論文 - 閻　紀旺

Effects of tool rake angle and tool nose radius on surface quality of ultraprecision diamond-turned porous silicon

M. Heidari, J. Akbari, J. Yan

Journal of Manufacturing Processes （Journal of Manufacturing Processes）  37   321 - 331 2019年01月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  15266125

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© 2018 The Society of Manufacturing Engineers This paper presents an investigation of the effects of tool rake angle and nose radius on the surface quality of ultraprecision diamond-turned porous silicon. The results showed that as rake angle decreases, the high-stress field induced by the tool edge increases, causing microcracks to propagate extensively near the pore walls. As a result, the ductile-machined areas shrank under a negative tool rake angle. On the other hand, brittle fracture occurred around pores released cutting pressure significantly. These trends of rake angle effects are distinctly different from those in the cutting of non-porous silicon. Finite element simulation of stress in the cutting area agreed with the experimental results. The results also indicated that using a tool with a bigger nose radius suppressed brittle fractures around the pore edge and improved surface quality. Raman spectroscopy of the ductile-machined surfaces revealed that the amorphization of the subsurface layer became more significant when decreasing tool rake angle or increasing tool nose radius. By choosing the optimal tool geometry, a high quality surface can be achieved on porous silicon, which demonstrates the capability of the diamond turning process to fabricate high-precision components.

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Investigation of Ultra-Precision Machining on Single Crystal Silicon Using Molecular Dynamics Simulation and Experiments

SN Ameli Kalkhoran, M Vahdati, J Yan

Amirkabir Journal of Mechanical Engineering 52 (3), 731-742 2019年

Single-grain cutting based modeling of abrasive belt wear in cylindrical grinding

He Z., Li J., Liu Y., Yan J.

Friction （Friction）  8 （ 1 ） 208 - 220 2019年

ISSN  22237690

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© 2019, The Author(s). A systematic wear model of the cylindrical grinding process with an alumina abrasive belt from the perspective of single grain sliding wear was established in this study. The model consists of three parts: a single cutting force model derived by applying a stress integration method, a single grain wear height analysis based on the wear rate of alumina, and a grinding mileage prediction of multiple grains with Gaussian distributed protrusion heights. Cutting force, single grain wear height and full-size grinding mileage verification experiments were conducted. The results indicated that the established model was in reasonable agreement with the experimental outcomes, which suggests that this model could be useful in the industry to predict the wear process of abrasive belts.

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Chip morphology and surface integrity in ultraprecision cutting of yttria-stabilized tetragonal zirconia polycrystal

Yan J., Okuuchi T.

CIRP Annals 2019年

ISSN  00078506

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© 2019 Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is an important material for dental, biomedical, and mechanical applications. In this study, Y-TZP was cut by a single-crystal diamond tool in the micro-nanometre scale. The chip morphology and machined surface/subsurface properties under various conditions were investigated by scanning electron microscopy, Raman spectroscopy and cross-sectional transmission electron microscopy. Two factors dominating the material removal were identified: (i) crystal grain refinement and (ii) tetragonal-to-monoclinic phase transformation, the mechanisms of which were established by experiments and finite element simulations. This study provides a possible solution to the rapid fabrication of small 3D features on Y-TZP with nanometric surface roughness and an ultra-fine-grained subsurface layer.

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Molecular Dynamics Investigation of Nanometric Cutting of Single-Crystal Silicon Using a Blunt Tool

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

JOM （JOM）  71 （ 12 ） 4296 - 4304 2019年

ISSN  10474838

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© 2019, The Minerals, Metals & Materials Society. A cutting process is strongly affected by depth of cut (h0) and tool edge radius (re), the relationship of which is described by relative tool sharpness (RTS = h0/re). In nanometric cutting, the depth of cut is far smaller than the tool edge radius, thus the tool is actually a very blunt one with a highly negative effective tool rake angle (~ − 90°). However, most previous studies have assumed the tool is extremely sharp with a nanometric edge radius, and to date there is very little literature on the cutting mechanism for a blunt tool (RTS < 1). In this study, the material deformation/removal behavior and forces under a small RTS from 1 to 0 were investigated via molecular dynamics. The results show that the surface integrity and chip formation are strongly affected by RTS. As RTS is reduced to 0.25 or smaller, rubbing and ploughing occur with no material removal. In such a circumstance, the force angle drops sharply with remarkable subsurface damage formation in the workpiece. These findings are distinctly different from the common belief, and provide new information for the optimization of the silicon wafer manufacturing process.

