John Wong wrote:

The purpose of this experiment is to determined the limiting operating temperature for Beta-SiC.  To do so, samples will be heated in sequence to observe any volatile Si coated on the window.  The coating is observed above 1400C for the conventional SiC (mixuture of alpha and beta) and this coating leads to HV shorting problem.  Thursday, May 19, 2016, 14:26 Beta-SiC (size ~1um) slurry was prepared and casted on a graphite foil.  Discs are cut into D-shape Average thickness (including graphite foil) = 0.349mm Graphite foil = 0.13mm Actual SiC thickness = 0.219mm (close to normal SiC thickness) Samples are loaded into a target boat. Total discs = 120 Total mass = 14.3507g Thursday, May 19, 2016, 14:32 Omega slope set to = 1.04 Heat-treatment #1: 1400C  Thursday, May 19, 2016, 17:04 TGHT ramping up to 250A at 0.5A/min

 Friday, May 20, 2016, 08:53

IGP1 = 9.2e-6 Torr.

Increasing ramping rate to 1.0A/min up to 250A

 Friday, May 20, 2016, 09:17

IGP1 = 2.1e-5 Torr

TGHT = 215A, 3.1V

OMEGA = 1035C

Stopping auto-ramp and tapping up manually...

 Friday, May 20, 2016, 12:26

OMEGA slope changed to 1.04

OMEGA reached ~1430C and kept there for ~1hr.

no change. no coating on window observed

tapped up manually to OMEGA =1500C

TGHT = 350A, 5.8V

 Friday, May 20, 2016, 14:17

Not much change to window.

Might be beginning of light dusting, hard to tell.

Will be better observed after longer period of time at 1500C

Will remain at 1500C over weekend.