A novel route for manufacturing asymmetric BSCF-based perovskite structures by a combined tape and freeze casting method

Abstract

In this work, we present an innovative route for the preparation of asymmetric structures by combining the tape and freeze casting methods A perovskite oxide ceramic based on BSCF (Ba0.5S0.5Co0.8Fe0.2O3-δ) was chosen as the mother material. BSCF freeze cast substrates showed highly ordered and interconnected pores networks with open porosity from 66% to 79%. The top layer for the tape cast was altered by doping BSCF with Zr, thus forming a slightly different compound BSCFZ. The BSCFZ slurries containing 1.0wt% dispersant and pH >6 were characterised by pseudoplastic behaviour, ideal for the preparation of tape cast layers. Coupling the BSCF freeze cast substrate with the BCSFZ tape cast green top layer to make asymmetric structures was achieved by the pre-sintering of the substrate between 900 and 1050°C. This allowed for the densification and coupling of the BSCFZ top layer, resulting in suitable adhesion with no cracks or delamination. Higher pre-sintering temperatures than 1050°C limited the densification of the BSCFZ top layer as the coefficient of expansion between the substrate and top layer did not match, leading to the formation of surfaces with high porosity.