PERMEABILITY OF THE ELECTROCERAMICS TO GAS AND ITS DEPENDENCE ON THE FIRING TEMPERATURE

Permeability and porosity of electroceramic material (50% kaolin, 25% quartz, 25% feldspar) were measured after firing at temperatures of 20 -1300 degrees C. Experimentally it was found that the permeability (me asured by means of the penetration of the pressed air through the samp le), caused by dehydroxylation, increased by 37%. The porosity (measur ed by the pycnometric method) increased by 6%, which is in agreement w ith geometric calculations. The value of the permeability is explained by creating the micropores in metakaolinite. (C) 1997 Elsevier Scienc e Limited and Techna S.r.l.