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Papers - Yan, Jiwang

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Tool Dynamics-induced Surface Topography Error in Fast Tool Servo-Based Diamond Turning of Micro Dome Arrays

Hashimoto T., Yan J.

Procedia CIRP (Procedia CIRP) 123 422 - 427 2024

ISSN 22128271

Micro dome arrays are applied as moulds to injection/press moulding to produce micro lens arrays. Fast tool servo (FTS) based diamond turning is a promising technique for manufacturing such micro dome arrays with high accuracy and machining efficiency. In this study, cutting of micro dome array (MDA) on copper with FTS was performed to evaluate the dynamics behaviour of the tool servo and its effects on surface topography. Results show that local surface speed dramatically affects the servo dynamics behaviour. When the local surface speed is higher than a critical value, overcutting and wavy patterns could be formed on the cut-in area of the domes and exit area, which is caused by the servo response and its limitation. By capturing and analysing the position signal and correlating it with the surface topography of the generated dome surface and considering its limitations, an effective strategy for optimizing micro dome array machining parameters was proposed. MDA cutting tests with optimized cutting conditions achieved a significantly improved form accuracy. This study will guide the optimal use of FTS systems in machining micro structured surfaces.

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Investigation on Monitoring Personal Health via Internet of Things-Based Wearable Device

Ngo H.Q.T., Nguyen L.D., Huynh P.K., Le T.Q., Yan J.

EAI/Springer Innovations in Communication and Computing 693 - 704 2024

ISSN 25228595

In our era, smart clothes for personal health monitoring in home care is a promising and innovative approach. These clothes are integrated with sensors and electronic devices that could follow vital signs, levels of activities, and other health metrics. Therefore, in this paper, the design of such smart clothes and their potential applications are presented to realize the novel concept in the healthcare service. Using various sensors, it is expected to obtain the health parameters or habitual activities of patients, while this cloth still maintains personal comfortability. Then, data is collected and transmitted via wireless communication to host server. Owing to this design, several algorithms could be deployed to predict any abnormal health status. Additionally, this approach could reduce the burden care from medical staff or nurses who are in the over-work circumstance. From this achievement, the potential applications of smart clothes on healthcare and the future research directions could be outlined clearly in the related fields.

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Achieving superhydrophobicity of Zr-based metallic glass surface with anti-corrosion and anti-icing properties by nanosecond laser ablation and subsequent heat treatment

Cui M., Huang H., Wu H., Zhang L., Yan J.

Surface and Coatings Technology (Surface and Coatings Technology) 475 2023.12

ISSN 02578972

Water repellency of superhydrophobic surfaces offers an opportunity to enhance the corrosion and icing resistance of metallic glasses (MGs). Inspired by the “lotus effect” in nature, hierarchical micro/nanostructures were constructed on a Zr-based MG surface using nanosecond laser ablation. By subsequent heat treatment in air, the structured surface showed a water contact angle (CA) of 168.2 ± 1.5° and a sliding angle (SA) of 4 ± 0.7° (adhesion force of 9.8 ± 1.7 μN), exhibiting repellency and low adhesion to water. Specifically, the superhydrophobic surface stored in air and immersed in water possessed stability and durability, and the superhydrophobic surface still maintained superhydrophobicity after mechanical scratching. The heat treatment temperature worked as a switch for controlling the wettability transition, and by tuning the temperature, the structured surface can switch from superhydrophobicity (CA: 168.2 ± 1.5°) to superhydrophilicity (CA: ~0°). Furthermore, compared to the polished MG surface, the superhydrophobic surface increased the corrosion resistance and freezing time, and delayed the freezing temperature. This study provides a facile non-fluorinated method for fabricating superhydrophobic MG surfaces with anti-corrosion and anti-icing properties, which would enhance the application of MGs as structural and functional materials under extreme conditions.

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Surface conditioning of zirconia ceramic by enhanced ultrasonic vibration-assisted burnishing

Tsuchida T., Huang W., Yan J.

