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Papers - Yan, Jiwang

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Nanosecond pulsed laser-induced formation of nanopattern on Fe-based metallic glass surface

Y Qian, H Huang, M Jiang, J Yan

Applied Surface Science, 151976 (Applied Surface Science) 577 2021

ISSN 01694332

Fe-based metallic glasses (MGs) have attracted much attention because of their cheap raw materials, outstanding soft magnetic properties and superior catalytic activity. Meanwhile, the fabrication of micro/nano-structures on its surface could further improve its functional properties. In this study, it was attempted to fabricate micro/nano-structures on a Fe-based MG (Fe52Cr13Mo12C15B6Er2, in at. %) surface by nanosecond pulsed laser irradiation technology. The surface characteristics and microstructural evolution of Fe-based MG were investigated. The experimental results showed that under different laser fluences, the laser-irradiated areas exhibited distinguished microstructures, i.e., nanoparticles, the network nanostructures or a combination of these two microstructures. Furthermore, oxygen and erbium were enriched inside the network nanostructures. By analyzing the microstructural evolution, formation mechanisms of the nanoparticles and the network nanostructures were discussed. The nanoparticles were actually caused by laser-induced element enrichment (i.e. amorphous erbium oxide) and the mismatch of its wettability with the substrate; the formation of the network nanostructures was attributed to the diffusion and connection of nanoparticles under the combined influence of recoil pressure and surface topography.

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Machinability exploration for high-entropy alloy FeCrCoMnNi by ultrasonic vibration-assisted diamond turning

L Zhang, T Hashimoto, J Yan

CIRP Annals (CIRP Annals) 70 ( 1 ) 37 - 40 2021

ISSN 00078506

High-entropy alloy (HEA) is an emerging alloy which consists of five or more metallic elements with equimolar concentrations and exhibits excellent mechanical properties at cryogenic temperature. However, its machinability is almost unknown. In this study, high frequency one-dimensional ultrasonic vibration-assisted diamond turning (UVDT) experiments were conducted on an FeCrCoMnNi-based HEA to investigate the micro-nanoscale material removal mechanisms. Compared with conventional diamond turning, UVDT produced thinner chips, lower cutting forces, less tool wear and better surface integrity. Due to the ultrasonic vibration-assisted burnishing effect, surface scratches were significantly eliminated. A freeform surface was test-fabricated with optical-level finish.

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Effects of relative tool sharpness on surface generation mechanism of precision turning of electroless nickel-phosphorus coating

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

Journal of Mechanical Science and Technology, 1-9 (Journal of Mechanical Science and Technology) 35 ( 7 ) 3113 - 3121 2021

ISSN 1738494X

Relative tool sharpness (RTS) is identified as the ratio of undeformed chip thickness to tool cutting edge radius. This paper studies the effects of RTS on the surface generation mechanism of precision turning of electroless nickel-phosphorus (Ni-P) coating. An R-shaped tungsten carbide (WC) tool was adopted for the face turning experiment. The cutting edge radius was 1.84 µm measured by a laser scanning confocal microscope (LSCM). The chip formation behavior, cutting forces and surface morphology were investigated under different RTS values. Results showed that the chip changes from continuous to discontinuous as RTS decreases from 0.54 to 0.27, indicating the transition of the material removal mechanism. The periodical fluctuations with small amplitudes on the machined surface are associated with the high-frequency tool-tip vibration. The low-frequency fluctuations of the cutting forces are related to the material swelling and recovery. The optimal machined surface roughness was obtained at the RTS of 0.38.

