Mechanical properties of NiO/Ni–YSZ composites depending on temperature, porosity and redox cycling
Mechanical properties of NiO/Ni–YSZ composites depending on temperature, porosity and redox cycling
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DOI：
10.1016/j.jeurceramsoc.2008.10.017
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发表时间：
2009-06
影响因子：
5.7
通讯作者：
M. Pihlatie;A. Kaiser;M. Mogensen
中科院分区：
文献类型：
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作者：
M. Pihlatie;A. Kaiser;M. Mogensen
采用脉冲激励技术（IET）对固体氧化物燃料电池（SOFC）用Ni/NiO-YSZ复合材料的弹性模量和比阻尼进行了测试。烧结态样品的孔隙率为9 ~ 38%，还原态样品的孔隙率为31 ~ 52%。所有样品的杨氏模量与孔隙率之间存在线性关系。用IET研究了烧结态和还原态复合材料的力学性能随温度的变化关系，最高温度为1200°C。在烧结状态下，首先观察到与NiO的Néel温度（250°C）一致的刚度的增加和峰值。高于该温度，发生线性下降。比阻尼在170-180°C下显示出峰值，并且在高于约100 ° C时增加。在NiO-YSZ中1000°C。在还原状态下，弹性模量随温度线性下降;比阻尼增加超过约。600°C，并且发现非常依赖于微观结构。氧化还原循环损伤降低了复合材料的弹性性能。从0.5 - 0.6%氧化还原应变开始线性降解，导致在约2.5% dL/Lo下肉眼可见样品失效。一个简单的连续弹性损伤模型拟合的退化数据。
The Impulse Excitation Technique (IET) was used to determine the elastic modulus and specific damping of different Ni/NiO–YSZ composites suitable for use in solid oxide fuel cells (SOFC). The porosity of the as-sintered samples varied from 9 to 38% and that of the reduced ones from 31 to 52%. For all samples a linear relation between Young's modulus and porosity was found. The temperature dependency of the mechanical properties of both as-sintered and reduced composites was investigated by IET up to 1200°C. In the as-sintered state, first an increase and peak of stiffness coinciding with the Néel temperature, 250°C, of NiO was observed. Above this temperature, a linear decrease occurred. Specific damping showed a peak at 170–180°C and increased above ca. 1000°C in NiO–YSZ. In the reduced state the elastic modulus decreased linearly with temperature; specific damping increased above ca. 600°C and was found to be very dependent on microstructure. Damage caused by redox cycling degraded the elastic properties of the composites. Degradation started linearly from 0.5 to 0.6% redox strain leading to macroscopic sample failures at about 2.5% dL/Lo. A simple continuum elastic damage model was fitted to the degradation data.