Basic properties of clay mineral raw materials and their influence on the microstructural formation during sintering

The goal of these examinations was to influence the sintering of technical porcelain through the specific use of different clays. This should result i n lower vitrification temperatures and the elimination of residual quartz, which poses a number of drawbacks in the technical properties. The comparat ive inspection of the various clays shows that the basic properties, with r espect to the occurrence of different clay minerals, play an essential role . Notable advantages were seen in higher amounts of three-layer minerals wi th lattice defects through the considerable inclusion of alkaline and alkal ine earth ions in the lattice structure. Thermoanalytical examinations and heat expansion curves of pre-fired clay samples made the benefits clear. SE M images of the microstructure confirm the results. Sintering processes occ urred earlier with a lesser but more aggressive melt phase. Vitrification a t lower temperatures is thus possible, and the residual quartz is almost co mpletely dissolved, with the benefits of the foreign ions built into the la ttice structures of the clay mineral apparent.