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Laser nitriding of Zr-based metallic glass: An investigation by orthogonal experiments

J Hong, Y Qian, L Zhang, H Huang, M Jiang, J Yan

Surface and Coatings Technology, 127657 (Surface and Coatings Technology) 424 2021

ISSN 02578972

Laser nitriding is a useful method to improve the surface hardness of materials, and it has been newly introduced to harden the surface of Zr-based metallic glass (MG). However, the currently achieved improvement in surface hardness is only 15.7%. To explore the potential of laser nitriding of Zr-based MG, orthogonal experiments were designed and performed in this study. By nanosecond pulsed laser irradiation in nitrogen atmosphere, the effects of laser parameters (average laser power, scanning speed, overlap rate and number of irradiation cycle) on the surface hardness of Zr-based MG were systematically investigated. The experimental results showed the highest surface hardness reached 18.21 GPa (Meyer's hardness) by orthogonal design, which is about 2 times higher than that of the as-cast MG. Furthermore, the laser affecting layer consisting of nitride phase reached tens of microns. The obtained results demonstrated that significant improvement in surface hardness could be achieved by selecting appropriate laser irradiation parameters, which would be beneficial to the engineering applications of MGs as surface contact materials.

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Machinability Investigation for Cellulose Nanofiber-Reinforced Polymer Composite by Ultraprecision Diamond Turning

Y Kamada, J Yan

International Journal of Automation Technology 15 (4), 475-482 (富士技術出版株式会社) 15 ( 4 ) 475 - 482 2021

ISSN 1881-7629

Cellulose nanofiber (CeNF)-reinforced polymer composites have wide potential applications in the manufacturing of optical and mechanical parts owing to their light weight, high mechanical strength, and optical transparency. In this study, CeNF-reinforced homogeneous polypropylene (PP-CeNF) was machined under various conditions by ultraprecision diamond turning, and the results were compared with those of pure PP without CeNF addition. The influence of CeNFs on material removal was investigated by examining the surface topography, chip morphology, cutting forces, and cutting temperature. It was found that the surface defects in pure PP cutting were surface tearing, while the surface defects of PP-CeNF were surface tearing and micro-holes induced by the pulling-outs of CeNFs. Surface tearing increased with cutting speed; pulling-outs of CeNFs were slightly affected by cutting speed but strongly dependent on the tool feed rate. Under a small tool feed rate, the surface roughness could be reduced to ∼10 nm Ra for PP-CeNF. The thermal effect was insignificant in the experiments, whereas the effect of strain rate-induced material hardening was dominant for both workpiece materials at a high cutting speed. This study helps to understand the mechanisms for ultraprecision cutting of CeNF-reinforced polymer composites and provides guidelines for improving the machined surface quality.

Tribological characteristics of electrical discharge coated layers using quarry dust suspension

CY Yap, PJ Liew, ISB Othman, MFB Abdollah, J Yan

Surface and Coatings Technology, 127895 (Surface and Coatings Technology) 428 2021

ISSN 02578972

In this research, a coating layer was formed on the tungsten carbide cobalt (WC-Co) substrate surface by using electrical discharge coating (EDC) with waste quarry dust powder suspension. The tribological test was carried out by using a micro pin-on-disc tribometer at a constant normal load (10N) and sliding speed (5 mm/s). The surface roughness, Vickers micro-hardness, coefficient of friction (CoF), wear weight loss, wear scar depth and wear track morphology of the coating layer were investigated and compared with the original surface of the WC-Co substrate in this study. The results indicated that under coating conditions of 5 A of peak current (Ip) and 300 μs of pulse on time (Ton), the Vickers micro-hardness increased by 28%, and the surface roughness, CoF, wear weight loss, and wear scar depth of coating layer reduced by 29%, 61%, 79%, 63%, respectively compared with the original WC-Co substrate. These results demonstrated that the coating layers produced by EDC with quarry dust waste powder suspension had good wear resistance, which could be beneficial to the cutting tool, mold and die industries.