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Generation of microcones on reaction-bonded silicon carbide by nanosecond pulsed laser irradiation

Meshram T., Yan J.

International Journal of Advanced Manufacturing Technology （International Journal of Advanced Manufacturing Technology）  108 （ 4 ） 1039 - 1048 2019年

ISSN  02683768

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© 2019, Springer-Verlag London Ltd., part of Springer Nature. Silicon carbide (SiC) is heavily used in the industry due to its resistance to chemical wear and excellent mechanical properties such as high hardness and high stiffness. However, these properties make it difficult to produce micro and nanostructures on the surface of SiC by conventional methods. In this study, high-density microcones that protrude ~ 10 μm above the initial surface have been fabricated by nanosecond pulsed Nd:YAG laser irradiation (λ = 532 nm) on reaction-bonded SiC. Geometrically aligned cones were also fabricated by modifying the laser scanning path, and effect of different parameters such as pulse frequency, laser fluence was studied. It was observed that the surface morphology of microcones was affected by the pulse width and beam overlap. X-ray spectroscopy and Raman spectroscopy showed that the microcones were mainly composed of silicon. Formation of these cone structures made the surface highly superhydrophilic with a contact angle of ~ 0°.

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Study on infrared transmittance of si-polymer hybrid structure press molded using a coupling agent

Ishide H., Yan J.

International Journal of Automation Technology （International Journal of Automation Technology）  13 （ 6 ） 817 - 824 2019年

ISSN  18817629

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© 2019, Fuji Technology Press. All rights reserved. Hybrid structures of single-crystal silicon and high-density polyethylene (HDPE) with high transmittance in the mid-to-far infrared region are used as infrared lens substrates. The hybrids are usually fabricated by high-precision press molding. The Si-HDPE hybrid lens previously fabricated had a low transmittance in the 9–10 μm wavelength region, thereby limiting its application for human body detection. In this study, a Si-polymer hybrid structure was fabricated using a new polymer without any silane coupling agent. Interfacial adhesion between the polymer and the Si substrate was realized with an extremely thin (a few micron thick) layer of an interfacial silane coupling agent. The press molding conditions that led to improved bonding strength and infrared transmittance of the hybrid substrate were investigated. A transmittance similar to that of a single-crystal Si substrate was achieved in the 9–10 μm wavelength range.

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シリコン切りくずと金属微粒子の高圧焼結によるポーラス複合構造体の創製

砂場勇輝，立川直樹，片山 靖，閻 紀旺

砥粒加工学会誌 62 （ 11 ） 584 - 588 2018年11月

研究論文（学術雑誌）, 共著, 査読有り

Experimental investigation of RB-SiC using Cu–CNF composite electrodes in electrical discharge machining

P. J. Liew, Z. Nurlishafiqa, Q. Ahsan, T. Zhou, J. Yan

International Journal of Advanced Manufacturing Technology （International Journal of Advanced Manufacturing Technology）  98 （ 9-12 ） 3019 - 3028 2018年10月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  02683768

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© 2018, Springer-Verlag London Ltd., part of Springer Nature. The performances of carbon nanofiber (CNF) reinforced copper (Cu) composite electrodes on the reaction-bonded silicon carbide (RB-SiC) ceramic were experimentally investigated by using electrical discharge machining (EDM). The effects of CNF content on material removal rate (MRR), electrode wear ratio (EWR), surface roughness (SR) and surface topography were examined. Results indicated that the addition of CNF to the Cu electrode increased the MRR of the workpiece. In addition, increasing the added CNF content increased the EWR of the Cu–CNF composite electrode and the SR of the machined surface. The results of one-way ANOVA indicated that the Cu–1.0 wt% CNF composite electrode exhibited the optimal MRR and EWR values, although this electrode resulted the maximum SR on the RB-SiC machined surface.

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Surface Flattening and Nanostructuring of Steel by Picosecond Pulsed Laser Irradiation

Kobayashi T., Sera H., Wakabayashi T., Endo H., Takushima Y., Yan J.

