Mg-Li-Gd alloys were prepared by electrochemical codeposition from LiCl-KCl-MgCl 2 -Gd 2 O 3 melts on molybdenum electrode with constant current density at 823 and 973 K. The microstructure of the Mg-Li-Gd alloys was ...Mg-Li-Gd alloys were prepared by electrochemical codeposition from LiCl-KCl-MgCl 2 -Gd 2 O 3 melts on molybdenum electrode with constant current density at 823 and 973 K. The microstructure of the Mg-Li-Gd alloys was analyzed by X-ray diffraction （XRD）, optical microscopy （OM） and scanning electron microscopy （SEM）. The results show that magnesium and gadolinium deposit mainly in the first 30 min, and the alloy obtained contains 96.53% Mg, 0.27% Li and 3.20% Gd （mass fraction）. Then, the reduction of lithium ions occurs quickly. The composition of alloy can be adjusted by controlling electrolysis time or Gd 2 O 3 concentration in LiCl-KCl melts. With the addition of Gd into Mg-Li alloys, the corrosion resistance of the alloys is enhanced. XRD results suggest that Mg 3 Gd and Mg 2 Gd can be formed in Mg-Li-Gd alloys. The distribution of Gd element in Mg-Li-Gd alloys indicates that Gd element mainly distributes at the grain boundaries of Mg-Li-Gd alloys.展开更多
The cyclic voltammetry, chronopotentiometry and chronoamperometry were used to study the behaviors of Fe 2+ on Pt, Cu, Ag and Ti electrodes in urea NaBr melt at 373 K. Electroreduction of Fe 2+ to metallic ...The cyclic voltammetry, chronopotentiometry and chronoamperometry were used to study the behaviors of Fe 2+ on Pt, Cu, Ag and Ti electrodes in urea NaBr melt at 373 K. Electroreduction of Fe 2+ to metallic Fe is irreversible in one step. The exchange current density determined on Ti electrode is 2 68×10 -5 A·cm -2 . Sm 3+ does not reduce to Sm alone, but can be inductively codeposited with Fe 2+ . Sm Fe alloy film contained over 90% Sm (mass fraction) can be obtained by potentiostatic electrolysis and galvanostatic electrolysis on Cu substrate. The Sm content in the alloy is related to the cathode potential, current density and the Sm 3+ /Fe 2+ molar ratio. The surface state of the Sm Fe deposit was studied by scanning electron microscopy.展开更多
The mechanism of the electrolytic codeposition of Y Al alloy in molten LiF AlF 3 Al 2O 3 YF 3, LiF YF 3 Y 2O 3 AlF 3 and LiF YF 3 Y 2O 3 Al 2O 3 systems was investigated by means of cyclic volta...The mechanism of the electrolytic codeposition of Y Al alloy in molten LiF AlF 3 Al 2O 3 YF 3, LiF YF 3 Y 2O 3 AlF 3 and LiF YF 3 Y 2O 3 Al 2O 3 systems was investigated by means of cyclic voltammetry. The electrodeposited products were analysed by X ray diffraction. The results show that the electrolytic codeposition of Y Al alloy in the LiF YF 3 Y 2O 3 Al 2O 3 system without AlF 3 can be achieved at the same potential for Y(Ⅲ) and Al(Ⅲ) which have great difference in deposition potential. It is beneficial to codeposition of Y(Ⅲ) and Al(Ⅲ) when temperature rises. The potential of beginning codeposition is about -0.85 V ( vs Pt reference electrode), but only at the potential of -0.95 V or more negative can Y based Al alloy containing a great amount of yttrium be obtained.展开更多
The electrolytic codeposition of lanthanum-cobalt in the melt consisting of urea-NaCl-NaAc-CoCl2-LaCl3 was studied by means of cyclic voltammetry, electron probe analyser, X-ray diffraction. Cathodic potential, curren...The electrolytic codeposition of lanthanum-cobalt in the melt consisting of urea-NaCl-NaAc-CoCl2-LaCl3 was studied by means of cyclic voltammetry, electron probe analyser, X-ray diffraction. Cathodic potential, current density, La3+/Co2+ molar ratio in the melt and the electrode substrates all exercise influence on the content of lanthanum deposied. The deposites consist of cobalt and lanthanum, but they don't form any intermetallic compound.展开更多
Electrochemical codeposition of Mg-Li alloys on molybdenum electrodes was investigated in LiCl-KCl（50 wt.%：50 wt.%） melts containing different concentrations of MgCl2 at 973 K.Cyclic voltammograms show that the und...Electrochemical codeposition of Mg-Li alloys on molybdenum electrodes was investigated in LiCl-KCl（50 wt.%：50 wt.%） melts containing different concentrations of MgCl2 at 973 K.Cyclic voltammograms show that the underpotential deposition of lithium on pre-deposited magnesium leads to the formation of liquid Mg-Li alloys.The deposition potentials of Mg（II） and Li（I） ions gradually near each other with MgCl2 concentration decreasing.Mg-Li alloys with typical α ＋ β phases could be obtained by potentiostatic electrolysis from LiCl-KCl melts containing 5 wt.% MgCl2 at -2.25 V vs.Ag/AgCl（cathodic current density 1.70 A·cm-2） for 2.5 h.α phase, α ＋ β phases, and β phase Mg-Li alloys with different lithium contents were obtained by potentiostatic electrolysis from LiCl-KCl melts with the different concentrations of MgCl2.The samples were characterized by X-ray diffraction and scanning electron microscopy.展开更多
