Being sick of using molybdenum, with its extreme oxygen sensitivity, and poring over a periodic table, it looks like Niobium might make a good material for high temperature furnace radiaion shields - up to 1750 C
Does niobium react less with O2 ? I haven't seen anything taht says its worse than moly, and I suspect (only suspect) its better
Would anyone confirm or deny its suitabiility please ?
Thanks !
Steve
It's too bad no one is responding. We use moly in our vacuum furnace and it's always been black. I'd love to find a better substitute.
Even in Vacuum ? No wonder we have been having fun in our "inert gas" atmosphere !
You're right, I'd rather hoped for some more comments.
Steve
This is all that I've been able to find: "THE REFRACTORY METALS include niobium (also known as columbium), tantalum, molybdenum, tungsten, and rhenium. With the exception of two of the platinum-group metals, osmium and iridium, they have the highest melting temperatures and lowest vapor pressures of all metals. The refractory metals are readily degraded by oxidizing environments at moderately low temperatures, a property that has restricted the applicability of the metals in low-temperature or nonoxidizing high-temperature environments. Protective coating systems have been developed, mostly for niobium alloys, to permit their use in high-temperature oxidizing aerospace applications." ASM Handbook Vol. 2, Niobium.
Thats pretty well all I have too. There doesn't SEEM to be any really nasty oxidation phenomena with it, like there is with moly, (MoO3 is particularly volatile, and Mo2O5 is a horrible purple dust) but it does still oxidise.
Steve
Tried it. It was actually pretty successful, I won't say it was bright after being fired at 1750 C, but it was pretty darned good. I can send you a picture if you are interested.
It DID go incredibly brittle though - more than our moly.
I don't know if there is a lanthanated version yet, it might help the recrystallisation problem.
Steve
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