The influence of Ga and Bi on the microstructure and electrochemical performance of Al-7Zn-0.1Sn （mass fraction,%） sacrificial anodes was investigated by means of optical microscopy （OM）,scanning electron microsco...The influence of Ga and Bi on the microstructure and electrochemical performance of Al-7Zn-0.1Sn （mass fraction,%） sacrificial anodes was investigated by means of optical microscopy （OM）,scanning electron microscopy/energy dispersive X-ray analysis （SEM/EDAX） and electrochemical measurements.It was found that the coarse dendrites structure transformed into the equiaxed grains as well as a small amount of dendrite grains after adding Ga and Bi into Al-Zn-Sn alloys.A high current efficiency of 97% and even corrosion morphology were obtained for Al-7Zn-0.1Sn-0.015Ga-0.1Bi alloy.The results indicate that the proper amount of Ga and Bi is effective on improving the microstructure and electrochemical performance of Al-Zn-Sn alloy.展开更多
Al/Co co-doped α-Ni（OH）2 samples were prepared by either ultrasonic co-precipitation method （Sample B） or co-precipitation method （Sample A）. The crystal structure and particle size distribution of the prepared...Al/Co co-doped α-Ni（OH）2 samples were prepared by either ultrasonic co-precipitation method （Sample B） or co-precipitation method （Sample A）. The crystal structure and particle size distribution of the prepared samples were examined by X-ray diffraction （XRD） and laser particle size analyzer, respectively. The results show that Sample B has more crystalline defects and smaller average diameter than Sample A. The cyclic voltammetry and electrochemical impedance spectroscopy measurements indicate that Sample B has better electrochemical performance than Sample A, such as better reaction reversibility, lower charge-transfer resistance and better cyclic stability. Proton diffusion coefficient of Sample B is 1.96×10-10cm2/s, which is two times as large as that （9.78×10-11cm2/s） of Sample A. The charge-discharge tests show that the discharge capacity （308 mA·h/g） of Sample B is 25 mA·h/g higher than that of Sample A （283 mA·h/g）.展开更多
ZnO varistor ceramics doped with Bi2O3, Sb2O3, CO2O3, Cr2O3, and MnO2 were prepared separately by two high-energy ball milling processes： oxide-doped and varistor ceramic powder. A comparison in the electrical and mi...ZnO varistor ceramics doped with Bi2O3, Sb2O3, CO2O3, Cr2O3, and MnO2 were prepared separately by two high-energy ball milling processes： oxide-doped and varistor ceramic powder. A comparison in the electrical and microstructural properties of the samples obtained by both methods was made. The best results on these characteristics were achieved through the high-energy ball milling varistor ceramic powder route, obtaining a nonlinear coefficient of 57 and a breakdown field of 617 V/mm at a sintering temperature of 1000 ℃ for 3 h. The samples synthesized by this technique show not only high density value, 95% of the theoretical density, but also a homogeneous microstructure, which compete with those obtained by the high-energy ball milling oxide-doped powder route. With the advantage that the high-energy ball milling varistor ceramic powder route can refine grain, increase the driving force of sintering, accelerate the sintering process, and reduce the sintering temperature.展开更多
The effect of friction pressure p and oxygen concentration xo on the fireproof performance of Ti40 titanium alloy was studied by frictional ignition test, the U--Xo relationship quantitatively describing the fireproof...The effect of friction pressure p and oxygen concentration xo on the fireproof performance of Ti40 titanium alloy was studied by frictional ignition test, the U--Xo relationship quantitatively describing the fireproof performance of Ti40 was established and the fireproof mechanism of Ti40 was analyzed by SEM, XRD and EDS. The results show that the p--xo relationship of Ti40 obeys parabolic rule. The varying range of xo is about 25% while p varies within 0.1-0.25 MPa. When Xo is 〉70%, Ti40 is ignited immediately at room temperature and develops into continual and steady burning, and the duration of burning is more than 10 s. The fireproof performance of Ti40 is better than TC4 while xo of Ti40 is at least 40% higher than TC4. When Xo is low, the fireproof performance of Ti40 is more sensitive to p; when Xo increases, it is more sensitive to Xo. The forming of fused oxides of V205, TiO2 and Cr203 with strong inner interaction during friction is the basic reason of high fireproof performance of Ti40.展开更多
