Microwave Hybrid Heating (MHH): Innovative and novel heating technology for industrial sintering furnaces. From lab-scale to prototype furnace

摘要

The sintering process is one of the most critical stage of ceramic processing. In order to avoid damages due to thermal stresses, a precisely controlled homogeneous heating is required. The optimised combination of microwave heating and gas firing - called microwave assisted sintering - should be a suitable way to prevent or reduce the thermal stresses throughout the sintered material. However, the combination of these two energy sources represents a technological challenge. It is obvious- that the furnace components, burners but also thermal insulators should not or nearly not absorb microwaves within the sintering temperature range (20-1600 deg C). For high temperature applications, the conventional furnaces are generally equipped with SiSiC (silicon infiltrated silicon carbide) burners. However their use in microwave furnaces is up to now restricted to only few laboratory studies. The low electrical conductivity of SiSiC materials should permit their application in microwave fields. Nevertheless, some microwave absorption can not be avoided. The resulting power loss may be minimised by reducing the total mass of the absorbing materials, especially the insulators. This paper discusses these above mentioned technological problems. Adequate materials will be investigated and selected in an already established lab-scale hybrid furnace. These preliminary studies will allow for the further design and development of an industrial prototype.