Monday, July 13, 2015, 11:53

A Ta foil is placed in the target boat with separate slots for each endcap [same as elog 200]

The target boat is wrapped with 3-layers of Ta-heat shield.

The boat is installed in EVAP2, chamber is currently being pumped down.

 Monday, July 13, 2015, 15:00

Opened HS water valves, no leaks detected.

IGP1 = 2.7e-6 Torr.

Tapping up manually.

 Monday, July 13, 2015, 15:41

Tapped up manually to 30A

TGHT = 30A, 0.05V

IGP1 = 7e-6 Torr.

Initiating auto-ramp at 0.2A/min up to 480A with a final desired temperature of 1800C

 Tuesday, July 14, 2015, 09:12

IGP1 = 7.8e-7 Torr

TGHT = 241A, 3.3V

OMEGA = 1010C

Increasing auto-ramp to 2.0A/min

 Tuesday, July 14, 2015, 11:12

Reached final setpoint of TGHT = 480A, 8.43V

OMEGA = 1667C

IGP1 = 3.3e-6 Torr.

Tapping up manually to reach final desired temperature of 1800C.

 Tuesday, July 14, 2015, 11:33

Reached TGHT = 500A, 8.8V by tapping up manually.

OMEGA = 1714V

IGP1= 3.5e-6 Torr.

Re-initiating auto-ramp at 2.0A/min with a final setpoint of 580A.

New final desired temperature min of 1900C

 Tuesday, July 14, 2015, 13:16

TGHT = 577A, 10.74V

OMEGA = 1938C

IGP1 = 3.2e-6 Torr

Endcaps have been at this temperature for just over an hour.

Spikes in vacuum started ~430A - this is due to the green TaC coating reacting with the Ta foil, the carbide is reacting directly with the Ta foil [see picture]

Stopping sintering early before endcaps break -> initiating auto-cool at 2.0A/min.

 Wednesday, July 15, 2015, 11:33

Vented in air and took out this morning.

Endcaps sintered on top side but not fully sintered on inner edge.

Inner edge is peeling off and unsintered green TaC.

The coating peeling off did not shrink, as seen with previous tests done, one would expect a shrinkage in the coating when heated.

The peeling is most likely due to the way to endcaps were placed  in the slots of the Ta foil.

This may have cause the foil to be hotter than the inside of the endcaps and subsequently the Ta foil and TaC coating on the inside reacted - with the Ta foil extracting the carbide from the coating.

This would cause the outer edges of the inside of the endcap to peel/curl inwards as it was heated [like a cast, as the cast dries the outer edges curl inwards].

See photos attached for clarification.

Endcaps will be re-coated and sintered again via a different procedure.