飞秒激光双脉冲可控加工金属玻璃表面织构及其减摩性能研究

RESEARCH ON CONTROLLABLE FABRICATION OF ANTI-FRICTION TEXTURES ON METALLIC GLASS VIA FEMTOSECOND DOUBLE-PULSE LASER MACHINING

李铁

11849008

硕士

机械工程领域工程

徐少林

2020-06-02

2020-07-20

哈尔滨工业大学

深圳

金属玻璃是一类兼有金属与玻璃优异力学性能的新型非晶材料，具有短程有序、长程无序的微观原子排布规律。自20世纪60年代首次被制备出以来，金属玻璃在材料合成与应用方面取得了迅猛的发展。在应用过程中，金属玻璃具有减摩功能性的需求，如用作人工关节植入体的金属玻璃材料在表面引入织构可显著提高其耐磨性，这可以有效降低人工关节在使用过程中因剧烈磨损而失效的风险。在此背景下，开发出具有高形状精度与高表面质量的减摩织构制备方法，不仅有利于提高金属玻璃表面减摩织构设计和制造的研究水平，也能够有效促进金属玻璃的实际应用。为了在金属玻璃表面制备出功能性减摩织构，本文分析比较了目前常用的表面织构加工技术的优缺点，其中超快激光加工方法具有灵活高效且能够实现相对冷加工的特性，适宜用于加工金属玻璃表面减摩织构。然而超快激光加工金属玻璃时会在加工区域留有缺陷，同时影响表面织构的轮廓精度。为了进一步提高金属玻璃表面织构的加工质量，本文采用飞秒激光双脉冲加工技术实现了质量可控的微织构制备，其主要原理为调整两个脉冲的延迟时间以实现飞秒激光的时域调控。本论文的主要研究内容与结论如下：（1）研究了飞秒激光双脉冲作用下金属玻璃表面形貌的演化规律。引入飞秒激光双脉冲延迟时间调控手段对金属玻璃飞秒激光加工特性进行研究，实验结果显示脉冲延迟时间可以对烧蚀形貌产生较为明显的调控效果。当两个脉冲的延迟时间接近金属玻璃材料的电子弛豫特征时间时，烧蚀形貌由无延迟调控下的粗糙形貌转变为极其平滑的状态，同时波纹结构消失，烧蚀颗粒沉积等表面缺陷显著减少。依据不同延迟时间下激光导致冲击波的作用模型，对飞秒激光双脉冲对金属玻璃的烧蚀机理进行了理论研究。（2）研究了表面织构在部分流体润滑状态下对于金属玻璃材料减摩特性的影响。通过建立并求解部分流体润滑条件下的微织构减摩仿真模型，分析织构表面轮廓参数、内部轮廓参数以及粗糙度参数对金属玻璃表面织构减摩效果的影响规律。（3）依据飞秒激光双脉冲对金属玻璃的烧蚀特性研究，比较了飞秒激光单脉冲与飞秒激光双脉冲加工金属玻璃表面织构的形貌差异。飞秒激光双脉冲方法能够提高织构的光洁度，并且在飞秒激光单脉冲加工后的表面进行双脉冲的二次加工能够实现粗糙织构的平整化。采用飞秒激光变能量加工方法完成了内部倾斜形轮廓与抛物线形轮廓织构的制备。（4）对织构化的金属玻璃样品进行摩擦磨损实验，研究具有不同表面轮廓参数、内部轮廓参数的织构对金属玻璃减摩性能的影响。实验得出的不同织构的减摩规律与仿真规律一致，这验证了部分流体润滑模型在设计金属玻璃减摩织构方面的有效性。

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 1960s, 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 anti-friction 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.

金属玻璃 减摩织构 飞秒激光 双脉冲

metallic glass anti-friction textures femtosecond laser double-pulse

中文

联合培养

南方科技大学

李铁. 飞秒激光双脉冲可控加工金属玻璃表面织构及其减摩性能研究[D]. 深圳. 哈尔滨工业大学,2020.