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A novel two-layer structural thermal barrier coating (TBC) system with a ~150-µm-thick CoCrAlY bond coat (BC) and a ~60-µm-thick yttria stabilized zirconia (YSZ) ceramic top coat (TC) was prepared on superalloy K444 matrix using electron beam physical vapor deposition (EB-PVD). This deposited coating was characterized using isothermal oxidation tests (1000 °C × 200 h). The results indicated that the deposited coating had a dense structure and close bonding between the layers. The thermally grown oxide (TGO) layer (predominantly alumina) that formed at the interface between the TC and the BC as a consequence of the oxidation process was effective in preventing the further oxidation of the BC. In the later stages of the oxidation process, embedded oxides of chromium/cobalt were observed among the TC's columnar grains, and the TGO underwent densification thinning. Through observations of the growth behavior of the TGO, the element diffusion, displacement reaction, and volatilization of the oxides were found to be related to the weight loss in the coating and the densification thinning of the TGO. These coatings displayed superior high-temperature oxidation resistance properties. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Mg–5.21Li–3.44Zn–0.32Y–0.01Zr alloy was prepared. And the microstructure of as-cast and extruded specimens was analyzed with OM, XRD, SEM and TEM. Results showed that the specimens are composed of α phase, β phase, W phase and Mg0.97Zn0.03 compound. After extruding process, the microstructure is refined and the precipitated phases are broken into small particles and distribute uniformly in the matrix along the direction of extrusion. Mechanical properties results showed that the strength and elongation are both improved after extruding deformation. XRD analysis revealed that the element Y brought about the formation of W-phase in the alloy. The phase-forming mechanism in Mg–Li–Zn–Y–Zr alloys is not in agreement with that in Mg–Zn–Y or Mg–Zn–Y–Zr alloys. [Copyright &y& Elsevier]

A novel sodium-promoted Fe-Co/NC catalyst prepared by incipient-wet-impregnation method using ZIF-67 as a support was employed to convert CO2 to light olefins through hydrogenation reaction. Properties of the synthesized catalysts calcinated at various temperatures (from 400 to 700 °C) were investigated by XRD, SEM, TEM and Mӧssbauer spectroscopy. Characterization results showed that the support could be fully converted into carbon support above 500 °C, which could anchor metal particles, thus resulting in a uniform dispersion of active components. Furthermore, the Fe-Co alloy was formed during N2 calcination, and was converted into active components, such as Fe3O4, Fe5C2, and Co2C during the reaction. The reaction result indicated that FeCo/NC-600 catalyst exhibited the highest selectivity of light olefins (C2= − C4=, 27%) and CO2 conversion could reach around 37% when this catalyst pyrolyzed at 600 °C in N2. The highest selectivity for light olefins may be related to the combination of suitable particle size and sufficient active sites of iron carbide. [ABSTRACT FROM AUTHOR]

The developed karst caves may become the seepage channels of heavy metal to the soil and underground water in Southwest China. Therefore, it is necessary to apply effective seepage treatments to the base of heavy metal tailing reservoirs. This paper addressed the high-pressure rotary jet technology and slurry systems used in the seepage treatment of the deep tailing sand of the Shenxiandong tailing pond located in Southwest China. In this study, the factors of fluidity, initial and final setting times, compressive strength, and permeability coefficient of the slurry were conducted. The mechanism analysis was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and inductively coupled plasma-mass spectrometry (ICP-MS). Three different types of slurry systems were proposed, and the permeability coefficients of the solidification body following 28 days of curing were less than 1 × 10−7 cm/s. The concentrations of Pb and Zn in the slurry system containing bentonite were reduced by 26.2% and 45.7%, respectively. In the presence of slaked lime and fly ash, the concentrations of Pb and Zn could be reduced by 26.8% and 30%, respectively. A total of 2142 high-pressure rotary jet piles were completed by the high-pressure rotary jet method in the field trial. The diffusion radius of these piles was over 1 m. Following 28 days of curing, the solidification body's compressive strength was 7.45 MPa and the permeability coefficient was 6.27 × 10−8 cm/s. Both the laboratory and on-site trials showed that this method produced a good pollution barrier effect, which could prevent the diffusion of heavy metal into the adjacent underground water through the karst caves. It is also an effective way of engineering technology concerning heavy metal pollution control that occurs in tailing ponds. [ABSTRACT FROM AUTHOR]

The unique molecular trapdoor mechanism of chabazite zeolites provides an ideal platform for CO 2 integrative adsorption and conversion. Herein, a mesoporous In-SSZ-13 (MP) catalyst was successfully synthesized through desiliconization combined with anchoring uniformly dispersed indium (In) active sites, which achieved the highest formate Faraday efficiency (FE HCOO -) of 92.0 % and a formate partial current density (j HCOO -) of 133.3 mA cm−2 for electrochemical CO 2 reduction reaction (CO 2 RR) at a moderate overpotential of 0.8 V. Experimental results combined with DFT calculations reveal the reaction mechanism of In-SSZ-13 (MP) electrocatalytic reduction of CO 2 : as the only channel into the In-SSZ-13 (MP) crystal, the gatekeeper (cation, In3+) in eight-membered ring (8MR) deviates from its original position induced by CO 2 molecule, then CO 2 poured into CHA cage and fully reacted with uniformly distributed indium active sites. Molecular trapdoor mechanism assists In-SSZ-13 (MP) catalyst for electrochemical reduction of CO 2 , achieving 92.0 % of FE HCOO - and 133.3 mA cm−2 of j HCOO - at − 1.0 V vs. RHE. [Display omitted] • Mesoporous In-SSZ-13 (MP) catalyst was successfully synthesized through desiliconization combined with ion exchange. • The gatekeeper cations induced the enrichment of CO 2 molecules on In-SSZ-13 (MP) and promoting the conversion of CO 2 to HCOOH. • The indium cations located at CHA cage in In-SSZ-13 (MP) provide the most active centers for CO 2 RR to formate. [ABSTRACT FROM AUTHOR]

The dissimilatory Fe(III)-reducing bacteria play a significant role in the mobility of antimony (Sb) under reducing environment. Sb-rich smelting slag is iron (Fe)-containing antimonic mine waste, which is one of the main sources of antimony pollution. In this study, the soluble antimony reacted with Fe(III) by S. oneidensis (Shewanella oneidensis strain MR-1) was performed in reduction condition, then the dissolution behavior of the Sb-rich smelting slag with S. oneidensis was investigated. The results showed that the released Sb was immobilized by S. oneidensis and the strain adsorbed Sb(III) preferentially. Sb(V) can be reduced by S. oneidensis without aqueous Fe. In the presence of Fe(III), S. oneidensis mediated Sb bio-adsorption and the chemical redox of Sb-Fe occurred simultaneously. Sb was co-precipitated with Fe to form the Sb(V)-O-Fe(III) secondary mineral, which was identified as the bidentate mononuclear edge-sharing structure by extended X-ray absorption fine structure (EXAFS) analysis. These results suggest that S. oneidensis has a positive effect on the immobilization and minimizing toxicity of antimony in anoxic soil and groundwater, which provides a theoretical basis for the treatment of antimony contamination. [Display omitted] • Sb was immobilized by S. oneidensis and Sb(III) was bio-adsorbed preferentially. • Sb(III) was indirectly oxidized to Sb(V) by S. oneidensis with aqueous Fe(III). • Sb was co-precipitated with the released Fe from the Sb-rich smelting slag. • Secondary mineral was bidentate mononuclear structure with Sb(V)-O-Fe(III). [ABSTRACT FROM AUTHOR]