The electrochemical behaviour of Al, Li, and Er were investigated by electrochemical techniques, such as cyclic voltammograms, chronopotentiometric, chronoamperograms, and open circuit chronopotentiogram on molybdenum...The electrochemical behaviour of Al, Li, and Er were investigated by electrochemical techniques, such as cyclic voltammograms, chronopotentiometric, chronoamperograms, and open circuit chronopotentiogram on molybdenum electrodes. The results showed that the underpotential deposition of erbium on pre-deposited Al electrodes formed two Al-Er intermetallic compounds. The codeposition of Al, Li, Er occurred and formed Al-Li-Er alloys in LiCl-KCl-AlCl3 -Er2O3 melts at 773K. Different phases such as Al2Er, Al2Er3 and βLi phase of Al-Li-Er alloys were prepared by galvanostatic electrolysis and characterized by X-ray diffraction （XRD）. Scanning electron microscopy （SEM） indicated that Er element mainly distributed at the grain boundary. ICP analyses showed that lithium and erbium contents of Al-Li-Er alloys could be controlled by AlCl3 and Er2O3 concentration and electrochemical parameters.展开更多
The electrochemical behavior of AI（III） ions was studied in molten LiC1-KC1 melts on a molybdenum electrode. Cyclic voltammetry, chronopotentiometry and chronoamperometry were used to explore the deposition mechanis...The electrochemical behavior of AI（III） ions was studied in molten LiC1-KC1 melts on a molybdenum electrode. Cyclic voltammetry, chronopotentiometry and chronoamperometry were used to explore the deposition mechanism of A1 and Li. Cyclic voltammetry expriment indicates that under potential deposition（UPD） of lithium on pre-deposited aluminium led to the formation of liquid A1-Li alloys at 853 K. The diffusion coefficient of AI（III） ions at 853 K in LiC1-KC1-AIF3（I%, mass fraction） melts was determined to be （2.79~0.05）x 10_5 cm2/s. Chronopotentio- grams and chronoamperograms demonstrate that the codeposition of AI（III） and Li（I） ions formed A1-Li alloys at ca- thodic current densities higher than -0.28 A/cm2 or cathodic potentials more negative than -2.20 V. X-Ray diffrac- tion（XRD） pattern indicates that A1-Li alloys with different phases formed via galvanostatic electrolysis. Inductively coupled plasma（ICP） analyses of the samples obtained by electrolysis show that lithium and aluminium contents of A1-Li alloys could be controlled by A1F3 concentration and current intensity.展开更多
The kinetic model of induced codeposition of nickel-molybdenum alloys from ammonium citrate solution was studied on rotating disk electrodes to predict the behavior of the electrode-position. The molybdate (MoO42?) co...The kinetic model of induced codeposition of nickel-molybdenum alloys from ammonium citrate solution was studied on rotating disk electrodes to predict the behavior of the electrode-position. The molybdate (MoO42?) could be firstly electro-chemically reduced to MoO2, and subsequently undergoes a chemical reduction with atomic hydrogen previously adsorbed on the inducing metal nickel to form molybdenum in alloys. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The electrochemical rate constants for discharge of nickel, molybdenum and water could been expressed as k1,(E) = 1.23 × 10?9 CNexp( - 0.198 FE/RT) mol/(dm2 · s), k2 (E) = 3.28 × 10?10 CMoexp ( - 0.208FE/ RT) mol/(dm2 · s) and k3(E) = 1.27 × 10?6 exp ( -0.062FE/ RT) mol/(dm2 · s), where CN and CMo, are the concentrations of the nickel ion and molybdate, respectively, and E is the applied potential vs. saturated calomel electrode (SCE). The codeposition process could be well simulated by this model.展开更多
Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanopa...Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanoparticles were dispersed in the electrodeposited nanocrystalline Ni grains （with a size range of 10-30 nm）. The isothermal oxidation behaviours of Ni-CeO2 nanocomposite coatings with two different CeO2 particles contents and the electrodeposited pure Ni coating were comparatively investigated in order to elucidate the effect of CeO2 at different temperatures and also CeO2 contents on the oxidation behaviour of Ni-CeO2 nanocomposite coatings. The results show that the as-codeposited Ni-CeO2 nanocomposite coatings have a superior oxidation resistance compared with the electrodeposited pure Ni coating at 800 °C due to the codeposited CeO2 nanoparticles blocking the outward diffusion of nickel along the grain boundaries. However, the effects of CeO2 particles on the oxidation resistance significantly decrease at 1050 °C and 1150 °C due to the outward-volume diffusion of nickel controlling the oxidation growth mechanism, and the content of CeO2 has little influence on the oxidation.展开更多
Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were...Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were obtained by potentiostatic electrolysis and galvanostatic electrolysis. With the cathode potential shift to negative direction and the increase of current density, the content of gadolinium in the alloy increases first, and then drops down gradually. The molar ratio of Gd(Ⅲ) to Ni(Ⅱ) and the time also influence the content of Gd. Crystalline GdNi 3 alloy was obtained after heat treatment of the deposit. [展开更多
The electroplating behavior of Zn P alloy on copper from light acid chloride solutions (LACS) was investigated using cyclic voltammetry and linear potential sweep method. It is found that, under the experimental condi...The electroplating behavior of Zn P alloy on copper from light acid chloride solutions (LACS) was investigated using cyclic voltammetry and linear potential sweep method. It is found that, under the experimental conditions, the concentrations of H 3PO 3 and ascorbic acid in LACS change the codeposition mechanism of Zn P alloy, the addition of H 3PO 3 into LACS promotes the three dimentional (3 D) instantaneous nucleation/growth, while the addition of ascorbic acid promotes the two dimentional (2 D) instantaneous nucleation and layer by layer growth. H 3PO 3 and zinc ions inhibit the deposition each other. The experimental results also show that H 3PO 3 in the LACS can be reduced on the cathode individually, and low pH value of the LACS promotes the reduction of H 3PO 3.展开更多
Co deposition of Ho with Co was studied in dimethylsulfoxide (DMSO) by cyclic voltammetry and potentiostatic deposition at room temperature. The cyclic voltammogram shows that the codeposition of Ho with Co can be at...Co deposition of Ho with Co was studied in dimethylsulfoxide (DMSO) by cyclic voltammetry and potentiostatic deposition at room temperature. The cyclic voltammogram shows that the codeposition of Ho with Co can be attributed to induced codeposition mechanism, for the codeposition potential is more negative than the deposition potential of Co but positive than that of Ho. For the potentiostatic deposition used in Ho Co alloys preparation, the results indicate that in the range of selected concentration the potential is the main factor determining the content of Ho in Ho Co alloys, while the composition of Ho 3+ and Co 2+ in electrolyte solution has less influence. According to the analysis of X ray diffraction, EDAX, and scanning electron microscopy, uniform, compact and amorphous films on Cu can be obtained at -1 8 V (vs.SCE) in 0 165 mol·L -1 Ho(NO 3) -0 135 mol·L -1 CoCl 2 DMSO solution.展开更多
The brown metallic luster La-Ni alloy powders were prepared by potentiostatic electrolysis technique in dimethylsulfoxide solution at room temperature. The atomic rate of La and Ni in alloy powders are 11∶1 and 10∶1...The brown metallic luster La-Ni alloy powders were prepared by potentiostatic electrolysis technique in dimethylsulfoxide solution at room temperature. The atomic rate of La and Ni in alloy powders are 11∶1 and 10∶1. The size of metal grains is about 0.1 to 100 μm. It shows that the micrometer powders of rare earth alloys can be obtained by controlling electrodeposition conditions. The peak potentials of -2.81 and 1.75 V are attributed to reduction of La 3+ and Ni 3+ ions, respectively. The peak potentials at -2.20 and -0.168 V are the oxidation peaks of lanthanum and nickel, respectively. When potential is more negative than -1.74 V, La(Ⅲ) and Ni(Ⅱ) will codeposit. Increasing cyclic times, the value of peak current is decreasing, and the reduction peak of La(Ⅲ) was finally disappeared.展开更多
