In-situ observation of microstructural evolution during heating and soaking process was carded out for a high nickel steel using HTCLSM. Dark phases were observed when soaking at 900℃. Results showed that the number ...In-situ observation of microstructural evolution during heating and soaking process was carded out for a high nickel steel using HTCLSM. Dark phases were observed when soaking at 900℃. Results showed that the number of the dark phases culminated in about 50 s during soaking at 900℃. With the increase of soaking time the area proportion of the dark phases increased and reached the maximum value in about 3 min, When temperature rose from 900 ℃, the dark phases remained steady initially, but started to dissolve into the matrix at about 1 060 ℃ and completely disappeared at 1 132℃. When the specimen soaked at 900 ℃ was cooled down to room temperature (RT), the dark phases kept stable. Energy spectrum analysis results showed that the dark phases contained much more Cr and Mn elements than the matrix and,were also rich in V. Tensile test results showed that the dark phase strengthened the steel with the maximum tensile strength obtained after soaking at 900 ℃ for 3 minutes.展开更多
An adequate wide temperature electrolyte for high nickel ternary cathode is urgent to further develop high energy density batteries.Herein,a comprehensive double-salt local high-concentration sulfolane-based electroly...An adequate wide temperature electrolyte for high nickel ternary cathode is urgent to further develop high energy density batteries.Herein,a comprehensive double-salt local high-concentration sulfolane-based electrolyte(DLi)is proposed with specific sheath structure to build stable interface on the LiNi_(0.8)Co_(0.1)Mn_(0.1O2)(NCM811)cathode at wide operating temperature between−60 and 55℃.Lithium perchlorate(LiClO_(4))in combination with high concentration lithium bis-(trifluoromethanesulfonyl)imide(LiTFSI)strengthens the internal interaction between anion and cation in the solvation structure,increasing Li+transference number of the electrolyte to 0.61.Moreover,the structure and component characteristics of the passive interface layer on NCM811 are modulated,decreasing desolvation energy of Li+ions,benefiting Li+transport dynamics especially at low temperature,and also ensuring the interfacial stability at a wide operating temperature range.As a result,the cathode with DLi exhibits excellent high-temperature storage performance and high capacity retention of 80.5%in 100 cycles at 55℃.Meanwhile,the Li||NCM811 cells can deliver high discharge capacity of 160.1,136.1,and 110.3 mAh·g^(−1)under current density of 0.1 C at−20,−40,and−60℃,maintaining 84.5%,71.8%,and 58.2%of the discharge capacity at 30℃,respectively.Moreover,it enables NCM811 cathode to achieve a reversible capacity of 142.8 mAh·g^(−1)in 200 cycles at−20℃and 0.2 C.Our studies shed light on the molecular strategy of wide operational temperature electrolyte for high nickel ternary cathode.展开更多
A new concentrated ternary salt ether-based electrolyte enables stable cycling of lithium metal battery(LMB)cells with high-mass-loading(13.8 mg cm^(−2),2.5 mAh cm^(−2))NMC622(LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2))cathodes ...A new concentrated ternary salt ether-based electrolyte enables stable cycling of lithium metal battery(LMB)cells with high-mass-loading(13.8 mg cm^(−2),2.5 mAh cm^(−2))NMC622(LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2))cathodes and 50μm Li anodes.Termed“CETHER-3,”this electrolyte is based on LiTFSI,LiDFOB,and LiBF4 with 5 vol%fluorinated ethylene carbonate in 1,2-dimethoxyethane.Commer-cial carbonate and state-of-the-art binary salt ether electrolytes were also tested as baselines.With CETHER-3,the electrochemical performance of the full-cell battery is among the most favorably reported in terms of high-voltage cycling stability.For example,LiNi_(x)Mn_(y)Co_(1-x-y)O_(2)(NMC)-Li metal cells retain 80%capacity at 430 cycles with a 4.4 V cut-off and 83%capacity at 100 cycles with a 4.5 V cut-off(charge at C/5,discharge at C/2).According to simulation by density functional theory and molecular dynamics,this favorable performance is an outcome of enhanced coordination between Li^(+)and the solvent/salt molecules.Combining advanced microscopy(high-resolution transmission electron microscopy,scanning electron microscopy)and surface science(X-ray photoelectron spectroscopy,time-of-fight secondary ion mass spectroscopy,Fourier-transform infrared spectroscopy,Raman spectroscopy),it is demonstrated that a thinner and more stable cathode electrolyte interphase(CEI)and solid electrolyte interphase(SEI)are formed.The CEI is rich in lithium sulfide(Li_(2)SO_(3)),while the SEI is rich in Li_(3)N and LiF.During cycling,the CEI/SEI suppresses both the deleterious transformation of the cathode R-3m layered near-surface structure into disordered rock salt and the growth of lithium metal dendrites.展开更多
