STEREOLOGICAL OBSERVATIONS OF PLATELET-REINFORCED MULLITE-MATRIX AND ZIRCONIA-MATRIX COMPOSITES

Recently, the effect of solid inclusions on the sintering of ceramic p owders has been explained in terms of a ''backstress'' that opposes de nsification. Several analyses have been proposed to describe this prob lem, However, little quantitative information exists concerning the ef fect of reinforcement on microstructural evolution. This study compare s the microstructural development of zirconia and mullite matrices in the presence of alumina platelets. The effect of platelet loading on d ensity is similar for both composites. Quantitative stereological exam inations reveal that the average grain size and pore size are finer fo r the zirconia-matrix composite. The platelet-loading does not have an y noticeable effect on the average grain size of the matrix in either composite, However, the average pore size increases as the volume frac tion of platelets increases for both materials. Contiguity measurement s have detected some aggregation of platelets in the zirconia-matrix c omposite.