Polymer Derived Ceramics based on SiAlOC glasses as novel protective coatings for ferritic steel

In this work, the potential of using Polymer Derived Ceramics based on SiAlOC glasses in the form of protective thin layers was demonstrated on Ferritic Stainless Steel (FSS) Crofer 22APU steel, an alloy often used for intermediate- and low-temperature Solid Oxide Fuel Cells (SOFC's) interconnects. Microstructural features were investigated by the detailed analysis combining Electron Probe Micro Analysis (EPMA) and Raman Confocal imaging (surface imaging and depth profiling), which revealed the formation of Si-O-Cr bridges, believed to play a crucial role to slow down oxidation of the steel. Additionally, the positive role of aluminum introduced into the SiOC system, which enhances the suppression of the degradation by transport processes. The most crucial value of such findings is the formation of a flexible coating material (SiAlOC glasses) that may be applied on a wide range of FSSs increasing their heat resistance. The application of the combination of methods to determine both chemical (EPMA) and phase (Raman) composition of a multi-layered complex system is also demonstrated.