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Papers - Yan, Jiwang

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Nitrogen assisted formation of large-area ripples on Ti6Al4V surface by nanosecond pulse laser irradiation

C Wang, H Huang, Y Qian, Z Zhang, W Huang, J Yan

Precision Engineering (Elsevier {BV}) 73 244 - 256 2022.01

ISSN 0141-6359

Ti6Al4V is one of the most widely used titanium alloys due to its excellent mechanical, physical, and chemical properties. Laser surface texturing is a promising method to endow new functions of material surfaces; however, direct generation of laser-induced periodic surface structure (LIPSS) on the Ti6Al4V surface by nanosecond laser is rarely reported. In this study, by nanosecond laser irradiation in nitrogen atmosphere, the ripples (a typical LIPSS) were directly fabricated on the Ti6Al4V surface. By single-line laser scanning, the effects of laser irradiation parameters including the laser power and repetition frequency on the formation and evolution of the ripples were systematically investigated, followed by optimizing the laser irradiation parameters to achieve the large-area regular and clear ripples with relatively good surface quality as well. Furthermore, by performing contrast experiments in argon atmosphere, the role of nitrogen atmosphere on the formation of ripples was confirmed. Accordingly, formation mechanism of the ripples was discussed. Finally, the effects of the formed ripples on the surface color and wettability were preliminarily characterized to demonstrate the potential applications of surface ripples. This paper provides a nitrogen assisted method to fabricate large-area ripples on the Ti6Al4V surface by nanosecond laser irradiation.

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The effects of simultaneous laser nitriding and texturing on surface hardness and tribological properties of Ti6Al4V

C Wang, J Hong, M Cui, H Huang, L Zhang, J Yan

Surface and Coatings Technology, 128358 (Surface and Coatings Technology) 437 2022

ISSN 02578972

The low hardness and poor tribological properties of titanium and its alloys significantly hinder their practical engineering applications, so surface nitriding or texturing is widely employed to improve the surface performances. However, previous studies mainly used the single method (surface nitriding or texturing), and simultaneous nitriding and texturing are rarely reported. Therefore, their combined effects on the surface mechanical and tribological properties are rarely investigated as well. In this study, by nanosecond pulse laser irradiation in nitrogen atmosphere, simultaneous nitriding and texturing of the Ti6Al4V surface were achieved. The effects of laser parameters including laser power, laser overlap rate, and number of scanning cycles, on the surface hardness and tribological properties of laser irradiated surfaces were comparatively studied. The experimental results showed that after simultaneous laser nitriding and texturing, the surface hardness of Ti6Al4V surface was increased by 50%~95%, and the coefficient of friction (COF) was reduced by 70%~80%. Furthermore, the laser processed surfaces obtained under various irradiation parameters presented quite different scratching characteristics, and the corresponding deformation mechanisms during scratching were analyzed. This study provides a simple and effective method by simultaneous laser nitriding and texturing for improving the surface properties of Ti6Al4V, which would be meaningful for its practical engineering applications.

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Generation of micro/nano hybrid surface structures on copper by femtosecond pulsed laser irradiation

Nakajima A., Omiya M., Yan J.

Nanomanufacturing and Metrology (Nanomanufacturing and Metrology) 5 ( 3 ) 274 - 282 2022

ISSN 2520811X

The delamination of copper lead frames from epoxy molding compounds (EMC) is a severe problem for microelectronic devices, as it leads to reduced heat dissipation or circuit breakage. The micro/nanoscale surface structuring of copper is a promising method to improve the copper–EMC interfacial adhesion. In this study, the generation of micro/nano hybrid structures on copper surfaces through femtosecond pulsed laser irradiation is proposed to improve interfacial adhesion. The micro/nano hybrid structures were realized by generating nanoscale laser-induced periodic surface structures (LIPSS) on microscale parallel grooves. Several types of hybrid surface structures were generated by changing the laser polarization direction, fluence, and scanning speed. At a specific aspect ratio of microgrooves, a latticed structure was generated on the sides of microgrooves by combining LIPSS formation and direct laser interference patterning. This study provides an efficient method for the micro/nanoscale hybrid surface structure formation for interfacial adhesion improvement between copper and EMC.

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Exploratory investigation of chip formation and surface integrity in ultra-high-speed gear hobbing

Ueda Y., Sakurai N., Takagi T., Ishizu K., Yan J.

