In this study, Manganese cobaltite (MnCo2O4) spinel powders were synthesized by co-precipitation method. X ray diffraction (XRD) patterns show that the spinel phase was formed at around 350°C. Formation of spinel phase was further completed by increasing temperature More
In this study, Manganese cobaltite (MnCo2O4) spinel powders were synthesized by co-precipitation method. X ray diffraction (XRD) patterns show that the spinel phase was formed at around 350°C. Formation of spinel phase was further completed by increasing temperature up to 1000°C. Additionally, XRD patterns prove that MnCo2O4 spinel material has been stable in this temperature range. Field emission scanning electron microscope observations show that plate like particles with an average diameter of 148 and thickness of 18 nm was converted to equiaxed particles with an average particle size of 1.5 µm by increasing calcination temperature from 350 to 1000°C. Investigation of the coating of uncalcined and calcined powder on AISI 430 ferritic stainless steel shows that a proper dense coating is developed on the stainless steel surface by using uncalcined precursor powders. And also, this coating performs well by prohibiting of outward diffusion of Fe from the substrate. In this way, a low thickness chromia layer (Cr2O3) is formed between the coating and the substrate. EDX analysis shows that a mixed spinel zone is formed in the interface of the coating and the substrate due to diffusion of some elements such as Mn, Cr, and Fe from substrate to the coating, as well as Mn and Co from coating to the substrate.
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Nowadays, various methods have been introduced for the fabrication of solid oxide fuel cells (SOFC). In this research, 3D printing technology has been used to produce oxide fuel cells. First, a 3D printer was constructed that has the ability to print the More
Nowadays, various methods have been introduced for the fabrication of solid oxide fuel cells (SOFC). In this research, 3D printing technology has been used to produce oxide fuel cells. First, a 3D printer was constructed that has the ability to print the slurry of anode, cathode and electrolyte layers with the desired thickness and speed. Then a suitable slurry consisting of NiO-YSZ materials was produced for the anode layer, YSZ for the electrolyte layer and LSM for the cathode, with suitable solvents and additives. After cell formation, drying and then sintering of the layers were performed. The composition and microstructure characterization of layers has been performed by XRD, SEM, Mapping, EDS. The I-V-P curve showed the maximum power is around 0.84 W / cm2 at 800 OC with constant oxygen. The impedance curve values under open-circuit voltage were 0.23 Ωcm-2 and 1.25 Ωcm-2 at high and low frequencies, respectively. The tensile experiments indicated values 111 GPa for Young modulus and 137 MPa and 120 MPa values for the fracture toughness and the yield strength, respectively.
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Oxidation resistance and electrical conductivity of stainless steels used as interconnects in solid oxide fuel cells can be improved by using a conductive and protective coating layer. In this study, AISI 304 austenitic stainless steel was coated in a cobalt powder base More
Oxidation resistance and electrical conductivity of stainless steels used as interconnects in solid oxide fuel cells can be improved by using a conductive and protective coating layer. In this study, AISI 304 austenitic stainless steel was coated in a cobalt powder base pack mixture. Isothermal oxidation test was used to investigate the oxidation resistance of coated and non-coated steel. Area specific resistance (ASR) was also measured as a function of oxidation time at 800 °C. Microstructure of coated and oxidized samples was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) device. The results showed that cobalt coated samples showed better oxidation resistance than non-coated samples. The results showed that increasing the temperature would increase the area specific resistance. The cobalt coating layer also converted to CoFe2O4, Co3O4 and CoCr2O4 spinels during the isothermal oxidation process. Cobalt spinels exhibited less ASR (27.4 mΩ cm2) compared to the uncoated sample (60.5 mΩ cm2).
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