High nickel content layered cathodes,represented by NCM(LiNi_(x)Co_(y)Mn_(z)O_(2),x+y+z=1),are now widely employed in the market of electric vehicles,owing to their high energy density.With the gradual increase of nic...High nickel content layered cathodes,represented by NCM(LiNi_(x)Co_(y)Mn_(z)O_(2),x+y+z=1),are now widely employed in the market of electric vehicles,owing to their high energy density.With the gradual increase of nickel content and capacity,the issues on cycling life and safety become more serious.In this review,various strategies for improving the performance of high nickel NCM are summarized on the aspects of surface coating,ionic doping,and singlecrystal NCM.The coating strategy was separately described according to the physical property of coating species,including inert material coating,Li^(+)-conductor coating,electronic conductor coating,and mixed conductor coating.These coating species help to suppress the interfacial oxidation of electrolytes by NCM,improving the cycling life and safety.The elemental doping in the crystal lattice of NCM is then presented in the aspects of cation,anion,and mixed-ion doping,which are beneficial to stabilize the layered structure during charge–discharge and so promote the electrochemical performance.In quite recent years,the strategy of single-crystal NCM was demonstrated to be a promising pathway,owing to the dramatically reduced surface area and grain boundary.Finally,the remaining unsolved challenges and future strategies for further development of NCM cathode materials are outlined.展开更多
The contents of Mg,Al,Si,Ti,Cr,Mn,Fe,Co,Cu,Ga,As,Se,Cd,Sb,Pb and Bi in high purity nickel were determined by high resolution inductively coupled plasma mass spectrometry(HR-ICP-MS).The sample was dissolved in HNO3 and...The contents of Mg,Al,Si,Ti,Cr,Mn,Fe,Co,Cu,Ga,As,Se,Cd,Sb,Pb and Bi in high purity nickel were determined by high resolution inductively coupled plasma mass spectrometry(HR-ICP-MS).The sample was dissolved in HNO3 and HCl by microwave digestion.Most of the spectral interferences could be avoided by measuring in the high resolution mode.The matrix effects because of the presence of excess HCl and nickel were evaluated.Correction for matrix effects was made using Sc,Rh and Tl as internal standards.The optimum conditions for the determination were tested and discussed.The detection limits range from 0.012 to 1.76 μg/g depending on the type of elements.The applicability of the proposed method is also validated by the analysis of high purity nickel reference material(NIST SRM 671).The relative standard deviation(RSD) is less than 3.3%.Results for determination of trace elements in high purity nickel were presented.展开更多
To inhibit the dissolution of Mg^2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bioleaching factors on the dissolution of Mg^2+ from olivine and serpentine was investigated...To inhibit the dissolution of Mg^2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bioleaching factors on the dissolution of Mg^2+ from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg^2+ from olivine and serpentine was temperature, followed by p H and particle size. A novel method of bioleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg^2+ and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.展开更多
A novel plastic/multi-walled carbon nanotube(MWNTs)-nickel(Ni)-platinum(Pt) electrode(PMNP) is prepared by chemical-reducing Pt onto the surface of Ni film covered plastic/MWNTs(PM) substrate. The MWNTs are ...A novel plastic/multi-walled carbon nanotube(MWNTs)-nickel(Ni)-platinum(Pt) electrode(PMNP) is prepared by chemical-reducing Pt onto the surface of Ni film covered plastic/MWNTs(PM) substrate. The MWNTs are adhered by a piece of commercial double faced adhesive tape on the surface of plastic paper and the Ni film is prepared by a simple electrodeposition method. The morphology and phase structure of the PMNP electrode are characterized by scanning electron microscopy,transmission electron microscope and X-ray diffractometer. The catalytic activity of the PMNP electrode for Na BH4 electrooxidation is investigated by means of cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the plastic paper and exhibits a good stability. MWNTs serve as both conductive material and hydrogen storage material and the Ni film and Pt are employed as electrochemical catalysts. The PMNP electrode exhibits a high electrocatalytic performance and the oxidation current density reaches to 10.76 A/(mg·cm) in 0.1 mol/dm3 Na BH4at0 V,which is much higher than those in the previous reports. The using of waste plastic reduces the discarding of white pollution and consumption of metal resources.展开更多
