Morphology of zinc alloy layer,from zincate solution with zinc sulfate and zinc oxide respectively,together with the consequent deposit was observed with SEM and back scattering electron image.EDS was applied to analy...Morphology of zinc alloy layer,from zincate solution with zinc sulfate and zinc oxide respectively,together with the consequent deposit was observed with SEM and back scattering electron image.EDS was applied to analyze the components of zinc alloy layer and the interface of high-Si aluminum alloy substrate-zinc alloy-deposit.Besides,the surface morphology of the zincated aluminum alloy after immersing in 3.5% NaCl solution for 7 d,is observed and the corrosion rate was calculate.Finally,tension test is conducted to quantify the adhesion between high-Si aluminum cast substrate and the deposit.The results show that,the zinc oxide contained zincating solution with sodium potassium tartrate and sodium citrate is a better one in multi-metal zincating solutions.The zinc alloy layer from this one gets stable performance,perfect adhesion with deposit,and good corrosion resistance.展开更多
Arrhenius formula was applied to calculate the apparent activation energy of zincate reaction. The standard electrode potential of all the metal coordinating ions and the order of galvanic couple of different metals i...Arrhenius formula was applied to calculate the apparent activation energy of zincate reaction. The standard electrode potential of all the metal coordinating ions and the order of galvanic couple of different metals in zincate solution were also calculated. Electrochemical behavior of zincate process was studied by Tafel polarization curves, E—t curves, and electrochemical impedance spectroscopy(EIS). The results show that the apparent activation energy of zincate reaction in non-cyanide multi-metal zincate solution is smaller than that in simple zincate solution, and precipitation sequence of all the metals in zincate solution is Cu, Ni, Fe and Zn. Relationship between the potential at 30 s before zincate and coverage was attained according to the change of potential of zincate. EIS shows that inductive reactance is produced during zincate.展开更多
In order to find out a multi-metal zincate solution to get good micromorphology and fine adhesion of coatings, sulfate zincate and zinc oxide zincate with different chelating agents combinations, of which there are 8 ...In order to find out a multi-metal zincate solution to get good micromorphology and fine adhesion of coatings, sulfate zincate and zinc oxide zincate with different chelating agents combinations, of which there are 8 solutions are designed. CHI630 electrochemical test system is applied to measure the φ—t curves of zincate process and Tafle curves of zincated plates in 3.5% NaCl medium. The analyzed results show that when molar ratio of sodium hydroxide to zinc ions is constant, the better chelating agents combination for multi-metal zincation solution is the combination of sodium potassium tartrate and sodium citrate in zinc oxide solution, from which zinc alloy is high in potential and perfect in corrosion resistance. After the second zincate immersion for 60s, the immersion potential is -1.606V(vs SCE). The corrosion current density is 6.612, J_ corr/(A·cm -2); and the corrosion potential is -1.381, φ_ corr(I=0)/V.展开更多
The effects of non-cyanide zincation process parameters on the microstructure of the zincation layer on A356 alloy were investigated by scanning electronic microscope.With the increasing of zincation time,the zinc gra...The effects of non-cyanide zincation process parameters on the microstructure of the zincation layer on A356 alloy were investigated by scanning electronic microscope.With the increasing of zincation time,the zinc grain size and the number density increase gradually,and the zinc grains adhere each other.The zinc grain obtained in the double-dipping process is finer,compacter and more homogeneous than that obtained in the single-dipping process.With the increasing of the zincation temperature,the morphology of zinc grains changes from spherical shape to flake-like shape.However,higher zincation temperature results in the flaking off of the zincation layer from the matrix.The optimized zincation temperature is 20-30 ℃.The quality of the zincation layer obtained in a low concentration,non-cyanide and multi-element zincation solutions is much better than these obtained in conventional high concentration zincation solution,dilute zincation solutions or a dilute zincation solution containing nickel.In addition,the matrix alloy and the pre-treatment also have significant influence on the morphology of the zincation layer.展开更多
This study was aimed at investigating the performance of anaerobic rotating biological cont- reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate redu condition. Statistically valid...This study was aimed at investigating the performance of anaerobic rotating biological cont- reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate redu condition. Statistically valid factorial design of experiments was carried out to understand dynamics of metal removal using this bioreactor system. Copper removal was maximum (〉98% followed by other heavy metals at their respective low inlet concentrations. Metal loading rates than 3.7 mg/L· h in case of Cu(II); less than 1.69 mg/L· h for Ni(II), Pb(II), Zn(II), Fe(III) and C are favorable to the performance of the An-RBC reactor. Removal efficiency of the heavy metals 1 mixture depended on the metal species and their inlet loading concentrations. Analysis of n precipitates formed in the sulfidogenic bioreactor by field emission scanning electron microscopyalong with energy dispersive X-ray spectroscopy (FESEM-EDX) confirmed metal sulfide precipitationby SRB. All these results clearly revealed that the attached growth biofilm bioreactor is well suited for heavy metal removal from complex mixture.展开更多
基金This work is financially supported by the Foundation of Basic Research of Harbin Engineering Universi-ty( HEUFT06030)
文摘Morphology of zinc alloy layer,from zincate solution with zinc sulfate and zinc oxide respectively,together with the consequent deposit was observed with SEM and back scattering electron image.EDS was applied to analyze the components of zinc alloy layer and the interface of high-Si aluminum alloy substrate-zinc alloy-deposit.Besides,the surface morphology of the zincated aluminum alloy after immersing in 3.5% NaCl solution for 7 d,is observed and the corrosion rate was calculate.Finally,tension test is conducted to quantify the adhesion between high-Si aluminum cast substrate and the deposit.The results show that,the zinc oxide contained zincating solution with sodium potassium tartrate and sodium citrate is a better one in multi-metal zincating solutions.The zinc alloy layer from this one gets stable performance,perfect adhesion with deposit,and good corrosion resistance.