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Laser induced micro-cracking of Zr-based metallic glass using 1011 W/m2 nano-pulses

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

Materials Today Communications (Materials Today Communications) 25 2020.12

© 2020 Elsevier Ltd Low power nanosecond laser irradiation has potential applications in surface processing of metallic glasses (MGs). However, the response of MGs to a relatively low power intensity (1011 W/m2) has not been investigated. In this study, surface microstructures and characteristics of Zr-based MG after low power nanosecond laser irradiation were studied. Micro-cracks with depth in nanoscale and width in microscale were observed on the irradiated MG surface. The effects of laser parameters on the formation and evolution of micro-cracks were further investigated, and surface characteristics were characterized by using X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The results showed that under the peak laser power intensity of 2.3 × 1011 W/m2, when increasing the scanning speed from 1 to 5 mm/s, the maximum width of micro-cracks reduced from 3 μm to be less than 1 μm; further increasing to 10 mm/s, no micro-cracks appeared. When increasing the laser power intensity, the micro-groove structure would be formed with pileup around it and line cracks, open cracks and laser pulse tracks on it. During multi-line laser scanning, the pulse overlap rate also affected the formation and distribution of micro-cracks. At last, the formation mechanism of micro-cracks was discussed. These results would be meaningful for understanding the laser-MG interaction as well as guiding the selection of laser parameters for various applications.

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Algorithm of Micro-Grooving and Imaging Processing for the Generation of High-Resolution Structural Color Images

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

Nanomanufacturing and Metrology (Nanomanufacturing and Metrology) 3 ( 3 ) 187 - 198 2020.09

ISSN 2520811X

© 2020, International Society for Nanomanufacturing and Tianjin University and Springer Nature Singapore Pte Ltd. The use of submicron structures for structural coloration of surfaces has broad applications for color filters, projection displays, virtual reality, and anti-counterfeiting. Currently, structural color images lack high resolution due to low manufacturing accuracy. In this study, the axial-feed fly cutting (AFC) method is proposed to fabricate submicron grooves for the diffraction of visible light to create structural color images. We establish the relationship between the color information in the pixels of the original image and the parameters of the array units corresponding to the pixels. An algorithm to determine groove spacing and the tool path is established, and array units with the desired groove spacing are machined to reproduce the structural color images. The submicron grooves fabricated by AFC have high quality and good consistency. Due to the excellent diffraction performance of the machined grooves, images with high saturation and resolution can be reproduced. It is verified that images with various colors can be efficiently fabricated using the proposed method and algorithm.

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Generation of high-saturation two-level iridescent structures by vibration-assisted fly cutting

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

Materials and Design (Materials and Design) 193 2020.08

ISSN 02641275

© 2020 The Authors The submicron-level structured surface induces viewing-angle-dependent iridescence, and has wide applications in multi-color printing, micro-display projection, invisibility cloak technology. In this study, several types of two-level structures, which consist of the first-order micro geometric features corresponding to the pattern shape and the second-order submicron grooves corresponding to the diffraction grating, are designed to directly induce a variety of iridescent patterns based on their shape regulations. To fabricate these two-level iridescent structures with high accuracy in a single step, vibration-assisted fly cutting (VAFC) is proposed. VAFC involves the low-frequency vibration of the workpiece in the vertical direction during the feed in the horizontal direction and the high-speed rotation of the diamond cutting tool. A 3D theoretical model is established for the numerical simulation of the generating process of the iridescent structures and the regulation of the first-order geometric feature by vibration parameters. As the key parameter to the iridescent color, the spacing of the second-order submicron grooves is flexibly controlled by the feed rate. A VAFC platform is developed to fabricate the two-level structures and an optical detection system is setup to test the surface iridescence. Various vivid colors are regulated by the two-level structures with high saturation and uniformity.

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Silicon nanoparticle generation and deposition on glass from waste silicon powder by nanosecond pulsed laser irradiation

Momoki K., Manabe T., Li L., Yan J.

