Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorpho...Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·n H2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2h, RuO2·n H2O electrode surface gains mass of2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly20% with voltage scan rate increasing from 5 to 250 m V/s.展开更多
The development of the recrystallization texture of the alloy AA3104 was investigated by analysis of orientation distribution functions determined by X-ray diffraction,supported by EBSD local texture analysis.A typic...The development of the recrystallization texture of the alloy AA3104 was investigated by analysis of orientation distribution functions determined by X-ray diffraction,supported by EBSD local texture analysis.A typical β-fiber with nearly 20%Bs orientation {011}211 was detected in the final hot rolled sheet.At the beginning of annealing at 350 ℃,the cube component{001}100 got a sharp increase.TEM results show that the growth of both number and size of precipitation appears to inhibit the advantage of Cube orientation {001}100 notably after annealing at 350 ℃ for 15 min.Finally,it comes out to be a random distributed orientation by full recry stallization.展开更多
The structural and electrical properties of lead free Srx-xLax（Tio.sFeo.5）O3 （SLTFO） prepared by standard solid state reaction technique were studied. The X-ray diffraction analysis confirmed the formation of a si...The structural and electrical properties of lead free Srx-xLax（Tio.sFeo.5）O3 （SLTFO） prepared by standard solid state reaction technique were studied. The X-ray diffraction analysis confirmed the formation of a single-phase cubic perovskite structure. The compositional dependence of lattice constant, density and microstructural studies show that they vary significantly with La3＋ content. When measured at 10 kHz, all the compositions of SLTFO at room temperature exhibit a high permittivity （about 104） and low dielectric loss （about 10-3）. SLTFO also display minimum dielectric loss within the lower and higher limits of frequency, indicating that the samples are of good quality. It is concluded from the calculated ac conductivity that the conduction is due to mixed polarons hopping. The complex impedance plot exhibits a tendency of forming a single semicircular arc for all compositions, which implies a dominance of grain boundary resistance on the impedance. Impedance parameters were determined by fitting the experimental data with Cole-Cole empirical formula. The results of the present experiment indicate that the lead free SLTFO materials with higher permittivity and lower dielectric loss have possible practical applications.展开更多
ZnO-Bi2O3-based varistor ceramics doped with Yb2O3 in the range from 0 to 0.4% （molar fraction） were obtained by a solid reaction route. The X-ray diffractometry （XRD） and scanning electron microscopy （SEM） were...ZnO-Bi2O3-based varistor ceramics doped with Yb2O3 in the range from 0 to 0.4% （molar fraction） were obtained by a solid reaction route. The X-ray diffractometry （XRD） and scanning electron microscopy （SEM） were applied to characterize the phases and microstructure of the varistor ceramics, and a DC parameter instrument for varistor ceramics was applied to investigate their electrical properties and V-I characteristics. The XRD analysis of the samples shows that the ZnO phase, Bi2O3 phase, ZnTSbaOl2-type spinel phase and Zn2Bi3Sb3O14-type pyrochlore are present, and the Yb2O3 phases and Sb2O4 phases are found in varistor ceramics with increasing amounts of Yb2O3. The average size of ZnO grain firstly increases and then decreases with the increase of Yb2O3 content. The result also shows that the threshold voltage is between 656 V/nun and 1 232 V/mm, the nonlinear coefficient is in the range of 14.1-22.3, and the leakage current is between 0.60 μA and 19.6 μA. The 0.20% Yb2O3-added ZnO-Bi2O3-based varistor ceramics sintered at 900 ℃ have the best electrical characteristics.展开更多
The effect of two alkylpyridinium ionic liquids （py-iLs） including N-butylpyridinium hydrogen sulfate （BpyHSO4） and N-hexylpyridinium hydrogen sulfate （HpyHSO4） on the kinetics of copper electrodeposition from a...The effect of two alkylpyridinium ionic liquids （py-iLs） including N-butylpyridinium hydrogen sulfate （BpyHSO4） and N-hexylpyridinium hydrogen sulfate （HpyHSO4） on the kinetics of copper electrodeposition from acidic sulfate solution was investigated by cyclic voltammetry and potentiodynamic polarization measurements. Results from cyclic voltammetry indicate that these py-iLs have a pronounced inhibiting effect on CuE＋ electroreduction and there exists a typical nucleation and growth process. Kinetic parameters such as Tafel slope, transfer coefficient and exchange current density obtained from Tafel plots, lead to the conclusion that py-iLs inhibit the charge transfer by slightly changing the copper electrodeposition mechanism through their adsorption on the cathodic surface. In addition, scanning electron microscope （SEM） and X-ray diffraction analyses reveal that the presence of these additives leads to more leveled and fine-grained cathodic deposits without changing the crystal structure of the electrodeposited copper but strongly affects the crystallographic orientation by significantly inhibiting the growth of （111）, （200） and （311） planes.展开更多