Nanomanufacturing and Metrology （Nanomanufacturing and Metrology）  1 （ 4 ） 217 - 224 2018年09月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  2520811X

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© 2018, International Society for Nanomanufacturing and Tianjin University and Springer Nature. Steel is used as a mold material for press/injection molding of plastic products. High accuracy and releasing ability are required for a steel mold surface. This paper proposes a surface finishing method for steel molds by using picosecond pulsed laser irradiation. The process involves two steps: one is surface flattening by removing the surface asperity through laser ablation, and the other is forming nanoscale laser-induced periodic surface structures (LIPSS) on the flattened surface. The two steps are realized by using the same laser at controlled laser fluence and focus position. Experimental results showed that LIPSS was successfully formed after surface flattening under specific ranges of laser fluence and defocus length. Furthermore, plastic forming experiments demonstrated that a steel surface with LIPSS significantly decreased the effective contact area and, in turn, reduced the mold releasing force. These findings provide the possibility of fabricating high-performance steel molds by picosecond pulsed laser irradiation.

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Surface roughness in ultrasonic-assisted and conventional milling of soda-lime glass

Y. El-Taybany, M. Hossam, J. Yan, H. El-Hofy

International Journal of Machining and Machinability of Materials （International Journal of Machining and Machinability of Materials）  20 （ 1-2 ） 82 - 99 2018年09月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  17485711

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© 2019 Inderscience. All Rights Reserved. Glass has an increasing demand in many industrial fields such as micro-channels and micro reactors in fluidic applications, lab-on-a-chip in medical applications, and micro lens arrays and optical devices. Machining of glass as one of hard-to-machine materials is challengeable due to its distinctive properties of high strength, hardness, and brittleness. Facing these challenges, ultrasonic-assisted milling (UAM); an advanced machining process; was provided for its effectiveness in machining such hard-to-machine materials. In this paper, the effects of feed rate, depth of cut, ultrasonic-vibration assistance, and cutting fluid on surface roughness in UAM of soda-lime glass compared with conventional milling (CM) were investigated. Results showed that, by introducing ultrasonic-vibration, higher surface roughness was obtained. The optimal cutting conditions were attained using response surface methodology. At the optimised parametric setting, the minimum surface roughness was found to be at wet conventional milling.

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Multi-scale dimple creation on metallic glass by a two-step method involving nanoindentation and polishing

Huang H., Yan J.

Applied Surface Science （Applied Surface Science）  462   565 - 574 2018年06月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  01694332

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© 2018 Elsevier B.V. Creation of micro dimples on material surface is significant for their functional applications. Because of unique properties, metallic glasses are regarded as emerging structural and functional materials but they are also a kind of difficult-to-cut materials due to high hardness and easy to crystallization and oxidation. In this study, a new method was proposed to fabricate micro dimples on metallic glass surface, which consisted of two steps, nanoindentation experiments to form the pre-indent array followed by polishing. Via this two-step method, square and rectangle dimples were successfully formed which exhibited multi-scale features with one relatively large dimple with width in micron-scale and depth in nanometer-scale, together with relatively small residual indents in nanometer-scale distributed on its bottom surface. The experimental results indicated that the depth of multi-scale dimples was affected by the spatial interval between two indents and the polishing time. Under the used experimental conditions, for the same polishing time, the depth of the large dimple was decreased when increasing the interval; for the same interval, with increase in the polishing time, the depth of the large dimple was also decreased. The possible formation mechanism of the large dimple was discussed, which was mainly ascribed to the enhanced material removal at the position of pre-indent array because of the concentration of polishing particles by the pre-indents.

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The coupling effects of laser thermal shock and surface nitridation on mechanical properties of Zr-based metallic glass

Huang H., Jiang M., Yan J.

Journal of Alloys and Compounds （Journal of Alloys and Compounds）  770   864 - 874 2018年06月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  09258388

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© 2018 Elsevier B.V. Laser processing is a versatile tool for applications in the field of metallic glasses (MGs). Previous studies reported that surface nitridation, i.e. the formation of ZrN phase, occurred when laser irradiation of Zr-based MG was performed in nitrogen gas. Additionally, it was reported that laser thermal shock usually softened the irradiated surface. Therefore, the coupling effects of laser thermal shock and surface nitridation on mechanical characteristics of Zr-based MG should be further clarified. For this purpose, in this study, laser irradiation of Zr-based MG was conducted under various experimental conditions, followed by evaluating the surface characteristics by X-ray diffraction (XRD), nanoindentation, and energy-dispersive X-ray (EDX) spectroscopy. Experimental results indicated that the nanoindentation hardness, serrated flow, and surface shear bands were significantly affected by laser irradiation in nitrogen gas. Both surface softening and hardening were observed which depended on the experimental conditions. A competition mechanism between laser thermal shock and the introduction of ZrN phase was employed to rationalize these results. Furthermore, the affecting layer of ZrN phase along the depth direction was measured by EDX. The obtained results suggest a new method to introduce secondary phase into Zr-based MG surface and further to tune the mechanical characteristics of MGs.

