High‐performance alumina composite ceramics with brick‐and‐mortar structure derived from microsphere

Abstract A series of alumina composite ceramics with a brick‐and‐mortar structure were successfully prepared by coating with different contents of ZrO 2 and alumina sol on Al 2 O 3 microspheres and hot pressing. By changing the process parameters, the influence of hot pressing on the mechanical properties of the material was explored. The synergistic effect of brick‐and‐mortar structure toughening, phase transformation toughening, and alumina sol self‐toughening improves the mechanical properties of the alumina composite ceramics. The samples coated with ZrO 2 and alumina sol achieved the best performance when hot pressing pressure is 30 MPa and the temperature is 1540°C, with a fracture toughness of 7.4 MPa·m 1/2 and a flexural strength of 671 MPa. The ZrO 2 content of this sample is only 2 wt%. Compared with the control group of Al 2 O 3 solid microspheres directly hot pressed, the fracture toughness increased by 17% and 26%, respectively. Self‐toughening Al 2 O 3 ceramics were successfully prepared by coating alumina sol. Its fracture toughness is 6.8 MPa·m 1/2 and its flexural strength is 600 MPa. This method is not only suitable for toughening alumina composite ceramics, but also maintains their high strength, with the potential for industrial production.