Abstract
It was demonstrated that neither direct observation of neck growth nor measurements of the shrinkage of composites can be applied to establish initial stage sintering kinetics for RuO2 in the presence of glass. Three secondary measurement techniques (microstructure determination, X-ray line broadening, and surface area measurements) were employed and results were shown to be consistent among the three techniques. Studies of the ripening process whereby large crystals of RuO2 grow in the glassy matrix uncovered a strong chemical interaction between the glass and the alumina substrate which significantly influences the rate of the ripening process. In particular, the substrate tends to inhibit the growth of RuO2 crystals, which is a desirable situation if the conductive network is to be preserved.