Mechanical strength and electrical conductivity of Ni-YSZ cermets fabricated by viscous processing

Abstract

A method for manufacturing of profiled Ni-YSZ anode support sheets by water-based viscous processing has been developed. Mechanical and electrical properties have been studied and were found to correlate with the microstructures and heat treatment. Electrical conductivities in the order of 1000 S/cm were obtained at 1000°C. The results reveal a linear dependence between the conductivity and pre-test reduction temperature: the conductivity increases by a factor of about 6 when reducing the anode support at 1000°C compared to 650°C. Heat treatment after the reduction at low temperature does not improve the conductivity. Insignificant degradation with time was observed at test temperatures between 800 and 1000°C. However, very high electrical loads did lower the conductivity. The developed microstructure withstood two redox cycles without decrease in conductivity. The mechanical strength of components, optimised with respect to both conductivity and strength, showed little change in strength upon reduction, i.e. when changing the structure from NiO/YSZ to Ni/YSZ, revealing that the YSZ matrix governs the mechanical strength.