用脉冲喷射电沉积法制备纳米晶镍镀层

Preparation of Nanocrystalline Nickel Coating by Pulse Jet-Electrodeposition

采用脉冲喷射电沉积方法制备了纳米晶镍镀层,用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射(XRD)等方法研究了镀层的生长形貌和微观结构,并考察了脉冲电流密度对镀层微观结构如晶粒尺寸、织构等的影响。结果表明:镀层内表面(基体一侧)具有比外表面(镀液一侧)更为精细的晶粒结构,说明随着厚度的增加,镀层中的晶粒逐渐粗化。随着电流密度从45A/dm2增加到180A/dm2,镀层中晶粒生长的择优取向由(111)织构逐渐转变为强(220)织构。当电流密度从45A/dm2增加到120A/dm2时,镀层平均晶粒尺寸逐渐减小;而进一步增加电流密度到180A/dm2,镀层晶粒尺寸又会有轻微的增大。

Nanocrystalline nickel coatings were prepared by pulse jet-electrodeposition.Scanning electron microscopy(SEM),transmission electron microscopy(TEM),and X-ray diffraction(XRD)were used to investigate the morphology and microstructure of the electrodeposited Ni coatings.The influence of current density on the microstructure such as average grain size and texture of Ni coatings was studied as well.The results showed that the inner layer(next to the substrate)of the nickel coatings was composed of more fine grains as compared to the outer layer(next to the bath solution),implying that the metallic grains experience a gradual coarsening with increasing thickness of the coating during the growth process.Moreover,an increase in the pulse peak current density from 45 A/dm2 to 180 A/dm2 resulted in a change in the preferential orientation from a(111)texture to a strong(220)texture,while the average grain size of the nickel coatings decreased with increasing current density from 45 A/dm2 to 120 A/dm2.However,the average grain size of the nickel coatings slightly increased as the current density reached 180 A/dm2.