【作者】 李海龙；

【导师】 郭瑞松；

【作者基本信息】 天津大学 ， 材料学， 2005， 硕士

【摘要】 众多学者对ZrO₂基固体电解质材料已进行了详尽的研究,虽然立方稳定氧化锆YSZ材料具有较高的电导率,但机械强度差、断裂韧性低。确保YSZ材料氧离子电导率的同时具有优良力学性能,以适应SOFC发展要求成为必然面临的课题。研制开发综合性能好,具有一定协同功能的电解质材料,必将受到越来越多材料工作者尤其是SOFC研究工作者的重视和开发。本论文针对8YSZ电解质材料强度差、断裂韧性值低的问题,利用3Y-TZP韧性好,高温氧离子电导率较低的特点,在8YSZ电解质中加入3Y-TZP,通过对致密度、力学性能、电性能和微观结构等的测试,探讨t-ZrO₂的引入对力学性能的提高作用和对电性能的影响,找出最佳掺杂量和改性条件。本论文通过实验证实:复相电解质材料最佳烧结制度为1450°C,保温2h。在YSZ电解质中加入3Y-TZP,由于Y的低扩散率,材料中Y并无严重均化现象,并可能形成了Y分布不均匀的核壳结构。材料的强度大大提高,断裂韧性略有改善,电导率稍有下降,但影响不大。当掺杂30wt% 3Y-TZP时,复相电解质材料的强度接近300MPa,较纯8YSZ提高一倍左右;韧性达到3.7MPa·m^1/2,提高80%以上;1000°C时的电导率为0.11S·cm^-1,较文献值降低不足10%,使材料具有良好的综合性能。更多还原

【Abstract】 The electrolyte material based on ZrO2 had been researched in tensing by many scholars. The 8YSZ material that has a high electrical conductivity is widely used as electrolytes for solid oxide fuel cells (SOFCs). But its low strength and low fracture hampered the development of SOFCs. Enhancing the mechanical property with a proper electrical conductivity had become more and more important to meet the need of the development of SOFC.In order to find a best method to improve the capability of YSZ electrolyte, the effects of 3Y-TZP additive on the density, strength, conductivity and microstructure were studied by means of X-ray diffraction and Vicker’s hardner. The strength and conductivity of YSZ electrolyte doped with different amount of 3Y-TZP were determined.It was shown that the samples sintered at 1450°C for 2h were the best in properties. When 3Y-TZP powder was added to the YSZ system, the tetragonal phase ratio increased, which resulted in non-uniform doping of Y2O3 into the ZrO2 grains and abnormal grain growth occurred for the sample with a higher Y2O3 content. The results demonstrated that strength of the electrolyte increased remarkably, and the fracture toughness got improved. The electrical conductivity was lowered only slightly. The results displayed that the flexure strength and the fracture toughness of ceramics with 30% TZP reached 300MPa and 3.7MPa·m1/2 respectively, and the conductivity at 1000°C reached 0.11S·cm-1.更多还原