超声波功率密度对镀镍层组织结构和内应力的影响

Effect of Ultrasonic Power Density on Microstructurc and Internal Stress of Electroplated Nickel Coatings

为了获得性能良好的镍镀层并将其用于电真空器件,在瓦特镍体系镀镍过程中引入超声场电沉积。利用扫描电子显微镜(SEM)、激光共聚扫描显微镜(CLSM)、孔隙率测试、X射线衍射仪(XRD)、弯曲阴极法研究了超声波功率密度对镀镍层形貌、粗糙度、孔隙率、物相、内应力的影响。结果表明:超声可以有效消除镀镍层的针孔现象,当超声波功率密度小于0.24 W/cm2时,镀层结晶颗粒细小、致密、孔隙率相对较小;超声波功率密度增加,有利于镀层在(200)晶面上的生长,晶面择优取向由(111)向(200)晶面转变;超声可以降低镀层的内应力,不用超声时为280 MPa,超声波功率密度0.48 W/cm2时降至120 MPa左右。

The morphology and phase structure of Ni coatings prepared form a Watts hath associated with ultrasound were analyzed with a scanning electron microscope,a confocal laser scanning electron microscope,and an X-ray diffractometer.The porosity and internal stress of the Ni coating were measured.Results showed that applying ultrasound helped to eliminate the pinholes in Ni coatings,and in particular,the Ni coating obtained under an ultrasound power density of below 0.24 W/cm^2 consisted of fine and compact grains and exhibited lowered porosity.Besides,increasing ultrasound power density favored the growth of Ni coating along the(200)crystal plane as well as the texture orientation transformation from(111) plane to(200) plane.Moreover,applying ultrasound contributed to greatly decreased internal stress of electroplated Ni contings.