Mullite–zirconia composites containing 20% zirconia（mass fraction） were prepared by reaction sintering route utilizing Indian coastal zircon flour and sillimanite beach sand. 4%-12% of CaO（mole fraction） with res...Mullite–zirconia composites containing 20% zirconia（mass fraction） were prepared by reaction sintering route utilizing Indian coastal zircon flour and sillimanite beach sand. 4%-12% of CaO（mole fraction） with respect to zirconia was used as additive. The effect of additive on densification, microstructure as well as various mechanical and thermo-mechanical properties was studied. Incorporation of CaO reduced the densification temperature of the composites to 1550 ℃ compared to 1600 ℃（for CaO free samples）. CaO formed small amount of liquid phase（calcium aluminosilicate）, which facilitated sintering. Average grain size of the composites decreased up to 4% CaO addition, afterwards grain size increased with further addition of CaO. Samples with 4% CaO exhibited ～225 MPa of flexural strength, ～6 MPa·m^1/2 of fracture toughness and significant improvement in thermal shock resistance. CaO stabilized the tetragonal zirconia phase and thus improved the mechanical properties.展开更多
基金the Council of Scientific and Industrial Research (CSIR), Govt. of India, for financial support under project No. ESC-0202
文摘Mullite–zirconia composites containing 20% zirconia（mass fraction） were prepared by reaction sintering route utilizing Indian coastal zircon flour and sillimanite beach sand. 4%-12% of CaO（mole fraction） with respect to zirconia was used as additive. The effect of additive on densification, microstructure as well as various mechanical and thermo-mechanical properties was studied. Incorporation of CaO reduced the densification temperature of the composites to 1550 ℃ compared to 1600 ℃（for CaO free samples）. CaO formed small amount of liquid phase（calcium aluminosilicate）, which facilitated sintering. Average grain size of the composites decreased up to 4% CaO addition, afterwards grain size increased with further addition of CaO. Samples with 4% CaO exhibited ～225 MPa of flexural strength, ～6 MPa·m^1/2 of fracture toughness and significant improvement in thermal shock resistance. CaO stabilized the tetragonal zirconia phase and thus improved the mechanical properties.