The mechanical behaviors and damping capacities of the binary Mg−Ga alloys with the Ga content ranging from 1 to 5 wt.%were investigated by means of optical microscope(OM),scanning electron microscope(SEM),X-ray diffr...The mechanical behaviors and damping capacities of the binary Mg−Ga alloys with the Ga content ranging from 1 to 5 wt.%were investigated by means of optical microscope(OM),scanning electron microscope(SEM),X-ray diffraction(XRD),hardness test,tensile test and dynamic mechanical analyzer(DMA).The hardness(HV_(0.5))increases with the increase of Ga content,which can be described as HV_(0.5)=41.61+10.35c,and the solid solution strengthening effect∆σ_(s)of the alloy has a linear relationship with c^(n),where c is the molar fraction of solute atoms and n=1/2 or 2/3.Ga exhibits a stronger solid solution strengthening effect than Al,Zn or Sn due to the large atomic radius difference and the modulus mismatch between Ga and Mg atoms.The addition of Ga makes the Mg−Ga alloys have better damping capacity,and this phenomenon can be explained by the Granato−Lücke dislocation model.The lattice distortion and the modulus mismatch generated because of the addition of Ga increase the resistance to motion of the dislocation in the process of swinging or moving,and thus the better damping capacity is acquired.展开更多
Ni0.5Zn0.5Fe2-xCrxO4(0≤x≤0.5)ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural,electrical and magnetic properties.X-...Ni0.5Zn0.5Fe2-xCrxO4(0≤x≤0.5)ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural,electrical and magnetic properties.X-ray powder diffraction results demonstrate that all the prepared samples are well crystallized single-phase spinel structures without secondary phase.As chromium concentration increases,the lattice parameter and crystallite size gradually decrease.The magnetic measurement indicates that saturation magnetization is substantially suppressed by Cr3+doping,changing from 73.5 A·m2/kg at x=0 to 46.3 A·m2/kg at x=0.5.While the room-temperature electrical resistivity is more than four orders of magnitude enhanced by Cr3+substitution,reaching up to 1.1×108Ω·cm at x=0.5.The dielectric constant monotonously decreases with rising frequency for these ferrites,showing a normal dielectric dispersion behavior.The compositional dependence of dielectric constant is inverse with that of electrical resistivity,which originates from the reduced Fe2+/Fe3+electric dipole number by doping,indicating inherent correlation between polarization and conduction mechanism in ferrite.展开更多
Zn plays an important role in the protection of iron and steel from corrosion in sea water, and the alloying of Zn and Ni can improve its corrosion resistance. The corrosion behavior of Zn？Ni alloys in synthetic sea ...Zn plays an important role in the protection of iron and steel from corrosion in sea water, and the alloying of Zn and Ni can improve its corrosion resistance. The corrosion behavior of Zn？Ni alloys in synthetic sea water （3.5% NaCl, mass fraction） was studied using Tafel plot and electrochemical impedance spectroscopy （EIS） techniques. The corrosion resistance of the investigated alloys with various Ni contents （0.5%？10%, mass fraction） was compared with that of Zn. The results show that the corrosion resistance of Zn？Ni alloys （except 0.5% Ni） is superior to that of Zn. The 10% Ni gives the highest corrosion resistance due to the formation ofγ-Zn3Ni withγ-ZnNi phases in the alloy. In the case of alloy I （0.5% Ni）, it exhibits a higher corrosion rate （less corrosion resistance） than Zn.展开更多
Two water soluble acryl terpolymers containing polyvinyl alcohol, acrylamide/acrylic acid and vinyl sulphonic acid （VSA） were synthesized by free radical polymerization in aqueous medium. The morphological structure...Two water soluble acryl terpolymers containing polyvinyl alcohol, acrylamide/acrylic acid and vinyl sulphonic acid （VSA） were synthesized by free radical polymerization in aqueous medium. The morphological structure of the polymers were analysed using FTIR and 1H NMR, while the thermal properties were analysed by TGA and DSC. The inhibitive action of the terpolymers on corrosion of mid-steel in 1 mol. L- 1 HCI was studied using gravimetric, potentiodynamic polarisation and electrochemical impedance spectroscopy （EIS） at 303 K. Both the polymers provided inhibition efficiency around 90% which clearly demonstrate that the grafted poly- mers have effective corrosion inhibiting ability on MS corrosion.展开更多
基金Project(094200510019) supported by Technology Creative Programmer of Henan for Excellent Talents,ChinaProject(092300410132) supported by the Natural Science Foundation of Henan Province,China
文摘The influence of Ga and Bi on the microstructure and electrochemical performance of Al-7Zn-0.1Sn （mass fraction,%） sacrificial anodes was investigated by means of optical microscopy （OM）,scanning electron microscopy/energy dispersive X-ray analysis （SEM/EDAX） and electrochemical measurements.It was found that the coarse dendrites structure transformed into the equiaxed grains as well as a small amount of dendrite grains after adding Ga and Bi into Al-Zn-Sn alloys.A high current efficiency of 97% and even corrosion morphology were obtained for Al-7Zn-0.1Sn-0.015Ga-0.1Bi alloy.The results indicate that the proper amount of Ga and Bi is effective on improving the microstructure and electrochemical performance of Al-Zn-Sn alloy.
