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At elevated operating temperatures, a large temperature gradient can cause irreparable damage to the solid oxide fuel cells (SOFCs) stack, eventually interrupting the durability of the stack. Metal substrate support could be used to overcome this challenge. However, the application of metal substrate support poses various challenges such as different thermal expansion coefficients, pore diameters, and complex fabrication techniques. Therefore, a first-ever novel and mechanically strong ferritic stainless-steel metal mesh-supported SOFC design is developed to mitigate these challenges. The metal mesh of 200 μm thickness is laminated with tape-casted green films of anode-support, anode functional layer (AFL), and electrolyte films of SOFC. The iso-static pressure of 300 MPa exhibits a firm attachment of the green films of SOFC with the metal mesh. Subsequently, the metal mesh-supported planar SOFC exhibits 3.3 times higher flexural strength compared to the conventional commercial anode-supported planar SOFC. The nano-CuO is added to constituent layers as a sintering aid to attain the maximum density at a lower sintering temperature of 1100 °C. The result shows that the practical application of the metal mesh-supported cell technology has a great potential to overwhelm the mechanical durability of SOFCs. [ABSTRACT FROM AUTHOR]

Herein, the effect of niobium pentoxide (Nb 2 O 5) and nano-sized cerium oxide (CeO 2) on oxidation behavior and area specific resistance (ASR) of the ferritic stainless steel has been investigated for the development of robust metallic interconnects. An oxide-dispersed ferritic stainless steel alloy is fabricated using the powder metallurgy (PM) process. The morphologies of the alloy before and after oxidation are observed through Scanning Electron Microscope (SEM), Scanning Transmission Electron Microscopy (STEM) and Secondary Ion Mass Spectrometry (SIMS) analyses. Addition of Nb 2 O 5 in the alloy formed a C14 Laves phase of (Fe, Cr) 2 (Nb, Si). The Laves phase and CeO 2 controlled the oxidation behavior of the ferritic stainless steels, consequently reducing the oxide scale thickness and improving the ASR. An alloy with 1 wt% Nb 2 O 5 and 3 wt% CeO 2 showed an ASR value of 27.1 mΩ cm2 at 800 °C for 1000 h, which is similar to the ASR value of the commercial Fe–Cr alloy. The results of this study indicate that Nb 2 O 5 and CeO 2 -dispersed ferritic stainless steel using the PM process can be more advantageous than the conventional process for manufacturing metallic interconnects with complex shapes and reducing production costs. [Display omitted] • The added Nb 2 O 5 in the alloy forms Laves phase of (Fe,Cr) 2 (Nb,Si). • More than 0.85 wt% Nb in the alloy improves the relative density to more than 95 %. • The S5 alloy with 1wt. Nb 2 O 5 and 3 wt% CeO 2 has the lowest ASR value. • The alloy produced by the PM process has similar properties to conventional process. [ABSTRACT FROM AUTHOR]

• The usefulness of nitriding as pre-treatment for SOFC interconnects is tested. • In situ oxidation of samples was recorded with environmental SEM. • The electrical properties of the steels are not clearly improved. • Nitriding demonstrated to decrease chromium evaporation with porous coating. • No intergranular corrosion is observed in the samples. Plasma nitriding was applied to ferritic stainless steel substrates to improve their performances as interconnects for solid oxide fuel cell devices. The samples underwent electrical conductivity test and SEM/EDS, TEM/EDS, environmental-SEM analyses. The first stages of corrosion were recorded in-situ with the e-SEM. Nitriding is effective in limiting the undesired chromium evaporation from the steel substrates and accelerates the corrosion kinetics, but its influence of the electrical conductivity is ambiguous. No intergranular corrosion is found in the steel substrate after long time operation. Nitriding helps commercially competitive porous coating to improve chromium retention properties of metal interconnects. [ABSTRACT FROM AUTHOR]

This study investigates the effect of Mn concentration in La 2 O 3 -dispersed ferritic steel on the oxidation behavior, area-specific resistance (ASR), and chromium volatilization for solid oxide fuel cell (SOFC) interconnects. The results show that increasing Mn concentrations lead to a gradual increase in the oxidation rate of the alloy samples. The alloy with 0.3 wt% Mn primarily forms Cr 2 O 3 during the initial oxidation stage, whereas the alloys containing more than 1.0 wt% Mn promote the growth of (Mn,Cr) 3 O 4 , leading to an accelerated oxidation rate. The ASR value exhibits a decreasing trend initially, followed by an increasing trend, as the Mn concentration in the alloy increases from 0.3 to 2.0 wt%. The alloy with 1.0 wt% Mn shows the lowest ASR value of 12.2 mΩ cm2 after 1000 h. The alloys demonstrate a tendency to reduce chromium volatilization as the Mn concentration increases, which can be attributed to the growth of (Mn,Cr) 3 O 4 at the topmost layer of the oxide. The study suggests that controlling the Mn concentration in the Fe-Cr alloys can help in reducing the ASR values and Cr volatilization, making the ferritic steel alloy with 1.0 wt% Mn an effective choice for SOFC interconnects. • Mn-containing ferritic stainless-steel alloy fabricated by powder metallurgy. • Manganese affects oxidation and Cr volatilization in alloy. • 1.0 wt% Mn alloy shows lowest ASR of 12.2 mΩ cm2 after 1000 h at 800 °C. • 1.0 wt% Mn addition reduces electrical resistance and Cr volatilization. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) can convert hydrocarbon fuels, such as methane, into heat and electricity with a high conversion efficiency. The fuel flexibility of the SOFC derives from the high operating temperature (600-900 °C). Such a high temperature stresses the materials used in the SOFC stacks, notably the metals constituting the interconnect (IC). Research centres developed in last twenty years specific alloys and coatings compositions. This led to a vast literature production of solutions to mitigate the degradation of the metals used in SOFC stacks. Unfortunately, the testing method and conditions change from one laboratory to another making the comparison of the results often impossible. This article compares systematically more than sixty different solutions to limit the degradation in the IC. The samples differed for the steel composition, the coating deposition technique, and the coating composition. A modified 4-probe technique and SEM/EDS post-test characterization measure the area specific resistance and chromium retention of the samples. Testing results indicate that i) deposition technique is the most relevant parameter, ii) in presence of coatings, the performances are independent of the type of ferritic stainless steel substrate iii) nitriding helps to limit the outward chromium diffusion in case of porous coatings. • More than 60 combinations of material solutions for SOFC interconnects are tested. • Chromium retention and area specific resistance of these solutions are measured. • Coating deposition technique is the key for an interconnect of good performance. • Cheaper commercial stainless steel (K41) can compete with SOFC-specific steels. • Steel nitriding improves chromium retention when coatings are porous. [ABSTRACT FROM AUTHOR]