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What is this soft metal, and is it toxic?
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John Griessen
It's parts of a plasma etcher that are in the high vacuum area. The ceramic plate had wafer lifting pins and was bonded to a thick aluminum plate with low temp metal brazing. I can gouge it easily at a temperature of 60 deg F and the tool feels sticky. A push and twist captures the tool and holds its cantilevered weight. Could this be Woods metal? Gallium? Toxic Mercury Cadmium Lead amalgam? I am thinking it must have been stable in vacuum with some warm temperatures when the etcher was running... |
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Chuck Harris
Why do you think it is metal? Is it shiny in a way
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that doesn't show in the pictures? If it is the black stuff, looks like epoxy. If it is the white stuff, looks like silicone heat sink compound. -Chuck Harris John Griessen wrote:
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Oh, sorry.? I missed this message which provides the context I was looking for.? ?I can't think of any reason one would build a plasma etcher out of something that is particularly toxic, BUT, I would be more concerned about what someone could etch in a plasma etcher.? Gallium Arsenide comes to mind.? But looking that up now on Wikipedia, it's debateably carcinogenic.? ?Just the same, I wouldn't play scratch and sniff with the stuff.? ?Wash your hands really well, and try not to inhale anything as you chip away or grind or sand.? Better yet, wear a mask.? ?
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None of the soft heavy metals and going to kill you instantaneously.? ?You'll just have to get them recycled properly.? ?You can burn a chip of the stuff to see if it melts or burns at a low temperature to try to identify it.? Definietly don't breath those vapors. First guess, without knowing more about this system is that it's some sort of a protective alumina/ceramic plate glued onto the aluminum cover plate of the etcher, to protect if from etching.? ?Just a guess.? You can measure the density of the metal plate once you clean it up. ? Dan On Sunday, December 2, 2018, 3:17:09 PM EST, John Griessen <john@...> wrote:
It's parts of a plasma etcher that are in the high vacuum area.? The ceramic plate had wafer lifting pins and was bonded to a thick aluminum plate with low temp metal brazing. I can gouge it easily at a temperature of 60 deg F and the tool feels sticky.? A push and twist captures the tool and holds its cantilevered weight. Could this be Woods metal?? Gallium?? Toxic Mercury Cadmium Lead amalgam? I am thinking it must have been stable in vacuum with some warm temperatures when the etcher was running... |
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Chuck Harris
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-Chuck Harris John Griessen wrote:
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Yeah, and now I eat crow because I didn't actually fully *read* the original post before I answered it and tried to be helpful.? ?I bet Chuck is right - Indium is commonly used in vacuum environments.? ?It's a good gasket material (RF and vacuum gaskets in a pinch).
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? There's an awareness about Cadmium that is likely to have prevented its use in anything more modern (last 20 years of so?).? Lead is a no-no in high-vacuum systems.? I has a high vapor pressure.? You don't even use brass since the lead will outgass at temperature.? ? ? How was the indium (or whatever it is) bonded to the ceramic?? ?Try melting it on a hot plate to determine its melting point and maybe scrape up enough to measure specific gravity.?? ? Don't rule out bismuth or tin either.? Try a flame test.? I just googled Indium (Flame Tests) and found this: | | | | | | | | | | | Flame Tests Dave Barthelmy Listing of Flame coloration which can be used to identify elements in minerals. | | | | In | The element?Indium?is named for the prominent blue lines in its spectrum. | On Sunday, December 2, 2018, 10:57:55 PM EST, Chuck Harris <cfharris@...> wrote:
<> -Chuck Harris John Griessen wrote:
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Chuck Harris
Indium solders just about anything that can stand the
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temperature. It is commonly used to solder glass to glass, in lasers. It also solders glass to ceramic, and ceramic to a variety of metals. Because it is soft, putty like, it gives a little, and accounts for variations in expansion rates of different metals. AFAIK, it is not poisonous, as it is commonly used in the alloys used in dental crowns. Its vapor pressure is very low, with its boiling point being over 2000C. -Chuck Harris Daniel Koller via Groups.Io wrote: Yeah, and now I eat crow because I didn't actually fully *read* the original post before I answered it and tried to be helpful. I bet Chuck is right - Indium is commonly used in vacuum environments. It's a good gasket material (RF and vacuum gaskets in a pinch). |
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hi
