LI Minghao, WANG Yakun, CHEN Guoqing, FU Liansheng, FU Xuesong, ZHOU Wenlong
(Dalian University of Technology, Dalian 116085, Liaoning, China)
Abstract: Exploring the preparation method of large-size eutectic ceramics is of great significance for its industrial application. Al2O3-ZrO2 eutectic bulks containing 0-4.4mol% Y2O3/Sm2O3 (the molar ratio of Y2O3 to Sm2O3 is 1 : 1) were prepared by the high temperature melting method. The influence of co-doping amount of Y/S (Y2O3/ Sm2O3) on the eutectic microstructure and some mechanical properties were investigated. The results demonstrated that the solidification structure changed from the eutectic cellular to eutectic seaweed as the co-doping amount of Y/S increased. The tip splitting was observed in eutectic seaweed and the zirconia phase inside the colony underwent a transition from a three-fold symmetric distribution of zirconia fibers to disordered dispersion of fine ZrO2 lamellae with the increase of the doping content. Y2O3 was easier to dissolve in the zirconia phase than Sm2O3 because of Y/S co-doped Al2O3–ZrO2 eutectic, which resulted in more Sm2O3 piled up in front of the S/L interface and the enhanced transformation of the eutectic morphology and the formation of SmAlO3 phase. The co-doping of Y/S is beneficial to increase the hardness of Al2O3-ZrO2 eutectic ceramics. The hardness value reached 17.29 ± 0.50 GPa at room temperature for 2.2mol% Y/S co-doped Al2O3–ZrO2 eutectic bulk. However, the fracture toughness decreased with the increase of Y/S doping content.
Key words: Al2O3-ZrO2; eutectic ceramic; Y2O3 /Sm2O3; microstructure; mechanical properties.