We used the surface-pretreated graphite paper(Gp)as a carrier and loaded BiOCl with high selectivity to Cl^(-)on its surface by solvothermal method to form BiOCl@Gp electrode.The morphology,structure,and composition o...We used the surface-pretreated graphite paper(Gp)as a carrier and loaded BiOCl with high selectivity to Cl^(-)on its surface by solvothermal method to form BiOCl@Gp electrode.The morphology,structure,and composition of the materials were characterized by scanning electron microscopy and nitrogen adsorption/desorption,and the results showed that the spherical BiOCl particles were uniformly dispersed on the surface of the Gp,forming a mesoporous BiOCl@Gp composite with a specific surface area of 22.82 m^(2)/g and a pore volume of 0.043 cm3/g.Furthermore,cyclic voltammetry and electrochemical impedance spectroscopy were used to test the electrochemical properties of the composites,and the stability of BiOCl and the high conductivity of Gp were synergistic,the BiOCl@Gp exhibited a specific capacitance of 30.2 F·g^(-1) at a current density of 0.5 A·g^(-1),and the selectivity of the BiOCl@Gp materials for Cl^(-)was significantly higher than that of SO_(4)^(2-),NO_(2)^(-),and HCO_(3)^(-).Therefore,BiOCl@Gp composite electrode materials can be used for the selective adsorption of Cl^(-)in wastewater,in order to achieve efficient wastewater recycling.展开更多
To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag sys...To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was analyzed.The results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply mode.The effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that order.By reducing the remelting current strength in the same power supply mode,the depth of metal pool is reduced.When compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during remelting.Utilizing the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial crystal.This effect is observed for both low frequency and direct current(DC)power supply modes.展开更多
Higher nickel content endows Ni-rich cathode materials LiNi_(x)Co_yMn_(1-x-y)O_(2)(x>0.6)with higher specific capacity and high energy density,which is regarded as the most promising cathode materials for Li-ion ba...Higher nickel content endows Ni-rich cathode materials LiNi_(x)Co_yMn_(1-x-y)O_(2)(x>0.6)with higher specific capacity and high energy density,which is regarded as the most promising cathode materials for Li-ion batteries.However,the deterioration of structural stability hinders its practical application,especially under harsh working conditions such as high-temperature cycling.Given these circumstances,it becomes particularly critical to clarify the impact of the crystal morphology on the structure and high-temperature performance as for the ultrahigh-nickel cathodes.Herein,we conducted a comprehensive comparison in terms of microstructure,high-temperature long-cycle phase evolution,and high-temperature electrochemical stability,revealing the differences and the working mechanisms among polycrystalline(PC),single-crystalline(SC)and Al doped SC ultrahigh-nickel materials.The results show that the PC sample suffers a severe irreversible phase transition along with the appearance of microcracks,resulting a serious decay of both average voltage and the energy density.While the Al doped SC sample exhibits superior cycling stability with intact layered structure.In-situ XRD and intraparticle structural evolution characterization reveal that Al doping can significantly alleviate the irreversible phase transition,thus inhibiting microcracks generation and enabling enhanced structure.Specifically,it exhibits excellent cycling performance in pouch-type full-cell with a high capacity retention of 91.8%after 500 cycles at 55℃.This work promotes the fundamental understanding on the correlation between the crystalline morphology and high-temperature electrochemical stability and provides a guide for optimization the Ni-rich cathode materials.展开更多
Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity.However,the poor thermodynamic stability(including cyclic performance ...Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity.However,the poor thermodynamic stability(including cyclic performance and safety performance or thermal stability)will restrain their wide commercial application.Herein,a single-crystal Ni-rich Li Ni_(0.83)Co_(0.12)Mn_(0.05)O_(2) cathode material is synthesized and modified by a dual-substitution strategy in which the high-valence doping element improves the structural stability by forming strong metal–oxygen binding forces,while the low-valence doping element eliminates high Li^(+)/Ni^(2+)mixing.As a result,this synergistic dual substitution can effectively suppress H2-H3 phase transition and generation of microcracks,thereby ultimately improving the thermodynamic stability of Ni-rich cathode material.Notably,the dual-doped Ni-rich cathode delivers an extremely high capacity retention of 81%after 250 cycles(vs.Li/Li+)in coin-type half cells and 87%after 1000 cycles(vs.graphite/Li^(+))in pouch-type full cells at a high temperature of 55℃.More impressively,the dual-doped sample exhibits excellent thermal stability,which demonstrates a higher thermal runaway temperature and a lower calorific value.The synergetic effects of this dual-substitution strategy pave a new pathway for addressing the critical challenges of Ni-rich cathode at high temperatures,which will significantly advance the high-energy-density and high-safety cathodes to the subsequent commercialization.展开更多
Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt ...Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na2CO3/paste mass ratio = 2.8:1; and the Zn O dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were Pb SO4→Pb and Pb SO4→Zn S, respectively. Sulfur was fixed in the form of Zn S, whereas the molten salt did not react with other components, serving only as a reaction medium.展开更多
The nose temperature for σ-phase precipitation in super-duplex stainless steel (SDSS) UNS S32750 was evaluated by hardness method.Color-optical microscopy,scanning electron microscopy,energy spectrum analysis,impact ...The nose temperature for σ-phase precipitation in super-duplex stainless steel (SDSS) UNS S32750 was evaluated by hardness method.Color-optical microscopy,scanning electron microscopy,energy spectrum analysis,impact and corrosion testing were carried out to investigate characteristics of microstructure and properties of the SDSS aged at the nose temperature.The experimental results indicate that the nose temperature of precipitation is 920℃ and aging at this temperature tiny σ phases can precipitate at phase interfaces or ferrite grain boundaries within 2min.Prolonging aging duration the amount ofσ-phase increases and a dual structure with σ and γ is obtained when aging for 120min.The precipitation ofσ-phase leads to severe deterioration in impact toughness (longitudinal/transverse direction) and corrosion resistance of SDSS.展开更多
