Batch Process for Microwave Sintering of Si3N4

Abstract

ABSTRACTA method for sintering silicon nitride using microwave energy at 2.45 GHz is described. Sintering takes place in air, in times of between 30 and 120 minutes and has been scaled up to give isothermal conditions over a batch size of 150 mm diameter by 200 mm in height and weighs approximately 1.0 kg. Additions of 5% alumina and 5% yttria result in a sintered product density of approximately 97% of theoretical, with a density variation better than:±0.5% throughout the batch.It has been estimated that a load of 7.0 kg can be conventionally sintered using a 12 hour cycle and an energy consumption of 19.7 kWh/kg. In contrast with microwave energy, a batch of 540 g can be sintered in 120 minutes with an energy consumption of approximately 3.1 kWh/kg. This results in a possible energy savings of up to 78% for microwave heating.