The tensile strength and ductility of a high nitrogen nickel-free austenitic stainless steel with solution and cold rolling treatment were investigated by performing tensile tests at different strain rates and at room...The tensile strength and ductility of a high nitrogen nickel-free austenitic stainless steel with solution and cold rolling treatment were investigated by performing tensile tests at different strain rates and at room temperature. The tensile tests demonstrated that this steel exhibits a significant strain rate and cold rolling dependence of the tensile strength and ductility.With the increase of the strain rate from 10^-4s^-1to 1 s^-1, the yield strength and ultimate tensile strength increase and the uniform elongation and total elongation decrease. The analysis of the double logarithmic stress–strain curves showed that this steel exhibits a two-stage strain hardening behavior, which can be well examined and analyzed by using the Ludwigson equation. The strain hardening exponents at low and high strain regions(n2and n1) and the transition strain(εL) decrease with increasing strain rate and the increase of cold rolling RA. Based on the analysis results of the stress–strain curves, the transmission electron microscopy characterization of the microstructure and the scanning electron microscopy observation of the deformation surfaces, the significant strain rate and cold rolling dependence of the strength and ductility of this steel were discussed and connected with the variation in the work hardening and dislocation activity with strain rate and cold rolling.展开更多
Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached...Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...展开更多
In order to enhance the high-temperature stress rupture strength of brazing seam by heat treatment, it was diffusion treated, then solution heat treated, and finally aging treated. The microstructure of brazing seam e...In order to enhance the high-temperature stress rupture strength of brazing seam by heat treatment, it was diffusion treated, then solution heat treated, and finally aging treated. The microstructure of brazing seam especially morphology of gamma ' phase and boride was observed and the strength of brazing seam was measured in this process. The results show that heat treatment can enhance high-temperature stress rupture strength by improving the microstructure of brazing seam. The strength of brazing seam after solution heat treatment decreases in comparison with that only after diffusion treatment while aging treatment after solution heat treatment increases the strength of brazing seam.展开更多
We report a molecular dynamics study of structural and transport properties of liquid nickel under high pres- sures. Pressure dependencies of pair distribution function and pair correlation entropy along the melting l...We report a molecular dynamics study of structural and transport properties of liquid nickel under high pres- sures. Pressure dependencies of pair distribution function and pair correlation entropy along the melting line indicate that the configuration change along melting lines decreases with increasing pressure. The calculated diffusion coefficients and viscosity by using entropy-scaling laws with modified parameters and ideal parameters are compared with those extracted from mean-square displacement or the Stokes-Einstein relation. The results suggest that the entropy-scaling laws hold well for coefficients and viscosity increase moderately with liquid nickel under high-pressure conditions, and the diffusion pressure along melting lines.展开更多