Copper-zirconium diboride （ZrB2） composite coatings were fabricated using pulse plating technique to acquire a new type of EDM （electro-discharge machining） electrode material. The effects of pulse parameters, i.e...Copper-zirconium diboride （ZrB2） composite coatings were fabricated using pulse plating technique to acquire a new type of EDM （electro-discharge machining） electrode material. The effects of pulse parameters, i.e., the average current density, the frequency and the duty cycle, on the incorporation of ZrB2 particles in the copper matrix were investigated. The amount＇of codeposited ZrB2 particles had a maximum at average current density of 3 A/din2 and increased with decreasing duty cycle as well as current frequency of the pulse current used for deposition. The hardness of the coatings increased with increasing ZrB2 percentage, whereas the incorporation of ZrB2 particles had little effect on the resistivity of the composites.展开更多
Electroreduction of Co(Ⅱ)to metallic cohalt in urea melt is irrevsible in one step.The transfer coeffi-cient of electrode reaction of Co(Ⅱ)+2e=Co(O)and the diffusion coefficient of Co(Ⅱ)were determined.The lanthanu...Electroreduction of Co(Ⅱ)to metallic cohalt in urea melt is irrevsible in one step.The transfer coeffi-cient of electrode reaction of Co(Ⅱ)+2e=Co(O)and the diffusion coefficient of Co(Ⅱ)were determined.The lanthanum can be inductively codeposited with cobalt. The contents of lanthanum in cobalt-lanthanum de-posts increase with the shift of electrode potential to the negative direction and the raise of La(Ⅲ)/Co(Ⅱ)mo-lar ratio in the melt. The cyclic voltammetry,open circuit potential-time curve after potentiostatic electrolysisand electron probe analyas were used.展开更多
Potentiostatic and pulse electrolysis techniques were used to prepare La-Co-Fe alloy films using ethylenediamine (EN) as complexant. Surfaces of alloy films obtained by these two techniques are smooth, adhesive, compa...Potentiostatic and pulse electrolysis techniques were used to prepare La-Co-Fe alloy films using ethylenediamine (EN) as complexant. Surfaces of alloy films obtained by these two techniques are smooth, adhesive, compact and metallic luster. The contents of La in alloy films obtained by potentiostatic electrolysis technique are in the range of 13.23%～47.67%. The contents of La in alloy films deposited by pulse electrolysis technique are in the range of 10.67%～16.29%.展开更多
The electrodeposition of zinc nickle alloy was obtained on a copper cathode of 1×1cm 2. The deposited alloys are quantitatively analyzed by atomic absorption spectrometry. The morphology of the deposits was obs...The electrodeposition of zinc nickle alloy was obtained on a copper cathode of 1×1cm 2. The deposited alloys are quantitatively analyzed by atomic absorption spectrometry. The morphology of the deposits was observed by means of scanning electron microscopy(SEM).We observed that the electrodeposition of zinc nickle alloy is an anomalous codeposition. The catalytic effects of SCN - on the electrochemical behavior of Ni deposition and hydrogen discharge are obvious. SEM analysis shows that the surface morphology of the coating appears to be more compact and homogeneous with the increase of SCN - concentration.展开更多
In spray atomization and codeposition, a molten stream of metal is disintegrated into a fine dispersion of droplets by high velocity gas jets. The resulting semi-solidified droplets are directed towards a substrate wh...In spray atomization and codeposition, a molten stream of metal is disintegrated into a fine dispersion of droplets by high velocity gas jets. The resulting semi-solidified droplets are directed towards a substrate where they impact and collect as rapidly solidified splats. Relatively high rates of solidification are achieved as a result of the thinness of the splats and the rapid heat extraction during flight and upon impacting with the substrate. The processing method uses codeposition of the metallic semi-solidified droplets (metallic matrix) with the injected reinforcement ceramic particles. In the present paper, the microstructures, mechanical properties, interfacial properties, thermal stability and aging behaviour of spray atomized and codeposited Al-Li-X MMC's (injected X=SiC, Al2O3) are reported and correlated to the processing conditions.展开更多
