Synergistic toughening effect of SiC whiskers and particles in ZrO₂-Al₂O₃-SiC ceramics

Zirconia ceramics have a good application prospect in the high-tech fields, whereas their potential utilization is highly limited by their mechanical properties. To fabricate zirconia based ceramics with superior mechanical properties, SiC whiskers (SiCw) and SiC particles (SiCp) were selected as the toughening phases for the preparation of ZrO2-Al2O3-SiC ceramics, and an advanced sintering technique called as oscillatory pressure sintering (OPS) was applied in the present work. The mechanical properties of such ceramics with 5 vol% SiCw and 10 vol % SiCp were significantly improved. The Vickers hardness increased to 15.26 GPa while the bending strength reached 917 MPa, and the fracture toughness rose to 6.83 MPa & sdot;m1/2. The toughness of the ceramics was improved by synergistic toughening effects including whisker toughening, stress-induced phase transformation toughening and particle dispersion toughening. Furthermore, SiCp and ZrO2, Al2O3 and SiCp, ZrO2 and SiCw as well as Al2O3 and SiCw formed a well-matched coherent phase boundary. The semi-coherent relationship was also generated at the phase boundary of SiCp and SiCw.