The absorption of low concentration SO2 in flue gas by using the module of liquid-containing microporous membrane which is made up of hollow fiber and citric acid-sodium citrate buffer solution was investigated.The ab...The absorption of low concentration SO2 in flue gas by using the module of liquid-containing microporous membrane which is made up of hollow fiber and citric acid-sodium citrate buffer solution was investigated.The absorption efficiency of hydrophilic and hydrophobic membranes by using the concept of dynamic contact angle was mainly studied.The influences on absorption efficiency from absorption time,flowrate of gas phase,SO2 concentration of gas phase,air pressure,citrate concentration,pH value of solution as well as the generation of sulfate radical in absorption solution were examined.The results indicate that the hydrophobic hollow fiber membrane is better than hydrophilic membrane,the absorption efficiency decreases with increasing absorption time,gas phase flowrate,gas phase SO2 concentration and air pressure,the absorption rate and capacity of SO2 can be improved by increasing the citrate concentration,the absorption efficiency can be improved by increasing the pH value of citrate solution,the concentration of SO42-in absorption solution increases linearly with the absorption time at a rate around 0.192 g/(L-h).展开更多
The most common and serious defect in Cu-Ni alloy casting is porosity. To solve the problem, accurate casting design and proper design of gating system are necessary. It can be predicted and designed by means of compu...The most common and serious defect in Cu-Ni alloy casting is porosity. To solve the problem, accurate casting design and proper design of gating system are necessary. It can be predicted and designed by means of computer simulation of casting solidification. Based on the casting process of the Cu-Ni alloy, the simulation software of diathermanous-flowing-stress coupling ProCAST was used to simulate the Cu-Ni alloy solidification process about the defects and temperature field. By combining experimental results with the simulation results, the quality of casting on some cooling conditions were analyzed. Furthermore, a better cooling condition for solidification process of the Cu-Ni alloy was chosen to improve the quality of the casting. The simulation results indicate that the quality of Cu-Ni alloy casting is the best when it is on the cooling condition of the permanent mold with the insulated riser system.展开更多
To further improve the metallurgical quality of electroslag remelting,remove the large inclusions in electroslag ingot and refine the solidification structure of electroslag ingot,an electroslag remelting furnace with...To further improve the metallurgical quality of electroslag remelting,remove the large inclusions in electroslag ingot and refine the solidification structure of electroslag ingot,an electroslag remelting furnace with electromagnetic stirring was designed,and the influence of different magnetic induction intensities on metallurgical quality of GCr15 electroslag ingot was studied.Inclusions with different sizes and types were analyzed by an ASPEX scanning electron microscope,and the morphology and composition of inclusions were further observed by a JSM-6510LV scanning electron microscope.The distribution of alloying elements on the cross section of electroslag ingot was analyzed by original position analysis(OPA).The results show that whether or not electromagnetic stirring is used,the inclusions in electroslag ingot are mainly composed of Al_(2)O_(3),MnS,MnS-oxide and other oxides,among which Al_(2)O_(3) is the most.Compared with an electroslag ingot without electromagnetic stirring,the number of inclusions decreases considerably,and the proportion of small inclusions increases while the proportion of large inclusions decreases when the electromagnetic stirring with remelting current of 1.1 kA and magnetic induction intensity of 62 Gs is applied.However,excessive electromagnetic force will cause the number and diameter of inclusions to increase again.Electromagnetic stirring has different effects on the segregation of different elements.Under the experimental conditions,the weak electromagnetic force with 1.1 kA and magnetic induction intensity of 108 Gs has little effect on the segregation of C,but decreases the segregation of P,and the excessive electromagnetic force aggravates the segregation of alloy elements.展开更多
A novel electroslag furnace with a rotating mold was fabricated, and the effects of mold rotational speed on the electroslag remelting process were investigated. The results showed that the chemical element distributi...A novel electroslag furnace with a rotating mold was fabricated, and the effects of mold rotational speed on the electroslag remelting process were investigated. The results showed that the chemical element distribution in ingots became uniform and that their compact density increased when the mold rotational speed was increased from 0 to 28 r/min. These results were attributed to a reasonable mold speed, which resulted in a uniform temperature in the slag pool and scattered the metal droplets randomly in the metal pool. However, an excessive rotational speed caused deterioration of the solidification structure. When the mold rotational speeds was increased from 0 to 28 r/min, the size of Al2O3 inclusions in the electroslag ingot decreased from 4.4 to 1.9 μm. But the excessive mold rotational speed would decrease the ability of the electroslag remelting to remove the inclusions. The remelting speed gradually increased, which resulted in reduced power consumption with increasing mold rotational speed. This effect was attributed to accelerated heat exchange between the consumable electrode and the molten slag, which resulted from mold rotation. Nevertheless, when the rotational speed reached 28 r/min, the remelting speed did not change because of limitations of metal heat conduction. Mold rotation also improved the surface quality of the ingots by promoting a uniform temperature distribution in the slag pool.展开更多
To remove the inclusions in the ingots by conventional electroslag remelting(ESR), the bearing steel was prepared using ESR process but with mold rotation in this study. Experimental results show a reduction in amount...To remove the inclusions in the ingots by conventional electroslag remelting(ESR), the bearing steel was prepared using ESR process but with mold rotation in this study. Experimental results show a reduction in amount of large inclusions when the mold rotation rate is 6 r·min-1, and the inclusions are uniformly distributed in the ESR ingot. As comparison with the electroslag ingots of conventional ESR(stationary mold), the portion of the Al2O3 inclusions smaller than 1 μm in size increase from 38% to 41.4%, whereas that of the SiO2 inclusions increases from 48% to 74% in the ingots when mold rotation is applied. This phenomenon is caused by the decrease in metal droplet size, resulting in large contact area between the slag pool and metal droplets in ESR process with mold rotation. Moreover, the metal droplets have relatively long movement routes, leading to long metal contact time between the slag pool and metal droplets when a relative motion between the consumable electrodes and mold is present. However, when the mold rotation rate is increased to 45 r·min-1, inclusion removing effect decreases. An excessive rotation rate causes wild motion in the slag pool, which drives the molten metal droplets to move violently, and as a result, the slag is entrapped into the metal pool, decreasing the ability of slag absorbing inclusions.展开更多
