how to detect 18/10 stainless steel...or another simple additive

May 12, 2013 8:30 AM

i am looking for a way to electronically detect 18/10 stainless steel - only. or preferably, (metallurgists please step forward) to include an easily electronically detected additive to the creation of 18/10 stainless.

i know that metal detectors will create an electrical field in stainless steel, and that they can be dialed in to discriminate between certain types of metals. however, i am looking to design a detector that will only pick up one type of metal (or metal additive) - ever. instead of trying to dial in a machine to only react to an electrical field generated by 18/10 stainless, i think the easier path is to incorporate some type of additive to the creation process of the metal. think along the lines of micro tagging your dog, but less micro chip, more elemental additive. in that way, i want to create an alloy that is mine only and can only be detected by my detector. does this exist out there already? can it be done theoretically? i have a basic understanding of metals and metal detection and am not looking to actually build something - only to describe it to someone with enough data to prove it can be done.

posted by ps_im_awesome to Technology (3 answers total)

I think it will be very hard to do this purely electrically, unless you are willing to do it with something like a microchip. If you're willing to add some unusual element (element X, say) to the alloy solely for the purpose of detecting it, it would be easy to identify it by something like x-ray fluorescence spectroscopy, but that would only tell you the presence of element X. If someone wanted to spoof your system, they would just have to add it and you would be fooled. You could also use X-ray fluorescence, or neutron activation, to measure the elemental composition of the steel - that's about as good as you'll get.

Electrically, probably all you can measure are the conductivity and magnetic properties of the metal. You could measure these and try to match to a database of metals, but I doubt it will be specific enough. Maybe you could do something with microwave or terahertz spectroscopy, I dunno.
posted by pombe at 10:02 AM on May 12, 2013

Off the top of my head, the problem from a 'proof' standpoint is that though you could create one alloy to have a specific signature, someone could probably create another alloy to have the same signature. It's not like the current metal detector technology is specifically identifying that there's X element in the metal - just identifying that its properties match a certain alloy, and so 'most likely' is that alloy.

There may be other technologies that give you elemental composition - X-ray Fluorescence, some types of laser/Xray scattering that can give you crystal structure at a level that'd be hard to spoof, etc. But with just electrical behavior all you can get is the electrical properties of the metal.
posted by Lady Li at 10:15 AM on May 12, 2013

I don't know if you are trying to build or buy. I am pretty sure it can be done by an XRF analyzer, like a Niton.

Check this out for an example
posted by ill3 at 10:45 AM on May 12, 2013