Within the Pressuriz3D project, significant progress was achieved in the development, evaluation, and integration of advanced materials and manufacturing routes for pressurized protonic ceramic electrochemical devices.
WP1 – Compatibility of electrolyte, glass sealant, and interconnect materials
A systematic compatibility study was performed between six Ba-based perovskite electrolyte compositions (with and without 1 wt% ZnO sintering aid), a commercial B/Ba-based glass sealant, and AISI 441 ferritic stainless-steel interconnects. Pellets were joined to metal interconnects at 700 °C for 30 min, subjected to six thermal cycles (50% air / 50% steam, up to 700 °C), and thermally aged at 600 °C for 500 h (50% air / 50% steam).
All joints remained mechanically intact after thermal exposure. The glass formed continuous, defect-free interfaces with both ceramic and metallic components. Localized crystallization occurred after ageing near the ceramic interface, involving Ca-, Ba-, and Al-rich phases, but without detrimental effects on adhesion or sealing integrity. ZnO-containing ceramics exhibited improved densification and fewer crystalline inclusions. No significant interdiffusion was observed at the ceramic/glass or metal/glass boundaries. Overall, the match between the B/Ba-based glass and the Ba-based perovskites demonstrated excellent chemical and mechanical stability, confirming their suitability for long-term, high-temperature, and humidified operation in pressurized solid oxide and protonic ceramic electrochemical devices.
WP2 – Additive manufacturing of dense ceramic membranes
Two complementary 3D printing approaches, Digital Light Processing (DLP) and robocasting, were explored for shaping dense BZY and BZCY electrolytes.
For DLP, BZY was selected over BZCY due to superior UV-curing behaviour. Thermal analysis guided a controlled three-step debinding cycle, followed by sintering at 1500 °C. Printed BZY membranes exhibited promising microstructural development, demonstrating the feasibility of DLP for electrolyte shaping.
In parallel, robocasting of BZCY using thermocurable yielded membranes with 99.5% theoretical density (6.15 g/cm³) after sintering at 1550 °C. SEM analysis confirmed crack-free, continuous structures. The inherent surface waviness from layer-by-layer deposition was retained and could be advantageous for electrode adhesion. As a first integration step, a porous BZCY–BLC composite electrode was applied and sintered at 1100 °C, achieving excellent adhesion and a favourable porous architecture.
WP3 – Electrode integration and electrochemical characterisation
A porous BZCY–BLC composite electrode was applied and sintered at 1100 °C on dense robocast BZCY membranes, achieving excellent adhesion and a favourable porous architecture. SEM revealed a defect-free, continuous electrode–electrolyte interface and a highly porous electrode structure conducive to gas transport.
Electrochemical testing with Ag, Au, and BLC electrodes under wet and dry air demonstrated clear proton conduction behaviour. The highest conductivity (~10⁻³ S·cm⁻¹ at 700 °C) was achieved with Ag electrodes in wet air (activation energy 1.1 eV). Conductivity decreased by one order of magnitude under dry air, with higher activation energies (1.3 eV), confirming hydration-dependent proton transport.
These results validate the use of thermocurable robocasting for producing high-quality, dense BZCY membranes and confirm their compatibility with porous electrodes for integration into protonic ceramic electrolysis and fuel cell devices.
