I’ve recently come into possession of a fair quantity of old lab
furnaces, kilns, pyrometers, temp controllers, etc. Some of the
pyrometers are type R and type S and some of the wire is marked for
use only with platinum / rhodium pyrometers, most of the wire is
unmarked. I suspect that some of the hookup wire is in fact platinum
and platinum / rhodium but I’m not certain how to positively identify
it. The interesting stuff is the wire with green or gray insulation.
It does melt using oxy/propane, but with difficulty and never exactly
flows per se. It does retain a shiny surface after heating.
Any specific tests I could be doing to determine the makeup?
Pt thermocouple wire tends to ball up when you heat the end with oxy
acet or oxy propane. The amount of Rh in the other wire is typically
10% so it scraps as platinum with most refiners.
The common alternatives are nichrome alloys but they are quite dull
in comparison, not bright like the Pt wires. They are not as ductile
as Pt either.
Platinum OR an alloy of it with rhodium will heat up to a brilliant
white heat inair and when it cools it will look like nothing ever
happened to it. You can melt it with propane/oxygen but your eyeballs
will be burned out of your head without welding goggles, before that
happens. Beyond that, I don’t evn know what a lab would do, in
detail, to detect a rhodium alloy. Certainly there is nothing you can
do in a typical shop oreven an atypical shop. That’s big time
assaying and refining stuff. Detecting platinum or “other” is about
as far as you can go. Determining what the other is is possible,
maybe.