CIRP Annals (CIRP Annals) 71 ( 1 ) 89 - 92 2022

ISSN 00078506

Gear hobbing is widely employed to manufacture automotive gears, where the productivity depends on the cutting speed. Currently, gear hobbing is performed at ∼300 m/min using high-speed steel hob cutters. In this study, ultra-high-speed gear hobbing was attempted using a large-diameter cemented carbide hob cutter on a gear grinder. This enabled a cutting speed up to 2450 m/min. Many interesting phenomena were acquired in this speed range. Chips were severely oxidized, whereas the gear surface was not affected. Compressive residual stress was generated at the gear surfaces with low surface roughness and high hardness, while the wear of hob cutter was insignificant.

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Dynamic modeling and in-process parametric compensation for fabricating micro straight thin walls by micromilling

Li Yang, Cheng Xiang, Zheng Guangming, Yan Jiwang, Liu Huanbao, Li Xuewei

JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T (Journal of Materials Research and Technology) 18 2480 - 2493 2022

ISSN 2238-7854

A comprehensive dynamic model is introduced try to further reduce dimensional errors of micromilled micro straight thin walls based on an in-process cutting parameter compensation device. First, a mathematical model is established to predict the dynamic elastic deformation of the thin walls in the micromilling process. Next, the radial deformation and the runout of the cutter are modeled. Then, the comprehensive in-process parametric compensation model and strategy are established. Finally, a real-time in-process cutting force measurement and cutting parameter compensation device is applied to the micromilling system and thin wall fabrication experiments have been conducted. It shows that the comprehensive dimensional error model and iterative compensation method are effective, and the dimension and shape precision of the micro straight thin wall has been obviously improved after the compensation of the radial cutting depth. The average relative errors have been reduced from 6.86% to 1.10%∼1.70%. The in-process compensation method introduced in this study is efficient and convenient as long as compensation strategies are integrated in the controlling unit for a specific micromilling process.

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Ultrasonic Vibration-Assisted Grinding of Carbon-Based Difficult-to-Cut Materials

Yan J.

Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering (Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering) 88 ( 7 ) 541 - 545 2022

ISSN 09120289

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A comparative study on mechanical polishing and laser polishing of laser-nitrided Zr-based metallic glass surface

Hong J., Zhang L., Zhang Z., Huang H., Yan J.

International Journal of Advanced Manufacturing Technology (International Journal of Advanced Manufacturing Technology) 124 ( 3-4 ) 959 - 971 2022

ISSN 02683768

As a promising surface modification method, nanosecond pulsed laser nitriding has been widely employed in enhancing the surface hardness and chemical corrosion of Zr-based metallic glass (MG). However, laser nitriding generally leads to poor finished surface quality, limiting its potential applications. For flattening the laser-nitrided surface, the most common methods, i.e., mechanical polishing (MP) and a novel proposed flattening approach, laser polishing (LP), were comparatively studied. A systematical comparison between MP and LP on three types of laser-nitrided surfaces was performed to evaluate the surface roughness, surface hardness, and plastic deformation. The experimental results indicate that the surface roughness of these three laser-nitrided surfaces is reduced by 56.4%, 58.1%, and 44.6% by MP. In contrast, a remarkable improvement in the surface quality is achieved with a maximum reduction in surface roughness by 80.4%, 81.5%, and 74.2% by LP, respectively. While in terms of the surface mechanical properties, the LP surfaces exhibit slightly lower hardness than the corresponding MP surfaces, which are both enhanced in hardness compared with as-cast MG. Additionally, no matter on the MP or LP surfaces, the shear bands and serrated flows have been significantly suppressed compared with as-cast MG, demonstrating that the micro-scale plastic deformation of as-cast MG has been modified. Although the obtained results indicate that the surface roughness of the laser-nitrided surface could be improved by both MP and LP, in terms of environmental friendliness, flexibility, and controllability, the LP shows dominant advantages and enormous potential in industry and consumer products.

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Effect of TiAlSiN coating residual stress on its sliding wear and cutting wear performance

Wu Z., Zheng G., Yan J., Cheng X., Liu H., Yang X.

