Effect of YSZ coatings as diffusion barrier between glass sealing and steel

In this work three experimental glass compositions have been applied and tested on ferritic stainless steel (FSS) substrates with and without yttria-stabilized zirconia (YSZ) coating deposited by plasma spraying. Samples have been tested at 780°C in static air up to 1000 hours to investigate the materials compatibility, stability and interactions at the interfaces. Microstructural changes and migration of elements have been characterized post-experiment in cross-section by means of scanning electron microscopy and energy dispersive X-ray analysis. Two of the tested compositions resulted well adherent to the metal substrate for the whole test duration and the interface evolved with the formation of a stable Cr, Mn-rich layer due to the steel oxidation. The application of YSZ allowed all the glass composition to bond to the substrate and effectively act as a diffusion barrier limiting the diffusion of the substrate elements.