SiC/ZTM nanocomposite with needlelike mullite grains and enhanced mechanical properties

Zirconia-toughened mullite (SiC/ZTM) nanocomposites were prepared by a chemical precipitation method. The samples showed good sinterability and could be densified to > 98.7 % of the theoretical density at 1350degrees-1550degreesC. Because of the addition of mullite seeds in the starting powder and the pinning effects of ZrO2 and SiC particles on mullite grain growth, a fine-grained microstructure formed. Mullite grains were generally equiaxed for the sample sintered at 1400degreesC; whereas, for the sample sintered at 1550degreesC, most mullite grains took a needlelike morphology, and SiC particles were primarily located within mullite grains. The strength and toughness increased with the increasing sintering temperature, and reached their respective maximum of 780 MPa and 3.7 MPa(.)m(1/2) for the sample sintered at 1550degreesC.