The recycling of spent LiFePO_(4)batteries has received extensive attention due to its environmental impact and economic benefit.In the pretreatment process of spent LiFePO_(4)batteries,the separation of active materi...The recycling of spent LiFePO_(4)batteries has received extensive attention due to its environmental impact and economic benefit.In the pretreatment process of spent LiFePO_(4)batteries,the separation of active materials and current collectors determines the difficulty of the re-covery process and product quality.In this work,a facile and efficient pretreatment process is first proposed.After only freezing the electrode pieces and immersing them in boiling water,LiFePO_(4)materials were peeled from the Al foil.Then,after roasting under an inert atmosphere and sieving,all the cathode and anode active materials were easily and efficiently separated from the Al and Cu foils.The active materials were subjected to acid leaching,and the leaching solution was further used to prepare FePO_(4)and Li_(2)CO_(3).Finally,the battery-grade FePO_(4)and Li_(2)CO_(3)were used to re-synthesize LiFePO_(4)/C via the carbon thermal reduction method.The discharge capacities of re-synthesized LiFePO_(4)/C cathode were 144.2,139.0,133.2,125.5,and 110.5 mA·h·g−1 at rates of 0.1,0.5,1,2,and 5 C,which satisfies the requirement for middle-end LiFePO_(4)batteries.The whole process is environmental and has great potential for industrial-scale recycling of spent lithium-ion batteries.展开更多
The effective recycling of waste printed circuit boards(WPCBs)can conserve resources and reduce environmental pollution.This study explores the pyrolysis and combustion characteristics of WPCBs in various atmospheres ...The effective recycling of waste printed circuit boards(WPCBs)can conserve resources and reduce environmental pollution.This study explores the pyrolysis and combustion characteristics of WPCBs in various atmospheres through thermogravimetric and Gaussian fitting analyses.Furthermore,this study analyses the pyrolysis products and combustion processes of WPCBs through thermogravimetric and Fourier transform infrared analyses(TG-FTIR)and thermogravimetry-mass spectrometry(TG-MS).Results show that the pyrolysis and combustion processes of WPCBs do not constitute a single reaction,but rather an overlap of multiple reactions.The pyrolysis and combustion process of WPCBs is divided into multiple reactions by Gaussian peak fitting.The kinetic parameters of each reaction are obtained by the Coats-Redfern method.In an argon atmosphere,pyrolysis consists of the overlap of the preliminary pyrolysis of epoxy resin,pyrolysis of small organic molecules,and pyrolysis of brominated flame retardants.The thermal decomposition process in the O_(2) atmosphere is mainly divided into two reactions:brominated flame retardant combustion and epoxy combustion.This study provided the theoretical basis for pollution control,process optimization,and reactor design of WPCBs pyrolysis.展开更多
The recycling of waste printed circuit board(WPCBs) is of great significance for saving resources and protecting the environment. In this study, the WPCBs were pyrolyzed by microwave and the contained valuable metals ...The recycling of waste printed circuit board(WPCBs) is of great significance for saving resources and protecting the environment. In this study, the WPCBs were pyrolyzed by microwave and the contained valuable metals Cu, Sn and Pb were recovered from the pyrolyzed WPCBs. The effect of pyrolysis temperature and time on the recovery efficiency of valuable metals was investigated. Additionally, the characterization for morphology and surface elemental distribution of pyrolysis residues was carried out to investigate the pyrolysis mechanism. The plastic fiber boards turned into black carbides, and they can be easily separated from the metals by manual. The results indicate that 91.2%, 96.1% and 94.4% of Cu, Sn and Pb can be recovered after microwave pyrolysis at 700 °C for 60 minutes. After pyrolysis, about 79.8%(mass)solid products, 11.9%(mass) oil and 8.3%(mass) gas were produced. These gas and oil can be used as fuel and raw materials of organic chemicals, respectively. This process provides an efficient and energy-saving technology for recovering valuable metals from WPCBs.展开更多
The 3, 5, 20 layer clad plate from austenitic stainless steel, pure aluminum and aluminum alloy sheets were fabricated in different ways. The stretch and interface properties were measured. The result shows that 20 la...The 3, 5, 20 layer clad plate from austenitic stainless steel, pure aluminum and aluminum alloy sheets were fabricated in different ways. The stretch and interface properties were measured. The result shows that 20 layer clad plate is better than the others. Well-bonded clad plate was successfully obtained in the following procedure: Basic clad sheet from 18 layer Al1060/Al3003 sheets was firstly obtained with an initial rolling reduction of 44% at 450 ℃, followed by annealing at 300 ℃, and then with reduction of 50% at 550 ℃ from STS304 on each side. The best 20 layer clad plate was of 129 MPa bonding strength and 225 MPa stretch strength.展开更多
An electroslag furnace with ultrasonic vibration introduced by a mold copper plate was designed. The effects of ultrasonic power on the element distribution and compactness in electroslag remelting(ESR) ingots were st...An electroslag furnace with ultrasonic vibration introduced by a mold copper plate was designed. The effects of ultrasonic power on the element distribution and compactness in electroslag remelting(ESR) ingots were studied,and the mechanism of ultrasonic assistance was analyzed in cold experiments. In the results,silicon,manganese and chromium are uniformly distributed at an ultrasonic power of 300–750 W. The absence of ultrasonic or higher ultrasonic power is not conducive to the uniformity of alloying elements. Carbon demonstrates a highly uneven distribution at 300 W,gradually reaches the uniform distribution as the ultrasonic power further increases,and shows the poor distribution at 1000 W. The compactness of ESR ingots gradually increases with increasing ultrasonic power and reaches the uniform distribution at 500 W. A further increase in ultrasonic power does not improve the compactness. Introducing ultrasonic vibrations by a mold copper plate can improve the solidification quality; however,an appropriate ultrasonic power level should be determined.展开更多
