CONVENTIONAL AND MICROWAVE SINTERING OF CONDENSED SILICA FUME

Condensed silica fume, a by-product from the production of silicon all oys, was sintered by (i) conventional heating in a dilatometric furnac e, both at constant heating rate and isothermal heating, and (ii) by t he microwave heating. The dense products with relative density up to 9 5% of theoretical can be obtained only by short runs at high heating r ates, preferentially accomplished by the microwave treatment. Prolonge d heating leads to the devitrification of the original glassy phase to cristobalite, accompanied by an arrest of densification.