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This paper presents corrosion resistance results of a 12Cr ferritic ODS steel (Fe-12Cr-2W-0.5Zr-0.3Y2O3) fabricated via a powder metallurgy route as a prospective applicant for fuel cladding materials. In a spent nuclear fuel reprocessing facility, nitric acid serves as the primary solvent in the PUREX method. Therefore, fundamental immersion and electrochemical tests were conducted in various nitric acid solutions to evaluate corrosion degradation behavior. Additionally, polarization tests were also performed in 0.61 M of sodium chloride solutions (seawater-like atmosphere) as a more general, all-purpose procedure that produces valid comparisons for most metal alloys. For comparison, martensitic X46Cr13 steel was also examined under the same conditions. In general, the corrosion resistance of the 12Cr ODS steel was better than its martensitic counterpart despite a lower nominal chromium content. Potentiodynamic polarization plots exhibited a lower corrosion current and higher breakdown potentials in chloride solution in the case of the ODS steel. It was found that the corrosion rate during immersion tests was exceptionally high in diluted (0.1–3 M) boiling nitric acid media, followed by its sharp decrease in more concentrated solutions (>4 M). The results of the polarization plots also exhibited a shift toward more noble corrosion potential as the concentrations increased from 1 M to 4 M of HNO3. The results on corrosion resistance were supported by LSCM and SEM observations of surface topology and corrosion products. [ABSTRACT FROM AUTHOR]

Doping is one of the possible ways to significantly increase the thermoelectric properties of many different materials. It has been confirmed that by introducing bismuth atoms into Mg sites in the Mg2Si compound, it is possible to increase career concentration and intensify the effect of phonon scattering, which results in remarkable enhancement in the figure of merit (ZT) value. Magnesium silicide has gained scientists’ attention due to its nontoxicity, low density, and inexpensiveness. This paper reports on our latest attempt to employ ultrafast self-propagating high-temperature synthesis (SHS) followed by the spark plasma sintering (SPS) as a synthesis process of doped Mg2Si. Materials with varied bismuth doping were fabricated and then thoroughly analyzed with the laser flash method (LFA), X-ray diffraction (XRD), scanning electron microscopy (SEM) with an integrated energy-dispersive spectrometer (EDS). For density measurement, the Archimedes method was used. The electrical conductivity was measured using a standard four-probe method. The See-beck coefficient was calculated from measured See-beck voltage in the sample subjected to a temperature gradient. The structural analyses showed the Mg2Si phase as dominant and Bi2Mg3 located at grain boundaries. Bismuth doping enhanced ZT for every dopant concentration. ZT = 0.44 and ZT=0.38 were obtained for 3wt% and 2wt% at 770 K, respectively [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effect of the support phase composition (Al2O3–TiO2) and the addition of gold on the catalytic properties in low-temperature CO oxidation. In this paper, the physicochemical properties and results of catalytic measurements performed for the obtained samples were investigated. The catalyst carriers were prepared using the sol-gel method with alkoxide Al(C3H7O)3 and Ti(C3H7O)4 employed to obtain the corresponding oxides, in the case of which the molar ratio (Al2O3:TiO2) was 0.75:0.25, 0.50:0.50 and 0.25:0.75, thus corresponding to the molar ratio of the Al:Ti elements, i.e. 1.5:0.25, 2:1 and 0.5:0.75 respectively. The gold catalysts were prepared through the deposition of gold by the deposition precipitation method using the theoretical loading of Au 2 wt.%. To examine the effect of the phase composition on the catalytic activity of the obtained samples, appropriate carriers were calcined at two different temperatures: 500°C and 1350°C. This made it possible to obtain the intended polymorphs of aluminum oxide and titanium dioxide (γ–Al2O3, α–Al2O3, anatase and rutile). For certain samples, calcined at a high temperature, the aluminum titanium oxide (Al2O5Ti) phase was also observed. The prepared samples were characterized by XRD, BET, SEM, and additionally both particle size distribution analysis and measurements of the catalytic activity were performed. The highest catalytic activity was shown by Au/75Al–25Ti_LT, where T90 was about 110°C.

The morphological characterization of a series of cobalt-cerium oxide composites prepared by the deposition of CeO2 onto Co3O4 powder with a molar ratio of cerium oxide to Co3O4 in the range of 0 to 1 was performed. The powders were also impregnated with a solution of K2CO3 to obtain the theoretical content of potassium atoms 2at·nm−2. To investigate the effect of adding specific amount of CeO2 on the catalytic activity, the X-ray diffraction, SEM-EDX, laser particle size distribution and BET surface area measurements were used. The catalysts were tested through the low-temperature decomposition of nitrous oxide in the temperature range of 50°C to 700°C. The addition of CeO2 and K always moved the temperature of a complete N2O conversion towards lower temperatures (480°C-540°C to 340°C-420°C). The best catalytic properties were shown by the samples in which the ratio of cerium oxide to cobalt oxide ranged from 0.4 to 0.7.