<正>The alloy 5052 was welded by friction stir welding(FSW)and tungsten inert gas(TIG)welding.The effect of welding processes(FSW and TIG)on the fatigue properties of 5052 aluminum-welded joints was analyzed bas...<正>The alloy 5052 was welded by friction stir welding(FSW)and tungsten inert gas(TIG)welding.The effect of welding processes(FSW and TIG)on the fatigue properties of 5052 aluminum-welded joints was analyzed based on fatigue testing,and the S-N curve of the joints were established.The results show that the fatigue properties of FSW welded joints are better than those of TIG welded joints.The fatigue strength is determined as 65 MPa under 10~6 cycling of fatigue life.The microstructure of joints is fine grains and narrow HAZ zone in FSW welds,which inhibit the growth of cracks and produce high fatigue life compared with that of TIG welds.Fracture morphologies also show that the fatigue fracture results from weld defects.展开更多
A novel biosorbent was synthesized by grafting bisthiourea(BTU)on a silk sericin(SS)matrix.This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy(FTIR),zeta potential measur...A novel biosorbent was synthesized by grafting bisthiourea(BTU)on a silk sericin(SS)matrix.This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy(FTIR),zeta potential measurements,elemental analysis,and X-ray photoelectron spectroscopy(XPS).As revealed by the adsorption experiments,both BTU-SS and SS showed low affinity towards coexisting base metallic ions in Ag(I)-Cu(II)-Zn(II)-Ni(II)-Pb(II)electronic waste leachate mixtures,while their adsorption capacities towards Ag(I)reached 30.5 and 10.4 mg∙g-1 at a pH of 5.0,respectively.BTU-SS showed higher selectivity towards Ag(I)than SS,as revealed by the Ag(I)partition coefficients between the biosorbents and the leachate(16634.6 and 403.3,respectively).As further demonstrated by column experiments,BTU-SS allowed the separation of Ag(I)from an electronic waste leachate.Thermodynamic studies showed that the adsorption of Ag(I)was exothermic and spontaneous,while adsorption kinetic experiments revealed that chemisorption dominated the adsorption process with activation energies of 47.67 and 53.27 kJ∙mol-1 for BTU-SS and SS,respectively.FTIR and XPS analyses of fresh and Ag(I)-loaded BTU-SS further revealed an adsorption mechanism mainly involving electrostatic and coordination interactions.展开更多
The titanium round wires could be prepared to the high precision flat wires with the sizes of 0.63mm×5.03mm by nine-pass cold continuous rolling process.Mechanical property and metallograph analysis were used to ...The titanium round wires could be prepared to the high precision flat wires with the sizes of 0.63mm×5.03mm by nine-pass cold continuous rolling process.Mechanical property and metallograph analysis were used to analyze the possibilities of preparing flat wire.Results show that the grain kept equiaxed grain in the rolling processes,and a large number of dislocation and a small amount of twin existed in the microstructure of final rolling flat wire.During the whole rolling processes,when the accumulated rolling deformation degree was at low degree,the deformation of titanium was controlled under the mutual control of dislocation slip and twinning.When the accumulated rolling deformation degree was at high degree,the deformation of titanium was controlled by the dislocation slip.展开更多
Due to its unique electronic structure and special size effect,two-dimensional(2D)nanomaterials have shown great potential far beyond bulk materials in the field of photocatalysis.How to deeply explore the photocataly...Due to its unique electronic structure and special size effect,two-dimensional(2D)nanomaterials have shown great potential far beyond bulk materials in the field of photocatalysis.How to deeply explore the photocatalytic mechanism of 2D nanomaterials and design more efficient 2D semiconductor photocatalysts are research hotspots.This review provides a comprehensive introduction to typical 2D nanomaterials and discusses their current application status in the field of photocatalysis.The effects of material properties such as band structure,morphology,crystal face structure,crystal structure and surface defects on the photocatalytic process are discussed.The main modification methods are highlighted,including doping,noble metal deposition,heterojunction,thickness adjustment,defect engineering,and dye sensitization in 2D material systems.Finally,the future development of 2D nanomaterials is prospected.It is hoped that this paper can provide systematic and useful information for researchers engaged in the field of photocatalysis.展开更多
基金Funded by the National Natural Science Foundation of China(No.52072180)the Graduate Research and Innovation Projects of Jiangsu Province(No.KYCX21_3461)。
文摘We used the surface-pretreated graphite paper(Gp)as a carrier and loaded BiOCl with high selectivity to Cl^(-)on its surface by solvothermal method to form BiOCl@Gp electrode.The morphology,structure,and composition of the materials were characterized by scanning electron microscopy and nitrogen adsorption/desorption,and the results showed that the spherical BiOCl particles were uniformly dispersed on the surface of the Gp,forming a mesoporous BiOCl@Gp composite with a specific surface area of 22.82 m^(2)/g and a pore volume of 0.043 cm3/g.Furthermore,cyclic voltammetry and electrochemical impedance spectroscopy were used to test the electrochemical properties of the composites,and the stability of BiOCl and the high conductivity of Gp were synergistic,the BiOCl@Gp exhibited a specific capacitance of 30.2 F·g^(-1) at a current density of 0.5 A·g^(-1),and the selectivity of the BiOCl@Gp materials for Cl^(-)was significantly higher than that of SO_(4)^(2-),NO_(2)^(-),and HCO_(3)^(-).Therefore,BiOCl@Gp composite electrode materials can be used for the selective adsorption of Cl^(-)in wastewater,in order to achieve efficient wastewater recycling.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52074002,52174289)Natural Science Foundation of Anhui Province(Grant No.2208085J37)。
文摘To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was analyzed.The results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply mode.The effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that order.By reducing the remelting current strength in the same power supply mode,the depth of metal pool is reduced.When compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during remelting.Utilizing the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial crystal.This effect is observed for both low frequency and direct current(DC)power supply modes.
