Mechanical properties of zirconia toughened mullite composites fabricated by slip casting

The main objective of this article is to obtain polyphasic ceramics belonging to the Al2O3-SiO2-ZrO2 system by reaction sintering of zircon, alumina, kaolinite and colemanite powder mixture was explored in this work. In addition, the study focused on low temperature synthesis and the mechanical properties of ZTM improved as expected following the addition of boron minerals such as colemanite (Ca2B6O11 center dot 5H(2)O). The effects of sintering temperature, solid concentration of the prepared suspensions and colemanite additive on the mechanical and other properties of mullite-zirconia composites were investigated. Green compacts were made by slip casting of stabilized aqueous suspensions with and without colemanite additive after which reaction-sintering was applied at temperatures ranging between 1450 to 1550 degrees C under different firing conditions. The resulting sintered materials were characterized in terms of bulk density, XRD and SEM and and mechanical properties such as flexural strength, elastic modulus, hardness and fracture toughness. It was observed as a result of a comparison between the mullite-zirconia composites prepared via slip casting and studies in literature from a mechanical standpoint that composites in literature have yielded similar results in terms of mechanical properties. Mullite grains in composites formed a nearly continuous phase in which zirconia grains were distributed yielding better mechanical and fracture properties.