The present study focused on the re-processing of copper and nickel from mine tailings. In this work, recovery of copper and nickel from mine tailing by combined process of flotation and high pressure oxidative leachi...The present study focused on the re-processing of copper and nickel from mine tailings. In this work, recovery of copper and nickel from mine tailing by combined process of flotation and high pressure oxidative leaching were considered. In the first stage, effects of flotation parameters including collector type, collector dosage, and pH and pulp density were examined. The results showed that over 80% copper recovery was achieved under the optimized flotation conditions while nickel recovery was lower than 30% due to its co-ex-istence with gangue minerals of pyrrhotite, pyrite and other clay minerals. In the second stage, key parameters, particularly concentration of sulfuric acid, temperature, pressure and leaching time were investigated to test the leaching efficiency of copper and nickel from the flotation concentrate with high pressure oxidative leaching (HPOL). A comparison was made between the leaching efficiencies of copper and nickel from flotation concentrates and mine tailing.展开更多
Nickel-metal hydride (Ni/MH) batteries are one of promising batteries for electric vehicle applications, but at high temperature the charge efficiency of nickel electrode is very low. In order to improve the high-te...Nickel-metal hydride (Ni/MH) batteries are one of promising batteries for electric vehicle applications, but at high temperature the charge efficiency of nickel electrode is very low. In order to improve the high-temperature-efficiency of nickel electrode, spherical nickel hydroxide mixed with various ratios of Lu2O3 was used as active material of pasted nickel electrodes. The results of charge/discharge experiments, cyclic voltammetric measurements and XRD characterizations have shown that after addition of Lu2O3, the oxygen evolution overpotcntial is elevated much, the charge efficiency of nickel electrode at high temperature is greatly improved and the content of β-NiOOH phase increases in charged electrodes. In addition, the mixed ratio of Lu2O3 has different effects on high temperature performances of nickel electrode at different charge/discharge currents, 3.5 % is the optimum mixed ratio, and the action of Lu2O3 on high temperature electrochemical behaviors is more apparent when nickel electrodes are charged at small current than large current.展开更多
The homogeneous catalyst system [ArN C(Nap)-C(Nap)=NAr]NiCl2 (Nap = 1,8-naphthdiyl, Ar = 2,6- diisopropylphenyl)/AlEt2Cl has been prepared and examined for ethylene polymerization. Polymerization conditions such...The homogeneous catalyst system [ArN C(Nap)-C(Nap)=NAr]NiCl2 (Nap = 1,8-naphthdiyl, Ar = 2,6- diisopropylphenyl)/AlEt2Cl has been prepared and examined for ethylene polymerization. Polymerization conditions such as cocatalyst, Al/Ni molar ratio and polymerization temperature (Tp) have a great effect on catalytic activity and properties of polyethylenes (PE). The activity of 5.1 × 10^5g PE/mol Ni. h was obtained by the catalyst, activated with AlEt2Cl at 120 of Al/Ni ratio and 30℃. Especially, Tp had a pronounced influence on branches and molecular weight of PE. Branching degree of PE increased with increasing temperature whereas their molecular weight decreased correspondingly. At Tp lower than about 70℃, the resultant PE was an elastic material. When Tp was higher than 70℃, the product was a viscous oil. The resultant PE was confirmed by ^13C-NMR to contain significant amounts of not only methyl but also ethyl, propyl, butyl, amyl, and longer branches (longer than six carbons). According to gel permeation chromatographic measurement, the weightaverage molecular weights of the polymers obtained ranged from 3.6 × 10^3 to 2.3 × 10^5.展开更多
基金Shougang Research Institute of Technology for the financial support to this project
文摘In-situ observation of microstructural evolution during heating and soaking process was carded out for a high nickel steel using HTCLSM. Dark phases were observed when soaking at 900℃. Results showed that the number of the dark phases culminated in about 50 s during soaking at 900℃. With the increase of soaking time the area proportion of the dark phases increased and reached the maximum value in about 3 min, When temperature rose from 900 ℃, the dark phases remained steady initially, but started to dissolve into the matrix at about 1 060 ℃ and completely disappeared at 1 132℃. When the specimen soaked at 900 ℃ was cooled down to room temperature (RT), the dark phases kept stable. Energy spectrum analysis results showed that the dark phases contained much more Cr and Mn elements than the matrix and,were also rich in V. Tensile test results showed that the dark phase strengthened the steel with the maximum tensile strength obtained after soaking at 900 ℃ for 3 minutes.