基金supported by the Natural Science Foundation of Jiangsu Province (BK20210887)the Jiangsu Provincial Double Innovation Program (JSSCB20210984)+1 种基金the Natural Science Fund for Colleges and Universities of Jiangsu Province (21KJB450003)the Jiangsu University of Science and Technology Doctoral Research Start-up Fund (120200012)。
文摘Higher nickel content endows Ni-rich cathode materials LiNi_(x)Co_yMn_(1-x-y)O_(2)(x>0.6)with higher specific capacity and high energy density,which is regarded as the most promising cathode materials for Li-ion batteries.However,the deterioration of structural stability hinders its practical application,especially under harsh working conditions such as high-temperature cycling.Given these circumstances,it becomes particularly critical to clarify the impact of the crystal morphology on the structure and high-temperature performance as for the ultrahigh-nickel cathodes.Herein,we conducted a comprehensive comparison in terms of microstructure,high-temperature long-cycle phase evolution,and high-temperature electrochemical stability,revealing the differences and the working mechanisms among polycrystalline(PC),single-crystalline(SC)and Al doped SC ultrahigh-nickel materials.The results show that the PC sample suffers a severe irreversible phase transition along with the appearance of microcracks,resulting a serious decay of both average voltage and the energy density.While the Al doped SC sample exhibits superior cycling stability with intact layered structure.In-situ XRD and intraparticle structural evolution characterization reveal that Al doping can significantly alleviate the irreversible phase transition,thus inhibiting microcracks generation and enabling enhanced structure.Specifically,it exhibits excellent cycling performance in pouch-type full-cell with a high capacity retention of 91.8%after 500 cycles at 55℃.This work promotes the fundamental understanding on the correlation between the crystalline morphology and high-temperature electrochemical stability and provides a guide for optimization the Ni-rich cathode materials.
基金financially supported by the Natural Science Foundation of Jiangsu Province,China (BK20210887)the Jiangsu Provincial Double Innovation Program,China (JSSCB20210984)+1 种基金the Natural Science Fund for Colleges and Universities of Jiangsu Province,China (21KJB450003)the Jiangsu University of Science and Technology Doctoral Research Start-up Fund,China (120200012)。
文摘Nickel(Ni)-rich cathode materials have become promising candidates for the next-generation electrical vehicles due to their high specific capacity.However,the poor thermodynamic stability(including cyclic performance and safety performance or thermal stability)will restrain their wide commercial application.Herein,a single-crystal Ni-rich Li Ni_(0.83)Co_(0.12)Mn_(0.05)O_(2) cathode material is synthesized and modified by a dual-substitution strategy in which the high-valence doping element improves the structural stability by forming strong metal–oxygen binding forces,while the low-valence doping element eliminates high Li^(+)/Ni^(2+)mixing.As a result,this synergistic dual substitution can effectively suppress H2-H3 phase transition and generation of microcracks,thereby ultimately improving the thermodynamic stability of Ni-rich cathode material.Notably,the dual-doped Ni-rich cathode delivers an extremely high capacity retention of 81%after 250 cycles(vs.Li/Li+)in coin-type half cells and 87%after 1000 cycles(vs.graphite/Li^(+))in pouch-type full cells at a high temperature of 55℃.More impressively,the dual-doped sample exhibits excellent thermal stability,which demonstrates a higher thermal runaway temperature and a lower calorific value.The synergetic effects of this dual-substitution strategy pave a new pathway for addressing the critical challenges of Ni-rich cathode at high temperatures,which will significantly advance the high-energy-density and high-safety cathodes to the subsequent commercialization.
基金financially supported by the National Nature Science Foundation of China (Nos. 51234009 and 51104182)the Natural Science Foundation of Hunan Province, China (No. 13JJ5035)the Scientific Research Fund of Hunan Provincial Education Department, China (No. 14C0349)
文摘Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na2CO3/paste mass ratio = 2.8:1; and the Zn O dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were Pb SO4→Pb and Pb SO4→Zn S, respectively. Sulfur was fixed in the form of Zn S, whereas the molten salt did not react with other components, serving only as a reaction medium.
