Prospects of producing solid oxide fuels interconnectors processed by metal injection moulding

Abstract

Solid oxide fuel cells (SOFCs) are one of the most promising and interesting devices for green energy production, especially for stationary applications, mainly because of their high efficiency in the development race to achieve the true energy transition in which hydrogen-related technologies are key. These devices operate at high temperatures and, therefore, several challenges related to the materials used need to be solved. Interconnectors are a significantly relevant part of SOFCs, as they allow the coupling of devices in series for power production in industrial quantities. This work presents meaningful comparisons between two Fe-based alloys with different Cr content, Crofer 22 and Crofer 30, and one Ni-based alloy, Inconel 718. The study presents the analysis of their processability by metal injection moulding (MIM) as the selected technique to combine the possibility of obtaining devices with high geometrical complexity and with realistic possibilities of industrialisation. The injection, debinding and sintering processes are optimized for each kind of material explaining the influence of the powder size distribution and shape. Additionally, functional properties of the interconnectors are analysed as the electrical resistivity and preliminary permeability tests proving the suitability of the properties obtained. Furthermore, different 3D printed inserts were used to facilitate possible interconnector designs, saving the costly development of MIM metal moulds. The work highlights the improvements that can be made in the development of interconnectors both by an adequate selection of raw materials and by an optimal performance of each stage of processing, opening up prospects for improvement that can soon be tackled.