Patent ID: 6344634
Filing Date: 2002-02-05
Classification: C04B,F27B,F27D,H05B

Abstract:
A method for firing a ceramic material comprising:placing the ceramic material in a microwave heating apparatus having a microwave cavity and subjecting the ceramic material to combination of microwave radiation and conventional heat energy according to predetermined time-temperature profile, the time-temperature profile comprising a series of target heating rate temperature setpoints and a series of corresponding core and surface core temperature setpoints with each of the core and surface temperature setpoints being offset from the target heating rate setpoints by a predetermined offset temperature; continuously measuring the ceramic body core temperature, TC, and the surface temperature TS and controlling the microwave power and the conventional heat in the following manner: a) the microwave power is adjusted in response difference between the core temperature setpoint and a biased core measured temperature, TBC, the biased core measured temperature calculated according to the following formula, TBC=(xTC+yTS)/(x+y), wherein x is greater than y; b) the amount of conventional heat is adjusted in response to the difference between the surface temperature setpoint and a biased surface temperature, TBS, the biased surface measured temperature calculated according to the following formula, TBS=(xTS+yTC)/(x+y), wherein x is greater than y; continuing to deliver and control the microwave power and the conventional heat until the ceramic body has at least reached is sintering soak temperature.