摘要
探索大尺寸共晶陶瓷的制备方法对其工业化应用具有重要意义。采用高温熔凝法制备了直径20 mm,不同Y_2O_3/Sm_2O_3含量的Al_2O_3-ZrO_2共晶陶瓷,研究了Y/S(Y_2O_3/Sm_2O_3)双掺杂对Al_2O_3-ZrO_2共晶陶瓷微观组织和力学性能的影响。结果表明,随掺杂量增加,共晶形貌由横截面呈三角形的共晶晶团转变为有尖端分裂特征的海藻状共晶,且共晶晶团内部的ZrO_2相由对称分布的规则纤维状转变为无序分布的层片状。较单一掺杂Y_2O_3相比,双掺杂时共晶形貌转变发生在较小的掺杂量(3mol%),且掺杂量较高时(4.4mol%)SmAlO_3相优先形成。掺杂量为2.2mol%时硬度达到最大值17.29±0.50 GPa。断裂韧性在低掺杂量时较高,随掺杂量继续增大,断裂韧性不断减小。
Exploring the preparation method of large-size eutectic ceramics is of great significance for its industrial application.Al_2O_3-ZrO_2eutectic bulks containing 0-4.4mol%Y_2O_3/Sm_2O_3(the molar ratio of Y_2O_3 to Sm_2O_3 is 1:1)were prepared by the high temperature melting method.The influence of co-doping amount of Y/S(Y_2O_3/Sm_2O_3)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 ZrO_2 lamellae with the increase of the doping content.Y_2O_3 was easier to dissolve in the zirconia phase than Sm_2O_3 because of Y/S co-doped Al_2O_3–Zr O_2 eutectic,which resulted in more Sm_2O_3 piled up in front of the S/L interface and the enhanced transformation of the eutectic morphology and the formation of SmAlO_3 phase.The co-doping of Y/S is beneficial to increase the hardness of Al_2O_3-Zr O_2 eutectic ceramics.The hardness value reached 17.29±0.50 GPa at room temperature for 2.2mol%Y/S co-doped Al_2O_3–Zr O_2 eutectic bulk.However,the fracture toughness decreased with the increase of Y/S doping content.
引文
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