基金Founded by the Special Project of Shaanxi Education Department(07JK309)Xi'an University of Architecture and Technology (JC0714)
文摘The nose temperature for σ-phase precipitation in super-duplex stainless steel (SDSS) UNS S32750 was evaluated by hardness method.Color-optical microscopy,scanning electron microscopy,energy spectrum analysis,impact and corrosion testing were carried out to investigate characteristics of microstructure and properties of the SDSS aged at the nose temperature.The experimental results indicate that the nose temperature of precipitation is 920℃ and aging at this temperature tiny σ phases can precipitate at phase interfaces or ferrite grain boundaries within 2min.Prolonging aging duration the amount ofσ-phase increases and a dual structure with σ and γ is obtained when aging for 120min.The precipitation ofσ-phase leads to severe deterioration in impact toughness (longitudinal/transverse direction) and corrosion resistance of SDSS.
基金Supported by Natural Science Foundation of China (No.50244012)National Science Foundation of Shaanxi Education Department (No.02JC37)
文摘The absorption of low concentration SO2 in flue gas by using the module of liquid-containing microporous membrane which is made up of hollow fiber and citric acid-sodium citrate buffer solution was investigated.The absorption efficiency of hydrophilic and hydrophobic membranes by using the concept of dynamic contact angle was mainly studied.The influences on absorption efficiency from absorption time,flowrate of gas phase,SO2 concentration of gas phase,air pressure,citrate concentration,pH value of solution as well as the generation of sulfate radical in absorption solution were examined.The results indicate that the hydrophobic hollow fiber membrane is better than hydrophilic membrane,the absorption efficiency decreases with increasing absorption time,gas phase flowrate,gas phase SO2 concentration and air pressure,the absorption rate and capacity of SO2 can be improved by increasing the citrate concentration,the absorption efficiency can be improved by increasing the pH value of citrate solution,the concentration of SO42-in absorption solution increases linearly with the absorption time at a rate around 0.192 g/(L-h).
文摘The most common and serious defect in Cu-Ni alloy casting is porosity. To solve the problem, accurate casting design and proper design of gating system are necessary. It can be predicted and designed by means of computer simulation of casting solidification. Based on the casting process of the Cu-Ni alloy, the simulation software of diathermanous-flowing-stress coupling ProCAST was used to simulate the Cu-Ni alloy solidification process about the defects and temperature field. By combining experimental results with the simulation results, the quality of casting on some cooling conditions were analyzed. Furthermore, a better cooling condition for solidification process of the Cu-Ni alloy was chosen to improve the quality of the casting. The simulation results indicate that the quality of Cu-Ni alloy casting is the best when it is on the cooling condition of the permanent mold with the insulated riser system.
基金financially supported by the National Natural Science Foundation of China(51774003/52074002/51974002)the Ministry of Industry and Information Technology(TC190A4DA-35)。
文摘To further improve the metallurgical quality of electroslag remelting,remove the large inclusions in electroslag ingot and refine the solidification structure of electroslag ingot,an electroslag remelting furnace with electromagnetic stirring was designed,and the influence of different magnetic induction intensities on metallurgical quality of GCr15 electroslag ingot was studied.Inclusions with different sizes and types were analyzed by an ASPEX scanning electron microscope,and the morphology and composition of inclusions were further observed by a JSM-6510LV scanning electron microscope.The distribution of alloying elements on the cross section of electroslag ingot was analyzed by original position analysis(OPA).The results show that whether or not electromagnetic stirring is used,the inclusions in electroslag ingot are mainly composed of Al_(2)O_(3),MnS,MnS-oxide and other oxides,among which Al_(2)O_(3) is the most.Compared with an electroslag ingot without electromagnetic stirring,the number of inclusions decreases considerably,and the proportion of small inclusions increases while the proportion of large inclusions decreases when the electromagnetic stirring with remelting current of 1.1 kA and magnetic induction intensity of 62 Gs is applied.However,excessive electromagnetic force will cause the number and diameter of inclusions to increase again.Electromagnetic stirring has different effects on the segregation of different elements.Under the experimental conditions,the weak electromagnetic force with 1.1 kA and magnetic induction intensity of 108 Gs has little effect on the segregation of C,but decreases the segregation of P,and the excessive electromagnetic force aggravates the segregation of alloy elements.
基金financially supported by the National Natural Science Foundation of China(Nos.51104001 and 51274004)
文摘A novel electroslag furnace with a rotating mold was fabricated, and the effects of mold rotational speed on the electroslag remelting process were investigated. The results showed that the chemical element distribution in ingots became uniform and that their compact density increased when the mold rotational speed was increased from 0 to 28 r/min. These results were attributed to a reasonable mold speed, which resulted in a uniform temperature in the slag pool and scattered the metal droplets randomly in the metal pool. However, an excessive rotational speed caused deterioration of the solidification structure. When the mold rotational speeds was increased from 0 to 28 r/min, the size of Al2O3 inclusions in the electroslag ingot decreased from 4.4 to 1.9 μm. But the excessive mold rotational speed would decrease the ability of the electroslag remelting to remove the inclusions. The remelting speed gradually increased, which resulted in reduced power consumption with increasing mold rotational speed. This effect was attributed to accelerated heat exchange between the consumable electrode and the molten slag, which resulted from mold rotation. Nevertheless, when the rotational speed reached 28 r/min, the remelting speed did not change because of limitations of metal heat conduction. Mold rotation also improved the surface quality of the ingots by promoting a uniform temperature distribution in the slag pool.