The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments...The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments. The microstructures, phases, residual stresses and retained austenite content of 1Cr5 Mo steel welding joint before and after LHT were analyzed with optical microscope and X-ray diffraction, respectively. The cracking morphologies and chemical compositions of corrosion products after salt spray corrosion were analyzed with field emission scanning electron microscopy(FESEM) and energy disperse spectroscopy(EDS), respectively, the polarization curves were measured on a PS-268 A type electrochemical workstation, and the mechanism of corrosion resistance by LHT was investigated as well. The results show that the passive film of original sample is destroyed owing to the corrosive media penetrating into the subsurface, resulting in the redox reaction. The content of residual austenite in the surface and the self-corrosion potential are increased by LHT, which is contributed to improving the capability of salt spray corrosion resistance.展开更多
Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction te...Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction temperature reduces compared with that under normal pressure, and the preferential order of products is Al404C, Al4C3, Al2OC, Al20 and A1. Experiment results show that the carbothermic reduction products of alumina are A1404C and A14C3, and neither A12OC, Al20 or Al was found. During the carbothermic reduction process, the reaction rate of Al203 and carbon decreases gradually with increasing time. Meanwhile, lower system pressure or higher temperature is beneficial to the carbothermic reduction of alumina process. A1404C is firstly formed in the carbothermic reaction, and then A14C3 is formed in lower system pressure or at higher temperature.展开更多
The hot-compression of Al-IMn-IMg （mass fraction, %） alloy sample was carried out on a Gleeble-1500 thermo-simulator at deformation temperatures from 320 to 400 ℃ and strain rates from 0.1 to 10 s 1 by total strain...The hot-compression of Al-IMn-IMg （mass fraction, %） alloy sample was carried out on a Gleeble-1500 thermo-simulator at deformation temperatures from 320 to 400 ℃ and strain rates from 0.1 to 10 s 1 by total strain of 1.4. Microstructure and texture evolution of the hot-compressed alloy were investigated by optical microscopy and X-ray diffraction analysis, respectively. The results show that the relationship among flow stress a, deformation temperature T and strain rate ε can be expressed in the form of βσ = lnε＋Q/（RT）-lnA. The threshold value of In Z （Z is Zener-Hollomon parameter） characterizing the dynamic recrystallization （DRX） is 46, below which the DRX takes place. A strong P orientation {011}（455） associated with a weak cube orientation { 100} （001） is found in the recrystallized sample during hot-compression.展开更多
ZnO-Bi2O3-based varistor ceramics doped with EU2O3 in a range from 0 to 0.4% were obtained by high-energy ball milling and fired at 900-1000 ℃ for 2 h. XRD and SEM were applied to determine the phases and microstruct...ZnO-Bi2O3-based varistor ceramics doped with EU2O3 in a range from 0 to 0.4% were obtained by high-energy ball milling and fired at 900-1000 ℃ for 2 h. XRD and SEM were applied to determine the phases and microstructure of the varistor ceramics. A DC parameter instrument was applied to investigate the electronic properties and V-I characteristics. The XRD analysis of Eu2O3-doped ZnO-Bi2O3-based varistor ceramics shows that the ZnO, Eu-containing Bi-rich, Zn7Sb2O12-type spinel and Zn2Bi3Sb3O14-type which is the pyrochlore phase are present. With increasing Eu2O3 content, the average size of ZnO grain firstly decreases and then increases. The grain boundary defect model was particularly used to explain the excellent nonlinearity of ZnO-Bi2O3-based varistor ceramics with the addition of0.1% Eu2O3 and sintered at 950 ℃.展开更多
An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process...An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that Pb F2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition is β-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.展开更多
The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. ...The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2, which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere, i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.展开更多
The corrosion inhibition of type 304 austenitic stainless steel by 2-amino-5-ethyl-1, 3, 4-thiadiazole(TTD) compound and the electrochemical behaviour in dilute HCl solution were investigated through potentiodynamic p...The corrosion inhibition of type 304 austenitic stainless steel by 2-amino-5-ethyl-1, 3, 4-thiadiazole(TTD) compound and the electrochemical behaviour in dilute HCl solution were investigated through potentiodynamic polarization test, mass loss techniques and potential measurements. The results show that the organic derivative is highly effective with a maximum inhibition efficiency of 70.22% from mass loss analysis, while 74.2% is obtained from polarization tests. Observation of the scanning electron micrographs shows the absence of corrosion products due to electrochemical influence of TTD on the surface morphology of the steel. X-ray diffractometry reveals the absence of phase compounds and complexes on the steel samples after exposure. TTD adsorption on the steel surface obeys the Langmuir, Frumkin and Freundlich adsorption isotherms. Corrosion thermodynamic calculations reveal the inhibition mechanism occurs through chemisorption process and results from statistical analysis depict the strong influence of inhibitor concentration on the electrochemical performance of the TTD.展开更多
