Experiment And Simulation Of Micro Texture Based On Transient Mechanical Effects Of Laser Cavitation

Material surface micro texture technology has been widely used in aerospace,micro electromechanical and other high-end manufacturing fields,but the existing micro texture processing methods,such as RIE and indentation technique,often have large pollution,complex process and high energy consumption.Therefore,it is of great research value to apply the laser-induced cavitation technology with no pollution,simple operation and low energy consumption to the processing of micro texture.In this paper,1060 aluminum alloy commonly used in micro electronic components is used as the target,and the micro scale transient high-pressure mechanical effect produced by laser-induced cavitation is applied to the material surface to prepare micro texture pits based on material micro plastic deformation.By building an integrated platform for laser cavitation mechanical effect detection and micro texture experiment,the transient impact pressure on the target is detected and described,and the micro deformation behavior of the target and the response law of material properties are studied.At the same time,based on the experimental data,a scheme of laser cavitation micro texture simulation model is proposed and verified,and the influence of different processing paths on the micro texture depth distribution and residual stress in the array is studied by using the simulation scheme.The specific research contents and results are as follows:(1)The growth and collapse mechanism and pulsation characteristics of laser cavitation are analyzed theoretically,which provides a theoretical basis for the study of mechanical effects caused by laser cavitation;The generation mechanism of various mechanical effects and the action mechanism of transient pressure in the process of laser cavitation are explored,which lays a theoretical foundation for micro texture experiment and simulation research.(2)High speed photography combined with hydrophone electrical signal capture is used to detect the mechanical effects in the process of laser-induced cavitation micro texture,and a cavitation mechanical curve description method based on negative voltage filtering is proposed.The results show that the electrical signal captured by the hydrophone has two obvious peak pressures,1.196 GPa and 515 MPa respectively.It can be judged by high-speed photography that they are the mechanical shock caused by laser plasma shock wave and cavitation collapse respectively.At the same time,the signal processing method of filtering negative voltage can effectively describe the mechanical curve caused by cavitation cavitation,and the duration of the mechanical action is about 20 μs.(3)The material performance response of 1060 Aluminum alloy target at the micro pits on its surface after different times of laser cavitation was experimentally studied.The results show that the micro shape is roughly in the shape of a slightly convex micro pit around the top.With the increase of the number of laser cavitation,the morphology consistency in all directions gradually improves,but the probability of laser ablation damage also increases,The number of laser cavitation is negatively correlated with the change rate of texture depth,positively correlated with the dispersion of deformation depth between different parts,and positively correlated with the surface hardness of micro texture pits,1060 Aluminum foil protective layer can effectively inhibit the increase of micro texture roughness.The increase of laser cavitation times will increase the value of residual stress on the inner surface of micro texture pit.(4)A scheme of laser cavitation micro texture simulation model based on hydrophone load data is proposed and verified,and the influence of different processing paths on the preparation of micro texture array is studied.The results show that the simulation results are in good agreement with the experimental data in the case of primary laser cavitation.Different processing paths will directly affect the deformation depth and residual stress distribution of each texture pit in the array processing area.Generally speaking,the depth and stress distribution in the ‘S’ path are more uniform,while the ‘Loop’ path is more concentrated.