The influence of the injection of reinforcing particles (for the production of metal matrix composites and of the droplets-to-substrate heat transfer on the resulting microstructural uniformity of spray atomized and c...The influence of the injection of reinforcing particles (for the production of metal matrix composites and of the droplets-to-substrate heat transfer on the resulting microstructural uniformity of spray atomized and codeposited composite material is analyzed. The reinforcement particles injection velocity has to be limited between an upper and a lower critical values. in order to ensure entrapment into the matrix droplets in flight. The thermal history of the injected droplets during the deposition stage is calculated with the assumption that the in-flight solidifying droplets reach the substrate while containing still at least 20% liquid volume fraction, in order to avoid porosity of the deposited material. The substrate to pouring-tube orifice distance where that condition is achieved depends strongly on the atomization pressure and the convective heat transfer coefficient of the substrate. It is demonstrated that 'tailoring' the microstructures and the reinforcement volume percent in the deposited material is feasible. The critical process parameters : the atomization pressure, the melt flow rate. the substrate to pouring-tube orifice distance, the reinforcement particles injection location and rate can all be adequately chosen in order to obtain any desired microstructure, grain size, reinforcement volume percent, with the additional benefit, if wanted, of rapid solidification processing展开更多
基金Project(2009AA050702)supported by the National High-tech Research and Development Program of ChinaProject(GC06A212)supported by the Scientific Technology Project of Heilongjiang Province,China+2 种基金Project(50871033)supported by the National Natural Science Foundation of ChinaProject(208181)supported by the Key Project of Ministry of Education,ChinaProject(HEUCF101002)supported by the Fundamental Research Funds for the Central Universities,China
文摘Mg-Li-Gd alloys were prepared by electrochemical codeposition from LiCl-KCl-MgCl 2 -Gd 2 O 3 melts on molybdenum electrode with constant current density at 823 and 973 K. The microstructure of the Mg-Li-Gd alloys was analyzed by X-ray diffraction （XRD）, optical microscopy （OM） and scanning electron microscopy （SEM）. The results show that magnesium and gadolinium deposit mainly in the first 30 min, and the alloy obtained contains 96.53% Mg, 0.27% Li and 3.20% Gd （mass fraction）. Then, the reduction of lithium ions occurs quickly. The composition of alloy can be adjusted by controlling electrolysis time or Gd 2 O 3 concentration in LiCl-KCl melts. With the addition of Gd into Mg-Li alloys, the corrosion resistance of the alloys is enhanced. XRD results suggest that Mg 3 Gd and Mg 2 Gd can be formed in Mg-Li-Gd alloys. The distribution of Gd element in Mg-Li-Gd alloys indicates that Gd element mainly distributes at the grain boundaries of Mg-Li-Gd alloys.
文摘The cyclic voltammetry, chronopotentiometry and chronoamperometry were used to study the behaviors of Fe 2+ on Pt, Cu, Ag and Ti electrodes in urea NaBr melt at 373 K. Electroreduction of Fe 2+ to metallic Fe is irreversible in one step. The exchange current density determined on Ti electrode is 2 68×10 -5 A·cm -2 . Sm 3+ does not reduce to Sm alone, but can be inductively codeposited with Fe 2+ . Sm Fe alloy film contained over 90% Sm (mass fraction) can be obtained by potentiostatic electrolysis and galvanostatic electrolysis on Cu substrate. The Sm content in the alloy is related to the cathode potential, current density and the Sm 3+ /Fe 2+ molar ratio. The surface state of the Sm Fe deposit was studied by scanning electron microscopy.
文摘The mechanism of the electrolytic codeposition of Y Al alloy in molten LiF AlF 3 Al 2O 3 YF 3, LiF YF 3 Y 2O 3 AlF 3 and LiF YF 3 Y 2O 3 Al 2O 3 systems was investigated by means of cyclic voltammetry. The electrodeposited products were analysed by X ray diffraction. The results show that the electrolytic codeposition of Y Al alloy in the LiF YF 3 Y 2O 3 Al 2O 3 system without AlF 3 can be achieved at the same potential for Y(Ⅲ) and Al(Ⅲ) which have great difference in deposition potential. It is beneficial to codeposition of Y(Ⅲ) and Al(Ⅲ) when temperature rises. The potential of beginning codeposition is about -0.85 V ( vs Pt reference electrode), but only at the potential of -0.95 V or more negative can Y based Al alloy containing a great amount of yttrium be obtained.
文摘The electrolytic codeposition of lanthanum-cobalt in the melt consisting of urea-NaCl-NaAc-CoCl2-LaCl3 was studied by means of cyclic voltammetry, electron probe analyser, X-ray diffraction. Cathodic potential, current density, La3+/Co2+ molar ratio in the melt and the electrode substrates all exercise influence on the content of lanthanum deposied. The deposites consist of cobalt and lanthanum, but they don't form any intermetallic compound.