2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols were investigated employing experimental and density functional theory （DFT） method at B3LYP/6-31G （d） level. The structure of syn-2,4-di-p-tolylpentane-2,4...2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols were investigated employing experimental and density functional theory （DFT） method at B3LYP/6-31G （d） level. The structure of syn-2,4-di-p-tolylpentane-2,4-diol （2b） was characterized by X-ray diffraction and compared with the crystal structures of anti- and syn-2,4-diphenylpentane-2,4-diols （la and lb）. X-ray diffraction indicates that inter and intra-molecular hydrogen bonds are formed in the crystal structures. There is n-n staking interaction in lb and 2b. Good linear correlations and similar results are found between the experimental 1H and 13C NMR chemical shifts （6~exp） and GIAO （Gauge Independent Atomic Orbital） method calculated magnetic isotropic shielding tensors （acalc）. HOMO and LUMO molecular orbitals were calculated at the same levels with the different results. UV-vis absorption spectra of the compounds were recorded in EtOH, MeCN, n-BuOH and cyclohexane with different dielectric constants. It is found that the solvent effect is obvious when e is 24.85（EtOH）, 35.69（MeCN） and it is weak when e is decreased to 17.33（n-BuOH）, 1.18 （cyclohexane）.展开更多
Hot-compression of aluminum alloy 5182 was carried out on a Gleeble- 1500 thermo-simulator at deformation temperature ranging from 350 ℃ to 500 ℃ and at strain rate from 0.01 s^-1 to 10 s^-1 with strain range from 0...Hot-compression of aluminum alloy 5182 was carried out on a Gleeble- 1500 thermo-simulator at deformation temperature ranging from 350 ℃ to 500 ℃ and at strain rate from 0.01 s^-1 to 10 s^-1 with strain range from 0.7 to 1.9. The microstructures and macro-textures evolution under different conditions were investigated by polarized optical microscopy and X-ray diffraction analysis, respectively. The basic trend is that the hot-compression stress increases with the decrease of temperature and increase of strain rate, which is revealed and elucidated in terms of Zener-Hollomon parameter in the hyperbolic sine equation with the hot-deformation activation energy of 143.5 kJ/mol. An empirical constitutive equation is proposed to predict the hot-deformation behavior under different conditions. As deformation temperature increases up to 400 ℃, at strain rate over 1 s^-1, dynamic recrystallization （DRX） occurs. Cube orientation { 100} （001） is detected in the recrystallized sample after hot-compression.展开更多
An A1 coating on Mg substrate was achieved by droplet spraying treatment. The microstructure was studied by electron probe microanalysis （EPMA） and X-ray diffraction （XRD）. The coating layer is composed of AI phas...An A1 coating on Mg substrate was achieved by droplet spraying treatment. The microstructure was studied by electron probe microanalysis （EPMA） and X-ray diffraction （XRD）. The coating layer is composed of AI phase and exhibits superior corrosion resistance. The formation of the coating is mainly attributed to the obstruction of expansion of the transition zone by primarily solidified Mg]7All2 during rapid cooling, and the diffusion is restricted in a thin layer. These results show that droplet spraying is a promising way to protect magnesium by using corrosion-resistant materials available now.展开更多
Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5...Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5SiO4 was studied. The final sample was identified as Li2Fe0.5Mn0.5SiO4 with a Pmn21 monoclinic structure by X-ray diffraction analysis. The crystal phases components and crystal phase structure of the Li2Fe0.5Mn0.4SiO4 material were improved as the increase of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+). Field-emission scanning electron microscopy verified that the Li2Fe0.5Mn0.5SiO4 particles are agglomerates of Li2Fe0.5Mn0.5SiO4 primary particles with a geometric mean diameter of 220 nm. The Li2Fe0.5Mn0.5SiO4 sample was used as an electrode material for rechargeable lithium ion batteries, and the electrochemical measurements were carried out at room temperature. The Li2Fe0.5Mn0.5SiO4 electrode delivered a first discharge capacity of 230.1 mAh/g at the current density of 10 mA/g in first cycle and about 162 mAh/g after 20 cycles at the current density of 20 mA/g.展开更多
基金Project(S2013040015492)supported by the Natural Science Foundation of Guangdong Province,ChinaProject(2007AA03Z240)supported by Hi-tech Research and Development Program of China
文摘Ru O2·n H2O film was deposited on tantalum foils by electrodeposition and heat treatment using Ru Cl3·3H2O as precursor.Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·n H2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2h, RuO2·n H2O electrode surface gains mass of2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly20% with voltage scan rate increasing from 5 to 250 m V/s.
