SURFACE PRECIPITATION ROUTE FOR THE DEVELOPMENT OF CORDIERITE ZIRCONIA COMPOSITES

Based on the interfacial electrochemical properties of aqueous cordierite dispersion, a novel interfacial scheme for fabricating cordierite-ZrO2 composite with a dense and homogeneous microstructure was proposed and tested. In the present processing route, cordierite particles were first uniformly coated with a thin layer (similar to 40 nm) of aluminum hydroxide by an in situ surface-induced coating. Then, a controlled surface precipitation of ultrafine zirconium hydroxide precursor onto the coated cordierite particles was performed to obtain a composite with a uniform spatial distribution of the dispersed ZrO2 particles throughout the matrix. The coated layer acted to suppress the formation of zircon phase during sintering. The enhanced fracture toughness observed in the presence of ZrO2 was partly attributed to the t --> m transformation toughening of the dispersed tetragonal ZrO2 particles.