Microwave tunnel kiln for ceramic sintering

Summary form only given, as follows. A tunnel kiln heated only by microwaves has been developed. The industrial ceramics are sintered continuously in the roller hearth. The minimum sintering time is an hour which is shorter than the time in the fastest conventional tunnel kiln with electric heaters. The maximum processing rate is 50 kg/hour. The dimensions of the tunnel are 0.3 m /spl times/ 0.3 m cross section and 6 m length of heating zone. The 60 magnetron generates 53 kW in total at 2.45 GHz. The thickness of the double layer thermal insulating wall varied to get a temperature gradient from 500 degC at the entrance to 1300 degC at the top zone along the tunnel axis. The work pieces were carried with the speed at which the temperature of them can synchronize to that of the inner most tunnel wall to ensure the adiabatic thermal insulation criteria. The work pieces would have body heating uniformly by microwave. The kiln will be applicable to many kinds of ceramics just by tuning up the speed or microwave power.