Lanthanum strontium cobaltite (LSCo) is considered as a good candidate cathode contact material for solid oxide fuel cells, due to high electrical conductivity. However, LSCo has a very large coefficient of thermal expansion (CTE) than the cells and metallic interconnects. As a result, poor mechanical stability is expected during thermal cycling. To minimize the CTE mismatch, we investigate a composite approach involving mixing LSCo with an inert material of low CTE, such as mullite at volume fractions from 0.1 to 0.4. Composite's CTE shows a decreasing trend with increasing mullite volume fractions and is consistent with model predictions. X‐ray powder diffraction analysis of sintered LSCo/mullite composites exhibits no presence of other phases for samples aged for 500 hours at 800°C, indicating chemical compatibility. Electrical conductivity by a 4‐pt method shows a decreasing trend with increasing mullite content. Contact strength of as‐sintered and thermally cycled samples show that only the composite with 0.4 volume fraction has a measurable strength; the other composites have no strength. Overall, the composite approach is demonstrated in the LSCo/mullite system to lower the CTE and hence achieve thermal cycle stability. The addition of the inert phase to the LSCo matrix, however, also reduces the electrical conductivity.

中文翻译：

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用于固体氧化物燃料电池的LSCo /莫来石复合接触材料的热，机械和电性能

由于高电导率，镧锶钴（LSCo）被认为是固体氧化物燃料电池的良好候选阴极接触材料。但是，与电池和金属互连相比，LSCo具有非常大的热膨胀系数（CTE）。结果，预计在热循环期间机械稳定性差。为了最大程度地减少CTE的不匹配，我们研究了一种复合方法，其中涉及将LSCo与低CTE的惰性材料（如莫来石）的体积分数从0.1到0.4混合。随着莫来石体积分数的增加，复合材料的CTE呈下降趋势，并且与模型预测一致。烧结LSCo /莫来石复合材料的X射线粉末衍射分析显示，在800°C下老化500小时的样品不存在其他相，表明其化学相容性。用4点法测得的电导率随莫来石含量的增加而降低。烧结和热循环样品的接触强度表明，只有0.4体积分数的复合材料具有可测量的强度。其他复合材料没有强度。总体而言，在LSCo /莫来石体系中证明了复合方法可降低CTE，从而达到热循环稳定性。但是，将惰性相添加到LSCo基质也会降低电导率。在LSCo /莫来石体系中证明了这种复合方法可以降低CTE，从而达到热循环稳定性。但是，将惰性相添加到LSCo基质也会降低电导率。在LSCo /莫来石体系中证明了这种复合方法可以降低CTE，从而达到热循环稳定性。但是，将惰性相添加到LSCo基质也会降低电导率。