基金supported by the National Natural Science Foundation of China(Nos.52172180 and 51872026)the National Key R&D Program of China(No.2018YFB0104300).
文摘An adequate wide temperature electrolyte for high nickel ternary cathode is urgent to further develop high energy density batteries.Herein,a comprehensive double-salt local high-concentration sulfolane-based electrolyte(DLi)is proposed with specific sheath structure to build stable interface on the LiNi_(0.8)Co_(0.1)Mn_(0.1O2)(NCM811)cathode at wide operating temperature between−60 and 55℃.Lithium perchlorate(LiClO_(4))in combination with high concentration lithium bis-(trifluoromethanesulfonyl)imide(LiTFSI)strengthens the internal interaction between anion and cation in the solvation structure,increasing Li+transference number of the electrolyte to 0.61.Moreover,the structure and component characteristics of the passive interface layer on NCM811 are modulated,decreasing desolvation energy of Li+ions,benefiting Li+transport dynamics especially at low temperature,and also ensuring the interfacial stability at a wide operating temperature range.As a result,the cathode with DLi exhibits excellent high-temperature storage performance and high capacity retention of 80.5%in 100 cycles at 55℃.Meanwhile,the Li||NCM811 cells can deliver high discharge capacity of 160.1,136.1,and 110.3 mAh·g^(−1)under current density of 0.1 C at−20,−40,and−60℃,maintaining 84.5%,71.8%,and 58.2%of the discharge capacity at 30℃,respectively.Moreover,it enables NCM811 cathode to achieve a reversible capacity of 142.8 mAh·g^(−1)in 200 cycles at−20℃and 0.2 C.Our studies shed light on the molecular strategy of wide operational temperature electrolyte for high nickel ternary cathode.
基金National Natural Science Foundation of China,Grant/Award Numbers:21905265,52072322,U1930402,61974042National Science Foundation,Civil,Mechanical and Manufacturing Innovation,Grant/Award Number:1911905+3 种基金Fundamental Research Funds for the Central Universities,Grant/Award Number:WK2060140026Department of Science and Technology of Sichuan Province,Grant/Award Numbers:2019‐GH02‐00052‐HZ,2019YFG0220Scientific and Technological Innovation Foundation of Shunde Graduate School,Grant/Award Number:BK19BE024National Key Research and Development Program of China,Grant/Award Number:2017YFA0303403。
文摘A new concentrated ternary salt ether-based electrolyte enables stable cycling of lithium metal battery(LMB)cells with high-mass-loading(13.8 mg cm^(−2),2.5 mAh cm^(−2))NMC622(LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2))cathodes and 50μm Li anodes.Termed“CETHER-3,”this electrolyte is based on LiTFSI,LiDFOB,and LiBF4 with 5 vol%fluorinated ethylene carbonate in 1,2-dimethoxyethane.Commer-cial carbonate and state-of-the-art binary salt ether electrolytes were also tested as baselines.With CETHER-3,the electrochemical performance of the full-cell battery is among the most favorably reported in terms of high-voltage cycling stability.For example,LiNi_(x)Mn_(y)Co_(1-x-y)O_(2)(NMC)-Li metal cells retain 80%capacity at 430 cycles with a 4.4 V cut-off and 83%capacity at 100 cycles with a 4.5 V cut-off(charge at C/5,discharge at C/2).According to simulation by density functional theory and molecular dynamics,this favorable performance is an outcome of enhanced coordination between Li^(+)and the solvent/salt molecules.Combining advanced microscopy(high-resolution transmission electron microscopy,scanning electron microscopy)and surface science(X-ray photoelectron spectroscopy,time-of-fight secondary ion mass spectroscopy,Fourier-transform infrared spectroscopy,Raman spectroscopy),it is demonstrated that a thinner and more stable cathode electrolyte interphase(CEI)and solid electrolyte interphase(SEI)are formed.The CEI is rich in lithium sulfide(Li_(2)SO_(3)),while the SEI is rich in Li_(3)N and LiF.During cycling,the CEI/SEI suppresses both the deleterious transformation of the cathode R-3m layered near-surface structure into disordered rock salt and the growth of lithium metal dendrites.