文摘The development of the recrystallization texture of the alloy AA3104 was investigated by analysis of orientation distribution functions determined by X-ray diffraction,supported by EBSD local texture analysis.A typical β-fiber with nearly 20%Bs orientation {011}211 was detected in the final hot rolled sheet.At the beginning of annealing at 350 ℃,the cube component{001}100 got a sharp increase.TEM results show that the growth of both number and size of precipitation appears to inhibit the advantage of Cube orientation {001}100 notably after annealing at 350 ℃ for 15 min.Finally,it comes out to be a random distributed orientation by full recry stallization.
基金Project supported by CASR of Bangladesh University of Engineering and Technology(BUET)
文摘The structural and electrical properties of lead free Srx-xLax（Tio.sFeo.5）O3 （SLTFO） prepared by standard solid state reaction technique were studied. The X-ray diffraction analysis confirmed the formation of a single-phase cubic perovskite structure. The compositional dependence of lattice constant, density and microstructural studies show that they vary significantly with La3＋ content. When measured at 10 kHz, all the compositions of SLTFO at room temperature exhibit a high permittivity （about 104） and low dielectric loss （about 10-3）. SLTFO also display minimum dielectric loss within the lower and higher limits of frequency, indicating that the samples are of good quality. It is concluded from the calculated ac conductivity that the conduction is due to mixed polarons hopping. The complex impedance plot exhibits a tendency of forming a single semicircular arc for all compositions, which implies a dominance of grain boundary resistance on the impedance. Impedance parameters were determined by fitting the experimental data with Cole-Cole empirical formula. The results of the present experiment indicate that the lead free SLTFO materials with higher permittivity and lower dielectric loss have possible practical applications.
基金Project(BK2011243) supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(2007DA10512711408) supported by the Visiting Scholarship of State Key Laboratory of Power Transmission Equipment & System Security and New Technology (Chongqing University),China+4 种基金Project(EIPE11204) supported by the State Key Laboratory of Electrical Insulation and Power Equipment,ChinaProject(KF201104) supported by the State Key Laboratory of New Ceramic and Fine Processing,ChinaProject(KFJJ201105) supported by the Opening Project of State Key Laboratory of Electronic Thin Films and Integrated Devices,ChinaProject(10KJD430002) supported by the Universities Natural Science Research Project of Jiangsu Province,ChinaProject(11JDG084) supported by the Research Foundation of Jiangsu University,China
文摘ZnO-Bi2O3-based varistor ceramics doped with Yb2O3 in the range from 0 to 0.4% （molar fraction） were obtained by a solid reaction route. The X-ray diffractometry （XRD） and scanning electron microscopy （SEM） were applied to characterize the phases and microstructure of the varistor ceramics, and a DC parameter instrument for varistor ceramics was applied to investigate their electrical properties and V-I characteristics. The XRD analysis of the samples shows that the ZnO phase, Bi2O3 phase, ZnTSbaOl2-type spinel phase and Zn2Bi3Sb3O14-type pyrochlore are present, and the Yb2O3 phases and Sb2O4 phases are found in varistor ceramics with increasing amounts of Yb2O3. The average size of ZnO grain firstly increases and then decreases with the increase of Yb2O3 content. The result also shows that the threshold voltage is between 656 V/nun and 1 232 V/mm, the nonlinear coefficient is in the range of 14.1-22.3, and the leakage current is between 0.60 μA and 19.6 μA. The 0.20% Yb2O3-added ZnO-Bi2O3-based varistor ceramics sintered at 900 ℃ have the best electrical characteristics.
