Q: I’m looking to get some 1/2″ hex head screws that can survive up to 2000C. It is not a vacuum, but it will be in an inert environment.
A: In regards to ceramics, Zirconia screws would be the only option for these temperatures, but unfortunately a 1/2″ diameter is too large to produce from Zirconia. Probably your best bet in this environment would be a tungsten or tantalum screw. A vacuum or inert environment is fine for for tantalum or tungsten metals at 2000C, as long as there is no oxygen present.