基金National Natural Science Foundation of China,Grant/Award Numbers:21875016,22179004Natural Science Foundation of Beijing,Grant/Award Number:2212014。
文摘High nickel content layered cathodes,represented by NCM(LiNi_(x)Co_(y)Mn_(z)O_(2),x+y+z=1),are now widely employed in the market of electric vehicles,owing to their high energy density.With the gradual increase of nickel content and capacity,the issues on cycling life and safety become more serious.In this review,various strategies for improving the performance of high nickel NCM are summarized on the aspects of surface coating,ionic doping,and singlecrystal NCM.The coating strategy was separately described according to the physical property of coating species,including inert material coating,Li^(+)-conductor coating,electronic conductor coating,and mixed conductor coating.These coating species help to suppress the interfacial oxidation of electrolytes by NCM,improving the cycling life and safety.The elemental doping in the crystal lattice of NCM is then presented in the aspects of cation,anion,and mixed-ion doping,which are beneficial to stabilize the layered structure during charge–discharge and so promote the electrochemical performance.In quite recent years,the strategy of single-crystal NCM was demonstrated to be a promising pathway,owing to the dramatically reduced surface area and grain boundary.Finally,the remaining unsolved challenges and future strategies for further development of NCM cathode materials are outlined.
基金Project(21075138) supported by the National Natural Science Foundation of ChinaProject(cstc2011jjA0780) supported by Natural Science Foundation of Chongqing City,ChinaProject(KJ121311) supported by Educational Commission of Chongqing City of China
文摘The contents of Mg,Al,Si,Ti,Cr,Mn,Fe,Co,Cu,Ga,As,Se,Cd,Sb,Pb and Bi in high purity nickel were determined by high resolution inductively coupled plasma mass spectrometry(HR-ICP-MS).The sample was dissolved in HNO3 and HCl by microwave digestion.Most of the spectral interferences could be avoided by measuring in the high resolution mode.The matrix effects because of the presence of excess HCl and nickel were evaluated.Correction for matrix effects was made using Sc,Rh and Tl as internal standards.The optimum conditions for the determination were tested and discussed.The detection limits range from 0.012 to 1.76 μg/g depending on the type of elements.The applicability of the proposed method is also validated by the analysis of high purity nickel reference material(NIST SRM 671).The relative standard deviation(RSD) is less than 3.3%.Results for determination of trace elements in high purity nickel were presented.
基金financially supported by the National Natural Science Foundation of China (Nos. 51574036 and 51404033)
文摘To inhibit the dissolution of Mg^2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bioleaching factors on the dissolution of Mg^2+ from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg^2+ from olivine and serpentine was temperature, followed by p H and particle size. A novel method of bioleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg^2+ and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.
