Wet powder spraying – A versatile and highly effective technique for the application of spinel-type protective coatings on SOC interconnects

Chromia-forming metallic interconnects used for solid oxide cells require protective coatings to prevent chromium poisoning of other cell components. This study focuses on Mn1.0Co1.9Fe0.1O4 -coated Crofer 22 H interconnects fabricated by wet powder spraying, which is a versatile, cost-effective, and scalable coating technique. The investigation and fine-tuning of relevant parameters along the process chain provide a fundamental understanding of their impact on coating quality and thermomechanical stability. The correlation with cross-sectional analysis and area-specific contact resistance (ASR) measurements supports the parameter evaluation. Mid-term thermal testing demonstrates excellent chromium retention, as well as chemical and mechanical stability of the protective layer on real component interconnect substrates. With an ASR below 10 mΩ cm2 after 1000 h at 800 °C, wet powder spraying represents a viable alternative to established but more expensive processes.