The resulting compacts were heated from room temperature
to 600 1C in 5 min and were then heated to the desired
temperatures (1500, 1600, and 1700 1C) at the various heating
rates (30, 50, 100, and 200 1C/min). The compacts were
maintained at the desired temperature for 10 min before the
power was turned off. Temperature monitoring during sintering
between 600 1C and the final sintering temperature was
carried out using an optical pyrometer, focused on a hole on
the surface of the carbon die