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
In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin additio...In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin addition on grain size and texture coefficient （TC= I（200）/I（111）） of the deposits were investigated by X-ray diffraction （XRD）. The results showed that in a bath containing 5 g/L saccharin, by increasing the bath temperature from 45℃ to 55℃, the grain size decreased, whereas further increase of bath temperature resulted in a contrary effect. By increasing the current density from 10 to 75 mA/cm^2, both the grain size and TC decreased, while further increase in current density had no significant effect on the grain size. At a given current density, the grain size and TC decreased rapidly by increasing the saccharin content before leveling off at 3 g/L of saccharin. Finally, based on the grain refining the optimum conditions for producing nanocrystalline nickel coating from Watts-type bath have been proposed.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supported by University of Tehran andRazi University
文摘In order to achieve the optimum conditions for electroplating nanocrystalline nickel coating from Watts-type bath, the effect of some process parameters namely, bath temperature, current density, and saccharin addition on grain size and texture coefficient （TC= I（200）/I（111）） of the deposits were investigated by X-ray diffraction （XRD）. The results showed that in a bath containing 5 g/L saccharin, by increasing the bath temperature from 45℃ to 55℃, the grain size decreased, whereas further increase of bath temperature resulted in a contrary effect. By increasing the current density from 10 to 75 mA/cm^2, both the grain size and TC decreased, while further increase in current density had no significant effect on the grain size. At a given current density, the grain size and TC decreased rapidly by increasing the saccharin content before leveling off at 3 g/L of saccharin. Finally, based on the grain refining the optimum conditions for producing nanocrystalline nickel coating from Watts-type bath have been proposed.
