The Incorporation of Waste Sludge into the Production of High-Temperature-Resistant Adhesive Ceramic Materials

In recent years, the interest of the scientific community has become focused on the integration of circular economy principles by eliminating end-of-life concepts and forming zero-waste strategies. The present paper suggests the possible application of innovative, eco-friendly, cost-effective, and highly efficient ceramic materials with the partial implementation of aluminosilicate-based waste in the form of wastewater sludge in advanced technology solutions. The specific objective was to demonstrate the effective utilization of the investigated waste in the production of refractory adhesives and/or sealants for Intermediate-Temperature Solid-Oxide Fuel Cells (IT-SOFCs). Different physical-mechanical and chemical properties were determined along with the performance of leaching tests, the thermal cycling procedure, and leakage tests in a single cell. Based on the maintenance of mechanical integrity after thermal cycling and satisfying crystal and microstructural stability after high-temperature treatment, it was concluded that the investigated materials may be considered promising candidates for application as heat-resistant adhesives for connecting components in heating systems. However, they were not found to be applicable as sealants for IT-SOFCs in raw form according to the failure of testing in a single cell. Still, requirements for this purpose could be met after certain modifications of the composition and synthesis methodology, which presents the major initiative for our further research in this field.