微纳米球形颗粒之间的毛细力研究

两球形颗粒之间的相互接触问题是研究微机械系统中纳米接触问题的一个重要课题.在微尺度下,毛细液桥现象尤为重要,在观测纳米级物体的相互接触作用力中不可避免地要研究微纳米尺度的液桥问题.本文采用液桥力学平衡、环形近似、体积守恒方法,建立了微纳米球形颗粒之间的液桥模型,通过精确的数学求解,分析球形颗粒的接触角对于毛细作用力和液桥的断裂高度的影响.模拟结果发现,当2个颗粒之间的毛细力作用都很小时,液桥的断裂高度随着接触角的增加而减小,当其中一个颗粒的毛细力作用比较大时,断裂高度随着接触角的增大而增大,接触角的大小对于液桥的断裂高度有直接的决定作用.研究结果为计算预测微观颗粒之间的相互作用力、探索纳米颗粒间的相关特性和机理提供参考.

Capillary Force between Microparticles

Contact problem of two particles has been a crucial research topic in the Micro Electro mechanical system.The capillary condensation is important in the microscopic.So it is inevitable to investigate the micro liquid bridge problem in the study of the nanoscale objects interaction forces.Based on the mechanical equilibrium,toroidal approximation,volume conservation and accurate mathematical methods,this paper develops a model to study the capillary bridge between two spherical microparticles,and analyses the influences of the contact angle on the liquid bridge rupture distance.It shows that the liquid bridge rupture distance decreases with the increasing contact angle as the capillary force is small,while it increases with increasing contact angle as the capillary force is large.The contact angle has a direct decisive effect on the rupture distance.The simulation results are useful for the prediction of the interaction force,the property and the mechanism of the microparticles.