Performance evaluation of machined and powder metallurgically fabricated Crofer®22 APU interconnects for SOFC applications

Abstract

This study aimed to evaluate the performances of solid oxide fuel cell (SOFC) interconnects made of commercially available bulk Crofer®22 APU alloy through machining, and powder metallurgy approach (P/M) from Crofer®22 APU powders. To this goal, interconnects with 40 × 40 mm2 active area were fabricated via both methods. Porosity, coefficient of thermal expansion (CTE) measurements, thermal shock, and single-cell performance tests were carried out. While no porosity was available for the machined interconnect, P/M interconnect was found to have 9% porosity so the increased surface area. CTE values of interconnects, one of the critical parameters in fuel cell stack design, were found to be in close agreement. The maximum power values of 3.12 and 2.97 W were obtained for machined, and P/M interconnects, respectively, at operating temperature condition of 800 °C. Even though P/M interconnect exhibited slightly lower performance in terms of power density, it was concluded that P/M interconnect can be considered a reliable alternative to the conventionally produced machined one due to ease of production, lower scrap rate, and potential to have a better cell performance as it has an increased surface area.