Production Engineering (Production Engineering) 18 ( 2 ) 353 - 366 2023.12

ISSN 09446524

Yttria-stabilized zirconia (YSZ) ceramic is a widely used material in mechanical and biomedical engineering, such as machine parts and dental implants. For most applications, surface conditioning methods are required to produce smooth and reinforced surfaces with compressive residual stress. This paper investigates the processing characteristics of YSZ under ultrasonic vibration-assisted burnishing (UVB) enhanced by flexible stage and tool rotation techniques, respectively. For the use of flexible stage-enhanced UVB, the fluctuation of burnishing force was greatly reduced. As results, a smooth surface with a roughness of 164 nm Ra was obtained, which shows 39.7% surface roughness reduction from the original surface, and 9.4% surface roughness reduction from the surface burnished with conventional UVB. The burnished surface yielded strong residual compressive stresses of 401 MPa in the burnishing direction and 695 MPa in the step-feed direction. For the use of tool rotation-enhanced UVB, tool rotation-induced arc-shaped surface textures were formed on the burnished surface, and the textures became more distinct and denser as the rotation speed increased. The surface roughness was reduced by 58.9% from the original surface with the tool rotation-enhanced UVB. Stress-induced phase transformation of YSZ was identified in all burnished surfaces. This study demonstrates the feasibility of one-step manufacturing of a smooth surface with high residual compressive stress, which expands the applications of YSZ.

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Ultra-low wear of titanium alloy surface under lubricated conditions achieved by laser texturing and simultaneous nitriding

Wang C., Huang H., Wu H., Hong J., Zhang L., Yan J.

Surface and Coatings Technology (Surface and Coatings Technology) 474 2023.12

ISSN 02578972

Titanium and its alloys are widely used in aerospace and biomedical fields but suffer from poor tribological properties. Surface coating and texturing have proven to be effective ways for improving tribological properties. However, integrating these methods may introduce complexity and increased costs. In this study, laser nitriding and surface texturing were simultaneously achieved on Ti6Al4V surface via a nanosecond pulse laser. The tribological properties of textured surfaces under lubricated conditions were investigated, and the wear mechanism was discussed. Experimental results showed significant improvements in the tribological properties, including a smaller and stable coefficient of friction (COF) and a remarkable 99.3 % reduction in wear rate. This study provides valuable insights for improving the tribological properties of titanium alloys, benefiting industrial and biomedical applications.

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Formation of Laser-Induced Periodic Surface Structures on Reaction-Bonded Silicon Carbide by Femtosecond Pulsed Laser Irradiation

Meshram T., Yan J.

Nanomanufacturing and Metrology (Nanomanufacturing and Metrology) 6 ( 1 ) 2023.12

ISSN 2520811X

Reaction-bonded silicon carbide (RB-SiC) is an excellent engineering material with high hardness, stiffness, and resistance to chemical wear. However, its widespread use is hindered due to the properties mentioned above, making it difficult to machine functional surface structures through mechanical and chemical methods. This study investigated the fundamental characteristics of laser-induced periodic surface structures (LIPSSs) on RB-SiC via femtosecond pulsed laser irradiation at a wavelength of 1028 nm. Low-spatial-frequency LIPSS (LSFL) and high-spatial-frequency LIPSS (HSFL) formed on the surface along directions perpendicular to the laser polarization. SiC grains surrounded by a large amount of Si show a reduced threshold for LIPSS formation. By varying laser fluence and scanning speed, HSFL–LSFL hybrid structures were generated on the SiC grains. Transmission electron microscopy observations and Raman spectroscopy were carried out to understand the formation mechanism of the hybrid LIPSS. A possible mechanism based on the generation of multiple surface electromagnetic waves due to the nonlinear response of SiC was proposed to explain the hybrid structure formation. Furthermore, the direction of laser scanning with respect to laser polarization affects the uniformity of the generated LIPSS.

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Multilayer Graphene-Coated Silicon Carbide Nanowire Formation Under Defocused Laser Irradiation

Minami K., Kobinata K., Yan J.

