Abstract
Effects of redox cycling on the mechanical properties of the Ni-YSZ cermets were investigated by using an in-situ small punch (SP) testing method as a function of porosity, and influence of the redox cycling on the volume expansion of Ni-YSZ cermets was examined by using a thermo-mechanical analysis (TMA) as a function of porosity and Ni/YSZ volume ratio. Experimental results obtained from the in-situ SP tests demonstrated that ductile-like fracture took place under the reducing environment at 800℃. It was shown that mechanical degradation due to redox cycling was mitigated for the Ni-YSZ cermets with higher porosities greater than 30 vol. %. Higher porosities and lower Ni content were useful to maintain the dimensional stability of the Ni-YSZ cermets. Based on the experimental results, a quantitative correlation was proposed which predict the volume expansion from porosity volume and Ni content.