基金financially supported by the National Natural Science Foundation of China (Grant No.51104001)
文摘To remove the inclusions in the ingots by conventional electroslag remelting(ESR), the bearing steel was prepared using ESR process but with mold rotation in this study. Experimental results show a reduction in amount of large inclusions when the mold rotation rate is 6 r·min-1, and the inclusions are uniformly distributed in the ESR ingot. As comparison with the electroslag ingots of conventional ESR(stationary mold), the portion of the Al2O3 inclusions smaller than 1 μm in size increase from 38% to 41.4%, whereas that of the SiO2 inclusions increases from 48% to 74% in the ingots when mold rotation is applied. This phenomenon is caused by the decrease in metal droplet size, resulting in large contact area between the slag pool and metal droplets in ESR process with mold rotation. Moreover, the metal droplets have relatively long movement routes, leading to long metal contact time between the slag pool and metal droplets when a relative motion between the consumable electrodes and mold is present. However, when the mold rotation rate is increased to 45 r·min-1, inclusion removing effect decreases. An excessive rotation rate causes wild motion in the slag pool, which drives the molten metal droplets to move violently, and as a result, the slag is entrapped into the metal pool, decreasing the ability of slag absorbing inclusions.
基金This work was financially supported by the Key-Area Research and Development Program of Guangdong Province,China(No.2020B090919003)the National Natural Science Foundation of China(Nos.51834008,51874040,and U1802253)the Fundamental Research Funds for the Central Universities(No.FRF-TP-18-020A3).
文摘The recycling of spent LiFePO_(4)batteries has received extensive attention due to its environmental impact and economic benefit.In the pretreatment process of spent LiFePO_(4)batteries,the separation of active materials and current collectors determines the difficulty of the re-covery process and product quality.In this work,a facile and efficient pretreatment process is first proposed.After only freezing the electrode pieces and immersing them in boiling water,LiFePO_(4)materials were peeled from the Al foil.Then,after roasting under an inert atmosphere and sieving,all the cathode and anode active materials were easily and efficiently separated from the Al and Cu foils.The active materials were subjected to acid leaching,and the leaching solution was further used to prepare FePO_(4)and Li_(2)CO_(3).Finally,the battery-grade FePO_(4)and Li_(2)CO_(3)were used to re-synthesize LiFePO_(4)/C via the carbon thermal reduction method.The discharge capacities of re-synthesized LiFePO_(4)/C cathode were 144.2,139.0,133.2,125.5,and 110.5 mA·h·g−1 at rates of 0.1,0.5,1,2,and 5 C,which satisfies the requirement for middle-end LiFePO_(4)batteries.The whole process is environmental and has great potential for industrial-scale recycling of spent lithium-ion batteries.
基金financially supported by the National Key R&D Program of China(Nos.2019YFC1908400 and 2019YFC1907405)the National Natural Science Foundation of China(Nos.51904124,51804139,52004111 and 52074136)+2 种基金the Jiangxi Provincial Cultivation Program for Academic and Technical Leaders of Major Subjects(Nos.20212BCJL23052 and 20212BCJ23007)the Distinguished Professor Program of Jinggang Scholars,China Institutions of Higher Learning Jiangxi Province,the Science and Technology Research Project of the Jiangxi Provincial Department of Education(No.gjj170507)the Science Research Foundation of Jiangxi University of Science and Technology(No.jxxjbs 17046)。
文摘The effective recycling of waste printed circuit boards(WPCBs)can conserve resources and reduce environmental pollution.This study explores the pyrolysis and combustion characteristics of WPCBs in various atmospheres through thermogravimetric and Gaussian fitting analyses.Furthermore,this study analyses the pyrolysis products and combustion processes of WPCBs through thermogravimetric and Fourier transform infrared analyses(TG-FTIR)and thermogravimetry-mass spectrometry(TG-MS).Results show that the pyrolysis and combustion processes of WPCBs do not constitute a single reaction,but rather an overlap of multiple reactions.The pyrolysis and combustion process of WPCBs is divided into multiple reactions by Gaussian peak fitting.The kinetic parameters of each reaction are obtained by the Coats-Redfern method.In an argon atmosphere,pyrolysis consists of the overlap of the preliminary pyrolysis of epoxy resin,pyrolysis of small organic molecules,and pyrolysis of brominated flame retardants.The thermal decomposition process in the O_(2) atmosphere is mainly divided into two reactions:brominated flame retardant combustion and epoxy combustion.This study provided the theoretical basis for pollution control,process optimization,and reactor design of WPCBs pyrolysis.
基金supported by the National Key Research and Development Program of China (2019YFC1908404)the National Natural Science Foundation of China (Nos. 51834008, 51874040,52034002)+1 种基金the Guangxi Innovation-Driven Development Project(AA18242042-1)the Fundamental Research Funds for the Central Universities (FRF-TP-18-020A3)。
文摘The recycling of waste printed circuit board(WPCBs) is of great significance for saving resources and protecting the environment. In this study, the WPCBs were pyrolyzed by microwave and the contained valuable metals Cu, Sn and Pb were recovered from the pyrolyzed WPCBs. The effect of pyrolysis temperature and time on the recovery efficiency of valuable metals was investigated. Additionally, the characterization for morphology and surface elemental distribution of pyrolysis residues was carried out to investigate the pyrolysis mechanism. The plastic fiber boards turned into black carbides, and they can be easily separated from the metals by manual. The results indicate that 91.2%, 96.1% and 94.4% of Cu, Sn and Pb can be recovered after microwave pyrolysis at 700 °C for 60 minutes. After pyrolysis, about 79.8%(mass)solid products, 11.9%(mass) oil and 8.3%(mass) gas were produced. These gas and oil can be used as fuel and raw materials of organic chemicals, respectively. This process provides an efficient and energy-saving technology for recovering valuable metals from WPCBs.
文摘The 3, 5, 20 layer clad plate from austenitic stainless steel, pure aluminum and aluminum alloy sheets were fabricated in different ways. The stretch and interface properties were measured. The result shows that 20 layer clad plate is better than the others. Well-bonded clad plate was successfully obtained in the following procedure: Basic clad sheet from 18 layer Al1060/Al3003 sheets was firstly obtained with an initial rolling reduction of 44% at 450 ℃, followed by annealing at 300 ℃, and then with reduction of 50% at 550 ℃ from STS304 on each side. The best 20 layer clad plate was of 129 MPa bonding strength and 225 MPa stretch strength.