Nanomanufacturing and Metrology (Nanomanufacturing and Metrology) 6 ( 1 ) 2023.12

ISSN 2520811X

Graphene-coated silicon carbide (SiC@C) core–shell nanostructures have attracted attention in the fields of energy storage and nanoelectronics. In this study, multilayer graphene-coated silicon carbide (SiC) nanowires were obtained through the laser irradiation of a mixture target of graphite powder and silicon (Si) grinding sludge discharged from Si wafer manufacturing. Laser irradiation was performed using an ytterbium (Yb) fiber pulsed laser with a pulse width of 10 ms and a wavelength of 1070 nm with various defocus distances. The effect of laser defocusing on the morphology of the generated nanostructures was investigated. Results showed that nanowires were produced under the defocused conditions, and nanoparticles were observed at the on-focus position. The products obtained under all defocused conditions showed a core–shell structure, and the SiC nanowires were covered by graphene layers. The aspect ratio of the nanowires increased with the defocus distance. Observation of the laser-induced plume using a high-speed camera showed that when the laser was defocused, the plume propagation speed slowed down, and the shape of the plume changed to a swirling vortex. The nanowire formation was closely related to the propagation speed and shape variation of the plume. This successful production of SiC@C core–shell nanowires from Si waste opens up the possibility of the sustainable development of new materials for energy storage and nanoelectronics.

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Fabrication of microlens arrays on single-crystal CaF<inf>2</inf> by ultraprecision diamond turning

Huang W., Nagayama K., Yan J.

Journal of Materials Processing Technology (Journal of Materials Processing Technology) 321 2023.12

ISSN 09240136

Single-crystal calcium fluoride (CaF2) is considered a superior optical material with good transmittance in a wide transmitted wavelength region. However, the production of high surface quality freeform surfaces on CaF2 is difficult owing to its soft, brittle, and anisotropic properties. This study attempted to fabricate spherical and hexagonal microlens arrays on CaF2 using diamond turning with a slow tool servo. In addition, the machining characteristics of CaF2 were systematically investigated. It was found that microcracks tended to be generated in the cut-in and cut-out regions of the lenses. When cutting along the [− 211] and [11 − 2] directions, the machined surfaces were very prone to cracking. When reducing the maximum undeformed chip thickness to less than approximately 60 nm, continuous ribbon-like chips were formed throughout the cutting process, and all lenses were machined in ductile mode without surface cracking. In addition, a spherical microlens array was successfully fabricated in ductile mode with a surface roughness of approximately 2 nm Sa. Consequently, a hexagonal microlens array with sharp edges and crack-free surfaces was achieved using the proposed depth-offsetting segment cutting method. The surface roughness was approximately 4.1 nm Sa with a form error of approximately 147 nm P-V (peak to valley). Tool wear was insignificant until a machining distance of approximately 50 m; however, with further increase in the machining distance, crater wear and microchipping were observed. This study demonstrated the feasibility of fabricating high-quality freeform microstructured surfaces on CaF2 and other soft-brittle materials via diamond turning.

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Analysis and development of elliptical tool path in trochoidal milling

Wagih M., Maher I., El-Hofy H., Yan J., Hassan M.A.

CIRP Journal of Manufacturing Science and Technology (CIRP Journal of Manufacturing Science and Technology) 47 168 - 183 2023.12

ISSN 17555817

Trochoidal milling has been developed to extend the cutting tool life as compared to conventional milling. It is widely used in the machining of slots and corners of molds and dies. There are several tool paths typically used in trochoidal milling such as true, circular, variable-feed, and variable-step trochoidal tool paths. However, these paths suffer from low material removal rates, low surface qualities, high CPU processing times, and/or the requirement of high-dynamic machine tools. Elliptical trochoidal tool path showed its capability to improve the material removal rate, but the expected low surface quality of the produced slot. In this paper, the elliptical tool path will be analyzed analytically and experimentally. The effect of elliptical tool path on material removal rate, cutting forces, walls waviness, and surface roughness have been investigated. A novel linear elliptical-based tool path has been proposed to enhance the elliptical tool path performance by improving both material removal rate and surface quality. A Performance index has been utilized to evaluate the performance of these processes. An analytical model for the local maximum chip thickness in elliptical tool path has been conducted to correlate this path with the cutting forces. The slot walls waviness has been modeled based on the cutting tool path geometry and validated experimentally with error less than 11%. The experimental results showed that the elliptical tool path improved the material removal rate by 11%, with a slight reduction in the maximum resultant cutting force by 3%. On the other hand, the walls waviness and surface roughness have been increased by 45% and 38% respectively as compared to the typical true trochoidal tool path. The introduction of linear paths at the elliptical path sides in the linear-elliptical tool path improved the performance index about 18 times by improving the material removal rate, waviness, and surface quality by 5%, 300%, and 74% respectively, without a significant effect on cutting forces. Therefore, the novel linear-elliptical paths are promising tool paths in increasing the performance of trochoidal milling due to the improved material removal rate, walls waviness, and surface quality, without a significant effect on cutting forces, which will improve the process machinability and cost-effectiveness.

