A fluid-flow approach in oxidation evaluation of SUS 430 steels coated by Fe/Mn-modified MnCo2O4 for solid oxide fuel cell application

Abstract

The Fe/Mn-modified Mn–Co spinel oxides (MCO) are coated on SUS430 interconnect to protect against oxidation and chromium diffusion by wet spray followed by nitrate solution impregnation for intermediate-temperature solid oxide fuel cell (IT-SOFC) application. 1000 h oxidation tests at 800 °C show that the FeMCO-coated sample have the minimum parabolic rate constant (9.02 × 10−7 mg2cm−4s−1), which is lower than half of the uncoated sample. The area-specific resistance (ASR) of the FeMCO-coated sample is 6.41 mΩcm2 at 800 °C after 1000 h oxidation, which is much lower than the MCO sample (19.38 mΩ cm2) and the uncoated sample (186.84 mΩ cm2). The samples microstructures are examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Based on a novel approach, the dimensionless fluid numbers are related to the high-temperature conductivity of coated interconnects, and the inward diffusion of oxygen is introduced as the limiting factor for oxide-scale growth of coated interconnects.