Al2O3-fiber-reinforced porous YSZ ceramics with high mechanical strength

Porous YSZ ceramics were prepared by a gel-casting method using tert-butyl alcohol (TBA) as solvent and Al2O3 fiber as reinforcement. Effects of sintering temperature, soaking time and Al2O3 fiber content on porosity, microstructure, compressive strength, and fracture toughness of the porous ceramics were studied. Compressive strength of porous YSZ ceramics was improved while the porosity decreased with the increase of sintering temperature and soaking time. Addition of Al2O3 fibers significantly strengthened and toughened porous YSZ ceramics; however, the laws of strengthening and toughening were different. The strength of the porous YSZ ceramics reached maximum at the addition of 10 vol% Al2O3 fibers, and the corresponding compressive strength and flexural strength were 100.2±25.4 MPa and 61.5±11.3 MPa, respectively. Fracture toughness of the porous YSZ ceramics monotonically increased with increasing of Al2O3 fibers, and could be improved from 0.5 MPa m1/2 to 1.2 MPa m1/2 (improved by 140%). The strengthening and toughening mechanisms of Al2O3 fibers were discussed.