Electrodeposition of Zn, Cu, and Zn-Cu Alloys from Deep Eutectic Solvents

Deep eutectic solvents (DESs) comprising choline chloride (ChCl) with either urea or ethylene glycol (EG) have been successfully used as powerful and potential electrolytes for extracting metals from their corresponding metal oxide precursors. In this work, for electrodeposition of Zn and Zn-Cu alloys, ChCl/urea-based DES was employed. Cyclic voltammetry study demonstrates that the reduction of Zn(II) to Zn is a diffusion-controlled quasi-reversible, one-step, two electrons transfer process. Micro-/nanostructured Zn and Zn-Cu alloys films have been electrodeposited directly from their metal oxide precursors in DES, and the Zn and Zn-Cu alloy films exhibit homogeneous morphologies with controlled particle sizes. Besides, the electrodeposition of Cu from CuO in the eutectics based on ChCl with urea and EG has been investigated, respectively. The higher coordinated Cu species in the ChCl/urea-based DES are obviously more difficult to reduce, and higher overpotential is needed to drive the nucleation process compared with the lower coordinated Cu species in the ChCl/EG-based DES. The surface morphology of the Cu electrodeposits is significantly affected by the type of DES and the electrodeposition potentials. Furthermore, the Cu electrodeposits obtained in the ChCl/urea-based DES possess more dense microstructures than those produced in the ChCl/EG-based DES

Effect analysis of coal seam water infusion based on genetic algorithm-BP neural network

In order to improve prediction accuracy of coal seam water infusion effect by using BP neural network, genetic algorithm was used to optimize weight value and threshold value of BP neural network. Genetic algorithm-BP neural network model was built and used to predict wetting radius of coal seam water infusion. The Matlab simulation result shows that the genetic algorithm-BP neural network model has more accurate prediction result than BP neural network model, average relative error of the genetic algorithm-BP neural network model is reduced by 40.29%, training steps are reduced by 1 665 steps, convergence speed is fast and stability is good. Key words

Numerical simulation on gas drainage and borehole arrangement parameters of bedding borehole in a coal mine

Based on comprehensive consideration of gas flow inertia and slippage effect, a gas drainage flow model was established. Based on engineering background of 12150 coal face of the No.15 coal seam in Songhe Coal Mine, the distribution law of gas pressure and the change of permeability under condition of single borehole and multi—borehole were analyzed by numerical simulation, and the reasonable diameter and the layout parameters of borehole were obtained combined with the effective radius of borehole drainage. When gas is extracted with single borehole for 240 days, it is more appropriate to select 65 mm diameter through comparing gas extraction effect of borehole with diameter among 40, 65, 75, 94 mm. When three boreholes are spaced at 3, 4 and 5 m respectively, it is concluded that when the pre—extraction time is more than 180 days, the boreholes spacing of 5 m is more appropriate on the basis of analysis of effective radius of gas extraction at different time periods. When the extraction time is between 120 days and 150 days, it is more appropriate to select the 4 m borehole spacing. When the extraction time is less than 120 days, it is more appropriate to select the 3 m borehole spacing. The permeability of coal seam increases gradually with the increasing of extraction time, but the increasing amplitude gradually decreases. At the initial stage of extraction, the gas pressure gradient is larger, a large amount of adsorption gas is desorbed, and the gas pressure is greater than the adsorption expansion stress, and the fracture—pore channel is opened, at this time the permeability is relatively large. In the middle and late stages of extraction, the gas pressure continues to decrease, the gas pressure has little advantage over the adsorption expansion stress, and the increase value of fracture—pore is small, resulting in a small increase of coal seam permeability during the middle and late stages of extraction

Numerical Simulation of Seepage-Heat-Solid Coupling of Gas Seepage in Prepumped Boreholes under Electrothermal High Temperature Field

In order to verify the law of coal bed gas desorption and permeability under electrothermal high-temperature field, by establishing the mathematical model of gas seepage-heat-solid coupling, and taking gas drainage working face in Guizhou as an engineering example, the characteristics of the high-temperature field of coal under different heating hole temperatures are simulated. The COMSOL software is used to simulate the high-temperature field characteristics, thermal damage, and permeability of coal under different heating hole temperatures. The numerical simulation results show the following:(1) the influence trend of a high-temperature field on coal thermal damage and permeability is consistent, when the heating temperature is higher than 600°C, the thermal damage and permeability of coal seam change suddenly and increase with the increase of temperature. (2) When the temperature of a heating hole is 200-800°C, the gas permeability in the damaged area increases with the increase of temperature. When the heating temperature is greater than 600°C, the radial and axial permeability around the heating hole will increase. (3) Compared with the experimental data obtained by the existing researchers, the simulation results of coal permeability under the electric heating high-temperature field have a high consistency with the experimental results of Junrong and others

