Effect of intermediate nickel layer on seal strength and chemical compatibility of glass and ferritic stainless steel in oxidizing environment for solid oxide fuel cells

The effects of intermediate nickel layer on seal strength and chemical compatibility of seal glass and interconnect materials for solid oxide fuel cells (SOFCs) were investigated. Two types of samples (metal/glass/metal sandwiches and glass coated metals) were prepared with the sheet of AISI 430 (nickel plated and uncoated) and slurry of compliant silicate sealing glass (SCN-1). The joined and coated samples were heated at 850 °C for different time durations (0.5-100 h). Tensile and impact tests were performed and SEM micrographs were used to analyze the glass/metal interaction. The results indicate that nickel plated AISI 430 shows higher adhesion strength at short durations of heating due to dendrite development at the interface. For longer durations, intermediate nickel layer leads to rapid loss of adhesion strength due to extension of unstable austenite zones but prevents the accelerated weakening near the triple-phase boundaries metal/glass/air (TPB) by compensating for absence of protective oxide layer (Cr-Mn oxide).