中國有色金屬學(xué)報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 26 No. 9 September 2016 |
（1. Refractories Division, CSIR–Central Glass and Ceramic Research Institute,
196 Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India;
2. Academy of Scientific and Innovative Research (AcSIR), CSIR–Central Glass & Ceramic Research Institute,
196 Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India）
Abstract: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 °C compared to 1600 °C (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·m1/2 of fracture toughness and significant improvement in thermal shock resistance. CaO stabilized the tetragonal zirconia phase and thus improved the mechanical properties.
Key words: reaction sintering; mullite-zirconia composites; flexural strength; refractory
