Preparation and properties of the ZrO2-dispersed MgO-Al2O3 ceramics .3. Influence of MgO-Al2O3 composition

ZrO2-dispersed MgO-Al2O3 ceramics with various MgO to Al2O3 compositional ratios were prepared from Mg(OH)(2) powder, alpha Al2O3 powder and Zr-n-butoxide by calcining at 1000 degrees C for 2h and sintering at 1600 degrees C for 1h. The influence of the MgO-Al2O3 compositional ratio on the sinterability and mechanical properties was studied. Addition of 10 vol% ZrO2 improved the relative density of the sintered specimens containing 50 and 62.5 mol% Al2O3. However, the addition tvas not effective at other compositional ratios. The bending strength was improved at composition containing more than 50 mol% Al2O3, where the dispersed ZrO2 particles were in the form of tetragonal phase. The bending strength increased with increase in Al2O3 content in the ZrO2 dispersed specimens. The fracture toughness was improved for all specimens by ZrO2 dispersion, especially, for the specimen in which MgO-Al2O3 component was in a single crystalline phase.