基金Project (10774030) supported by the National Natural Science Foundation of ChinaProject (2008J1-C161) supported by the Science and Technology Program of Guangzhou City of China
文摘Al/Co co-doped α-Ni（OH）2 samples were prepared by either ultrasonic co-precipitation method （Sample B） or co-precipitation method （Sample A）. The crystal structure and particle size distribution of the prepared samples were examined by X-ray diffraction （XRD） and laser particle size analyzer, respectively. The results show that Sample B has more crystalline defects and smaller average diameter than Sample A. The cyclic voltammetry and electrochemical impedance spectroscopy measurements indicate that Sample B has better electrochemical performance than Sample A, such as better reaction reversibility, lower charge-transfer resistance and better cyclic stability. Proton diffusion coefficient of Sample B is 1.96×10-10cm2/s, which is two times as large as that （9.78×10-11cm2/s） of Sample A. The charge-discharge tests show that the discharge capacity （308 mA·h/g） of Sample B is 25 mA·h/g higher than that of Sample A （283 mA·h/g）.
基金Project (BK2011243) supported by the Natural Science Foundation of Jiangsu Province,ChinaProject (EIPE11204) supported by the State Key Laboratory of Electrical Insulation and Power Equipment,China+4 种基金Project (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 (2011-22) supported by State Key Laboratory of Inorganic Synthesis and Preparative Chemistry,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 varistor ceramics doped with Bi2O3, Sb2O3, CO2O3, Cr2O3, and MnO2 were prepared separately by two high-energy ball milling processes： oxide-doped and varistor ceramic powder. A comparison in the electrical and microstructural properties of the samples obtained by both methods was made. The best results on these characteristics were achieved through the high-energy ball milling varistor ceramic powder route, obtaining a nonlinear coefficient of 57 and a breakdown field of 617 V/mm at a sintering temperature of 1000 ℃ for 3 h. The samples synthesized by this technique show not only high density value, 95% of the theoretical density, but also a homogeneous microstructure, which compete with those obtained by the high-energy ball milling oxide-doped powder route. With the advantage that the high-energy ball milling varistor ceramic powder route can refine grain, increase the driving force of sintering, accelerate the sintering process, and reduce the sintering temperature.
基金Project(20123021004) supported by the Key Program of the Aeronautical Science Foundation of ChinaProject(51312030501) supported by the Pre-Research Program of China
文摘The effect of friction pressure p and oxygen concentration xo on the fireproof performance of Ti40 titanium alloy was studied by frictional ignition test, the U--Xo relationship quantitatively describing the fireproof performance of Ti40 was established and the fireproof mechanism of Ti40 was analyzed by SEM, XRD and EDS. The results show that the p--xo relationship of Ti40 obeys parabolic rule. The varying range of xo is about 25% while p varies within 0.1-0.25 MPa. When Xo is 〉70%, Ti40 is ignited immediately at room temperature and develops into continual and steady burning, and the duration of burning is more than 10 s. The fireproof performance of Ti40 is better than TC4 while xo of Ti40 is at least 40% higher than TC4. When Xo is low, the fireproof performance of Ti40 is more sensitive to p; when Xo increases, it is more sensitive to Xo. The forming of fused oxides of V205, TiO2 and Cr203 with strong inner interaction during friction is the basic reason of high fireproof performance of Ti40.
