Thermo-mechanical properties of mullite–zirconia composites derived from reaction sintering of zircon and sillimanite beach sand: Effect of CaO

氧化钙对锆石和硅线石海滩砂反应烧结制备莫来石-氧化锆复合材料热力性能的影响（英文）

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.

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225MPa,断裂韧度约为6MPa·m^(1/2),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。