The purpose of this experiment is to improve the TaC coating mixed with other metals as additives. The coating solution will be sprayed on Ta metal (0.015" thick, same thickness as the target container).
The samples will be sintered at ~ 1800C. Once the process is completed, a graphite tube will be inserted into the tube, and then re-heated it up to 1800C.
This test will show how good the protective layer to prevent the graphite to react with the Ta metal.
Wednesday, November 06, 2013, 17:11
Step #1
Two samples:
1. A short tube (same diameter as the usual container)
2. A cross section of the tube.
Both samples are coated with the TaC matrix spray:
0.05 moles TaC
0.005 moles of Mo2C, VC, Cr3C2, NbC
A Rh foil is used as a protective under layer.
see links for pictures: https://www.dropbox.com/sh/866zsp44nnjeg2z/LqCThu-G_0
The target boat is wrapped with 3 layers of heat shields.
Samples will be heated up to 600A ~1800C
Chamber is currently being pumped down.
Friday, November 08, 2013, 17:13
Chamber was pumped down to ~2e-6 Torr. HS water valve is opened and no leaks were detected.
TGHT will be ramped up to 580A at 1A/min.
Monday, November 11, 2013, 08:10
TGHT has reached to 580A; samples has been heated at that current for over the weekend.
IGP2 currently at 3.5e-7 Torr.
Auto cooling initiated, ramping rate at -2.0A/min.
Step 2:
The coated tube is sintered with TaC-matrix.
The graphite tube is inserted in the tube and will be heated back up; see link for details:
https://www.dropbox.com/sh/ji0rhlj0v1tfj1w/cRv1I3VJXE
Chamber is currently pumped down to 1.8e-6 Torr.
TGHT will first be ramped up to 450A (1A/min) to see how the reaction behaves, then a caution ramp up to 600A will take place.
Friday, November 15, 2013, 11:04
TGHT reached to 450A. Cooling down to 0A. Chamber will be vented for inspection.
Monday, November 18, 2013, 17:22
Continue Step#2:
The sample looks ok after heating at 450A.
Re-heating it to 500A.
Chamber has been pumped down to 4.0e-6 Torr.
Initiated auto-ramping...
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