The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,aver...The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and microhardness measurement.In addition,the corrosion resistances of coating and substrate were compared.It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density,although some pores and defects are still present in coatings.With the increase of average current density,the average grain size of nickel coatings is reduced at first and then increased.The coating with the optimum compactness,the smallest average grain size(13.7 nm)and the highest microhardness are obtained at current density of 39.8 A/dm2.The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition;however,the corrosion rate is increased after a certain period due to the penetration of the corrosive media.展开更多
Ni nanoparticles plating was prepared in reverse microemulsion. The deposition was carried out through the Brownian motion of water pools in the reverse microemulsion and the adsorption of water pools on the electrode...Ni nanoparticles plating was prepared in reverse microemulsion. The deposition was carried out through the Brownian motion of water pools in the reverse microemulsion and the adsorption of water pools on the electrode surface. Effects of electrolytic parameters on the size of Ni particles were studied. The performances of hydrogen evolution and hydrogen storage of the Ni nanoparticles plating electrode were also investigated. The results indicate that the size of Ni nanoparticles decreases with the increase of Ni2+ concentration and the decrease of current density. The electrochemical activity of Ni nanoparticles plating electrode is much higher than that of bulk Ni electrode.展开更多
Ni-Co alloys were electroplated from sulphate electrolyte using addition agents including sodium gluconate, boric acid and eysteine on copper foil by the galvanostatic technique and ultrasound waves. The chemical comp...Ni-Co alloys were electroplated from sulphate electrolyte using addition agents including sodium gluconate, boric acid and eysteine on copper foil by the galvanostatic technique and ultrasound waves. The chemical composition, surface morphologies, crystalline structure and hardness of the Ni-Co alloys were studied using energy dispersive spectroscopy, scanning electron microscope, X-ray diffraction and Vickers testing method, respectively. The effect of current density and addition agents on the microstructure and morphology of Ni-Co alloys were examined. The appropriate concentration of additives and ultrasound waves were found to produce fine and smooth crystals leading to higher hardness of Ni-Co alloys. The microhardness of the Ni-Co alloys was varied between 4860-7530 HV. The surface morphology of coatings was changed from granular to fine due to using of gluconate, boric acid, cysteine and ultrasound waves. The mechanical properties of nanocrystalline Ni-Co alloys showed an increase of the hardness with the growing of Ni content in the alloy. The X-ray diffraction studies indicated that nanocrystalline structure was face-centred cubic for pure Ni and Ni-Co alloys with Co content in the range of 1-75 wt.%. A hexagonal closed-package structure was obtained for pure Co and Ni-Co alloys with the cobalt content with range of 75-99 wt.%.展开更多
基金Project(50175053) supported by the National Natural Science Foundation of China
文摘The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel.The effects of average current density on the surface morphology,microstructure,average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD)and microhardness measurement.In addition,the corrosion resistances of coating and substrate were compared.It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density,although some pores and defects are still present in coatings.With the increase of average current density,the average grain size of nickel coatings is reduced at first and then increased.The coating with the optimum compactness,the smallest average grain size(13.7 nm)and the highest microhardness are obtained at current density of 39.8 A/dm2.The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition;however,the corrosion rate is increased after a certain period due to the penetration of the corrosive media.
基金Projects(20673036,J0830415) supported by the National Natural Science Foundation of ChinaProject(09JJ3025) supported by Hunan Provincial Natural Science Foundation of ChinaProject(09GK3173) supported by the Planned Science and Technology Project of Hunan Province,China
文摘Ni nanoparticles plating was prepared in reverse microemulsion. The deposition was carried out through the Brownian motion of water pools in the reverse microemulsion and the adsorption of water pools on the electrode surface. Effects of electrolytic parameters on the size of Ni particles were studied. The performances of hydrogen evolution and hydrogen storage of the Ni nanoparticles plating electrode were also investigated. The results indicate that the size of Ni nanoparticles decreases with the increase of Ni2+ concentration and the decrease of current density. The electrochemical activity of Ni nanoparticles plating electrode is much higher than that of bulk Ni electrode.
文摘Ni-Co alloys were electroplated from sulphate electrolyte using addition agents including sodium gluconate, boric acid and eysteine on copper foil by the galvanostatic technique and ultrasound waves. The chemical composition, surface morphologies, crystalline structure and hardness of the Ni-Co alloys were studied using energy dispersive spectroscopy, scanning electron microscope, X-ray diffraction and Vickers testing method, respectively. The effect of current density and addition agents on the microstructure and morphology of Ni-Co alloys were examined. The appropriate concentration of additives and ultrasound waves were found to produce fine and smooth crystals leading to higher hardness of Ni-Co alloys. The microhardness of the Ni-Co alloys was varied between 4860-7530 HV. The surface morphology of coatings was changed from granular to fine due to using of gluconate, boric acid, cysteine and ultrasound waves. The mechanical properties of nanocrystalline Ni-Co alloys showed an increase of the hardness with the growing of Ni content in the alloy. The X-ray diffraction studies indicated that nanocrystalline structure was face-centred cubic for pure Ni and Ni-Co alloys with Co content in the range of 1-75 wt.%. A hexagonal closed-package structure was obtained for pure Co and Ni-Co alloys with the cobalt content with range of 75-99 wt.%.
