超声雾化制备高性能球形金属微粉的研究进展

Research Progress on Producing Fine Spherical Metal Powder by Ultrasonic Atomization

金属球形微粉是增材制造、粉末冶金工业、粉末注射成型、表面喷涂工艺、三维焊接技术等制造领域的基础原材料,高性能的球形金属微粉具有球形度高、粒度分布窄的特点,使得其在应用于相关领域的制造技术时能够得到质量好、致密度高、尺度精度高、表面均匀且致密度好的金属零件,因此高性能球形金属微粉的制备已成为机械制造行业研究的热点。目前采用的制备方法主要有水雾化法、气雾化法、等离子雾化法和超声雾化法等,其中水雾化法制得的粉末球形度差,含氧量高;气雾化法制得的粉末易形成气孔,且雾化过程不可控;等离子雾化法制备粉末的收得率低;超声雾化制备方法具有适用范围广、设备和工艺简单、可控性高、成本低、制得粉末的球形度好、粒度分布窄、粉末收得率高的显著优势,具有很好的应用前景。本文综述了超声雾化制备高性能球形微细金属粉末的方法及其研究进展,分别从接触式超声制粉技术和非接触式超声制粉技术两方面介绍了国内外制粉技术的研究现状,其中国内的研究现状只针对接触式超声雾化技术,对于非接触式超声雾化技术的研究主要集中在国外;并对影响非接触式超声雾化制粉效果的几种因素进行了分析与展望。

Spherical metal powder is a raw material used in additive manufacturing,powder metallurgy industry,metal powder injection molding technology and metal spraying and 3D welding technology.High-performance metal powder,applied in manufacturing,increases the quality,density,precision and strength of metal parts due to its good spherical morphology and narrow size distribution.Therefore,the preparation of high-performance spherical metal powder has become a popular research topic in mechanical manufacturing industry.Currently,the major preparation methods are water atomization,gas atomization,plasma rotating electrode process(PREP),plasma atomization(PA)and ultrasonic atomization.However,water atomization only leads to fine metal powder with poor sphericity and high oxygen content.Metal powder produced with gas atomization,susceptible to its unpredictable process,is likely to have pores.Preparation of fine spherical metal powder with particle size<45μm by PREP requires higher rotational speed of the electrode,and the powder collection rate of PA is only 40%.Compared with other methods,ultrasonic atomization has wider range of application and higher controllability,and requires simpler equipment and process as well as lower cost.Moreover,the prepared powder has good spherical morphology and narrow size distribution,and thus a better application prospect.The paper summarizes the preparation method of fine spherical metal powder and its research progress on producing high-performance spherical metal powder by ultrasonic atomization.Contact ultrasonic atomization and ultrasonic standing wave atomization are introduced respectively to demonstrate the development of metal powder production around the world.Researches within the country mainly focus on contact ultrasonic atomization,while ultrasonic standing wave atomization proceeds chiefly in other countries.Several factors affecting the ultrasonic standing wave atomization techno-logy are analyzed and forecasted.