads!
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Pulverulescent
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So...Anyway, who's going to be first to put their head over the parapet to tell me my first post is pure wishful thinking, or worse. . .?
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Pulverulescent
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(sigh. . .!)Here's what I think might have happened---heating the plat/ir wire close to its mp. "reordered" in some way the alloy surface allowing the
formation of more complete oxygen adlayers. There's a strong possibility that the rectifiers(two)were damaged by the current used in heating the alloy
and ac might subsequently have been superimposed on the dc pulses.
I'd assume that the heating step produced at least a "clean" alloy surface ready for adsorption.
On switching on the ("operating current?"), oxygen, being paramagnetic, would have been attracted to the metal surface where under the influence of
the rising first pulse fast adsorption/chemisorption would occur. As the voltage/energy in the pulse rose desorption(breaking metal/oxygen bonds)
might occur at a point near peak-voltage(~7.5v).
The desorbate would be unlikely to come off in triatomic form, but it's just possible.
It'd, more likely, be single atoms "ejected" into surrounding dioxygen, forming ozone by recombination and leaving the surface ready for the next
electron-induced adlayer to form.
Ozone, being diamagnetic, would be repelled by the weak field surrounding the wire, thereby escaping the heated zone close to the wire surface without
decomposing.
Each 50hz. pulse would produce a small(ish) amount of presumably pure ozone which would quickly leave the reaction-zone(platinum decomposes ozone).
As Parthian Shot---the mechanisms behind adsorption/desorption reactions are *still* poorly understood because hard information is hard to come by in
the field of catalysis.
Surface reactions can't easily be observed.
BTW, academia basically told me to eff' off. Don Kennedy(retired) admired my persistence and then told me to eff off. Out-of-hand dismissals to me are
water off a... blah, blah!
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Pulverulescent
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If not an interrogation, I'd expected a *few* questions at least!
Isn't there anyone who'll engage me on this? (sniff...!)
P
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Pulverulescent
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This is very odd; I may, and I *stress* "may", have stumbled upon a new, more efficient process for ozone synthesis, and no one's interested enough to
muster a serious comment one way or the other.
And yes, I'm I'm all too aware that I may be holding myself up to ridicule, at some point, but the only thing worse than ridicule is indifference.
It may, if you'll pardon the pun, be fall-out from the cold-fusion debacle.
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Pulverulescent
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This may be of some slight interest to someone messing with PGMs as anode material.
When I was fiddling around with plat/ir something a bit unexpected happened.
70/30-pt/ir is fairly brittle and its electrical conductivity only moderate, so to tweak the cell to enhance productivity, I found myself trying to
solder copper wire to a piece of alloy which had been sealed into the closed end of a short glass tube(soda glass).
I was using multicored solder and an ordinary iron.
Within seconds of the molten solder making contact with the alloy, a eutectic of some sort was formed.
Several millimetres of the alloy became liquid so that solder and alloy seemed to coalesce.
I realised that nh4cl in the flux must have been oxidised to aqua-regia, which dissolved the alloy, possibly allowing some mixing with the metals in
the solder.
IIRC, the melting point of 70/30-plat/ir is close to 2000*C.
I found too, that repeated vigorous heating of the alloy causes it to degrade fairly rapidly.
A marked roughening is noted at first, further heating exacerbates this, producing little nodules along the length of the wire which grow in size with
further heating steps to the point where the wire between the nodules becomes so thin and fragile that the least pressure (or high temperature) causes
breakage.
I found out subsequently, that this phenomenon is caused by agglomeration of various oxides produced, into clumps which enlarge each time the metal is
heated to redness.
The effect is called "bambooing", for fairly obvious reasons!
P
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12AX7
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Soft solders are well known to dissolve and pit noble metals.
The copper tip on your soldering iron typically survives thanks to a plating of iron; when that wears through, the tip isn't long behind.
Tektronix, a famous test equipment manufacturer, used to (and may still) use ceramic terminal strips, which have evenly spaced divots metallized with
silver. Older oscilloscopes using them often had a small roll of silver-bearing soft solder clipped inside the chassis, so repair technicians would
realize that ordinary solder would dissolve the silver, loosening the connection from the terminal strip!
I have a book centered primarily on making jewelry; a mixture of acids is suggested to remove soft solder from noble metals to prevent pitting on
further handling (which often involves silver brazing, diffusion, forging, etc., all high temperature processes).
Finally, tin tends to form intermetallics as well as oxides. A browse through my phase diagram database suggests both Pb and Sn form numerous
intermetallics with Pd at least. I don't have data on Pt-Pb, but Pt-Sn does. (Interestingly, Zn-Pd looks like a clean system; zinc can probably be
used to strengthen palladium, making something analogous to German silver, a Ni-Cu-Zn alloy. But alas, I digress.)
NH4Cl does NOT hydrolyze, pyrolyze OR oxidize to anything near aqua regia. NH4Cl <--> NH3 + HCl with heat -- it appears to sublimate.
Tim
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Pulverulescent
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Tim, you make some good points(while continuing to studiously ignore the large trunked pachyderm in the room).
My old Weller, though, has been through many coils of solder without noticeable damage, of any kind, to the copper tip.
Anyway, the molten blob of of mixed metals was a bit larger than a match-head and I lost it, in more ways than one, when it hit a fairly cluttered and
unswept floor.
And you're, with respect, incorrect in thinking nh4cl won't oxidise on pt. to aqua-regia. Nh3 from dissociated nh4cl is obviously oxidised to no at
pt..
The wisps of smoke from molten solder in contact with the hot tip normally contain some sublimed nh4cl, but a significant portion, in this case, also
oxidised to form hno3. Surface pitting is one thing, formation of liquid eutectic blobs, quite another.
Iridium, interestingly enough, isn't itself, attacked by aqua-regia, possibly because of its extreme density.
What I saw was a eutectic formed at a relatively low temperature(~400*), and hot solder of whatever lead/tin ratio doesn't normally attack pt/ir in
this way.
This is all peripheral to ozone generation by any means, and I'd prefer you to concentrate on the "main dish", if that's okay
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