Characterisation and thermochemical stability analysis of 3D printed porous ceria structures fabricated via composite extrusion Modelling

Composite Extrusion Modelling (CEM) is an advanced additive manufacturing technique that enables rapid, cost-effective production of complex, customisable designs. In this study, CEM 3D printing of porous ceria structures is reported for the first time. First, the ceramic injection molding (CIM) feedstock with thermoplastic properties was prepared and optimised in terms of its rheological properties to ensure good workability for the printing process at 140-150°C. Subsequently, the thermoplastic feedstock was used to print porous ceria structures for thermochemical splitting. The feasibility of printing various porous structures with different dimensions, geometries, and macropore sizes was investigated, and the printing parameters: extrusion multiplier (EM), extrusion temperature (ET), nozzle velocity (NV), and layer thickness (LT), were optimised to prevent clogging of the printing nozzle and to achieve homogeneous overlap of the printed layers. The optimised printing parameters for ceria structures are EM 1.3, ET 150 °C, LT ∼0.13 mm, and NV 50 mm/s, which were determined by multiple response optimisation process. The sintered 3D-printed bars yielded relative densities of ≥ 98% and a total microporosity of 0.29%, measured with a Hg porosimeter. Thermogravimetric analysis (TGA) and cyclic stability experiments were performed on the printed porous ceria structures and showed stability over 100-redox cycles.