Materials Science in Semiconductor Processing (Materials Science in Semiconductor Processing) 111 2020.06

ISSN 13698001

© 2020 Elsevier Ltd Silicon nanoparticles can be used for fabricating electrodes in high-performance lithium ion batteries and other high value-added products. Currently, silicon nanoparticles are fabricated by pulsed laser irradiation of single-crystal silicon wafers in water. In this study, we proposed silicon nanoparticle generation by using a nanosecond pulsed laser to irradiate waste silicon powder which is disposed from wire-saw slicing processes of silicon ingots. The laser-induced nanoparticles were backward-transferred and deposited on a glass substrate. It was found that the morphology and amount of the deposited nanoparticles was strongly dependent on the distance between the glass substrate and the waste silicon powder target. Raman spectroscopy showed that the silicon nanoparticles were crystalline, and the average size was ~10 nm. The obtained silicon nanoparticles had high purity, as the diamond abrasives included in the waste silicon powder were removed through oxidation and vaporization during laser irradiation.

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Generating Nanodot Structures on Stainless-Steel Surfaces by Cross Scanning of a Picosecond Pulsed Laser

Kobayashi T., Yan J.

Nanomanufacturing and Metrology (Nanomanufacturing and Metrology) 3 ( 2 ) 105 - 111 2020.06

ISSN 2520811X

© 2020, The Author(s). Ultrashort pulsed laser-induced periodic surface structures (LIPSS) can be generated on different kinds of materials, which are widely utilized for modifying surface properties such as wettability, adhesion, and tribological, as well as optical performances. Previous studies have focused mainly on one-dimensional LIPSS (i.e., line structure) generation. In this study, a picosecond pulsed laser was used to irradiate stainless-steel surfaces for generating two-dimensional LIPSS, namely nanodot structures, by cross-scanning the laser beam for a different number of times. The obtained nanodot structures were found to be super hydrophilic just after laser irradiation, but turned to be hydrophobic after exposure in air for a few days. By cross-scanning the laser beam for the same number of times, local LIPSS rewriting was realized. This study showed the possibility of improving the homogeneity of the surface properties of steel materials through laser-induced nanodot structuring.

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Surface formation mechanism in ultraprecision diamond turning of coarse-grained polycrystalline ZnSe

Huang W., Yan J.

International Journal of Machine Tools and Manufacture (International Journal of Machine Tools and Manufacture) 153 2020.06

ISSN 08906955

© 2020 Elsevier Ltd Zinc selenide is an excellent infrared optical material. In this study, ultraprecision diamond turning experiments were carried out on coarse-grained polycrystalline ZnSe (p-ZnSe) under various conditions and the corresponding surface formation mechanisms were investigated by examining the surface topography, chip morphology, material microstructural change, and cutting forces. Two kinds of surface defects were observed (i.e. plowing-induced micron-scale cleavage craters and tearing-induced submicron-scale tearing pits). It was determined that plowing induced micron-scale cleavage craters could be suppressed by reducing undeformed chip thickness. Furthermore, it was ascertained that tearing-induced submicron-scale tearing pits could be restrained by using a cutting tool with a zero rake angle. The minimal surface roughness was dominated by grain boundary steps formed when the cutting tool crossed twin boundaries at a large angle. A model was proposed for correlating surface defects and boundary steps with crystal orientations and cutting directions. By using a large-nose diamond tool for cutting, a smooth surface of 1.5 nm Sa was obtained. In addition, a zinc blende to cinnabar phase transformation was observed in the cutting chips, and metallization of cutting chips occurred at an extremely small undeformed chip thickness (~20 nm). Moreover, it was discovered that phase transformation inside the workpiece depends on the radius of the tool nose. The findings of this study provide an important reference for ultraprecision machining of brittle polycrystalline materials.

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Drilling of cemented carbide by ultrasonic vibration-assisted grinding on a flexible stage

A. Teramachi, S. Tarvainen, J. Yan

Journal of the Japan Society for Abrasive Technology 64 ( 6 ) 320 - 325 2020.06

Research paper (scientific journal), Joint Work, Accepted

Additive manufacturing of three-dimensional metal-glass functionally gradient material components by laser powder bed fusion with in situ powder mixing

Zhang X., Chueh Y.h., Wei C., Sun Z., Yan J., Li L.

