Effects of Ca-, Mg- and Si-doping on microstructures of alumina-zirconia composites

摘要

The aim of this work was to obtain zirconia toughened alumina composites with different microstructures, using a simple process (powder mixing and natural sintering). Adjusting the amount of zirconia directly controls the size and localization of zirconia grains and the size of the alumina grains. Doping the composite with CaO, MgO and SiO_2 allows further control of the microstructures. The influence of the thermal treatments is also investigated. The composites exhibit different structures (nanoano-, microano- and micro-composites) with zirconia and alumina grains as small as 100 and 200 run, respectively, and with the proportion of intragranular zirconia grains varying between 0% and 90%. Zirconia plays amajor role on grain size distributions as compared to CaO and MgO, whose role is almost negligible. The use of SiO_2 leads to microano composites with intragranular zirconia particles. The influence of these different additions is related to adjustments of the grain boundaries mobility.