基金Projects(51204080, 51274108) supported by the National Natural Science Foundation of ChinaProject(2011FA009) supported by the Natural Science Foundation of Yunnan Province, ChinaProject(2011FZ020) supported by the Application Research Foundation of Yunnan Province, China
文摘The effect of two alkylpyridinium ionic liquids （py-iLs） including N-butylpyridinium hydrogen sulfate （BpyHSO4） and N-hexylpyridinium hydrogen sulfate （HpyHSO4） on the kinetics of copper electrodeposition from acidic sulfate solution was investigated by cyclic voltammetry and potentiodynamic polarization measurements. Results from cyclic voltammetry indicate that these py-iLs have a pronounced inhibiting effect on CuE＋ electroreduction and there exists a typical nucleation and growth process. Kinetic parameters such as Tafel slope, transfer coefficient and exchange current density obtained from Tafel plots, lead to the conclusion that py-iLs inhibit the charge transfer by slightly changing the copper electrodeposition mechanism through their adsorption on the cathodic surface. In addition, scanning electron microscope （SEM） and X-ray diffraction analyses reveal that the presence of these additives leads to more leveled and fine-grained cathodic deposits without changing the crystal structure of the electrodeposited copper but strongly affects the crystallographic orientation by significantly inhibiting the growth of （111）, （200） and （311） planes.
基金Project(CXLX14-1098)supported by Jiangsu Province Postgraduate Scientific Research Innovation Program,China
文摘The surface of 1Cr5 Mo heat-resistant steel welding joint was processed with CO2 laser, and the corrosion behaviors before and after laser heat treatment(LHT) were investigated in the salt spray corrosion environments. The microstructures, phases, residual stresses and retained austenite content of 1Cr5 Mo steel welding joint before and after LHT were analyzed with optical microscope and X-ray diffraction, respectively. The cracking morphologies and chemical compositions of corrosion products after salt spray corrosion were analyzed with field emission scanning electron microscopy(FESEM) and energy disperse spectroscopy(EDS), respectively, the polarization curves were measured on a PS-268 A type electrochemical workstation, and the mechanism of corrosion resistance by LHT was investigated as well. The results show that the passive film of original sample is destroyed owing to the corrosive media penetrating into the subsurface, resulting in the redox reaction. The content of residual austenite in the surface and the self-corrosion potential are increased by LHT, which is contributed to improving the capability of salt spray corrosion resistance.
基金Project(U0837604) supported by the Natural Science Foundation of Yunnan Province,ChinaProject(Jinchuan 201114) supported by the Pre Research Foundation of Jinchuan Group Ltd.,ChinaProject(2011148) supported by the Analysis and Testing Funds of Kunming University of Science and Technology,China
文摘Carbothermic reduction alumina in vacuum was conducted, and the products were analysed by means of XRD and gas chromatography. Thermodynamic analysis shows that in vacuum the initial carbothermic reduction reaction temperature reduces compared with that under normal pressure, and the preferential order of products is Al404C, Al4C3, Al2OC, Al20 and A1. Experiment results show that the carbothermic reduction products of alumina are A1404C and A14C3, and neither A12OC, Al20 or Al was found. During the carbothermic reduction process, the reaction rate of Al203 and carbon decreases gradually with increasing time. Meanwhile, lower system pressure or higher temperature is beneficial to the carbothermic reduction of alumina process. A1404C is firstly formed in the carbothermic reaction, and then A14C3 is formed in lower system pressure or at higher temperature.
基金Project(2007BAE38B01) supported by National Science and Technology Pillar Program
文摘The hot-compression of Al-IMn-IMg （mass fraction, %） alloy sample was carried out on a Gleeble-1500 thermo-simulator at deformation temperatures from 320 to 400 ℃ and strain rates from 0.1 to 10 s 1 by total strain of 1.4. Microstructure and texture evolution of the hot-compressed alloy were investigated by optical microscopy and X-ray diffraction analysis, respectively. The results show that the relationship among flow stress a, deformation temperature T and strain rate ε can be expressed in the form of βσ = lnε＋Q/（RT）-lnA. The threshold value of In Z （Z is Zener-Hollomon parameter） characterizing the dynamic recrystallization （DRX） is 46, below which the DRX takes place. A strong P orientation {011}（455） associated with a weak cube orientation { 100} （001） is found in the recrystallized sample during hot-compression.
