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 ZrO₂ and alumina sol on Al₂O₃ 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 ZrO₂ 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 ZrO₂ content of this sample is only 2 wt%. Compared with the control group of Al₂O₃ solid microspheres directly hot pressed, the fracture toughness increased by 17% and 26%, respectively. Self-toughening Al₂O₃ 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.