基金supported by the Fundamental Research Funds for the Central Universities (HEUCF201403018)the Heilongjiang Postdoctoral Fund (LBHZ13059)+1 种基金the China Postdoctoral Science Foundation (2014M561332)the National Natural Science Foundation of China (21403044)
文摘A novel plastic/multi-walled carbon nanotube(MWNTs)-nickel(Ni)-platinum(Pt) electrode(PMNP) is prepared by chemical-reducing Pt onto the surface of Ni film covered plastic/MWNTs(PM) substrate. The MWNTs are adhered by a piece of commercial double faced adhesive tape on the surface of plastic paper and the Ni film is prepared by a simple electrodeposition method. The morphology and phase structure of the PMNP electrode are characterized by scanning electron microscopy,transmission electron microscope and X-ray diffractometer. The catalytic activity of the PMNP electrode for Na BH4 electrooxidation is investigated by means of cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the plastic paper and exhibits a good stability. MWNTs serve as both conductive material and hydrogen storage material and the Ni film and Pt are employed as electrochemical catalysts. The PMNP electrode exhibits a high electrocatalytic performance and the oxidation current density reaches to 10.76 A/(mg·cm) in 0.1 mol/dm3 Na BH4at0 V,which is much higher than those in the previous reports. The using of waste plastic reduces the discarding of white pollution and consumption of metal resources.
基金Project supported by the National Natural Science Foundations of China(Grant Nos.51371089 and 51401083)
文摘The tensile strength and ductility of a high nitrogen nickel-free austenitic stainless steel with solution and cold rolling treatment were investigated by performing tensile tests at different strain rates and at room temperature. The tensile tests demonstrated that this steel exhibits a significant strain rate and cold rolling dependence of the tensile strength and ductility.With the increase of the strain rate from 10^-4s^-1to 1 s^-1, the yield strength and ultimate tensile strength increase and the uniform elongation and total elongation decrease. The analysis of the double logarithmic stress–strain curves showed that this steel exhibits a two-stage strain hardening behavior, which can be well examined and analyzed by using the Ludwigson equation. The strain hardening exponents at low and high strain regions(n2and n1) and the transition strain(εL) decrease with increasing strain rate and the increase of cold rolling RA. Based on the analysis results of the stress–strain curves, the transmission electron microscopy characterization of the microstructure and the scanning electron microscopy observation of the deformation surfaces, the significant strain rate and cold rolling dependence of the strength and ductility of this steel were discussed and connected with the variation in the work hardening and dislocation activity with strain rate and cold rolling.
基金Supported by the Natural Science Foundation of Department of Education (05Z008) and the Science and Technology Projects of Guangdong Province (2007B030101007).
文摘有高特定的体积能力的圆柱的镍金属氢化物(Ni-MH ) 电池被使用 oxyhydroxide Ni 准备(哦) 2 并且 AB5 类型氢存储合金并且调整积极、否定的电极的设计参数。oxyhydroxide Ni (哦) 2 被氧化综合有化学方法的球形的 -Ni(OH)2。X 光检查衍射(XRD ) 模式和 Fourier 转变红外线(英尺红外) 系列显示 -NiOOH 在 oxyhydroxide Ni 上被形成(哦) 2 粉末,和一些 H2O 分子被插入到他们的晶体格子间距。当时,电池能力不能被改进 oxyhydroxide Ni (哦) 2 样品直接被用作积极活跃材料。然而,基于传导力和 oxyhydroxide Ni 的剩余能力(哦) 2 搽粉,与 2560 妈一起的 AA 尺寸 Ni-MH 电池?
基金supported by the 863 National Research and Development Project Foundation of China (2006AA11A151)
文摘Effects of flaky rare earth oxide additives including Er2O3,Tm2O3,and Yb2O3,Lu2O3 on high temperature and high rate discharge performance of nickel electrodes were investigated.The discharge efficiency at 0.2C reached 96% at 60 oC for electrodes with 1 at.% flaky rare earth oxides.The high rate discharge performance for electrodes with flaky rare earth oxides were improved significantly,for example,discharge efficiency at 5C improved from 50% to 70%.The results showed that the end charging potential of the ...
文摘In order to enhance the high-temperature stress rupture strength of brazing seam by heat treatment, it was diffusion treated, then solution heat treated, and finally aging treated. The microstructure of brazing seam especially morphology of gamma ' phase and boride was observed and the strength of brazing seam was measured in this process. The results show that heat treatment can enhance high-temperature stress rupture strength by improving the microstructure of brazing seam. The strength of brazing seam after solution heat treatment decreases in comparison with that only after diffusion treatment while aging treatment after solution heat treatment increases the strength of brazing seam.
