摘要
超声辅助电火花放电是一种绿色环保、易于控制的制备微纳米金属粉末的方法。为研究超声功率对微纳米金属粉末粒径分布的影响,本工作通过COMSOL仿真软件模拟声压在工作液中随时间的变化趋势,得出不同换能器功率下工作液中的最大声压值。利用测量得到的最大声压值与工作液理论空化阈值的比较确定了换能器的功率值,通过理论计算得到了不同超声功率对粒径的影响范围。最后采用实验室自制设备制备镍粉,通过SEM观测制备的镍粉的形貌,采用激光粒度分析仪分析镍粉的粒径分布,验证了理论分析结果。结果表明:超声的空化与振动效应能够破碎火花放电产生的汽化和熔融金属液滴;工作液中的空化泡破裂所产生的冲击波使小粒径的镍粉颗粒发生碰撞,动能转换成热能,产生的高温使镍颗粒烧结形成金属烧结颈,使多个小颗粒团聚成不规则的大颗粒。
The ultrasonic-assisted electrical discharge is a green, easy and controllable approach to generate micro-nano metallic powders. To investigate the effect of focused ultrasonic power on the morphology and particle size distribution of micro-nano metallic powders, the COMSOL multiphasic simulation software was applied to simulate the sound pressure distribution of ultrasonic in the working box to determine the discharge position. By comparing the maximum sound pressure value with the ultrasonic cavitation threshold, the transducer power required to form cavita- tion was determined, and the influence range of different ultrasonic power on particle size was obtained through theoretical calculation. Finally, the experiment of preparing nickel powder was carried out by using self-made laboratory equipment. The morphology of the prepared nickel powder was observed by SEM, and the particle size distribution of nickel powder was analyzed by laser particle size analyzer to verify the theoretical analysis results. The results show that the ultrasonic cavitation and vibration effects can break the vaporized and molten metal droplets generated by spark discharge;the shock wave generated by the cavitation bubble burst in the working fluid causes the collision of small-sized nickel powder particles, and the kinetic energy is converted into thermal energy, the high temperature generated forms sinter necks between the metal particles, causing multiple small particles to reunite into irregular large particles.
作者
林发明
侯启龙
王杰
李翔龙
LIN Faming;HOU Qilong;WANG Jie;LI Xianglong(School of Mechanical Engineering,Sichuan University,Chengdu 610065,China;School of Mechanical Engineering,Southwest Jiaotong University,Chengdu 610031,China)
出处
《材料导报》
EI
CAS
CSCD
北大核心
2021年第2期2115-2119,共5页
Materials Reports
基金
国家自然科学基金(51275324,51435011)
科技部创新方法工作专项:四川省创新方法推广应用示范(20171M010700)。
关键词
电火花
超声功率
声压
空化泡阈值
粒径分布
EDM
ultrasonic power
sound pressure
cavitation bubble threshold
particle size distribution