文摘Arrhenius formula was applied to calculate the apparent activation energy of zincate reaction. The standard electrode potential of all the metal coordinating ions and the order of galvanic couple of different metals in zincate solution were also calculated. Electrochemical behavior of zincate process was studied by Tafel polarization curves, E—t curves, and electrochemical impedance spectroscopy(EIS). The results show that the apparent activation energy of zincate reaction in non-cyanide multi-metal zincate solution is smaller than that in simple zincate solution, and precipitation sequence of all the metals in zincate solution is Cu, Ni, Fe and Zn. Relationship between the potential at 30 s before zincate and coverage was attained according to the change of potential of zincate. EIS shows that inductive reactance is produced during zincate.
文摘In order to find out a multi-metal zincate solution to get good micromorphology and fine adhesion of coatings, sulfate zincate and zinc oxide zincate with different chelating agents combinations, of which there are 8 solutions are designed. CHI630 electrochemical test system is applied to measure the φ—t curves of zincate process and Tafle curves of zincated plates in 3.5% NaCl medium. The analyzed results show that when molar ratio of sodium hydroxide to zinc ions is constant, the better chelating agents combination for multi-metal zincation solution is the combination of sodium potassium tartrate and sodium citrate in zinc oxide solution, from which zinc alloy is high in potential and perfect in corrosion resistance. After the second zincate immersion for 60s, the immersion potential is -1.606V(vs SCE). The corrosion current density is 6.612, J_ corr/(A·cm -2); and the corrosion potential is -1.381, φ_ corr(I=0)/V.
文摘The effects of non-cyanide zincation process parameters on the microstructure of the zincation layer on A356 alloy were investigated by scanning electronic microscope.With the increasing of zincation time,the zinc grain size and the number density increase gradually,and the zinc grains adhere each other.The zinc grain obtained in the double-dipping process is finer,compacter and more homogeneous than that obtained in the single-dipping process.With the increasing of the zincation temperature,the morphology of zinc grains changes from spherical shape to flake-like shape.However,higher zincation temperature results in the flaking off of the zincation layer from the matrix.The optimized zincation temperature is 20-30 ℃.The quality of the zincation layer obtained in a low concentration,non-cyanide and multi-element zincation solutions is much better than these obtained in conventional high concentration zincation solution,dilute zincation solutions or a dilute zincation solution containing nickel.In addition,the matrix alloy and the pre-treatment also have significant influence on the morphology of the zincation layer.
基金Project(2014CB643401)supported by the National Basic Research Program of ChinaProjects(51134007,51404299)supported by the National Natural Science Foundation of China
文摘This study was aimed at investigating the performance of anaerobic rotating biological cont- reactor treating synthetic wastewater containing a mixture of heavy metals under sulfate redu condition. Statistically valid factorial design of experiments was carried out to understand dynamics of metal removal using this bioreactor system. Copper removal was maximum (〉98% followed by other heavy metals at their respective low inlet concentrations. Metal loading rates than 3.7 mg/L· h in case of Cu(II); less than 1.69 mg/L· h for Ni(II), Pb(II), Zn(II), Fe(III) and C are favorable to the performance of the An-RBC reactor. Removal efficiency of the heavy metals 1 mixture depended on the metal species and their inlet loading concentrations. Analysis of n precipitates formed in the sulfidogenic bioreactor by field emission scanning electron microscopyalong with energy dispersive X-ray spectroscopy (FESEM-EDX) confirmed metal sulfide precipitationby SRB. All these results clearly revealed that the attached growth biofilm bioreactor is well suited for heavy metal removal from complex mixture.