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Softening of Zr-based metallic glass induced by nanosecond pulsed laser irradiation

Huang H., Jiang M., Yan J.

Journal of Alloys and Compounds （Journal of Alloys and Compounds）  754   215 - 221 2018年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  09258388

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© 2018 Elsevier B.V. Laser irradiation has been recently used to tune the mechanical properties of metallic glasses (MGs). However, the mechanism for plasticity improvement by laser irradiation is still not completely clear and requires further investigation. In this study, nanosecond pulsed laser irradiation is applied on a Zr-based MG surface under various laser powers, scanning speeds, and numbers of irradiation cycles. Then, the mechanical properties of the as-cast and laser-irradiated MG surfaces are characterized by nanoindentation tests. In particular, the indentation hardness, load-depth curve, serrated flow, and residual indent morphology of the surfaces are compared. The results show that the nanosecond pulsed laser irradiation softens the irradiated regions; the effect of the irradiation is slightly dependent on the laser irradiation parameters, and especially the laser scanning speed. Furthermore, laser irradiation considerably affects serrated flows in the load-depth curve and shear bands on the top surface, denoting different plastic deformation characteristics compared with the non-irradiated sample. These differences could be rationalized in terms of laser irradiation-induced formation of pre-existing shear bands in the subsurface layer, as well as thermal effects. The present results are expected to enhance the general understanding of the effects of laser irradiation on the mechanical properties of MGs.

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Material removal mechanism and surface integrity in ultraprecision cutting of porous titanium

Heidari M., Yan J.

Precision Engineering （Precision Engineering）  52   356 - 369 2018年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  01416359

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© 2018 Elsevier Inc. Porous titanium presents unique material properties with a wide variety of mechanical and biomedical applications. Porous titanium components fabricated by near net-shape technologies require further machining processes to improve the surface quality and form accuracy, and in turn, the added value of the products. In this work, major factors dominating the surface integrity in ultraprecision cutting of porous titanium using single-crystal diamond tools were investigated. The results demonstrated that the presence of pores significantly changed mechanism of cutting. The chip morphology and surface topography depended on pore size and undeformed chip thickness. At an extremely small undeformed chip thickness, a majority pores were closed due to the welding phenomenon, leading to a sharp drop of surface porosity. In contrast, large pores cause craters on the machined surface and segmentation of chips and protruding lamella, especially at a large undeformed chip thickness. A coolant could lubricate the tool-workpiece interface and the shear deformation, which decreased cutting forces. On the other hand, the rapid cooling effect enhanced the work hardening effect and increase the hardness of the machined surface. Tool wear in cutting porous titanium is suppressed compared with that of pure titanium, especially in wet cutting.

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Nanosecond pulsed laser irradiation of sapphire for developing microstructures with deep V-shaped grooves

Takayama N., Asaka S., Yan J.

Precision Engineering （Precision Engineering）  52   440 - 450 2018年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  01416359

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© 2018 Elsevier Inc. A nanosecond pulsed Nd:YAG laser was used to irradiate a sapphire substrate to produce 3-dimensional microstructures with sharp V-shaped grooves. In initial experiments, where single grooves were machined, a maximum taper angle of ∼79° was obtained. At constant laser parameters, the taper angle remained constant. As the taper angle increases from a flat surface, the irradiated area increases while incident fluence decreases; once the incident fluence approaches the ablation threshold, the taper angle becomes constant. The taper angle could be controlled by the laser fluence, scanning speed and incident angle of the laser beam. Using these results, a kind of surface microstructure, comprised of micropyramids with steep walls, was successfully machined for optical measurement applications. The surface roughness, transmittance and crystallinity of the microstructure surface could be controlled by the laser scanning speed. By applying the taper formation mechanism proposed in this study, the micromachining of sharp microstructures with steep walls on various hard brittle materials becomes possible.

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Microgrooving of a single-crystal diamond tool using a picosecond pulsed laser and some cutting tests

Takayama N., Ishizuka J., Yan J.

