Development of glass-ceramic sealing materials and deposition techniques for Oxygen Transport Membranes (OTM’s) integration onto metal supports

Energy consumption has significantly increased as technology advances and the world population grows. Unfortunately, the primary energy source remains fossil fuels, which has led to massive carbon dioxide (CO2) emissions. These emissions have contributed to the greenhouse effect and climate change. In this context, pure oxygen has emerged as a crucial element in the energy transition due to its ability to enhance various energy production and storage technologies. However, the current methods of cryogenic distillation, water electrolysis, and pressure swing adsorption (PSA) for air separation are either energy-intensive or produce non-high purity oxygen. A comparative analysis of inorganic dense ceramic-based oxygen transport membranes (OTMs) with traditional oxygen production technologies shows that OTMs have irreplaceable advantages. OTMs comprise ceramic gastight mixed ionic and electronic conductors (MIEC), which, under differences in partial pressure across the membrane, allow for the simultaneous transport of oxygen ions and electrons at high temperatures (800-900°C). To be integrated into industrial processes, such as oxy-fuel combustion power plants, OTMs must be assembled in modules. OTMs modules consist of multiple single repeating units (SRU), each of which typically includes three main components: the membrane, the glass-ceramic sealing material, and the metal support. The sealant is a crucial component of the SRU, as it prevents gases from mixing within the stack and consequence device failure. Glass ceramics offer the best option for various applications as their properties can be customized by adjusting their composition to achieve the desired wettability, thermal expansion, and thermodynamic stability. The best results are obtained when they are applied using automated systems that ensure control over the thickness and proper distribution of the jointing material on the substrate. This work presents the development of a glass ceramic material chosen to join ceramic membranes (LSCF) to metallic support, which can withstand high temperatures ranging from 800- 900°C. The thermomechanical properties of the material were tested through specific thermal analyses to determine the optimal sintering-crystallization treatment for making the joined samples. These samples were then tested to assess the thermochemical compatibility of the materials used. Additionally, the study aimed to identify alternative surface treatments or materials for the metal counterpart to improve its adhesion properties, building on the results of previous research activities. Extensive testing has been conducted using robocasting, an automated deposition technique. Optimized organic-based inks containing ceramic glass powders were studied and rheologically characterized to enhance their printability and shape fidelity during extrusion. Various printing parameters were analyzed to achieve the required thickness and width of the sealing profiles. Additionally, a study was conducted on the best joint assembly technique, wherein jointed samples made with and without the intermediate drying phase of the paste were prepared and tested.