International Journal of Advanced Manufacturing Technology (International Journal of Advanced Manufacturing Technology) 123 ( 11-12 ) 3885 - 3900 2022

ISSN 02683768

It is indispensable to explore the appropriate level of surface residual stress to enhance the wear resistance of coated tools. TiAlSiN-coated carbide tools with dissimilar surface residual compressive stresses (− 300 ~ − 600 MPa) are acquired via micro-sandblasting, which are used in the high-speed sliding friction experiments and turning experiments. The influence of residual stress on the sliding wear and cutting wear performance of TiAlSiN coated tools is investigated. The results show that with the improvement of surface residual compressive stress (absolute value), the friction coefficient and wear rate are reduced. The sliding wear resistance of the coated tool is enhanced. In addition, the cutting performance of the tool is also improved with the increase of residual compressive stress (absolute value). However, the excessive surface residual compressive stresses (absolute value) can lead to severe coating peeling, which in turn impairs the capability of wear resistance. The TiAlSiN-coated carbide tool with the stress of − 500 MPa presents the best wear resistance in the high-speed sliding wear and cutting wear process.

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New insights into the mechanisms of ultrasonic vibration cutting of brittle materials via multi-cyclic nanoindentation

Huang W., Yan J.

European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 22nd International Conference and Exhibition, EUSPEN 2022 (European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 22nd International Conference and Exhibition, EUSPEN 2022) 501 - 504 2022

Ultrasonic vibration cutting is a potential method for ductile machining of brittle materials. Although there are some research works trying to answer why the ultrasonic vibration promotes ductile machining of brittle materials, most of them are based on geometrical and kinematic analysis. In this study, plunge-cutting experiments under the conventional and vibration-assisted cutting conditions were conducted on single crystalline silicon and the results were compared to those of multi-cyclic nanoindentation tests. The surface morphology and subsurface microstructure of both machined grooves and residual indents were characterized. Results of plunge-cutting experiments show that with ultrasonic vibration cutting, the critical depth of cut for ductile-to-brittle transition and the amorphous phase in cutting chips are increased compared with conventional cutting. Results of multi-cyclic nanoindentation tests show that the indentation-induced amorphous layer increased as the cyclic number increased, which is consistent with the cutting results. The findings from this study may help understand the removal mechanism of brittle materials during ultrasonic vibration cutting.

Optimization of fast tool servo diamond turning for enhancing geometrical accuracy and surface quality of freeform optics

Zhang L., Sato Y., Yan J.

Fast tool servo (FTS) diamond turning is a promising technique for high-precision generation of freeform optics with remarkable efficiency. However, the conventional constant scheme for control point sampling fails to consider the surface variation, which might lose some details of the surface profile and result in low form accuracy and non-uniform surface quality. Facing this issue, this manuscript proposes a novel optimization method for control points sampling, which restrains the deviations and contains as much of the surface details. In the optimization method, the sampling intervals between two adjacent control points are actively adjusted to adapt the surface variation of the desired surface. By adopting this method, the sampling induced interpolation error between the control points is restrained within the tolerance and eliminates lack/over-definition of control points in the machining area. The feasibility of the proposed optimization method is demonstrated by both theoretical prediction and fabrication experiment of sinusoid freeform surface. Compared with the conventional sampling method, both the predicted and measured form error of the proposed method are remarkably reduced about 35 % with the same amount of control points. This technique provides a new route to sampling control points in FTS diamond turning to achieve high accuracy and flexible fabrication of freeform surface machining.

Surface functionalization of Zr-based metallic glass by direct nanosecond laser texturing

Y Qian, M Jiang, Z Zhang, H Huang, J Yan

Vacuum 194, 110635 (Elsevier {BV}) 194 110635 2021.12

ISSN 0042207X

The functional properties of metallic glasses (MGs) can be enhanced by introducing special micro/nano-structures on their surface. In this study, a nanosecond pulsed laser was used to texture micro-convex array structures with different pitches (P) on a Zr-based MG surface to enrich its engineering applications. The reflection characteristics and wettability of polished and textured surfaces were compared. The experimental results showed that unlike the bright spot reflected from the polished surface, the light reflected from the textured surface would induce a well-defined diffraction pattern. In addition, the wettability of the surfaces covered with micro-convex array structures was also different from that of the polished surface. That is, without post-processing, the textured array structures would promote hydrophilicity; while after exposing in the air for 100 days or fluoroalkylsilane modification, the textured array structures facilitated hydrophobicity.