基金Projects(BK2011243,BK2012156) supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(20123227120021) supported by the Specialized Research Fund for the Doctoral Program of Higher Education,China+3 种基金Project(KFJJ201105) supported by the Opening Project of State key Laboratory of Electronic Thin Films and Integrated Devices,ChinaProject(10KJD430002) supported by the Universities Natural Science Research Project of Jiangsu Province,ChinaProject(13KJB430006) supported by the Application Program for Basic Research of Changzhou,ChinaProject supported by the Industrial Center of Jiangsu University Undergraduate Practice-Innovation Training Project,China
文摘ZnO-Bi2O3-based varistor ceramics doped with EU2O3 in a range from 0 to 0.4% were obtained by high-energy ball milling and fired at 900-1000 ℃ for 2 h. XRD and SEM were applied to determine the phases and microstructure of the varistor ceramics. A DC parameter instrument was applied to investigate the electronic properties and V-I characteristics. The XRD analysis of Eu2O3-doped ZnO-Bi2O3-based varistor ceramics shows that the ZnO, Eu-containing Bi-rich, Zn7Sb2O12-type spinel and Zn2Bi3Sb3O14-type which is the pyrochlore phase are present. With increasing Eu2O3 content, the average size of ZnO grain firstly decreases and then increases. The grain boundary defect model was particularly used to explain the excellent nonlinearity of ZnO-Bi2O3-based varistor ceramics with the addition of0.1% Eu2O3 and sintered at 950 ℃.
基金Projects(51204208,51374240)supported by the National Natural Science Foundation of ChinaProject(2014zzts028)supported by the Fundamental Research Funds for the Central Universities of Central South University,China
文摘An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that Pb F2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition is β-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.
基金Project(50525619) supported by the National Natural Science Foundation of ChinaProject(306012) supported by the Key Foundation of Ministry of Education of China
文摘The temperature dependence on the reaction of desulfurization reagent CaCO3 and SO2 in O2/CO2 coal combustion was investigated by thcrmogravimetric analysis, X-ray diffraction measurement and pore structure analysis. The results show that the conversion of the reaction of CaCO3 and SO2 in air is higher at 500-1 100 ℃ and lower at 1 200 ℃ compared with that in O2/CO2 atmosphere. The conversion can be increased by increasing the concentration of SO2, which causes the inhibition of CaSO4 decomposition and shifting of the reaction equilibrium toward the products. XRD analysis of the product shows that the reaction mechanism of CaCO3 and SO2 differs with temperature in O2/CO2 atmosphere, i.e. CaCO3 directly reacts with SO2 at 500 ℃ and CaO from CaCO3 decomposition reacts with SO2 at 1 000 ℃. The pore analysis of the products indicates that the maximum specific surface area of the products accounts for the highest conversion at 1 100 ℃ in O2/CO2 atmosphere. The results reveal that the effect of the atmosphere on the conversion is temperature dependence.
文摘The corrosion inhibition of type 304 austenitic stainless steel by 2-amino-5-ethyl-1, 3, 4-thiadiazole(TTD) compound and the electrochemical behaviour in dilute HCl solution were investigated through potentiodynamic polarization test, mass loss techniques and potential measurements. The results show that the organic derivative is highly effective with a maximum inhibition efficiency of 70.22% from mass loss analysis, while 74.2% is obtained from polarization tests. Observation of the scanning electron micrographs shows the absence of corrosion products due to electrochemical influence of TTD on the surface morphology of the steel. X-ray diffractometry reveals the absence of phase compounds and complexes on the steel samples after exposure. TTD adsorption on the steel surface obeys the Langmuir, Frumkin and Freundlich adsorption isotherms. Corrosion thermodynamic calculations reveal the inhibition mechanism occurs through chemisorption process and results from statistical analysis depict the strong influence of inhibitor concentration on the electrochemical performance of the TTD.
