喷印金属微滴撞击粗糙表面的分子动力学模拟

Molecular dynamics simulation of printed metal microdroplets impacting on rough surfaces

研究金属微滴撞击固体表面的行为对预测微滴形态和实现高精度的喷印制造具有重要的意义.然而,由于微纳尺度下金属微滴撞击实验的难以开展,目前涉及金属微滴撞击粗糙表面的形态变化和热毛细效应机理尚不清楚.本文采用分子动力学模拟研究了镓铟微滴撞击粗糙表面的动态行为,定量分析了撞击速度、粗糙结构和不同温度对微滴撞击行为的影响.结果表明:随着撞击速度的提高,微滴先后呈现沉积、弹跳和破碎飞溅三种模式,且微滴的最大铺展因子与韦伯数呈幂函数关系.此外,通过修饰基底粗糙结构发现,结构间距或高度的变化对微滴的弹跳行为存在不同的影响机制,可以有效促使或抑制微滴的弹跳行为.最后,分析得出随着温度的提高,微滴的铺展直径会变大,产生的黏性耗散也会增大.研究结果对金属微滴撞击行为的有效预测提供了理论基础.

The study of the behavior of the metal microdroplet impacting on a solid surface is of great significance for predicting the morphology of the microdroplet and realizing high-precision print manufacturing.However,due to the difficulty of performing experiments on metal microdroplets impacting at the micro/nano-scale,the morphology change and thermo-capillary effect mechanism involving metal microdroplets impacting on rough surfaces are still unclear.In this paper,molecular dynamics simulations are used to study the dynamic behavior of the gallium-indium microdroplet impacts on rough surfaces,and quantitatively analyze the effects of the impact velocity,the rough structure,and the different temperatures on the impact behavior of the microdroplet.The results show that with the increase of the impact velocity,the microdroplet shows three modes of deposition,bouncing and splashing,and the maximum spreading factor of the microdroplet shows a power function relationship with the Weber number.In addition,by modifying the rough structure of the substrate,it is found that changes in the spacing or height of the structure have different influences on the bouncing behavior of the microdroplet,which could effectively promote or inhibit the bouncing behavior.Finally,it is analyzed that the spreading diameter of the microdroplet becomes larger with the increase of temperature,and the viscous dissipation generated also increases.The results provide a theoretical basis for the effective prediction of the impact behavior of metal microdroplets.