材料期刊网

采用印度沿海锆石粉与硅线石海滩砂反应烧结，制备含20%(质量分数)氧化锆的莫来石?氧化锆复合材料。添加4%~12%(摩尔分数)的氧化钙作为添加剂。研究了添加剂对压实性能、显微组织、力学性能和热力性能的影响。添加氧化钙可以使压实温度从1600°C降低至1550°C。氧化钙可以形成少量的液相(铝硅酸钙)，有利于烧结进行。添加4%氧化钙可使复合材料的晶粒尺寸减小，当添加量大于4%时，材料的晶粒尺寸随氧化钙添加量的增加而增大。添加4%氧化钙样品的弯曲强度约为225 MPa，断裂韧度约为6 MPa?m1/2，且抗热冲击性能得到明显提高。氧化钙可以稳定四方氧化锆，从而提高材料的力学性能。

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.