基金Projects(21072053,20772028)supported by the National Natural Science Foundation of ChinaProjects(10K025,11C0527)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProject(LKF0901)supported by the Open Foundation of Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education,Hunan University of Science and Technology,China
文摘2,4-diphenylpentane- and 2,4-di-p-tolylpentane-2,4-diols were investigated employing experimental and density functional theory （DFT） method at B3LYP/6-31G （d） level. The structure of syn-2,4-di-p-tolylpentane-2,4-diol （2b） was characterized by X-ray diffraction and compared with the crystal structures of anti- and syn-2,4-diphenylpentane-2,4-diols （la and lb）. X-ray diffraction indicates that inter and intra-molecular hydrogen bonds are formed in the crystal structures. There is n-n staking interaction in lb and 2b. Good linear correlations and similar results are found between the experimental 1H and 13C NMR chemical shifts （6~exp） and GIAO （Gauge Independent Atomic Orbital） method calculated magnetic isotropic shielding tensors （acalc）. HOMO and LUMO molecular orbitals were calculated at the same levels with the different results. UV-vis absorption spectra of the compounds were recorded in EtOH, MeCN, n-BuOH and cyclohexane with different dielectric constants. It is found that the solvent effect is obvious when e is 24.85（EtOH）, 35.69（MeCN） and it is weak when e is decreased to 17.33（n-BuOH）, 1.18 （cyclohexane）.
基金Project(50905188) supported by the National Natural Science FoundationProject(2012CB619500) supported by Key Basic Research Program of China
文摘Hot-compression of aluminum alloy 5182 was carried out on a Gleeble- 1500 thermo-simulator at deformation temperature ranging from 350 ℃ to 500 ℃ and at strain rate from 0.01 s^-1 to 10 s^-1 with strain range from 0.7 to 1.9. The microstructures and macro-textures evolution under different conditions were investigated by polarized optical microscopy and X-ray diffraction analysis, respectively. The basic trend is that the hot-compression stress increases with the decrease of temperature and increase of strain rate, which is revealed and elucidated in terms of Zener-Hollomon parameter in the hyperbolic sine equation with the hot-deformation activation energy of 143.5 kJ/mol. An empirical constitutive equation is proposed to predict the hot-deformation behavior under different conditions. As deformation temperature increases up to 400 ℃, at strain rate over 1 s^-1, dynamic recrystallization （DRX） occurs. Cube orientation { 100} （001） is detected in the recrystallized sample after hot-compression.
基金Project(J12LA53)supported by Shangdong Provincial Higher Education Science and Technology Program,ChinaProject(KZJ-48)supported by the Science and Technology Development Program of Qingdao,China
文摘An A1 coating on Mg substrate was achieved by droplet spraying treatment. The microstructure was studied by electron probe microanalysis （EPMA） and X-ray diffraction （XRD）. The coating layer is composed of AI phase and exhibits superior corrosion resistance. The formation of the coating is mainly attributed to the obstruction of expansion of the transition zone by primarily solidified Mg]7All2 during rapid cooling, and the diffusion is restricted in a thin layer. These results show that droplet spraying is a promising way to protect magnesium by using corrosion-resistant materials available now.
基金Projects(13A047,10B054)supported by the Scientific Research Fund of Hunan Provincial Education Department,ChinaProjects(2011GK2002,2011FJ3160)supported by the Planned Science and Technology Project of Hunan Province,China
文摘Li2Fe0.5Mn0.5SiO4 material was synthesized by a citric acid-assisted sol-gel method. The influence of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+) on the electrochemical properties of Li2Fe0.5Mn0.5SiO4 was studied. The final sample was identified as Li2Fe0.5Mn0.5SiO4 with a Pmn21 monoclinic structure by X-ray diffraction analysis. The crystal phases components and crystal phase structure of the Li2Fe0.5Mn0.4SiO4 material were improved as the increase of the stoichiometric ratio value of n(citric acid) to n(Fe2+-Mn2+). Field-emission scanning electron microscopy verified that the Li2Fe0.5Mn0.5SiO4 particles are agglomerates of Li2Fe0.5Mn0.5SiO4 primary particles with a geometric mean diameter of 220 nm. The Li2Fe0.5Mn0.5SiO4 sample was used as an electrode material for rechargeable lithium ion batteries, and the electrochemical measurements were carried out at room temperature. The Li2Fe0.5Mn0.5SiO4 electrode delivered a first discharge capacity of 230.1 mAh/g at the current density of 10 mA/g in first cycle and about 162 mAh/g after 20 cycles at the current density of 20 mA/g.
