A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were te...A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope(AFM),scanning electron microscope(SEM),focused ion beam(FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.展开更多
In this work,we comprehensively investigate the response of amorphous and crystalline Zr-based alloys under nanosecond pulse laser ablation.The in situ multiphysics processes and ablation morphologies of the two alloy...In this work,we comprehensively investigate the response of amorphous and crystalline Zr-based alloys under nanosecond pulse laser ablation.The in situ multiphysics processes and ablation morphologies of the two alloy targets are explored and compared.The results indicate that the dynamics of laser-induced plasma and shock waves obey the idea blast wave theory and are insensitive to the topological structures of targets.Both targets experience significant superheating and culminate in explosive boiling.This ablation process leads to the formation of a hierarchical structure in the resultant ablation crater:microdents covered by widespread nanovoids.The amorphous target shows shallower microdents and smaller nanovoids than their crystalline counterparts because the former has a smaller heat-affected zone and experiences a higher degree of superheating.The hierarchical structure can adjust the surface wettability of targets from initial hydrophilic to hydrophobic,showing an increase of the contact angle approximately 119% for amorphous alloy compared with the crystal approximately 64%.This work demonstrates that amorphous alloys have a better performance against nanosecond pulse laser ablation and provides a feasible and one-step method of wettability modification for either amorphous or crystalline alloys.展开更多
基金Supported by Foundation of Characteristic Specialty of Higher Educational Institution(TS2375)Foundation of Science and Technology Depart ment of Guizhou Province[2007]
基金Supported by National High Technology Research and Development Program of China ("863"Program) (No.2006AA04Z327)National Natural Science Foundation of China (No.60372006)Program for New Century Excellent Talents in University
文摘A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope(AFM),scanning electron microscope(SEM),focused ion beam(FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.
基金supported by the National Outstanding Youth Science Fund Project(Grant No.12125206)of the National Natural Science Foundation of China(NSFC)the NSFC Basic Science Center for"Multiscale Problems in Nonlinear Mechanics"(Grant No.11988102)the NSFC(Grant Nos.11972345 and 11790292).
文摘In this work,we comprehensively investigate the response of amorphous and crystalline Zr-based alloys under nanosecond pulse laser ablation.The in situ multiphysics processes and ablation morphologies of the two alloy targets are explored and compared.The results indicate that the dynamics of laser-induced plasma and shock waves obey the idea blast wave theory and are insensitive to the topological structures of targets.Both targets experience significant superheating and culminate in explosive boiling.This ablation process leads to the formation of a hierarchical structure in the resultant ablation crater:microdents covered by widespread nanovoids.The amorphous target shows shallower microdents and smaller nanovoids than their crystalline counterparts because the former has a smaller heat-affected zone and experiences a higher degree of superheating.The hierarchical structure can adjust the surface wettability of targets from initial hydrophilic to hydrophobic,showing an increase of the contact angle approximately 119% for amorphous alloy compared with the crystal approximately 64%.This work demonstrates that amorphous alloys have a better performance against nanosecond pulse laser ablation and provides a feasible and one-step method of wettability modification for either amorphous or crystalline alloys.
