Study On The Adhesion Between Lunar Dust Particles And Surfaces With Low Free Energy

Lunar dust particles are micro particles formed by rock weathering on the surface of the moon.Due to the photoelectric effect,it is easy to adhere to the surface of the detector,resulting in the failure of the device and even the whole system.The protection of lunar dust is still an essential research topic in lunar exploration project.In this thesis,the adhesion mechanism model between the lunar dust particles and the contact surface is described.And the influence of surface energy and roughness on the adhesion mechanism are discussed.The purpose of this thesis is to seek optimal surface parameters to improve the protection effect on the surface,providing protection for the smooth implementation of the exploration project.The main research work includes the following contents.Based on the existing adhesion model of solid particle,the stress of lunar dust particles was analyzed after considering its’ characteristic.Then the adhesion mechanism model between lunar dust particles and contact surface was constructed.At the same time,the effects of surface energy,roughness and other factors on adhesion of aluminum-based materials were analyzed.The result shows for the same surface,both electrostatic and van der Waals forces are positively correlated with particle size.In addition,there is only a rough surface that minimizes the van der Waals force when the particle size is fixed.The characterization model of rough surface which based on fractal theory was established.According to the adhesion mechanism,the surrogate model based on BP neural network was established,and it was combined with genetic algorithm to optimize the surface parameters.In order to obtain different surface morphology and roughness,the aluminum-based surface was etched using electrochemical,chemistry,and composite etching processes,and it was modified with fluoride.It was discovered that the adhesion of lunar dust particles could be reduced which contacted with aluminum-based surface with low surface energy and micronano structure.What’s more,it can be seen from the results that for lunar dust particles with particle size of 70 μm,when the fractal dimension is about 1.6,the van der Waals force reaches the minimum value,and the optimal root mean square roughness of the surface is about 14.8 nm.Further,on the basis of numerical analysis and experimental studies,solid models of rough surfaces with different fractal dimensions were generated by ANSYS.The simulation model of the lunar dust particles and rough surfaces was used to establish by discrete element method,which further verifies the effectiveness and reliability of the lunar dust particulate mechanical model.This thesis systematically analyzes the adhesion mechanism between lunar dust particles and the surface,and the effect of surface properties and morphology on adhesion is considered.Above all,the surface parameters are optimized.These studies provide theoretical and experimental basis for the construction of micro-nano surface with dustproof function.