Microstructure and Mechanical Properties of ZrO2 Toughened Mullite Synthesized by Sol-Gel Method
Zirconia dispersed mullite composites were prepared by adopting the sol-gel method. The maximum amount of ZrO2 that could be dispersed in mullite without causing a decrease in strength was 15 vol%. The flexural strength and fracture toughness of 15 vol% ZrO2 dispersed mullite-zirconia ceramic at room temperature were 500 MPa and 4.3 MPa.m 1/2, respectively. The flexural strength at 1400°C of the same composition was 300 MPa. The ZrO2 in these composites occupy both inter and intra granular positions.
Morphology of mullite grains changed from equiax to needle like on sintering at temperatures above 1670°C. The mechanical properties were deteiorated with the phange of microstructure.
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