基于超声雾化的金属零件3D打印用球形粉末制备技术基础研究

With the development and application of 3D printing technology, the preparation of metal powder as the most important raw materials used in 3D printing for metal parts is of great concern. In order to solve the problems in the preparation process of high-quality metal spherical micro powder for 3D printing, the technique of atomizing metal melt by ultrasonic standing wave field for preparing spherical metal powder is proposed. For the requirements of the fine particle size, the stability of material composition, the physical stability of powder and the rate of powder preparation, the mechanism and control technology of non-contact atomization of molten metal by action of ultrasonic standing wave will be studied systemically. The project focus on the distribution of ultrasonic standing wave, the critical condition for atomizing metal melt under the action of the ultrasonic standing wave field, the mechanism of the ultrasonic standing wave field distribution on atomization and the stability control of ultrasonic standing wave field. An atomization model of molten metal under multi-parameter coupling of ultrasonic standing wave will be established to analysis the effect on average size, particle size distribution and sphericity of powders. The atomization process will also be studied to reveal the influence degree and regularity of control parameters on the atomized powder. The research in this project will provide the theoretical basis and technical support for the development of micro powder preparation technology in 3D printing for metal parts.

随着3D打印技术的发展应用，3D打印金属粉末作为金属零件3D打印最重要的原材料，其制备备受关注。针对3D打印所需的高品质金属球形粉末制备过程中的问题，提出了利用超声驻波对金属熔体进行雾化制备球形金属粉末的技术，解决球形金属粉末制备过程中对粉末细粒度、成分稳定性、物理性能稳定性及成品率的要求，系统地研究超声驻波声场作用下金属熔体非接触雾化制粉的机理及其控制技术。研究超声驻波声场分布规律、金属熔体在超声驻波声场作用下雾化的临界条件，明确超声驻波声场分布对雾化的影响机理，并进行超声驻波声场的稳定性控制研究；建立超声驻波声场多参数耦合作用下金属熔体雾化模型，分析多参数耦合作用下金属粉末平均尺寸、粒径分布、球形度等的影响规律；最后进行超声驻波雾化金属熔体的工艺研究，揭示各控制参数对雾化粉末的影响程度及规律。本项目的研究将为金属零件3D打印用粉末超声驻波雾化制备技术的发展提供理论基础和工艺技术支撑。

针对高品质金属球形微粉制备的问题，提出了利用超声驻波对熔体进行雾化制备球形粉末的技术。通过分析国内外超声驻波场形成的几种结构形式，优选了双端发射、球面端面工具头激励下的超声驻波场形成方式。通过仿真分析了超声参数、环境背压、结构尺寸等参数对超声驻波声场特性的影响规律，通过实验测量了声场分布特性，验证了仿真分析的正确性。通过将声场与两相流进行耦合，建立了液滴/液流在声场作用下的雾化模型，分析了液滴/液流雾化的机制，获得了各参数对液滴/液流雾化过程的影响规律。搭建了超声驻波雾化实验系统平台，进行了不同参数作用下液滴/液流雾化实验，通过高速摄像对液滴/液流雾化过程进行拍摄，验证了仿真结果。对超声驻波非接触雾化得到的球形粉末进行分析，粒径分布服从正态分布，对雾化过程中碰撞粘连的粉末进行了分类及统计。本项目的研究为超声驻波声场熔体非接触式雾化在球形微粉制备领域的应用奠定了基础。