Thursday, August 06, 2015, 15:36
The endcaps are stacked together with a punched out disc of graphite foil placed in between each endcap for separation so endcaps won't fuse together.
The end caps are further wrapped in a larger piece of graphite foil to hold together as a tube [same method used in elogID # 158]
There are two separate tubes in the target boat:
1) endcaps coated with TaC coating - never been sintered
2) previously sintered [but not fully] endcaps with a second coating done on the one side of each endcap
The boat is wrapped with 3-layers of Ta heatshields.
Chamber is currently being pumped down.
Friday, August 07, 2015, 08:45
HS water valves opened, no leaks detected.
IGP1 = 3.6e-7 Torr.
Tapped up manually to 30A.
Friday, August 07, 2015, 11:23
IGP1 = 2.2e-6 Torr.
Vacuum stable.
Initiating auto-ramp at 0.2A/min with a final setpoint of 480A.
Will ramp up over the weekend, confirm temperature readings on monday and tap up to final desired temperature of 1800C manually.
Friday, August 07, 2015, 13:04
Vacuum climbed quite fast.
IGP1 = 6.3e-6 Torr.
Stopped auto-ramp to allow vacuum to settle.
Waited ~1hr.
IGP1 = 4.3e-6 Torr.
Re-initiating auto-ramp.
Monday, August 10, 2015, 09:22
TGHT reached 480A, 8.2V on the weekend.
OMEGA = 1708C
IGP1 = 3.8e-7 Torr.
Tapped up manually to 1803C, 520A, 9.0V
IGP1 = 5.9e-7 Torr.
Monday, August 10, 2015, 14:50
EVAP2 remained at 1800C for 4.5hours.
Internal temperature taken at new window port read 1800C using the mikron.
Initiating auto-cool at 2.0A/min.
Tuesday, August 11, 2015, 09:23
Vented in air and opened up this morning.
The following observations were noted:
1) single round sintered endcaps:
-Batch of green endcaps, single round of sintering look good. fully sintered.
-however when applying a scratch test, excess TaC scrapes off.
[see single round sintering photos]
2) Re-sintering of batch from july 14th
-Outside of endcap [concave side] was re-coated, Inside of endcap had good first coating - therefore no second coating applied [see photos from elog ID#230]
-A few endcaps almost heated too long and started to appear brittle/ further crystallization on inside of endcap - the side that did not have a second coating applied.
-Outside of endcap looks good/ fully sintered - the side that had a second round of TaC coating
-further tests confirm this batch should still be okay to use
[see round2 batch photos]
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