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Evolution and control of deformation mechanisms in micro-grooving of Zr-based metallic glass

P Qiu, B Meng, S Xu, Y Rong, J Yan

Journal of Manufacturing Processes 68, 923-931 (Journal of Manufacturing Processes) 68 923 - 931 2021.08

ISSN 15266125

The evolution of deformation mechanisms with increasing depth of cut (DOC) in micro-grooving of Zr-based metallic glass was deeply investigated in this study for the first time. The micro-grooving characteristics of metallic glass were initially studied by nanoscratch test, which verified that the material removal mode abruptly changes from extrusion mode to cutting mode with increase of DOC. Based on the free-volume theory, a dynamic model coupling stress, temperature and free volume concentration was used to simulate the change of deformation characteristics with DOC. The results showed that the deformation mechanism of metallic glass is closely related to free volume flow, which is significantly affected by average strain rate and free volume flow coefficient in deformation zone and can be tuned with different DOC. Considering that free volume flow is determined by its flow coefficient and concentration, we proposed to control the deformation characteristics of metallic glass in micro-grooving by heat treatment and verified its effectiveness experimentally.

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On the transformation between micro-concave and micro-convex in nanosecond laser ablation of a Zr-based metallic glass

Y Qian, M Jiang, Z Zhang, H Huang, J Yan

Journal of Manufacturing Processes 68, 1114-1122 (Journal of Manufacturing Processes) 68 1114 - 1122 2021.08

ISSN 15266125

Understanding the physical mechanism of laser-material interaction is significant and meaningful in both pure science and engineering applications. Laser ablation induced micro-concave is a commonly-observed phenomenon, but the formation of micro-convex by laser ablation is rarely reported. In this study, the transformation in surface microstructure from micro-concave to micro-convex, then to micro-concave again was reported for the first time in laser ablation of a typical Zr-based metallic glass (MG). The experimental results indicated that such transformations strongly depended on the peak laser power intensity and number of laser pulses. The coupling effects of the recoil pressure and Marangoni flow were proposed to explain the observed transformation. By locally overlapping adjacent micro-convexes, various surface patterns could be fabricated on the MG surface, which could tune its surface wettability. This study would not only enhance the understanding of laser-MG interaction but also provide new methods for patterning MG surface.

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Evolution of high-pressure metastable phase Si-XIII during silicon nanoindentation: A molecular dynamics study

Zhang L., Yan J.

Computational Materials Science (Computational Materials Science) 191 2021.04

ISSN 09270256

© 2021 Elsevier B.V. Berkovich indenters are widely employed in nanoindentation experiments of single-crystal silicon, in molecular dynamic simulations of silicon nanoindentation, however, spherical indenters are generally employed. To close this gap, in this paper, a series of molecular dynamic simulations are conducted on (0 0 1), (1 0 1), and (1 1 1) silicon surfaces to explore the evolution of high-pressure phases. Several possible silicon phases are tracked by coordination number (CN), radial distribution function (RDF), and angular distribution function (ADF). Results show that the metastable phases and the high-pressure phases present different symmetrical patterns along different crystallographic orientations. A large amount of high-pressure phase Si-XIII, which is seldomly observed in nanoindentation using a spherical indenter, is first discovered under the Berkovich indenter, and the evolution mechanism is characterized by tracking the position transition of labeled silicon atoms. As a transition phase for high-pressure phase Si-II and Si-XIII, bct5 phase is found in the {1 1 1} [1 1 0] slip systems, which is related with slipping flatten lattice structures. Different from the phase transformation criterion for Si-II, the transformation from Si-I to Si-XIII companies with the local elastic deformation of (0 0 1) surface. The atoms in the three neighboring unit cells are compressed into a uniform long-distance ordered crystal structure. Upon indenter extraction and rapid stress releasing, the elastic deformation of the crystal surface resumes incompletely. A part of Si-XIII recovers to pristine Si-I and the rest changes into amorphous phase. The distribution of local hydrostatic pressure and von Mises stress in the phase transformation regions indicates that the concentrated hydrostatic pressure and specific stress induce this high-pressure silicon phase. This research clarifies the evolutionary process of Si-XIII phase generation and enriches fundamental understanding on the mechanisms of silicon phase transformations in nanoindentation.