you could try to dissolve, or soften at least, a little bit of it in kerosene, WD-40, or contact cleaner¡ some kind of organic solvent. If it softens but doesn't all dissolve, it is some kind non-metallic material, with maybe a metal filler...like heatsink compound. If it is Wood's metal, or Gallium, it is going to melt pretty quickly in boiling water...or near boiling water. Basically, it will look like a little blob of mercury, at those temperatures. (Don't heat it directly...see below!) Different amalgams of mercury, have different physical properties. Mercury lead can form a brittle solid.. about the composition of a cookie. Mercury cadmium is similar. But in plastic, or pasty form (lots of liquid mercury in the mix)¡ I don't recall them being sticky. If it is an amalgam... as long as you have ventilation, don't smear it on your skin... or especially don't eat it or heat it strongly so the metal boils... then you should be fine. The solid or liquid forms of these metals/amalgams have low vapor pressures, unless you strongly heat and boil them. The vapor/gas is very dangerous, when inhaled. If its an amalgam, sweep up, or shovel up any contaminated areas, without raising dust...into a doubled up clear plastic bag(s)¡ and dispose of it as you would batteries (how every you do that locally.) If its organic...like thermal paste...it could have a metal filler like aluminum, or silver; but, I don't think they use cadmium, or mercury amalgams for fillers. I'm not sure how to dispose of thermal paste... other than to dispose of it the way you do solvents and paint. I guess, if one doesn't want a toxic surprise, and is scrapping, or recovering parts from scientific, medical, or industrial equipment, it might pay to know what to expect. My neighbor smashes microwave oven magnetrons, for the aluminum, even though I told him berylliosis is very serious. |
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in the implant refurbish business we used an elastomer for the platens. Under some conditions it turned hard, some other materials were indium. depends on who made the platen and when. contaminated- most likely not, although depends on the ion being spewed......just use gloves and do not breath the stuff. masks not necessary.
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¸é±ð²Ô¨¦±ð On 2018-12-02 3:20 p.m., Chuck Harris wrote:
Why do you think it is metal? Is it shiny in a way |
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hi:
Indium... at least mostly pure Indium (not an allow) is very shiny...it doesn't tarnish in air... they used to use it for the reflectors in headlights. At room temperature, it is soft, and it cuts¡ but, it isn't sticky. It also cries when you bend it. There are Indium/lead solders, for soldering to gold...and alternative to tin/lead that leeches the gold plating. Also, I seem to recall, Indium...or Indium/Gallium alloys wet glass, and leave a mirror like surface. They use Indium in vacuum gaskets; but, usually those are shaped like O rings, or like copper gasket on spark plugs... the Indium flattens and seals under pressure. Anyway, Indium won't melt in boiling water. You can do a flame test... usually its a paste of the metal sample and hydrochloric acid, dipped onto a platinum wire, in a non-luminous flame...like a propane torch flame... natural gas in the lab. Pure Indium isn't known to be toxic; but, the solder alloys (with lead) probably are. I've seen rubber (Buna), fluoropolymers, silicone rubber, Teflon, gold, copper, and Indium gaskets, in vacuum systems. |
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As noted by other posts, it may be indium. If so, it¡¯s melting point is 313F (easily reached in an oven). It has a very low vapor pressure (also noted) so it is suitable to high vac systems. Typically used for soft metal seals and thermal transfer joints. It¡¯s Young¡¯s modulus is 11GPa (similar to wood!) so it deforms easily, fills voids and contours even at low temperatures. It will wet many metals, so maybe it is there as a thermal conductive layer.
If it is indium, it will talk to you (squeak) if bent by the ear. Something to do with crystal migration. Kjo |
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Hi,
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Indium is also used by the Vandervell Co. for their tri metal copper lead engine bearings as the overlay to the copper for the actual bearing surface. The US uses lead as the overlay but the English/Vandervell process used lead/indium and hold the patent for it. The lead/indium is a better bearing surface. Jim O On December 2, 2018 at 11:37 PM Roy Thistle <roy.thistle@... mailto:roy.thistle@... > wrote: |
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I have a 250g ingot of pure Indium. It was purchased during the developement phase of a 500W Band II amplifier module, to see if it could be formed into thermally-conductive washers (RF transistor flange to heatsink interface). The answer was no: despite being very soft, it was not soft enought to flow at the pressures involved in bolting down the transistors. Gram for gram it's close to silver in cost. Perhaps I should make up some solder for use on gold connections?
John |
John Sykes
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