基金supported by the National High-Tech Research and Development Program of China (No. 2006AA03Z510)the National Natural Science Foundation of China (No. 50871033)+1 种基金the Scientific Technology Project of Heilong jiang Province, China (No. GC06A212)the fund from Harbin Municipal Science & Technology Bureau (No. 2006PFXXG006)
文摘Electrochemical codeposition of Mg-Li alloys on molybdenum electrodes was investigated in LiCl-KCl（50 wt.%：50 wt.%） melts containing different concentrations of MgCl2 at 973 K.Cyclic voltammograms show that the underpotential deposition of lithium on pre-deposited magnesium leads to the formation of liquid Mg-Li alloys.The deposition potentials of Mg（II） and Li（I） ions gradually near each other with MgCl2 concentration decreasing.Mg-Li alloys with typical α ＋ β phases could be obtained by potentiostatic electrolysis from LiCl-KCl melts containing 5 wt.% MgCl2 at -2.25 V vs.Ag/AgCl（cathodic current density 1.70 A·cm-2） for 2.5 h.α phase, α ＋ β phases, and β phase Mg-Li alloys with different lithium contents were obtained by potentiostatic electrolysis from LiCl-KCl melts with the different concentrations of MgCl2.The samples were characterized by X-ray diffraction and scanning electron microscopy.
基金Project supported by the National 863 Project of the Ministry of Science and Technology of China(2009AA050702,2011AA03A409)National Natural Science Foundation of China(21173060)
文摘The electrochemical behaviour of Al, Li, and Er were investigated by electrochemical techniques, such as cyclic voltammograms, chronopotentiometric, chronoamperograms, and open circuit chronopotentiogram on molybdenum electrodes. The results showed that the underpotential deposition of erbium on pre-deposited Al electrodes formed two Al-Er intermetallic compounds. The codeposition of Al, Li, Er occurred and formed Al-Li-Er alloys in LiCl-KCl-AlCl3 -Er2O3 melts at 773K. Different phases such as Al2Er, Al2Er3 and βLi phase of Al-Li-Er alloys were prepared by galvanostatic electrolysis and characterized by X-ray diffraction （XRD）. Scanning electron microscopy （SEM） indicated that Er element mainly distributed at the grain boundary. ICP analyses showed that lithium and erbium contents of Al-Li-Er alloys could be controlled by AlCl3 and Er2O3 concentration and electrochemical parameters.
基金Supported by the High Technology Research and Development Program of China（Nos.2009AA050702, 2011AA03A409） and the National Natural Science Foundation of China（No.21173060）.
文摘The electrochemical behavior of AI（III） ions was studied in molten LiC1-KC1 melts on a molybdenum electrode. Cyclic voltammetry, chronopotentiometry and chronoamperometry were used to explore the deposition mechanism of A1 and Li. Cyclic voltammetry expriment indicates that under potential deposition（UPD） of lithium on pre-deposited aluminium led to the formation of liquid A1-Li alloys at 853 K. The diffusion coefficient of AI（III） ions at 853 K in LiC1-KC1-AIF3（I%, mass fraction） melts was determined to be （2.79~0.05）x 10_5 cm2/s. Chronopotentio- grams and chronoamperograms demonstrate that the codeposition of AI（III） and Li（I） ions formed A1-Li alloys at ca- thodic current densities higher than -0.28 A/cm2 or cathodic potentials more negative than -2.20 V. X-Ray diffrac- tion（XRD） pattern indicates that A1-Li alloys with different phases formed via galvanostatic electrolysis. Inductively coupled plasma（ICP） analyses of the samples obtained by electrolysis show that lithium and aluminium contents of A1-Li alloys could be controlled by A1F3 concentration and current intensity.
文摘The kinetic model of induced codeposition of nickel-molybdenum alloys from ammonium citrate solution was studied on rotating disk electrodes to predict the behavior of the electrode-position. The molybdate (MoO42?) could be firstly electro-chemically reduced to MoO2, and subsequently undergoes a chemical reduction with atomic hydrogen previously adsorbed on the inducing metal nickel to form molybdenum in alloys. The kinetic equations were derived, and the kinetic parameters were obtained from a comparison of experimental results and the kinetic equations. The electrochemical rate constants for discharge of nickel, molybdenum and water could been expressed as k1,(E) = 1.23 × 10?9 CNexp( - 0.198 FE/RT) mol/(dm2 · s), k2 (E) = 3.28 × 10?10 CMoexp ( - 0.208FE/ RT) mol/(dm2 · s) and k3(E) = 1.27 × 10?6 exp ( -0.062FE/ RT) mol/(dm2 · s), where CN and CMo, are the concentrations of the nickel ion and molybdate, respectively, and E is the applied potential vs. saturated calomel electrode (SCE). The codeposition process could be well simulated by this model.
