Characterization of metallic interconnects extracted from Solid Oxide Fuel Cell stacks operated up to 20,000 h in real life conditions: The fuel side

Investigation of a Metallic Interconnect Extracted from an SOFC Stack after 40,000 h of Operation

“…In addition, this second layer of LSCM placed on the ribs was unaffected by the operating time. The absence of Cr in the cathode contact layer confirmed the efficacy of the protective coating towards the solid-state diffusion of MIC alloying elements into the cell [21]. On the other hand, the cross-section shows the presence of a TGO formed within the MCO and the metal substrate with the chemical composition corresponding to Cr 2 O 3 with small amounts of Mn.…”

“…The fuel side showed two main features separated by a visible borde positioned a few centimeters after the center of the interconnect, where a sudden chang in color and roughness was noticed (Figure 1). Ghiara et al [21] suggest that the oxidatio of the MIC at the anode side was due to the interaction of the bare metal substrate wit the water vapor present in the stream. The H2/H2O ratio evolving from inlet to outlet to The MIC was made of Crofer 22 APU ® ferritic stainless steel of commercial grade (Table 2) and fully coated with (Co, Mn, Fe) 3 O 4 spinel oxide (MCO) on the side exposed to the cathode.…”

“…A number of stacks manufactured according to internal standards were put under operation and stopped after a fixed number of hours before any failure. Two previous papers [21,22] were published to describe the status of the interconnect after operation up to 20,000 h, and the present paper was meant to complete the study by describing the results gathered after 40,000 h of working life as an SOFC.…”

“…Due to the high quality of the FSS in use, investigations need extremely long-lasting experiments and the reproduction of "real-life conditions" (i.e., temperature, atmospheres, and materials) to obtain a correct overview of the phenomena. The validation of laboratory tests and the refinement of degradation models can only occur by comparison with components extracted from operated stacks [21][22][23][24]. The project, Ad Astra, offers such an opportunity and several field-operated SOFC stacks over various periods have been studied.…”

“…The present paper refers to the longest period of operation. The post-mortem characterization of MIC samples extracted from a field stack operated in the fuel cell mode for 40,000 h completed a study carried on identical stacks operated in the range 5000-20,000 h [21,22]. The results are of fundamental importance for the modeling of the stack's performance evolution and for a better understanding of samples issued by accelerated tests.…”