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Annealed high-phosphorus electroless Ni–P coatings for producing molds for precision glass molding

Yu Q., Zhou T., He Y., Liu P., Wang X., Jiang Y., Yan J.

Materials Chemistry and Physics (Materials Chemistry and Physics) 262 2021.04

ISSN 02540584

© 2021 Elsevier B.V. An annealed high-phosphorus electroless Ni–P coating was developed as the mold material for precision glass molding. The coating with a phosphorus content of 11.6 wt% was prepared on heat-resistant stainless steel via an intermittent ultrasonic-assisted electroless plating method. The effects of annealing temperature and heating rate on phase transformation, grain size variation, and mechanical properties were investigated. An annealing temperature of 600 °C with a heating rate of 5 °C/min was determined to be the optimal choice for heat treatment. Microgrooves were machined on the coating surface. After heat treatment, the increased hardness and modulus helped the microgrooves on the coating resist thermal deformation during the PGM process. The PV value decreased from 0.58 to 0.32 μm, and the surface roughness decreased from Sa 104.5 to Sa 62.6 nm. The mold produced by heat-treated coating was beneficial for improving the forming accuracy of precision glass molding.

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Deterministic error compensation for slow tool servo-driven diamond turning of freeform surface with nanometric form accuracy

Nagayama K., Yan J.

Journal of Manufacturing Processes (Journal of Manufacturing Processes) 64 45 - 57 2021.04

ISSN 15266125

© 2021 The Society of Manufacturing Engineers Slow tool servo (STS) turning takes an important role in fabrication of freeform optical elements. However, in conventional STS turning, it is technologically difficult to obtain nanometer-level form accuracy due to multiple error factors such as tool trajectory errors, tool alignment errors and dynamic follow-up errors of machine tools used. In this study, a deterministic process flow was proposed where all the main error factors were comprehensively analyzed, simulated and then compensated before machining based on the feedforward method, and the workpiece form error after compensation was predicted accurately. The proposed process flow enabled achieving nanometer-level form accuracy by a single cut without the necessity of repetitive trial-and-error. To demonstrate the effectiveness of the proposed method, cutting tests of a two-dimensional sine wave grid were attempted on single-crystal silicon and the proposed error compensation was applied. As a result, the form error was reduced to 8 nm P–V (peak to valley) with a surface roughness of 1 nm Sa by a single cut.

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Diffraction manipulation of visible light with submicron structures for structural coloration fabrication

He Y., Zhou T., Dong X., Zhu Z., Yu Q., Liu P., Zhao W., Wang X., Hu Y., Yan J.

Optics Express (Optics Express) 29 ( 6 ) 9294 - 9311 2021.03

© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement The structural coloration of glass induced by submicron structures is eco-friendly, ink-free, and has profound scientific significance. However, it is difficult to manufacture the submicron structures for glass optics due to the high hardness of glass and the miniature size of the microstructures. In this paper, the diffraction manipulation mechanism of groove shape to structural coloration and optimization theory are studied by establishing the theoretical and simulation mode. Moreover, a newly-developed axial-feed fly-cutting (AFC) technology and the PGM technology are introduced to precisely create the designed submicron V-shape grooves and structural color pattern on a Ni-P mold and then replicating them on a glass surface. Between these two kinds of typical submicron grooves that can be machined by mechanical cutting technology, it is found that the diffraction intensity and efficiency of V-shape grooves are higher than these of jagged-shape grooves, which indicates that V-shape grooves is more suitable to be used for structural coloration with high brightness. The structural color resolution is dramatically increased with the reduction of groove spacing and can be flexibly regulated by AFC, which significantly contributes to the structural coloration manufacturing. Structural pixel segments composed of submicron grooves are arranged row-by-row to form color patterns, and the letters of different colors are fabricated on the mold and transferred to the glass surface. Methods of optical diffraction manipulation, flexible manufacturing of submicron structures, and structural color image construction proposed in this paper for the production of a structural color pattern are beneficial to a wide range of fields.

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Chip-free surface patterning of toxic brittle polycrystalline materials through micro/nanoscale burnishing

Huang W., Yan J.

