Sunday, April 07, 2019, 08:10

A graphite insert (with conical caps) was loaded in tantalum tube previously coated with TaC,

and wrapped with 3 tantalum foils,

a tanalum cap was inserted in one side of the Ta tube and sealed.

The tube was set in the EVAP2 and the furnace was pumped down.

IGP1 = 1.24e-7 Torr.

The current was tapped to 40 A

Autoramp was set to 1 A/min to 300 A.

At TGHT 335.53 S, 5.28 V the temperature was 1560

The autoramp was set to 450 A.

At TGHT 474.75 S, 7.96 V the temperature was 1560

The autoramp was set to 450 A.

To reach 2000 C, TGHT = 500.25 A, 8.45 V.

After 1hr the temperature stabilized to 1959 C

and the  current was increased to TGHT = 510.28 A, 8.64 V.

After stabilization the temperature reached 2010 C.

The current was decreased to TGHT = 503.15 A, 8.45 V

and the temperature stabilized to 2001 C.

The voltage increased  unexpectedly to 8.89 V and the temperature increased to 2055,

the current was reduced to keep the tube at 2000 C.

The voltage kept increasing and we kept decreasing the current to keep the tube at 2000

The final current before venting and getting out the container was

TGHT = 466.219 A and 8.467 V.

Test result: Broken tantalum tube.