Additive Manufacturing (Additive Manufacturing) 33 2020.05

© 2020 Elsevier B.V. Existing commercial three-dimensional (3D) printing systems based on powder bed fusion approach can normally only print a single material in each component. In this paper, functionally gradient materials (FGM) with composition variation from a copper alloy to a soda-lime glass were manufactured using a proprietary nozzle-based multi-material selective laser melting (MMSLM) system. An in situ powder mixing system was designed to mix both metal and glass powders at selective ratios and the mixed powders were dispensed with an ultrasonic vibration powder feeding system with multiple nozzles. From the cross section analysis of the gradient structures, glass proportion increased gradually from the metallic matrix composite (MMC), transition phase to ceramic matrix composite (CMC). The pure copper alloy joined the MMC part and the pure glass phase penetrated into the CMC part during laser processing, which anchored the glass phase, as the main mechanism of combining pure metal and pure glass by FGM in 3D printed parts. From results of indentation, tensile and shear tests on the gradient material samples, it showed that mechanical properties of the FGM gradually changed from ductility (metal side) to brittle (glass side). The weakest part of the FGM structure occurred at the interface between transition phase and the CMC, which was also the interface between the ductile and brittle phases.

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Generating silicon nanofiber clusters from grinding sludge by millisecond pulsed laser irradiation

Momoki K., Takahashi K., Kobinata K., Kobayashi Y., Kawai A., Yan J.

Nanomaterials (Nanomaterials) 10 ( 4 ) 2020.04

© 2020 by the authors. Licensee MDPI, Basel, Switzerland. Silicon nanofiber clusters were successfully generated by the irradiation of millisecond pulsed laser light on silicon sludge disposed from wafer back-grinding processes. It was found that the size, intensity, and growing speed of the laser-induced plume varied with the gas pressure, while the size and morphology of the nanofibers were dependent on the laser pulse duration. The generated nanofibers were mainly amorphous with crystalline nanoparticles on their tips. The crystallinity and oxidation degree of the nanofibers depended on the preheating conditions of the silicon sludge. This study demonstrated the possibility of changing silicon waste into functional nanomaterials, which are possibly useful for fabricating high-performance lithium-ion battery electrodes.

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Effect of relative tool sharpness on subsurface damage and material recovery in nanometric cutting of mono-crystalline silicon: A molecular dynamics approach

Ameli Kalkhoran S., Vahdati M., Yan J.

Materials Science in Semiconductor Processing (Materials Science in Semiconductor Processing) 108 2020.03

ISSN 13698001

© 2019 Elsevier Ltd Depth of cut (h0) and tool edge radius (re) are two key parameters in nanometric cutting, investigating both of the two parameters simultaneously can provide comprehensive understanding of the cutting mechanism. In this paper, relative tool sharpness (RTS), which is quantified as h0/re, is employed as a factor to examine the subsurface damage and material recovery in nanometric cutting of mono-crystalline silicon using molecular dynamics (MD) simulation. Various RTS values were generated by changes of cutting depth at different tool edge radius of 1, 3 and 5 nm respectively. Results indicate that there is always a layer of particles which sticks on the tool surface and influences the machined surface, even at RTS = 0. Besides that, the increase of RTS results in subsurface damage layer serration, which is caused by stick-slip phenomenon between the tool and workpiece. A bigger RTS causes a bigger depth of serrations, although the number of serrations remains constant. Increase in RTS also causes the formation of the hexagonal diamond structure. The material recovery drops dramatically by RTS increase. Using a sharper tool edge (RTS<0.25) at a cutting depths below 1 nm does not necessarily decrease subsurface damage due to the drastic stress concentration. It is also demonstrated that silicon amorphisation can occur in the unmachined region in front of the tool due to the hydrostatic pressure wave caused by tool advancement.