Precision Engineering （Precision Engineering）  53   252 - 262 2018年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  01416359

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© 2018 Elsevier Inc. Irradiation of a single-crystal diamond tool was performed with a picosecond pulsed laser to produce a tool with a microgrooved edge. This tool was then used in a metal cutting process to transfer the edge grooves onto a workpiece. Suitable conditions for laser irradiation on the diamond tool were experimentally investigated in terms of groove shape and laser-induced damage to diamond. Two different kinds of cutting experiments were performed; a uniformly grooved surface and a hierarchically structured surface were obtained. The chip formation mechanisms in the metal grooving process were examined. A copper workpiece was rapidly machined the surface of which had microgrooves with a pitch of a few micrometers. An increase of the contact angle was observed on the grooved surface, indicating the improvement of water repellency. This study presents an efficient method to machine microgrooves on metal materials for functional surfaces.

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Nanoscale surface patterning of diamond utilizing carbon diffusion reaction with a microstructured titanium mold

Yan J., Imoto Y.

CIRP Annals – Manufacturing Technology （CIRP Annals）  67 （ 1 ） 181 - 184 2018年05月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  00078506

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© 2018 A novel method was proposed for generating nanoscale surface patterns on single-crystal diamond by carbon diffusion with a microstructured titanium mold under controlled temperature and pressure. The depth, geometry, and surface integrity of the fabricated patterns were investigated by laser micro-Raman spectroscopy and white-light interferometry, and the titanium molds were analyzed by energy dispersive X-ray spectroscopy. The results showed that at specific temperatures and pressures, three-dimensional patterns with a depth of tens of nanometers and sloped/curved walls could be generated on a diamond surface after a few minutes, without causing any surface graphitization. The intensity profile and penetration depth of carbon atoms into the titanium were experimentally measured.

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Noncontact on-machine measurement system based on capacitive displacement sensors for single-point diamond turning

Li X., Zhang Z., Hu H., Li Y., Xiong L., Zhang X., Yan J.

Optical Engineering （Optical Engineering）  57 （ 4 ） 044105 2018年04月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  00913286

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© 2018 Society of Photo-Optical Instrumentation Engineers (SPIE). On-machine measurements can improve the form accuracy of optical surfaces in single-point diamond turning applications; however, commercially available linear variable differential transformer sensors are inaccurate and can potentially scratch the surface. We present an on-machine measurement system based on capacitive displacement sensors for high-precision optical surfaces. In the proposed system, a position-Trigger method of measurement was developed to ensure strict correspondence between the measurement points and the measurement data with no intervening time-delay. In addition, a double-sensor measurement was proposed to reduce the electric signal noise during spindle rotation. Using the proposed system, the repeatability of 80-nm peak-To-valley (PV) and 8-nm root-mean-square (RMS) was achieved through analyzing four successive measurement results. The accuracy of 109-nm PV and 14-nm RMS was obtained by comparing with the interferometer measurement result. An aluminum spherical mirror with a diameter of 300 mm was fabricated, and the resulting measured form error after one compensation cut was decreased to 254 nm in PV and 52 nm in RMS. These results confirm that the measurements of the surface form errors were successfully used to modify the cutting tool path during the compensation cut, thereby ensuring that the diamond turning process was more deterministic. In addition, the results show that the noise level was significantly reduced with the reference sensor even under a high rotational speed.

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Characterization of recrystallized depth and dopant distribution in laser recovery of grinding damage in single-crystal silicon

Niitsu K., Tayama Y., Kato T., Maehara H., Yan J.

Materials Science in Semiconductor Processing （Materials Science in Semiconductor Processing）  82   54 - 61 2018年04月

研究論文（学術雑誌）, 共著, 査読有り,  ISSN  13698001

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© 2018 Elsevier Ltd A nanosecond pulsed Nd:YAG laser was irradiated on a boron-doped single-crystal silicon wafer with a diamond grinding finish to recover the grinding-induced subsurface damage. In order to visualize and measure the depth of the laser melted/recrystallized layer, small-angle beveled polishing was performed in pure water followed by KOH etching. It enabled the direct observation of the recrystallized region using a differential interference microscope and the measurement of its depth using a white light interferometer. Crystallinity analysis of the recrystallized region was carried out by using laser micro-Raman spectroscopy, and the dopant concentration profile was characterized by using radio frequency glow discharge optical emission spectrometry (rf-GD-OES). The results showed that the crystallinity and boron distribution in the recrystallized region changed after laser recovery. The dopant concentration becomes higher at the boundary of the recrystallized region and the bulk. This study demonstrates the possibility of boron concentration control by using suitable laser parameters.

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