Sintering behaviour of steatite materials with barium carbonate flux

Steatite porcelains show excellent properties for insulating applications. New applications as small insulators for halogen bulbs lighting for instance, place increasing demands on material performance. The purpose of this work is to study the sintering behaviour and microstructural development of steatite ceramics formulated with BaCO3 flux. Both constant heating rate and isothermal sintering experiments together with microstructure characterization have revealed important differences related to the presence of BaCO3 and different amounts of clay. Increasing the amount of clay leads to higher vitreous/crystalline phase ratios but also to smaller grain sizes. This result is interesting because of the relevant role played by the grain size for the protoenstatite to clinoenstatite transformation, which in turns is the origin of material aging and degradation.