c/MgO composite powders were prepared by combustion synthesis using magnesium oxalate and magnesium powders as raw materials. The phase composition and microstructure of the composite powders were investigated by X-ra...
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c/MgO composite powders were prepared by combustion synthesis using magnesium oxalate and magnesium powders as raw materials. The phase composition and microstructure of the composite powders were investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy/energy dispersive spectroscopy (FESEM/EDS), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy. The synthetic mechanism was explored through TG-FTIR and combustion front quenching techniques. It was found that the c/MgO composite powders contained a large quantity of MgO nanofibers. When the molar ratio of magnesium oxalate and magnesium was 1:4, the carbon content of the product reached a maximum of 9.45 wt %. In the composite powders, cubic MgO particles were encapsulated by a thin carbon layer, and there was a tiny gap between MgO and the carbon layer;a large number of MgO nanofibers with aspect ratios of 80?100 were found. The cubic MgO particles of the products are the direct decomposition of Mgc2O4, and the MgO nanofibers are the reaction product of gaseous Mg and cO2/cO at high temperature. Meanwhile, the carbon deposited on the MgO particles can inhibit the grain growth of MgO particles and result in the refinement of MgO particles. The uniform dispersion of carbon and the weak c/MgO interface combine, making the composite powders a potential additive for low-carbon MgO?c refractories with excellent thermal shock resistance.
In order to study the effects of temperature on the material behavior of Liquid Silicon Infiltration (LSI) based continuous carbon fiber reinforced silicon carbide (c/c-Sic), the mechanical properties at room temperat...
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In order to study the effects of temperature on the material behavior of Liquid Silicon Infiltration (LSI) based continuous carbon fiber reinforced silicon carbide (c/c-Sic), the mechanical properties at room temperature (RT) in in-plane and out-of-plane directions are summarized and the tensile properties of c/c-Sic were then determined at high temperature (HT) 1200 degrees c and 1400 degrees c under quasi static and compliance loading. The stressstrain response of both HT tests is similar and almost no permanent strain can be observed compared to the RT, which can be explained through the relaxation of residual thermal stresses and the crack distribution under various states. The different fracture mechanisms are confirmed by the analysis of fracture surface. Furthermore, based on the analysis of hysteresis measurements at RT, a modeling approach for the prediction of material behavior at HT has been developed and a good agreement between test and modeling results can be observed.
A process parameter strategy to manufacture a Ti6Al4V-5wt%cr 3 c 2 metal matrix composite using laser powder bed fusion was investigated. Several deposition strategies were developed and attempted to find dense, crack...
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A process parameter strategy to manufacture a Ti6Al4V-5wt%cr 3 c 2 metal matrix composite using laser powder bed fusion was investigated. Several deposition strategies were developed and attempted to find dense, crack-free, non-porous composites with high hardness. Low energy densities resulted in composites with cracks and low hardnesses, while high energy densities resulted in crack-free composites with pores and relatively high hardness. While an optimal deposition parameter set was found to produce crack-free samples with good density and hardness, the samples still showed keyhole porosity. The addition of the cr 3 c 2 to Ti6Al4V stabilized the titanium-β phase since cr is a β stabilizer, and small amounts of Tic and the brittle ω phase were formed. The micro-hardness increased with the addition of the cr 3 c 2 due to the presence of the brittle phases. An annealing heat treatment led to an elimination of the ω phase which consequently decreased the hardness of the composite.
Photocatalytic hydrogen evolution from water splitting is a promising strategy to solve the energy demand of human beings. Here, we first designed a c-Mn0.5cd0.5S/cu3P ternary heterojunction catalyst for photocatalyti...
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Photocatalytic hydrogen evolution from water splitting is a promising strategy to solve the energy demand of human beings. Here, we first designed a c-Mn0.5cd0.5S/cu3P ternary heterojunction catalyst for photocatalytic hydrogen production. The results show that the combination of c and cu3P can effectively improve the photocatalytic activity of Mn0.5cd0.5S. c-Mn0.5cd0.5S loading with 5 wt% cu3P exhibits the highest hydrogen evolution rate (44.1 mmol g(-1) h(-1)), which is 3.2 and 2.8 times higher than that of pure Mn0.5cd0.5S (13.7 mmol g(-1) h(-1)) and Mn0.5cd0.5S/3 wt%Pt (15.6 mmol g(-1) h(-1)), respectively. In addition, it shows a high hydrogen evolution rate (19.6 mmol g(-1) h(-1)) under visible light (>= 420 nm) irritation and the apparent quantum efficiency (AQE) is detected to be 3.2% at 420 nm. The enhanced photocatalytic activity can be attributed to the good conductivity of c and the formation of p-n heterojunction, which is beneficial for light harvesting and the separation and transportation of charge carriers. Besides, a possible mechanism is proposed. This work provides an effective way to improve the photocatalytic activity of Mn0.5cd0.5S by using non noble metal co-catalysts. (c) 2021 Hydrogen Energy Publications LLc. Published by Elsevier Ltd. All rights reserved.
A low cost-effective and simple synthesis method was adopted to acquire three-dimensional flower-like structure Fe3O4/c that has large specific area, suitable pore structure and sufficient saturation magnetism. The ob...
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A low cost-effective and simple synthesis method was adopted to acquire three-dimensional flower-like structure Fe3O4/c that has large specific area, suitable pore structure and sufficient saturation magnetism. The obtained Fe3O4/c exhibits outstanding preconcentration ability and was applied to extracting non-steroidal anti-inflammatory drugs from complex environmental and biological samples. The parameters of magnetic solid-phase extraction were optimized by univariate and multivariate methods (Box-Behnken design). The high degree of linearity from 2.5 to 1000.0 ng mL(-1) (R-2 >= 0.9976), the limits of detection from 0.25 to 0.5 ng mL(- 1) (S/N =3), and the limits of quantitation from 1.0 to 2.0 ng mL(- 1) (S/N =10) were yielded by adopting this novel method after the optimization. Moreover, the recoveries of non-steroidal anti-inflammatory drugs from 89.6 to 107.0% were acquired in spiked plasma, urine and lake samples. In addition, the adsorption of non-steroidal anti-inflammatory drugs on Fe3O4/c was explored by adsorption isotherms and kinetic studies. Furthermore, the adsorption mechanism for non-steroidal anti-inflammatory drugs by Fe3O4/c was proposed, which was hydrogen bonding and - interaction between non-steroidal anti-inflammatory drugs and Fe3O4/c.
A progressive oxidative damage model of c/Siccomposites, which is based on the oxidation mechanism and mechanical model of c/Siccomposites, is presented to simulate the damage process of c/Siccomposite under stress...
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A progressive oxidative damage model of c/Siccomposites, which is based on the oxidation mechanism and mechanical model of c/Siccomposites, is presented to simulate the damage process of c/Siccomposite under stressed oxidation environments. Firstly, the oxidation failure time of fibers was calculated according to the fiber stress and the fiber strength decline rule under stressed oxidation environments. Secondly, the stress redistribution and crack propagation around fracture fibers were given by combining the fracture position of fibers with the mechanical model, and the crack propagation would cause more fibers to be oxidized. Thirdly, the progressive oxidative damage process of c/Siccomposites under stressed oxidation environments was simulated by repeating the cyclic process of fiber oxidation fracture and crack propagation around the fracture fibers. Finally, through the progressive oxidative damage model, the stress-strain curves and fracture morphology of the unidirectional c/Siccomposites after stressed oxidation were predicted. The simulation results were correlated well with the experimental results, in terms of stressed oxidation life, stress-strain curve and variation law of fracture morphology, which indicated the reliability of the model.
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