Niobium at High Temperature environment

[KKYT]

Hi All,

I was told that pure niobium coating is not recommended to be used at high temperature in open air environment, because it will form niobium oxide and white smoke will form. How does it happen, and what exactly does it mean? Does it mean the purity of the niobium coating will be reduced over time? Or would that niobium oxide containminate the material in surrounding? (FYI... the idea is to coat a layer of pure niobium on a steel tube which will carry molten alumium at about 700C).

Thank you in advance!
KKYT

 

[btrueblood]

I know Tantalum will go away (oxidize itself to destruction) at that temperature, and supposedly it is more resistant than Nb, so, I would say yes. And yes, the oxide (if in vapor form) will deposit (smut) on surrounding colder surfaces. If done in thin layers, it can make some really pretty diffraction colors...

 

[KKYT]

Thank you, btrueblood.