Study on gas emission effect of coal seam borehole under high temperature field

Aiming at the difficult problem of gas drainage in low permeability outburst coal seam in China, taking the transportation lane of coal mining face in K15 coal seam of Maizigou Coal Mine in Guizhou Province as the engineering background, through the establishing the multi-field coupling model of gas flow in coal mining face under high temperature field, the gas drainage effect of coal seam boreholes under different heating temperature, borehole diameter and borehole spacing conditions was simulated and studied. The research shows that temperature has a significant impact on the effect of coal seam gas emission. When the heating temperature is 86 ℃, the gas pressure decreases significantly; the borehole diameter has a great influence on the effect of coal seam gas emission. When the borehole diameter is 113 mm, the maximum gas pressure between boreholes is 0.36 MPa, the maximum gas pressure decreases by 14.28% year on year, and the gas emission from boreholes increases by 27.27%. The effect of borehole spacing on coal seam gas pressure and discharge effect is also very obvious. When the borehole spacing is 1 m, the maximum gas pressure between boreholes is 0.45 MPa, and the influence range is 5.72 m. The decrease range of gas pressure increased by 37.8% compared with the hole spacing of 1.5 m and the influence range increased by 18.18% compared with the hole spacing of 1.5 m. The comprehensive gas discharge effect was the best. Comparing the simulation results of different schemes, the numerical simulation scheme 9 has the best gas emission effect

Electrodeposition behaviour and characterization of copper-zinc alloy in deep eutectic solvent

Cu?Zn alloy films have been electrodeposited directly from their oxide precursors in choline chloride (ChCl)/urea-based deep eutectic solvent (DES). The reaction mechanism and the influence of the cathodic potential on the characteristics of the Cu?Zn alloy films are studied. Cyclic voltammetry and energy dispersive spectroscopy analyses reveal that the reduction of Cu(II) species relatively more preferentially occurs in comparison with the reduction of Zn(II) species, and Cu?Zn codeposition process can be controlled in the DES. Chronoamperometric investigation further confirms that the electrodeposition of Cu?Zn alloy on a Fe electrode follows the three-dimensional instantaneous nucleation-growth process. The micro/nanostructured Cu?Zn alloy films with different phase compositions can be facilely produced by controlling the cathodic potential. The obtained Cu?Zn alloy films typically exhibit enhanced corrosion resistances in 3 wt% NaCl aqueous solution. It is suggested that Cu?Zn alloy films can be sustainably electrodeposited from their abundant and inexpensive oxide precursors in DESPeer reviewe

Microstructure and wear resistance of in-situ TiC reinforced Stellite 6 coating using PTA cladding

To enhance the durability of copper tuyeres in blast furnaces, it is necessary to apply coatings on their surfaces to protect against wear caused by high-temperature coke. In this study, a series of in-situ synthetic TiC-reinforced Stellite 6 alloy coatings containing a Ni60A interlayer were successfully produced on copper substrates using 5–45 wt% TiFe/Cr3C2 precursor powders. The coatings exhibited excellent metallurgical bonding with the Ni60A interlayer, and an elemental transition zone was formed at the interface between the coating and the interlayer. XRD Rietveld refinement analysis revealed that the T45 coating with 45 wt% of precursor powder showed the highest TiC phase content of 12.27 %, with an average hardness of 658.15 HV0.2, which was 31.2 % higher than that of the Stellite 6 alloy. The wear mechanism of the Stellite 6 coating was plastic delamination at 25 °C, and oxidative wear at 500 °C. As the TiC particle content in the coating increased, the dominant wear mechanism tended to shift towards abrasive wear. The specific wear mechanism of the coating was influenced by the content of coating phases and the operating temperature. The best wear resistance was achieved by the T45 coating, which showed an abrasive wear mechanism at both 25 °C and 500 °C, with a wear resistance of 4.47 and 5.94 times higher than that of the Stellite 6 alloy respectively

Electrosynthesis of Ti3AIC2 from oxides/carbon precursor in molten calcium chloride

Layered micron-scale Ti3AlC2 powders have been successfully synthesized from TiO2/Al2O3/C precursor by a facile electrochemical process at 900 ?C and 3.1 V in molten CaCl2. Porous TiO2/Al2O3/C mixture pellet was served as the cathode and a graphite rod was employed as the anode. The influence of carbon content on the products was systematically investigated. The lattice parameters of the electrosynthesized Ti3AlC2 were determined. In addition, three reaction periods from TiO2/Al2O3/C to Ti3AlC2 including the generation of CaTiO3/Ca12Al14O33 intermediate compounds, the reduction of the oxides/compounds and the formation of Ti3AlC2 were investigated and confirmed. The results show that the electrochemical process is of great potential to the facile synthesis of Ti3AlC2, which may also have implication for the production of other Mn+1AXn phases from their inexpensive and abundantly available oxides precursorsPeer reviewe