Research On Controllable Fabrication Of Anti-friction Textures On Metallic Glass Via Femtosecond Double-pulse Laser Machining

Metallic glass is a new type of amorphous material with excellent mechanical properties of both metal and glass.It has the rules of short-range ordered and long-range disordered atomic arrangement.Since it was first prepared in 1960 s,metallic glass has made rapid development in material synthesis and applications.Metallic glass has a huge demand for anti-friction function in practical applications.For example,surface textures of metallic glass may significantly improve its anti-friction performance,which can effectively reduce the risk of failure of artificial joint due to severe wear in practical use.In this case,the development of good applicability and higher profile precision antifriction texture preparation method is not only conducive to the research of anti-friction textures on the surface of metallic glass,but also provides a new opportunity for the expansion of the applications of metallic glass.In order to prepare the functional antifriction textures on the surfaces of metallic glass,this paper analyzes and compares the advantages and disadvantages of the surface textures processing technology,in which the ultrafast laser method has the characteristics of processing flexibility,high efficiency and relatively cold processing,which is suitable for processing the antifriction textures on the surface of metallic glass.However,when processing metallic glass via ultrafast laser,there will be defects in the processing areas,which will affect the profile accuracy of the surface textures.In order to further improve the textures processing quality of metallic glass,this paper proposes to use femtosecond laser double-pulse processing technology to achieve quality controlled micro textures preparation.The main principle is to adjust the delay time of two pulses to achieve the time-domain control of femtosecond laser.The main research contents and conclusions of this paper are as follows:(1)The evolution of the surface morphology of metallic glass under the action of femtosecond laser double pulse was studied.In this paper,the femtosecond laser processing characteristics of metallic glass were studied by means of femtosecond laser double pulse delay time control.The experimental results showed that the pulse delay time may produce a more obvious control effect on the ablation morphology.When the delay time of the two pulses was close to the electron phonon coupling characteristic time of the metallic glass material,the ablation morphology changed from the rough morphology without delay control to the extremely smooth state.At the same time,the LIPSS structures disappeared,and the surface defects such as ablation particle deposition were very few.According to the model of shock wave caused by laser in different delay time,the ablation mechanism of femtosecond double-pulse laser on metallic glass was studied.(2)The influence of surface texture on the antifriction characteristics of metallic glass under partial hydrodynamic lubrication was studied.By establishing and solving the simulation model of micro textures friction reduction under partial hydrodynamic lubrication,the influence of texture surface profile parameters,internal profile parameters and roughness parameters on the effect of metal glass surface texture friction reduction was analyzed.(3)Based on the study of ablation characteristics of metallic glass by femtosecond double-pulse laser,the surface textures differences between femtosecond single-pulse laser and femtosecond double-pulse laser machining were compared.The femtosecond double-pulse laser method could improve the textures smoothness,and the surface after femtosecond single-pulse laser could be processed by double pulse twice to achieve the smooth textures.By using femtosecond laser variable energy processing method,the textures of internal inclined profile and parabolic profile were prepared.(4)Friction and wear experiments were carried out on the textured metallic glass samples to study the effects of different surface profile parameters,internal profile parameters and roughness parameters on the friction reduction performance of metallic glass.The experimental results showed that the friction reduction laws of various textures were consistent with the simulation results,which verified the effectiveness of partial hydrodynamic lubrication model for the design of antifriction textures of metallic glass.