基金Supported by the Science and Research Foundation of Sichuan Educational Committee under Grant Nos 13ZB0211 and 13ZA0198the Open Research Fund of Computational Physics Key Laboratory of Sichuan Province under Grant No JSWL2014KF06
文摘We report a molecular dynamics study of structural and transport properties of liquid nickel under high pres- sures. Pressure dependencies of pair distribution function and pair correlation entropy along the melting line indicate that the configuration change along melting lines decreases with increasing pressure. The calculated diffusion coefficients and viscosity by using entropy-scaling laws with modified parameters and ideal parameters are compared with those extracted from mean-square displacement or the Stokes-Einstein relation. The results suggest that the entropy-scaling laws hold well for coefficients and viscosity increase moderately with liquid nickel under high-pressure conditions, and the diffusion pressure along melting lines.
文摘The present study focused on the re-processing of copper and nickel from mine tailings. In this work, recovery of copper and nickel from mine tailing by combined process of flotation and high pressure oxidative leaching were considered. In the first stage, effects of flotation parameters including collector type, collector dosage, and pH and pulp density were examined. The results showed that over 80% copper recovery was achieved under the optimized flotation conditions while nickel recovery was lower than 30% due to its co-ex-istence with gangue minerals of pyrrhotite, pyrite and other clay minerals. In the second stage, key parameters, particularly concentration of sulfuric acid, temperature, pressure and leaching time were investigated to test the leaching efficiency of copper and nickel from the flotation concentrate with high pressure oxidative leaching (HPOL). A comparison was made between the leaching efficiencies of copper and nickel from flotation concentrates and mine tailing.
文摘Nickel-metal hydride (Ni/MH) batteries are one of promising batteries for electric vehicle applications, but at high temperature the charge efficiency of nickel electrode is very low. In order to improve the high-temperature-efficiency of nickel electrode, spherical nickel hydroxide mixed with various ratios of Lu2O3 was used as active material of pasted nickel electrodes. The results of charge/discharge experiments, cyclic voltammetric measurements and XRD characterizations have shown that after addition of Lu2O3, the oxygen evolution overpotcntial is elevated much, the charge efficiency of nickel electrode at high temperature is greatly improved and the content of β-NiOOH phase increases in charged electrodes. In addition, the mixed ratio of Lu2O3 has different effects on high temperature performances of nickel electrode at different charge/discharge currents, 3.5 % is the optimum mixed ratio, and the action of Lu2O3 on high temperature electrochemical behaviors is more apparent when nickel electrodes are charged at small current than large current.
基金This work was supported by the Foundation of Guangdong Province (No. 31598).
文摘The homogeneous catalyst system [ArN C(Nap)-C(Nap)=NAr]NiCl2 (Nap = 1,8-naphthdiyl, Ar = 2,6- diisopropylphenyl)/AlEt2Cl has been prepared and examined for ethylene polymerization. Polymerization conditions such as cocatalyst, Al/Ni molar ratio and polymerization temperature (Tp) have a great effect on catalytic activity and properties of polyethylenes (PE). The activity of 5.1 × 10^5g PE/mol Ni. h was obtained by the catalyst, activated with AlEt2Cl at 120 of Al/Ni ratio and 30℃. Especially, Tp had a pronounced influence on branches and molecular weight of PE. Branching degree of PE increased with increasing temperature whereas their molecular weight decreased correspondingly. At Tp lower than about 70℃, the resultant PE was an elastic material. When Tp was higher than 70℃, the product was a viscous oil. The resultant PE was confirmed by ^13C-NMR to contain significant amounts of not only methyl but also ethyl, propyl, butyl, amyl, and longer branches (longer than six carbons). According to gel permeation chromatographic measurement, the weightaverage molecular weights of the polymers obtained ranged from 3.6 × 10^3 to 2.3 × 10^5.