基金Project(11531319)supported by Scientific Research Fund of Heilongjiang Provincial Education Department,China
文摘Ni-CeO2 nanocomposite coatings with different CeO2 contents were prepared by codeposition of Ni and CeO2 nanoparticles with an average particle size of 7 nm onto pure Ni surfaces from a nickel sulfate. The CeO2 nanoparticles were dispersed in the electrodeposited nanocrystalline Ni grains （with a size range of 10-30 nm）. The isothermal oxidation behaviours of Ni-CeO2 nanocomposite coatings with two different CeO2 particles contents and the electrodeposited pure Ni coating were comparatively investigated in order to elucidate the effect of CeO2 at different temperatures and also CeO2 contents on the oxidation behaviour of Ni-CeO2 nanocomposite coatings. The results show that the as-codeposited Ni-CeO2 nanocomposite coatings have a superior oxidation resistance compared with the electrodeposited pure Ni coating at 800 °C due to the codeposited CeO2 nanoparticles blocking the outward diffusion of nickel along the grain boundaries. However, the effects of CeO2 particles on the oxidation resistance significantly decrease at 1050 °C and 1150 °C due to the outward-volume diffusion of nickel controlling the oxidation growth mechanism, and the content of CeO2 has little influence on the oxidation.
文摘Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were obtained by potentiostatic electrolysis and galvanostatic electrolysis. With the cathode potential shift to negative direction and the increase of current density, the content of gadolinium in the alloy increases first, and then drops down gradually. The molar ratio of Gd(Ⅲ) to Ni(Ⅱ) and the time also influence the content of Gd. Crystalline GdNi 3 alloy was obtained after heat treatment of the deposit. [
文摘The electroplating behavior of Zn P alloy on copper from light acid chloride solutions (LACS) was investigated using cyclic voltammetry and linear potential sweep method. It is found that, under the experimental conditions, the concentrations of H 3PO 3 and ascorbic acid in LACS change the codeposition mechanism of Zn P alloy, the addition of H 3PO 3 into LACS promotes the three dimentional (3 D) instantaneous nucleation/growth, while the addition of ascorbic acid promotes the two dimentional (2 D) instantaneous nucleation and layer by layer growth. H 3PO 3 and zinc ions inhibit the deposition each other. The experimental results also show that H 3PO 3 in the LACS can be reduced on the cathode individually, and low pH value of the LACS promotes the reduction of H 3PO 3.
基金Project supported by Natural Science Foundation of Guangdong Province (011215)
文摘Co deposition of Ho with Co was studied in dimethylsulfoxide (DMSO) by cyclic voltammetry and potentiostatic deposition at room temperature. The cyclic voltammogram shows that the codeposition of Ho with Co can be attributed to induced codeposition mechanism, for the codeposition potential is more negative than the deposition potential of Co but positive than that of Ho. For the potentiostatic deposition used in Ho Co alloys preparation, the results indicate that in the range of selected concentration the potential is the main factor determining the content of Ho in Ho Co alloys, while the composition of Ho 3+ and Co 2+ in electrolyte solution has less influence. According to the analysis of X ray diffraction, EDAX, and scanning electron microscopy, uniform, compact and amorphous films on Cu can be obtained at -1 8 V (vs.SCE) in 0 165 mol·L -1 Ho(NO 3) -0 135 mol·L -1 CoCl 2 DMSO solution.
文摘The brown metallic luster La-Ni alloy powders were prepared by potentiostatic electrolysis technique in dimethylsulfoxide solution at room temperature. The atomic rate of La and Ni in alloy powders are 11∶1 and 10∶1. The size of metal grains is about 0.1 to 100 μm. It shows that the micrometer powders of rare earth alloys can be obtained by controlling electrodeposition conditions. The peak potentials of -2.81 and 1.75 V are attributed to reduction of La 3+ and Ni 3+ ions, respectively. The peak potentials at -2.20 and -0.168 V are the oxidation peaks of lanthanum and nickel, respectively. When potential is more negative than -1.74 V, La(Ⅲ) and Ni(Ⅱ) will codeposit. Increasing cyclic times, the value of peak current is decreasing, and the reduction peak of La(Ⅲ) was finally disappeared.
