Identifying metals?

One recurrent theme in this NG and in the mags is how to
identify an old piece of metal from the scrap bin.
ISTR from my school chemistry days that there were certain
flame tests that could be conducted, and also that Tubal Cain's
book gave an estimation for types of steel based upon their
being ground (grinded?).
Is there a simple way for us to identify the content of metals,
perhaps based on an old Lott's or Merit chemistry set?
Or should we consider using the power of our home computer
systems to perform X-Ray crystallography. ("The Boy Electrician",
1941 edition details making an X-Ray generator, as did an old
Scientific American, based on using EL34's or similar)
Reply to
Airy R. Bean
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As about three-quarters of metals are FCC, please explain how you would use XRC to determine what metal(s) are present in a sample.
When you've done that, please explain what else you would need - beside your home computer - to carry out such a determination.
Then, indicate the sorts of things that would go into your risk assessment in ordere to inform you of what safe practices you would need to perform.
You are a troll, AICMFP.
Reply to
Binary Era
For steels the spark test (grinding) is quite effective. To tell quantatively though is rather hard.
Modern scrap sorting is done by Optical Emission Analysis - see this link for the Metascop:
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I have an older version that forms an arc against the sample and lets you visually see the spectrum line by line and work out what's there - again not very accurate quantatively but fine qualatively if you have the time.
The flame test that you mention is really doing the same thing - heating the sample to let it radiate so you see the characteristic colour of the metals. Green for copper, white for zinc etc. Trouble is almost everything gets contaminated with sodium and looks yellow !
Andrew Mawson
Reply to
Andrew Mawson
Indeed, something of a Airy Brained idea.
Metals are generally analysed by:
1. Emission or absorption spectrometry techniques 2. Chemical analysis techniques (salt formation, that is using salt in the generic sense not he stuff you sprinkle on chips, metal deposition etc) 3. Some mechanical tests to determine hardness. 4. Possibly electron microscope use 5. For the steels, carbon and sulphur content is determined by burning in a gas I can't remember the name of (hex something). 6. Electrolysis techniques.
X-rays are used to spot fatigue cracks etc, but not chemical composition.
Do model engineers use that wide a range of metals- I'm familiar with the problem from the aircraft industry where there is a multitude of aluminium alloys. Do models engineers have a similar problem?
Reply to
Brian Reay
I wonder whether the two posters quoted below intended to make a meaningful contribution to the discussion, or intended to continue their rather infantile and silly obsessive trolling habits together with their alternative agendas of malice and spite and at the same time demonstrate a sense-of-humour failure?
With broomstick-up-the-bum attitudes such as these two demonstrate, is it any wonder that education standards are falling so low and that, for example, why the traditional technical pursuit that is Ham Radio is degenerating into a mire of untechnical turnip-brains who sneer 'n' jeer at every technical query?
Grow up, stupid boy and stupid girl!
Reply to
Airy R. Bean
A worthwhile topic to pursue - thanks for the link.
Reply to
Airy R. Bean
Staying with 'modeling', there are a few areas that cause confusion:
Discriminating between brass, gun metals, bronzes, and sometimes copper alloys (beryllium copper for eg.,) Between stainless and non-stainless alloys (magnetic properties reveal autenistic stainless steel, but there are magnetic stainless alloys). Between different carbon steels (tool steels - HSS, carbon steel)). Between heat-treated or hardened steels (is it hardend throughout or case-hardened?). Between alloy steels of unknown parentage (e,g,. leaded, mild steels).
You can find metals from most of these broad catagories somewhere in a typical loco, and it's fine if you have bought new metal stock and know exactly what you have. If you are less than careful documenting your metal storage, or you have aquired scrap metal, it's useful to know how to identify just what you have.
The spark test is probably the easiest for ferrous metals, experience helps with the non-ferrous stuff (just looking at it and rubbing a file across it).
ChrisH
Reply to
ChrisH
Serious points have been raised. Your response strongly indicates that your proposal is a troll, and that you did not intend to undertake a technical discussion. You have descended into childishness at your first response. Shame on you.
Reply to
Binary Era
Bean proposed using his home computer and an EL34 valve to perform XRC analyses.
Niton's portable XRF analyser is far removed from this, and the technicque is completely different from XRC. They claim to be able to determine Fe, Ti, Cu, and Ni based alloy identification, while 'other bases may be available on request'.
This strongly suggests that databases are used, something that Bean's original proposal rather forgot to account for.
Reply to
Binary Era
The copper sulphate test with visual checks is pretty crude but very easy to carry out and gives some clues to identity. Pehaps some chemist can tell us the best formulation - I use something near a saturated solution plus a few drops - maybe 1% total of battery acid. Metal is abraded shining clean and the solution wiped on with a tuft of cotton wool on the end of a stainless steel rod.
Iron and common steels Almost instant thin copper plate. Magnetic Unless protected there will be some degree of rust. Mild and low alloy steels grow a fairly uniform coat. If exposed for a long time high carbon steels degenerate to a deeply pitted surface.
HSS Copper plate but slower to form Magnetic and file hard Clean or pretty light rust. In bad cases light pitting.
Stellite No reaction Non-magnetic and file hard Rust free
Austenetic Stainless Steel No reaction Non or very weakly magnetic and not file hard Rust free
Martensic and Ferritic Stainless Steel No reaction Magnetic Rust free Some alloys are heat treatable and may be file hard
Zinc alloys Almost immediate dense black
Aluminium alloys No reaction
Magnesium alloys Purple black Exposed unprotected surfaces usually show some white corrosion
Not a very complete or unambiguous list but useful for quickly distinguishing between stainless and non stainless also between aluminium alloys and magnesium or zinc.
Jim
Reply to
pentagrid
< crap snipped >
"Power of our home computer systems"? Do you mean the CMOS backup battery? ...(_!_)...
Reply to
Frank Turner-Smith G3VKI
Seems to me that both of the posters you criticise have made a valuable contribution to the thread. You have, again, been shown to be a technical know nothing. You don't like that, do you?
Tell us about Westinghouse.
Reply to
Gareth S Nemisis
As we've come to expect of Gareth.
Reply to
Gareth S Nemisis
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Reply to
Bill
Your response is itself a troll and is wasteful of others' time and attention. You contribute nothing to the NG nor the discussions therein.
Stupid boy.
Reply to
Airy R. Bean
Serves me right for not following the standard advice of:
Don't feed the Troll
Reply to
Bill
Once again, your remarks contribute nothing to the discussion thread and are a continuation of your random and unnecessary ad hominem attack.
It is not clear as to why you have started such a pointless side-track. I do not think that it is for the benefit of the readers as whole.
If there be any trolling, it is coming from you.
Stupid boy.
Reply to
Airy R. Bean
[...]
My wife's a meteorite geologist, and a few months back came home from a trade show excitedly holding a brochure for a device called a TOF-SIMS, which is apparently a 'time of flight ion spectroscope'. According to the brochure, this machine can analyse a sample to give you the percentages of various elements in it - in three dimensions; it scans accross the surface and (somehow) probes down into it, too. They had pictures of scans of things like TFT screen pixels and transistors on microchips, showing the internal structure in 3D.
Costs a few million to buy the thing, of course...
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ABS
Reply to
Alaric Snell-Pym

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