Search Results (5)

The present study provides fundamental information on the resource recyclability of the interconnect assembly, i.e., the steel interconnector and the nickel meshes, from an end-of-life JÜLICH Solid Oxide Cell Stack—F10 design. The interconnector is composed of iron, chromium, and less than 4 wt.% of other alloying elements, mainly cobalt and manganese. Calculated blended compositions with the nickel meshes revealed their potential as a raw material in the production of 4xx, 2xx, or 3xx stainless steels. The melting behavior of the interconnect assembly was investigated under different conditions, i.e., in inert and oxidizing atmospheres, with and without the addition of slag-forming fluxes. The results demonstrated preferential oxidation of chromium in a trivalent state within the stable cubic spinel phase. Finally, the experimental results were compared with the thermodynamic equilibrium calculations based on the available databases (FToxid, SGTE, and SGPS) in FactSage 8.1 software. The calculated tendency to oxidize is in the order of Cr > Mn > Fe > Co > Ni at P(O₂) greater than 10⁻¹⁰ bar, validating the experimental results. Full article

To enhance the comprehensive performance of solid oxide fuel cells (SOFCs) ferritic stainless steel (FSS) interconnectors, a novel approach involving composite electrodeposition and thermal conversion is proposed to prepare Ni-doped Co-Mn composite spinel protective coatings on FSS surfaces. The process involves the composite electrodeposition of a Ni-doped Co-Mn precursor coating, followed by thermal conversion to obtain the Co-Mn-Ni composite spinel coating. Crofer 22H was used as the substrate and orthogonal experiments were designed to investigate the influences of deposition solution pH, stirring rate, cathode current density, and the element content of Mn and Ni on the surface morphology and properties of the composite coatings, respectively. The characterization of the prepared coatings was conducted through macroscopic and microscopic morphology observations of the component surface, energy dispersive spectroscopy (EDS) analysis, and area specific resistance (ASR) testing, etc. Finally, the optimized composite electrodeposition parameters and the Mn-Ni content ratio in the solution were obtained. Experimental results indicated that the composite spinel coating prepared with the optimized process parameters exhibited excellent adhesion to the substrate, and the diffusion and migration of Cr element has been effectively inhibited. Compared with the substrate, the ASR of the coated components has also been decreased simultaneously, which provided an effective method for the surface modification of SOFC FSS interconnectors. Full article

Single planar fuel cell elements consisting of metallic interconnectors that are bonded and sealed by a thin glass solder layer form the core of a solid oxide fuel cell. For reliable operation, the bonding layer has to adhere well and must be without voids or foreign material inclusions, which might cause gas leakage, electrical shorts or mechanical weakening and structural failure. Nondestructive testing (NDT) by the high-frequency ultrasound in immersion technique and by air-coupled ultrasound was optimized to find such defects. Another technique was flash light excited thermography for detection of voids. The NDT techniques used are complementary to each other, as they are based on different physical principles. Voids and small steel platelets of different sizes were prepared in the glass solder layer before the high-temperature bonding process and then monitored by the NDT techniques through the interconnector plates. Two selected NDT techniques were then validated in a probability of detection (POD) study. The study resulted in detection limits for the two main types of defects. As a step towards production testing, a demonstrator was built combining testing by air-coupled ultrasound and that by flash thermography. During the testing steps, the cell elements were handled by a collaborative robot. Full article

The recycling of exhausted lithium-ion batteries from mobile phones originate five solutions with different Co and Mn proportions that were used as electrolytic solutions to obtain Mn-Co spinel coatings on the surface of AISI430 stainless steel. The coatings are intended to contain chromium volatility in the working conditions of Solid Oxide Fuel Cells (SOFC) metallic interconnectors. Potentiostatic electrodeposition was the technique used to obtain Mn-Co coatings from low concentration electrolytes at pH = 3.0 and potential applied −1.3 V. Charge efficiency data were used for sample optimization. Three optimized samples were subjected to oxidation heat treatment at 800 °C for 300 h and then characterized by XRD, SEM and EDS. The results showed that the addition of manganese ions instead of cobalt ions in the electrolytic bath produces more stable and well-distributed deposits as the ratio of the two ions becomes equal in the electrolytic bath. Thin, homogeneous and stable spinel coatings (Mn, Co)₃O₄ 2.8 μm and 3.9 μm thick were able to block chromium volatility when exposed to SOFC operating temperature. Full article

: Two grades of chromium-free alloys were studied in order to apply them as interconnectors for solid oxide fuel cells. The surface modification methods were proposed for each alloy with the purpose of forming of oxide scales considering the required physicochemical properties. Investigations of the structure and properties of the obtained oxide scales were performed and the efficiency of the chosen surface modification methods was approved. The samples with the surface modification exhibited higher conductivity values in comparison with the nonmodified samples. A compatibility study of samples with surface modification and glass sealant of chosen composition was accomplished. The modified samples demonstrated good adhesion during testing and electrical resistance less than 40 mOhm/cm² at 850 °C in air, which allowed us to recommend these alloys with respective modified oxide scales as interconnectors for SOFC. Full article