氧化还原处理对Ysz-NiO (Ni)体系阳极材料微观结构及脆性断裂影响的评价
引用次数: 7
摘要
研究了高温(600℃)含氢环境下的还原处理对固体氧化物燃料电池阳极用YSZ-NiO (Ni)材料显微组织和脆性断裂倾向的影响。为了评估陶瓷的抗裂纹扩展能力，采用了维氏压痕技术，该技术可以估计复合材料的显微硬度和断裂韧性。对阳极的高孔隙率的要求，以确保功能性能表明，强度可能是阳极承载能力的一个不足的特点。需要更多的结构敏感特性来评估其抗裂纹扩展能力。通过实验测定了YSZ-NiO陶瓷和YSZ-NiO (Ni)陶瓷在烧结状态下的平均显微硬度(分别为2.0 GPa和0.8 GPa)和断裂韧性(分别为3.75 MPa·m1/2和2.9 MPa·m1/2)。结果表明，经氧化还原处理后的YSZ - nio (Ni)陶瓷的微观结构是由YSZ陶瓷骨架与Ni相晶粒以网状结构结合而成，具有较高的导电性。随着金属陶瓷孔隙率的提高，由于实现了断裂的桥接增韧机制，其断裂韧性不低于一次性还原金属陶瓷。所提出的处理方法允许形成阳极材料的微观结构，在机械载荷下抵抗裂纹扩展。通过对阳极材料抗裂纹扩展性能的评价和微观组织及断裂微观机制的分析，证实了阳极材料的脆性断裂倾向。这个结果从理论的角度来看是有趣的。从实用的角度来看，所开发的技术可以确定燃料电池阳极制造技术中氧化还原处理的条件。本文章由计算机程序翻译，如有差异，请以英文原文为准。
Estimation of the Effect of Redox Treatment on Microstructure and Tendency to Brittle Fracture of Anode Materials of Ysz–NiO(Ni) System
The effect of reduction treatment in a high-temperature (600 °C) hydrogen-containing environment on the microstructure and tendency to brittle fracture of YSZ–NiO(Ni) materials for solid oxide fuel cell anodes has been studied. To assess the crack growth resistance of the ceramics, the Vickers indentation technique was adapted, which allowed estimating the microhardness and fracture toughness of the material in the complex.
The requirements for high porosity of the anodes to ensure functional properties show that the strength may be an insufficient characteristic of the bearing capacity of the anode. More structurally sensitive characteristics are needed to assess its crack growth resistance.
The average levels of microhardness of YSZ–NiO ceramics in the as-sintered state and YSZ–NiO(Ni) cermets (2.0 GPa and 0.8 GPa, respectively) and their fracture toughness (3.75 MPa·m1/2 and 2.9 MPa·m1/2, respectively) were experimentally determined.
It was found that the microstructure of YSZ–NiO(Ni) cermet after redox treatment is formed by a YSZ ceramic skeleton with refined Ni-phase grains combined in a network, which provides increased electrical conductivity. Along with higher porosity of the cermet, its fracture toughness is not lower than that of the one-time reduced cermet due to the implementation of the bridging toughening mechanism of fracture.
The proposed treatment method allowed forming the microstructure of the anode material, resistant to crack propagation under mechanical load. The propensity of the anode material to brittle fracture on the basis of evaluation of its crack growth resistance and analysis of the microstructure and fracture micromechanism was substantiated. This result is interesting from a theoretical point of view. From a practical point of view, the developed technique allows determining the conditions of redox treatment in the technology of manufacturing fuel cell anodes.
The requirements for high porosity of the anodes to ensure functional properties show that the strength may be an insufficient characteristic of the bearing capacity of the anode. More structurally sensitive characteristics are needed to assess its crack growth resistance.
The average levels of microhardness of YSZ–NiO ceramics in the as-sintered state and YSZ–NiO(Ni) cermets (2.0 GPa and 0.8 GPa, respectively) and their fracture toughness (3.75 MPa·m1/2 and 2.9 MPa·m1/2, respectively) were experimentally determined.
It was found that the microstructure of YSZ–NiO(Ni) cermet after redox treatment is formed by a YSZ ceramic skeleton with refined Ni-phase grains combined in a network, which provides increased electrical conductivity. Along with higher porosity of the cermet, its fracture toughness is not lower than that of the one-time reduced cermet due to the implementation of the bridging toughening mechanism of fracture.
The proposed treatment method allowed forming the microstructure of the anode material, resistant to crack propagation under mechanical load. The propensity of the anode material to brittle fracture on the basis of evaluation of its crack growth resistance and analysis of the microstructure and fracture micromechanism was substantiated. This result is interesting from a theoretical point of view. From a practical point of view, the developed technique allows determining the conditions of redox treatment in the technology of manufacturing fuel cell anodes.
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