On the other hand, the presence of 10 vol% of zirconia seems to slow grain growth. The alumina platelets of the AP sample appear coarser than the platelets of the AP-Zm and AP-Zt samples (FIGURE ), which were sintered under the same conditions, i.e. up to 1450°C, up to 40 MPa and without glass phase (FIGURE ). In addition, the AP-Zt-HP sample was sintered at 1450°C and 80 MPa and does not show a coarser microstructure, yet for similar sintering conditions and without zirconia, coarser grains have already been observed .