Microstructure and mechanical properties of La2Zr2O7–(Zr0.92Y0.08)O1.96 composite ceramics prepared by spark plasma sintering

Dense composite ceramics composing of pyrochlore La 2 Zr 2 O 7 and metastable tetragonal (Zr 0.92 Y 0.08 )O 1.96 phases were synthesized by sol-spray pyrolysis method and were densified by using spark plasma sintering at 1450   °C. The microstructure and mechanical properties of the composites were studied. Microstructure analysis showed that particle size of the La 2 Zr 2 O 7 and (Zr 0.92 Y 0.08 )O 1.96 phases of the composites was in the range of 0.2–1.3   μm. The results of mechanical property measurement revealed that high fracture toughness, almost twice that of single phase La 2 Zr 2 O 7 has been achieved for the La 2 Zr 2 O 7 –(Zr 0.92 Y 0.08 )O 1.96 composite ceramics with 50   mol% 4YSZ addition. The improved toughness was attributed to crack blocking of the (Zr 0.92 Y 0.08 )O 1.96 crystals.