On the microwave sintering technology for improving the properties of semiconducting electronic ceramics

Microwave (millimeter wave) sintering technology used for enhancing the densification behavior and electrical properties of ZnO electronics ceramic materials was described. Successfulness in application of such a novel technique to sinter ceramics relies heavily on the microwave (millimeter-wave) absorption efficiency of the materials. Semiconducting oxides such as Bi2O3-doped ZnO materials perform satisfactorily in microwave (millimeter-wave) sintering. Using susceptors to facilitate absorption efficiency of the samples greatly improves the sinterability of the materials. The advantage of the microwave (millimeter-wave) sintering process over the conventional sintering technique is best demonstrated by fast firing of Bi2O3-based ZnO varistor materials, in which, the whole sintering process required only 18 min. The varistor characteristics obtainable are: α=38, JL=55.5×10−6 A/cm2 and Vbk=600 V/mm.