基金supported by the National Natural Science Foundation of China(Nos.51571089, 51871093)the Natural Science Foundation of Hunan Province, China(No. 2019JJ40044)
文摘The mechanical behaviors and damping capacities of the binary Mg−Ga alloys with the Ga content ranging from 1 to 5 wt.%were investigated by means of optical microscope(OM),scanning electron microscope(SEM),X-ray diffraction(XRD),hardness test,tensile test and dynamic mechanical analyzer(DMA).The hardness(HV_(0.5))increases with the increase of Ga content,which can be described as HV_(0.5)=41.61+10.35c,and the solid solution strengthening effect∆σ_(s)of the alloy has a linear relationship with c^(n),where c is the molar fraction of solute atoms and n=1/2 or 2/3.Ga exhibits a stronger solid solution strengthening effect than Al,Zn or Sn due to the large atomic radius difference and the modulus mismatch between Ga and Mg atoms.The addition of Ga makes the Mg−Ga alloys have better damping capacity,and this phenomenon can be explained by the Granato−Lücke dislocation model.The lattice distortion and the modulus mismatch generated because of the addition of Ga increase the resistance to motion of the dislocation in the process of swinging or moving,and thus the better damping capacity is acquired.
基金Project(11604147)supported by the National Natural Science Foundation of ChinaProject(M32048)supported by the Foundation of National Laboratory of Solid State Microstructures,ChinaProject(20142BBE50014)supported by the Jiangxi Province Key Projects of Science and Technology Support Plan,China。
文摘Ni0.5Zn0.5Fe2-xCrxO4(0≤x≤0.5)ferrites were successfully prepared by conventional solid state reaction method to investigate the effect of chromium substitution on the structural,electrical and magnetic properties.X-ray powder diffraction results demonstrate that all the prepared samples are well crystallized single-phase spinel structures without secondary phase.As chromium concentration increases,the lattice parameter and crystallite size gradually decrease.The magnetic measurement indicates that saturation magnetization is substantially suppressed by Cr3+doping,changing from 73.5 A·m2/kg at x=0 to 46.3 A·m2/kg at x=0.5.While the room-temperature electrical resistivity is more than four orders of magnitude enhanced by Cr3+substitution,reaching up to 1.1×108Ω·cm at x=0.5.The dielectric constant monotonously decreases with rising frequency for these ferrites,showing a normal dielectric dispersion behavior.The compositional dependence of dielectric constant is inverse with that of electrical resistivity,which originates from the reduced Fe2+/Fe3+electric dipole number by doping,indicating inherent correlation between polarization and conduction mechanism in ferrite.
文摘Zn plays an important role in the protection of iron and steel from corrosion in sea water, and the alloying of Zn and Ni can improve its corrosion resistance. The corrosion behavior of Zn？Ni alloys in synthetic sea water （3.5% NaCl, mass fraction） was studied using Tafel plot and electrochemical impedance spectroscopy （EIS） techniques. The corrosion resistance of the investigated alloys with various Ni contents （0.5%？10%, mass fraction） was compared with that of Zn. The results show that the corrosion resistance of Zn？Ni alloys （except 0.5% Ni） is superior to that of Zn. The 10% Ni gives the highest corrosion resistance due to the formation ofγ-Zn3Ni withγ-ZnNi phases in the alloy. In the case of alloy I （0.5% Ni）, it exhibits a higher corrosion rate （less corrosion resistance） than Zn.
基金Tamil Nadu State Council for Science and Technology (Tnscst/rfrs/vr/2013-14) for catalysing and financially supporting the research work under the RFRS scheme
文摘Two water soluble acryl terpolymers containing polyvinyl alcohol, acrylamide/acrylic acid and vinyl sulphonic acid （VSA） were synthesized by free radical polymerization in aqueous medium. The morphological structure of the polymers were analysed using FTIR and 1H NMR, while the thermal properties were analysed by TGA and DSC. The inhibitive action of the terpolymers on corrosion of mid-steel in 1 mol. L- 1 HCI was studied using gravimetric, potentiodynamic polarisation and electrochemical impedance spectroscopy （EIS） at 303 K. Both the polymers provided inhibition efficiency around 90% which clearly demonstrate that the grafted poly- mers have effective corrosion inhibiting ability on MS corrosion.
