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首页> 外文期刊>Materials >3D Microstructure Effects in Ni-YSZ Anodes: Prediction of Effective Transport Properties and Optimization of Redox Stability
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3D Microstructure Effects in Ni-YSZ Anodes: Prediction of Effective Transport Properties and Optimization of Redox Stability

机译:Ni-YSZ阳极中的3D微观结构效应:有效传输性能的预测和氧化还原稳定性的优化

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摘要

This study investigates the influence of microstructure on the effective ionic and electrical conductivities of Ni-YSZ (yttria-stabilized zirconia) anodes. Fine, medium, and coarse microstructures are exposed to redox cycling at 950 °C. FIB (focused ion beam)-tomography and image analysis are used to quantify the effective (connected) volume fraction (Φeff), constriction factor (β), and tortuosity (τ). The effective conductivity (σeff) is described as the product of intrinsic conductivity (σ0) and the so-called microstructure-factor (M): σeff = σ0 × M. Two different methods are used to evaluate the M-factor: (1) by prediction using a recently established relationship, Mpred = εβ0.36/τ5.17, and (2) by numerical simulation that provides conductivity, from which the simulated M-factor can be deduced (Msim). Both methods give complementary and consistent information about the effective transport properties and the redox degradation mechanism. The initial microstructure has a strong influence on effective conductivities and their degradation. Finer anodes have higher initial conductivities but undergo more intensive Ni coarsening. Coarser anodes have a more stable Ni phase but exhibit lower YSZ stability due to lower sintering activity. Consequently, in order to improve redox stability, it is proposed to use mixtures of fine and coarse powders in different proportions for functional anode and current collector layers.
机译:这项研究调查了微观结构对Ni-YSZ(氧化钇稳定的氧化锆)阳极的有效离子电导率的影响。精细,中等和粗糙的微观结构在950°C下经受氧化还原循环。 FIB(聚焦离子束)断层扫描和图像分析用于量化有效(连接)体积分数(Φ eff ),收缩因子(β)和曲折度(τ)。有效电导率(σ eff )描述为固有电导率(σ 0 )与所谓的微结构因子(M)的乘积:σ eff 0 ×M。使用两种不同的方法评估M因子:(1)通过使用最近建立的关系进行预测,M pred = εβ 0.36 /τ 5.17 ,以及(2)通过提供电导率的数值模拟,可以推导模拟的M因子(M sim )。两种方法都提供了有关有效传输特性和氧化还原降解机理的补充和一致的信息。初始的微观结构对有效电导率及其降解有很大影响。较细的阳极具有较高的初始电导率,但会经历更强烈的Ni粗化。粗阳极具有更稳定的Ni相,但由于较低的烧结活性而具有较低的YSZ稳定性。因此,为了提高氧化还原稳定性,提出了将功能性的阳极层和集电体层使用不同比例的细粉和粗粉的混合物。

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