基金financially supported by the National Natural Science Foundation of China(Nos.51274004 and 51574001)
文摘An electroslag furnace with ultrasonic vibration introduced by a mold copper plate was designed. The effects of ultrasonic power on the element distribution and compactness in electroslag remelting(ESR) ingots were studied,and the mechanism of ultrasonic assistance was analyzed in cold experiments. In the results,silicon,manganese and chromium are uniformly distributed at an ultrasonic power of 300–750 W. The absence of ultrasonic or higher ultrasonic power is not conducive to the uniformity of alloying elements. Carbon demonstrates a highly uneven distribution at 300 W,gradually reaches the uniform distribution as the ultrasonic power further increases,and shows the poor distribution at 1000 W. The compactness of ESR ingots gradually increases with increasing ultrasonic power and reaches the uniform distribution at 500 W. A further increase in ultrasonic power does not improve the compactness. Introducing ultrasonic vibrations by a mold copper plate can improve the solidification quality; however,an appropriate ultrasonic power level should be determined.
文摘<正>The alloy 5052 was welded by friction stir welding(FSW)and tungsten inert gas(TIG)welding.The effect of welding processes(FSW and TIG)on the fatigue properties of 5052 aluminum-welded joints was analyzed based on fatigue testing,and the S-N curve of the joints were established.The results show that the fatigue properties of FSW welded joints are better than those of TIG welded joints.The fatigue strength is determined as 65 MPa under 10~6 cycling of fatigue life.The microstructure of joints is fine grains and narrow HAZ zone in FSW welds,which inhibit the growth of cracks and produce high fatigue life compared with that of TIG welds.Fracture morphologies also show that the fatigue fracture results from weld defects.
基金This work was supported by the Natural Science Foundation of Education Department of Shaanxi Provincial Government(2013JK0873).
文摘A novel biosorbent was synthesized by grafting bisthiourea(BTU)on a silk sericin(SS)matrix.This biosorbent was denoted as BTU-SS and characterized by Fourier transform infrared spectroscopy(FTIR),zeta potential measurements,elemental analysis,and X-ray photoelectron spectroscopy(XPS).As revealed by the adsorption experiments,both BTU-SS and SS showed low affinity towards coexisting base metallic ions in Ag(I)-Cu(II)-Zn(II)-Ni(II)-Pb(II)electronic waste leachate mixtures,while their adsorption capacities towards Ag(I)reached 30.5 and 10.4 mg∙g-1 at a pH of 5.0,respectively.BTU-SS showed higher selectivity towards Ag(I)than SS,as revealed by the Ag(I)partition coefficients between the biosorbents and the leachate(16634.6 and 403.3,respectively).As further demonstrated by column experiments,BTU-SS allowed the separation of Ag(I)from an electronic waste leachate.Thermodynamic studies showed that the adsorption of Ag(I)was exothermic and spontaneous,while adsorption kinetic experiments revealed that chemisorption dominated the adsorption process with activation energies of 47.67 and 53.27 kJ∙mol-1 for BTU-SS and SS,respectively.FTIR and XPS analyses of fresh and Ag(I)-loaded BTU-SS further revealed an adsorption mechanism mainly involving electrostatic and coordination interactions.
文摘The titanium round wires could be prepared to the high precision flat wires with the sizes of 0.63mm×5.03mm by nine-pass cold continuous rolling process.Mechanical property and metallograph analysis were used to analyze the possibilities of preparing flat wire.Results show that the grain kept equiaxed grain in the rolling processes,and a large number of dislocation and a small amount of twin existed in the microstructure of final rolling flat wire.During the whole rolling processes,when the accumulated rolling deformation degree was at low degree,the deformation of titanium was controlled under the mutual control of dislocation slip and twinning.When the accumulated rolling deformation degree was at high degree,the deformation of titanium was controlled by the dislocation slip.
基金supported by the National Natural Science Foundation of China Youth Program (52204399)the Postdoctoral Research Foundation of China (2021MD703866)+6 种基金the Scientific and Technological Innovation Team Project of Shaanxi Innovation Capability Support Plan (2022TD-30)Youth Innovation Team of Shaanxi Universities (2019-2022)Fok Ying Tung Education Foundation (171101)Natural Science Basic Research Program of Shaanxi Province (2022JQ-478)the Scientific Research Program of Youth Innovation Team of Shaanxi (22JP037)the Science and Technology Project of Universities and Institutes StaffServing Enterprises in Xi'an (22GXFW0059)Top Young Talents Project of“Special Support Program for High Level Talents”in Shaanxi Province (2018-2023)。
文摘Due to its unique electronic structure and special size effect,two-dimensional(2D)nanomaterials have shown great potential far beyond bulk materials in the field of photocatalysis.How to deeply explore the photocatalytic mechanism of 2D nanomaterials and design more efficient 2D semiconductor photocatalysts are research hotspots.This review provides a comprehensive introduction to typical 2D nanomaterials and discusses their current application status in the field of photocatalysis.The effects of material properties such as band structure,morphology,crystal face structure,crystal structure and surface defects on the photocatalytic process are discussed.The main modification methods are highlighted,including doping,noble metal deposition,heterojunction,thickness adjustment,defect engineering,and dye sensitization in 2D material systems.Finally,the future development of 2D nanomaterials is prospected.It is hoped that this paper can provide systematic and useful information for researchers engaged in the field of photocatalysis.
