中文摘要：

火花放电法制备镍微球是一种新兴的方法。为了减小微球尺寸,提出一种复合型制备方法——电火花-超声复合加工法。通过改变超声参数（频率和功率）和工作液（煤油和纯水）,分析这两种工艺参数对微球尺寸的影响。使用扫描电镜观察试验样本,X射线衍射分析样本成分,Smile View软件测量微球粒径,Origin Pro软件得到粒径分布百分比。结果表明：加入超声波之后,小粒径（0-10μm）镍微球比例明显升高,且小粒径微球比例随着超声波频率的增大而降低,随着超声波功率的增大而升高。和煤油相比,以纯水为工作液所制备的微球尺寸普遍偏小,可得到粒径小于1μm比例为6%-10%,小于5μm比例为50%-80%,且超声波对微球尺寸减小效果比在煤油中显著。以纯水为工作液所得微球成分中Ni单质比例更高（？99%）。此外,在加入超声试验组中发现有少量空心球存在,并初步分析了空心球成型机理。

英文摘要：

Spark erosion is a method for producing nickel microspheres. To reduce the size of microspheres, a combined machining technology called ultrasound-aided electrical discharge machining（EDM） is proposed. To investigate the effect of non-electrical parameters on the size of microspheres, the experiments are carried out by changing ultrasonic parameters（frequency and intensity） and dielectric mediums（kerosene and pure water）. The morphology and composition of microspheres are characterized by using scanning electron microscope（SEM） and X-ray diffraction（XRD）. Smile View software is used to measure the size of the microspheres and Origin Pro software is used for statistical analysis to determine the size distribution percentages. The results show the percentage of small particles（in the range of 0 to10 μm） increases significantly by introducing ultrasound. Meanwhile, the percentage of small particles decreases with increasing ultrasonic frequency and increases with increasing ultrasonic intensity. The size of microspheres prepared in pure water is generally smaller than kerosene. In the pure water, the percentage of microspheres with a smaller size（less than 1 μm） and a small size（less than 5 μm） are 6%-10% and 50%-80% respectively. The effect of ultrasound in pure water is better than kerosene on reducing the size of microspheres. The microspheres made up of almost purenickel（≥99%） are produced in pure water. In addition, a few hollow microspheres are found in the experiments with ultrasound and the formation mechanism of the hollow spheres is analyzed preliminary.