International Journal of Machine Tools and Manufacture (International Journal of Machine Tools and Manufacture) 162 2021.03

ISSN 08906955

© 2021 Elsevier Ltd Brittle crystalline materials have important applications in optics and optoelectronics. However, their powders are highly toxic; thus, the chips generated in material removal processes such as cutting, grinding, and polishing are harmful to human health and the environment. In this study, micro/nanoscale burnishing tests were conducted on polycrystalline zinc selenide (p-ZnSe) to explore the feasibility of high-precision surface patterning of a toxic material by local plastic deformation without chip generation. The local deformation behaviours and subsurface damage formation mechanisms were investigated under dry and oil-lubricated conditions. Two types of cracks occurred when the force exceeded a critical value: cracks along the slip planes at the groove bottom and cracks along the cleavage planes at the groove edge. Below the critical force value, however, a crack-free surface was obtained with lower surface roughness than those for diamond-turned surfaces. No phase transformation was detected after burnishing, but lattice distortion appeared in the subsurface layer. A model was developed to predict the activated slip planes by calculating the maximum Schmid factors of the slip systems, and the distribution of subsurface defects was clarified by cross-sectional direct observations. It was also found that the use of a lubricating oil could greatly reduce material pile-ups around the tool. As test pieces, microgrid patterns were fabricated by crossing and overlapping the grooves, and smooth surfaces with surface roughness of 1.85 nm Sa and 4.5 nm Sa, respectively, were achieved. The findings from this study demonstrate the feasibility of chip-free surface patterning on toxic brittle polycrystalline materials by micro/nanoscale burnishing, which is an effective alternative to cutting and grinding for the fabrication of micro structured optical elements and microfluidics.

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Fundamental Investigation of Diamond Cutting of Micro V-shaped Grooves on a Polycrystalline Soft-Brittle Material

W Huang, J Yan

Journal of Manufacturing and Materials Processing 5 (1), 17 (Journal of Manufacturing and Materials Processing) 5 ( 1 ) 2021.03

Fabricating micro-structures on optical materials has received great interest in recent years. In this work, micro-grooving experiments were performed on polycrystalline zinc selenide (ZnSe) to investigate the feasibility of surface micro-structuring on polycrystalline soft-brittle material by diamond turning. A photosensitive resin was coated on the workpiece before cutting, and it was found that the coating was effective in suppressing brittle fractures at the edges of the grooves. The effect of tool feed rate in groove depth direction was examined. Results showed that the defect morphology on the groove surface was affected by the tool feed rate. The crystallographic orientation of grains around the groove was characterized by electron backscatter diffraction (EBSD), and it was found that the formation of defects was strongly dependent on the angle of groove surface with respect to the cleavage plane of grain. The stress distribution of the micro-grooving process was investigated by the finite element method. Results showed that the location of tensile stresses in the coated workpiece was farther from the edge of the groove compared with that in the uncoated workpiece, verifying the experimental result that brittle fractures were suppressed by the resin coating.

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One-step fabrication of regular hierarchical micro/nano-structures on glassy carbon by nanosecond pulsed laser irradiation

Wang C., Huang H., Qian Y., Zhang Z., Yan J.

Journal of Manufacturing Processes (Journal of Manufacturing Processes) 62 108 - 118 2021.02

ISSN 15266125

Fabrication of hierarchical micro/nano-structures on glassy carbon (GC) surface is important for the application of GC as the mold material for glass molding, but it is still challenging due to the high brittleness and hardness of the material. In this study, by using a nanosecond pulsed laser, a hierarchical micro/nano-structure, i.e., micro-dimple with ring-like nanostructure on its inner wall, was generated on the GC surface. The effects of laser parameters, such as laser irradiation time and fluence, on the formation and evolution of the hierarchical micro/nano-structure were experimentally studied. By comparative experiments with graphite, the role of amorphous nature of GC on the formation of very regular hierarchical micro/nano-structure was confirmed. The results obtained by irradiating GC in argon and nitrogen gas further indicated that the formation of hierarchical micro/nano-structure was independent of the gas atmosphere. By controlling the relative positions of point shots, various micro-dimple arrays were successfully fabricated on the GC surface which significantly changed its wetting behavior. Finally, formation mechanism of the hierarchical micro/nano-structure was discussed according to the experimental results as well as some previous literatures. This study provides a one-step method for fabricating hierarchical micro/nano-structures on the GC surface by nanosecond pulsed laser irradiation, which would be meaningful for the functional applications of GC.

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