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Quince
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The three-turn heater winding on a microwave oven transformer plus rectifier/filter voltage drop should do it.
Also, I thought you were vulture instead of chemoleo, that's why I posted that.
[Edited on 17-3-2005 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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Mumbles
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I mentioned this on the other board you posted this on. I'll throw it out here and see what people think. Use a soluble copper salt solution.
It will dissolve the iron, and most of the metal in the steel, and replace it with copper which will more than likely fall to the bottom of the
solution or be able to flake it off the pan. Digest all the steel off and scour or sand the copper. It will remove all the pits, and carbon, any
glue used, and any undissolved metal. It may be worth it to give it a final washing with HCl to get as much off as you can.
I don't think copper metal will be attacked by copper solution. Someone better at inorganic chem should know.
[Edited on 3-18-2005 by Mumbles]
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chemoleo
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That's a good idea mumbles. I am just not sure how the CuSO4 (i.e.) will deal with stainless steel. Many a time I have dealt with
spatulas/spoons made of SS and hot CuSO4 solution, and they didn't corrode. I guess it depends on the type of SS. Still, that is def. a good
idea!
CuCl2 can react with copper, forming 2 CuCl. It's a way to prepare CuCl. But under those conditions it's unlikely to happen. As long as you
use the sulphate rather than chloride.
[Edited on 18-3-2005 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Quince
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Perhaps I'll use HCL until some copper starts showing off, and finish off with the CuSO4. This way I also save on the sulfate, as I haven't
found a source here; the one I have I brought with me from Europe over a decade ago.
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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The_Davster
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You can find copper sulfate in hardware stores in the cleaning products section as a drain opener of sorts. I think I have seen it at either rona or
home depot.
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neutrino
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Drain opener? Around here, it is used to keep roots out of your pipes.
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kryss
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Best idea is the Copper Sulphate one - add some HCl as well that will def corrode the stainless steel all right. Especially if its a cheap coating.
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uber luminal
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Stainless comes in many different combinations. Some are rich in Ni and Chrome, some are not. The best thing to kill stainless is heating it over
750ishC to diffuse the chrome. It looses its luster and becomes dull. Its easily etched or reduced at that point. the problem with that is that the Cu
would suck away the heat that your putting on the SS. and once the Cu became saturated it would melt.
The other methods people have talked about would be difficult since there are so many different grades of stainless, and its hard to tell what
composition you have. If these pans are so dang pricey, they might just have the 18% Chrome, 32% Ni. in any case, im not sure why you want to use
nothing but copper to cook anyway?
Copper works great as a heat sink, giving up a lot of heat to the air... Stainless keeps heat where you put it, and it takes quite a bit of it. I
would think the added SS layer would be helpful to cooking. Unless you like wasting heat or something.
(btw, quince, Cu doesnt have a better tc. than Al. Al is almost 2x better) This might be the reason the world uses Aluminum for heat sinks on
everything important, rather than copper. However copper does do better at higher temps. The copper arc melter hearths that I use take the 5K C temps
just fine where Al would have melted or reacted with the metal being melted haha)
Since the stainless is so thin, and exposing Chrome and Nickle to your FOOD cookware is a really dumb idea, I think your best option is to just grind
it out. or try cutting it and peeling it out.
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Saerynide
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| Quote: | | Stainless comes in many different combinations. Some are rich in Ni and Chrome, some are not. The best thing to kill stainless is heating it over
750ishC to diffuse the chrome. It looses its luster and becomes dull. Its easily etched or reduced at that point. the problem with that is that the Cu
would suck away the heat that your putting on the SS. and once the Cu became saturated it would melt. |
Well, if you can keep the temp around 800-900C it should be fine. Copper doesnt melt til 1083C. As for how you're supposed to keep the temp
around 900C? That, I have no idea.
[Edit]: typo
[Edited on 19-3-2005 by Saerynide]
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satisfy any applicable law, regulation or legal process"
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12AX7
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Don't forget to sit the copper part in charcoal or coat it with flux (glass) otherwise it'll burn through too. (Well not really, but it
will oxidize to all hell, oxygen diffuses into it nicely both as gas and oxides.)
Tim
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vulture
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Copper will get mighty soft at temperatures around 800-900C, so I wouldn't go that high.
One shouldn't accept or resort to the mutilation of science to appease the mentally impaired.
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unionised
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"(btw, quince, Cu doesnt have a better tc. than Al. Al is almost 2x better) This might be the reason the world uses Aluminum for heat sinks on
everything important, rather than copper."
Er, wrong, copper is a better conductor*. A plausible reason for using Al is cost, another is ease of extrusion.
There are plenty of high-end heatsinks made from copper.
Anyway, if you put copper sulphate solution in the pan you will cover the steel with a layer of copper. Then the reaction will stop.
You will convert the relatively easy problem of removing steel from copper into the more difficult problem of "removing copper from copper, but
only in the right places"
BTW, if heating stainless above 700C kills it, how do they cast it?
* CRC handbook, Cu 4.01 W/cm/K vs Al 2.37 W/cm/K
[Edited on 20-3-2005 by unionised]
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12AX7
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| Quote: | Originally posted by unionised
BTW, if heating stainless above 700C kills it, how do they cast it?
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Quickly.  Obviously only repeated heating, cooling, oxidation and whatnot will
kill the chromium content (leaving a porous (as I recall) nickel iron which is not corrosion-resistant).
Tim
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uber luminal
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| Quote: | Originally posted by unionised
Er, wrong, copper is a better conductor*.
* CRC handbook, Cu 4.01 W/cm/K vs Al 2.37 W/cm/K
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No, your correct. I misread the alloy I was looking at (I read C26000 series instead. The point I was getting at was neither pure Al or pure copper
are used commercialy since they are both rather soft. (especialy when heated) Pure Al tears like butter, and pure copper is warped very easily. I
compared Al1100 and Al6061 to C26000... and in that case Al is much better  but
since we are looking at a 90%+ copper alloy and not cartridge brass... im wrong.
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Twospoons
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| Quote: | Originally posted by unionised
BTW, if heating stainless above 700C kills it, how do they cast it?
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Turns out that chromium carbide forms over a reasonably narrow temperature range. I can't remember what the exact temps are, but at much higher
temps (as in casting, forging, welding) the chromium redissolves into the alloy. The trick with keeping stainless "stainless" is rapid
cooling though the carbide formation zone. There are also 'weldable' alloys designed to minimise this problem.
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Quince
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HCL+H2O2 definitely etches the stuff, but so slowly that I don't see how I can remove a 1/4 mm coating of stainless from the copper without
several hours of scrubbing with the solution. Also, the bad thing about this solution is that it destroys the copper as well, so I'd have to
find a different method for finishing off the process.
[Edited on 7-6-2005 by Quince]
\"One of the surest signs of Conrad\'s genius is that women dislike his books.\" --George Orwell
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