Study On Process Of Ablation On Metal By Ultraviolet Nanosecond Pulse Laser

Pulse laser processing is essential for identifying field in nano-manufacture,biomedical and aerospace.Metal membrane constructions are widely implemented in industry,national defense and military.The post processing and surface construction management in certain metal membranes by laser pulse processing pose attention with many scholars.Thus,getting higher laser processing accurate and efficiency,as well as satisfying robust and adaptive requirements of various materials and structures have been current spotlight in researches.In this paper,we started from the study of ultraviolet nanosecond pulse laser processing on the membrane of Cr(chromium)which bases on Si(silicon),then carried out a series of analyses of laser ablation.Next,we computed the quantitative session of single-pulse energy,focal offset and heat transmission by the finite element method,and the influence of above parameters on laser ablation was predicted.A series of experiments were designed and carried out on ultraviolet nanosecond pulse laser micro-construction processing system for verifying predictive results.Contributions are as follows:The mathematical relation between nanosecond laser energy and the ablation of Cr was given depending on the process of absorption,reflection and transition of Gaussian laser energy on metal.Considering the focal offset in multi-pulse laser processing,we inducted the distribution of non-focal Gaussian energy as well as the above relation under current state.Then,we constructed the nanosecond pulse laser processing model based on TTM(Two-temperature Model)and simulated the dynamic process of laser processing by the tool of FEM(Finite Element Simulation).The simulative results of single-pulse laser process predicted the relation among laser energy,focal offset and the removal depths of materials,which also suggested the formation time of the micro-construction on the surface in certain laser energy.Besides,we inducted the dynamical evolution of temperature by tracing the temperature of materials in heat affected zone.The simulative results of multi-pulse laser processing predicted the relation among laser energy,focal offset,pulse number and the removal depths of materials.Micro-constructions were formed on the membrane of Cr by laser ablation.Removal depths of materials and surface constructions were measured by AFM(Atomic Force Microscope),as well as the morphology around processing zone.Experimental results suggested a quantitative relation among laser energy,focal offset,pulse number,depths of materials and surface constructions.The relation between predictive values and experimental values were interpreted by the connection between laser energy and material removal mechanism which was obtained from experiments.