Influence of doctor blade gap on the properties of tape cast NiO/YSZ anode supports for solid oxide fuel cells

Abstract

In this study, various tape cast NiO/YSZ anode support layers with similar geometric properties are fabricated by varying the doctor blade from 100 µm to 200 µm with an increment of 25 µm. The mechanical properties of the anode support layers are investigated by three point bending tests of 30 samples for each doctor blade gap. The reliability curves of the flexural strength data are also obtained via two-parameter Weibull distribution method. The effects of the doctor blade gap on the microstructure and the electrochemical performance of the anode support layers are determined via SEM investigations and single cell performance-impedance tests, respectively. The apparent porosities of the samples are also measured by Archimedes’ principle. The results indicate that the doctor blade gap or the resultant tape thickness influences the microstructure of tape cast NiO/YSZ anode supports significantly, yielding different mechanical and electrochemical characteristics. At a reliability level of 70%, the highest flexural strength of 110.20 MPa is obtained from the anode support layer with a doctor blade gap of 175 µm and the 16 cm2 active area cell with this anode support layer also exhibits the highest peak performance of 0.483 W/cm2 at an operating temperature of 800 °C. Thus, a doctor blade gap of 175 µm is found to have such a microstructure that provides not only better mechanical strength but also higher electrochemical performance.