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Electrical Discharge/Electrochemical Hybrid Machining Based on the Same Machine and Tool Electrode

R Kishi, J Yan

Journal of Micro and Nano-Manufacturing 8 (1) (Journal of Micro and Nano-Manufacturing) 8 ( 1 ) 2020.03

ISSN 21660468

Electrical discharge machining (EDM) causes surface defects such as resolidified layer and microcracks, and a finishing process is usually needed to remove these defects. In this paper, a hybrid process was proposed where electrochemical machining (ECM) was performed as a finishing process after EDM using the same tool electrode on the same machine. By using two kinds of disk-type rotary electrodes, rectangular grooves and grooves with convex inner structures were fabricated. Surface topography were investigated by using scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDX), and laser-probe surface profilometer. The material removal mechanism of resolidified layers was clarified. The surface roughness of the rectangular groove was improved from 3.82 μm Ra to 0.86 μm Ra after ECM. Electrode rotation was effective for flushing electrolytic products when fabricating inner structures. As there is no need for exchanging tools and machines, tool alignment error can be prevented and productivity can be improved. Therefore, the proposed EDM/ECM hybrid process contributes to rapid fabrication of microscale products with high surface integrity.

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Effects of deep subsurface damages on surface nanostructure formation in laser recovery of grinded single-crystal silicon wafers

Niitsu K., Yan J.

Precision Engineering (Precision Engineering) 62 213 - 222 2020.03

ISSN 01416359

© 2019 Elsevier Inc. A nanosecond pulsed Nd:YVO4 laser was irradiated on a boron-doped single-crystal silicon wafer after rough and fine grinding processes to recover the grinding-induced subsurface damages. The surface topography of samples was investigated by using a white-light interferometer, a scanning electron microscope, and an atomic force microscope; while the crystallinity was analyzed by a laser micro-Raman spectrometer. It was found that surface nanostructures were generated by the Mullins-Sekerka instability, which remained on the surface under recoil pressure and surface tension. The rough grinding-induced deep subsurface damages influenced the interface instability between liquid and solid silicon during recrystallization process. By increasing pulse width and decreasing laser peak irradiance, the subsurface damage was recovered and a flat surface with surface roughness of ~1 nm Sa was obtained. This study reveals important correlations among grinding-induced latent subsurface defects, laser peak irradiance and nanoscale surface topography formation in laser recovery, which contributes to high quality silicon wafer manufacturing.

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Surface modification and functionalization by electrical discharge coating: A comprehensive review

Liew P.J., Yap C.Y., Wang J., Zhou T., Yan J.

International Journal of Extreme Manufacturing (International Journal of Extreme Manufacturing) 2 ( 1 ) 2020.03

ISSN 26318644

© 2020 The Author(s). Published by IOP Publishing Ltd on behalf of the IMMT Hard coatings are extensively required in industry for protecting mechanical/structural parts that withstand extremely high temperature, stress, chemical corrosion, and other hostile environments. Electrical discharge coating (EDC) is an emerging surface modification technology to produce such hard coatings by using electrical discharges to coat a layer of material on workpiece surface to modify and enhance the surface characteristics or create new surface functions. This paper presents a comprehensive overview of EDC technologies for various materials, and summarises the types and key parameters of EDC processes as well as the characteristics of resulting coatings. It provides a systematic summary of the fundamentals and key features of the EDC processes, as well as its applications and future trends.

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Nanoparticle generation from various types of silicon materials by nanosecond-pulsed laser irradiation

Momoki K., Yan J.

Applied Physics Express (Applied Physics Express) 13 ( 2 ) 2020.02

ISSN 18820778

© 2020 The Japan Society of Applied Physics. A huge amount of silicon sludge is disposed of from silicon wafer manufacture, and its reuse is a critical issue. In this study, silicon nanoparticle generation from sludge was explored by nanosecond-pulsed laser irradiation. The nanoparticle production efficiency from silicon sludge was compared with that from silicon wafers. The result showed that using silicon sludge as a laser irradiation target leads to a distinctly higher production efficiency of nanoparticles; the smaller the powder size of the silicon sludge, the higher the efficiency. The generated silicon nanoparticles were crystalline with sizes at the 10 nm level.

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