The flexural strength, fracture toughness, hardness and densification behaviour of various amount of Al2O3-doped 8YSCZ/Al2O3 composites used as an electrolyte for solid oxide fuel cell

The dependence of flexural strength, fracture toughness, hardness and densification behaviour of 8YSCZ/Al2O3 composite on Al2O3 content was examined using fine-grained 8 mol% yttria-stabilized cubic zirconia (8YSCZ) doped with 0, 1, 5 and 10 wt% Al2O3. The densification behaviour of 8YSCZ/Al2O3 composites in the temperature range 1250-1400 degrees C was studied. It was seen that Al2O3 contents up to 1 wt% enhanced densification, but further increase in Al2O3 contents led to a decrease in densification. The addition of Al2O3 enhanced the hardness, flexural strength and fracture toughness of 8YSCZ/Al2O3 composites. The maximum values obtained for hardness, flexural strength and fracture toughness were 1459 kg/mm(2), 330 MPa and 2.41 +/- 0.02 MPa/m(1/2), respectively, for the specimen containing 10 wt% Al2O3 while these values were 1314 kg/mm(2), 275 MPa and 1.5 +/- 0.03 MPa/m(1/2) for monolithic 8YSCZ. (c) 2004 Elsevier Ltd. All rights reserved.