基金This work was supported by the National Natural Science Foundation of China under grant No. 59935110.
文摘Copper-zirconium diboride （ZrB2） composite coatings were fabricated using pulse plating technique to acquire a new type of EDM （electro-discharge machining） electrode material. The effects of pulse parameters, i.e., the average current density, the frequency and the duty cycle, on the incorporation of ZrB2 particles in the copper matrix were investigated. The amount＇of codeposited ZrB2 particles had a maximum at average current density of 3 A/din2 and increased with decreasing duty cycle as well as current frequency of the pulse current used for deposition. The hardness of the coatings increased with increasing ZrB2 percentage, whereas the incorporation of ZrB2 particles had little effect on the resistivity of the composites.
文摘Electroreduction of Co(Ⅱ)to metallic cohalt in urea melt is irrevsible in one step.The transfer coeffi-cient of electrode reaction of Co(Ⅱ)+2e=Co(O)and the diffusion coefficient of Co(Ⅱ)were determined.The lanthanum can be inductively codeposited with cobalt. The contents of lanthanum in cobalt-lanthanum de-posts increase with the shift of electrode potential to the negative direction and the raise of La(Ⅲ)/Co(Ⅱ)mo-lar ratio in the melt. The cyclic voltammetry,open circuit potential-time curve after potentiostatic electrolysisand electron probe analyas were used.
基金Project (011215) supported by the Science Foundation of Guangdong Province
文摘Potentiostatic and pulse electrolysis techniques were used to prepare La-Co-Fe alloy films using ethylenediamine (EN) as complexant. Surfaces of alloy films obtained by these two techniques are smooth, adhesive, compact and metallic luster. The contents of La in alloy films obtained by potentiostatic electrolysis technique are in the range of 13.23%～47.67%. The contents of La in alloy films deposited by pulse electrolysis technique are in the range of 10.67%～16.29%.
基金theStateKeyLab .forPhys .Chem .ofSolidSur face XiamenUniversity
文摘The electrodeposition of zinc nickle alloy was obtained on a copper cathode of 1×1cm 2. The deposited alloys are quantitatively analyzed by atomic absorption spectrometry. The morphology of the deposits was observed by means of scanning electron microscopy(SEM).We observed that the electrodeposition of zinc nickle alloy is an anomalous codeposition. The catalytic effects of SCN - on the electrochemical behavior of Ni deposition and hydrogen discharge are obvious. SEM analysis shows that the surface morphology of the coating appears to be more compact and homogeneous with the increase of SCN - concentration.
文摘In spray atomization and codeposition, a molten stream of metal is disintegrated into a fine dispersion of droplets by high velocity gas jets. The resulting semi-solidified droplets are directed towards a substrate where they impact and collect as rapidly solidified splats. Relatively high rates of solidification are achieved as a result of the thinness of the splats and the rapid heat extraction during flight and upon impacting with the substrate. The processing method uses codeposition of the metallic semi-solidified droplets (metallic matrix) with the injected reinforcement ceramic particles. In the present paper, the microstructures, mechanical properties, interfacial properties, thermal stability and aging behaviour of spray atomized and codeposited Al-Li-X MMC's (injected X=SiC, Al2O3) are reported and correlated to the processing conditions.
文摘The influence of the injection of reinforcing particles (for the production of metal matrix composites and of the droplets-to-substrate heat transfer on the resulting microstructural uniformity of spray atomized and codeposited composite material is analyzed. The reinforcement particles injection velocity has to be limited between an upper and a lower critical values. in order to ensure entrapment into the matrix droplets in flight. The thermal history of the injected droplets during the deposition stage is calculated with the assumption that the in-flight solidifying droplets reach the substrate while containing still at least 20% liquid volume fraction, in order to avoid porosity of the deposited material. The substrate to pouring-tube orifice distance where that condition is achieved depends strongly on the atomization pressure and the convective heat transfer coefficient of the substrate. It is demonstrated that 'tailoring' the microstructures and the reinforcement volume percent in the deposited material is feasible. The critical process parameters : the atomization pressure, the melt flow rate. the substrate to pouring-tube orifice distance, the reinforcement particles injection location and rate can all be adequately chosen in order to obtain any desired microstructure, grain size, reinforcement volume percent, with the additional benefit, if wanted, of rapid solidification processing