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Laser polishing and simultaneous hardening of the electrical discharge machined Zr-based metallic glass surface

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

Materials & Design (Materials and Design) 237 2023.12

ISSN 02641275

Wire electrical discharge machining (WEDM) is highly suitable for processing the hard-brittle materials like metallic glasses (MGs). However, the electro-thermal energy conversion involved in the WEDM process inevitably introduces some surface defects including bulges, discharge craters, and recast materials on the WEDMed MG surface, which significantly impedes its practical application. Here, an emerging automated polishing technology, laser polishing (LP), was performed in the nitrogen-rich environment to simultaneously improve the surface quality and hardness of the WEDMed Zr-based MG surface. The detailed effects of LP parameters on the surface roughness and morphology were systematically investigated. The morphology evolution and temperature distribution of the molten pool during LP were analyzed by simulation analysis. The experimental results indicated that after single LP of four representative WEDMed Zr-based MG surfaces using the optimized laser parameters, the surface roughness (Sa) was remarkably reduced from 1.27, 2.10, 3.49, and 4.58 μm to 0.09, 0.14, 0.17, and 0.21 μm, respectively, accompanied by an increase in surface hardness from 6.30 GPa to 7.39, 7.67, 8.51 and 8.99 GPa. This study demonstrated that LP could effectively achieve simultaneous enhancement of the quality and hardness of WEDMed MG surfaces, which would contribute to expanding the application prospects of MGs.

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Femtosecond Pulsed Laser Irradiation of Zirconia for Embedding Silver Nanoparticles in Surface Nanopores

Yamamuro, Y; Shimoyama, T; Nagata, H; Yan, JW

Applied Sciences (Applied Sciences (Switzerland)) 13 ( 24 ) 2023.12

Featured Application: Functional surfaces of zirconia with antibacterial properties. Femtosecond pulsed laser irradiation was performed to investigate the feasibility and fundamental characteristics of embedding silver nanoparticles onto zirconia ceramic surfaces. By irradiating laser, nanopores were fabricated on the surface of the yttria-stabilized zirconia (YSZ) substrate, and silver nanoparticles were infiltrated and immobilized into the pores using a commercial nano-silver dispersion solution. Numerous nanopores embedded with silver nanoparticles were successfully obtained on the YSZ surface while keeping the grains’ shapes unchanged by controlling laser parameters. Optimizing laser fluence and scanning speed near the ablation threshold made it possible to remove only the excess dispersant that remained on the surface while keeping silver in the pores and without causing machining of the surface of the YSZ substrate. In addition, about 60% embedding in the nanopores was achieved. It was found that the shorter pulse width was suitable to avoid evaporating both dispersant and silver. Cross-sectional observation revealed that the silver nanoparticles were agglomerated to form clumps and were embedded without a gap at the bottom of the pores at a depth of about 600 nm. After laser irradiation, no significant laser-induced phase change was observed in the YSZ substrate, indicating that there was no in-process thermal damage to the bulk. These findings demonstrated the possibility of adding a metal nanoparticle to the zirconia surface by using only a laser process without damaging the properties of the base material during the process. New applications of zirconia, such as the generation of functional surfaces with antibacterial properties, are expected.

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Electrical discharge machining of Ti6Al4V alloy with nitrogen gas assistance

Liu Z., Li L., Yan J., Liu X., Meng J., Bai X.

International Journal of Advanced Manufacturing Technology (International Journal of Advanced Manufacturing Technology) 129 ( 5-6 ) 2609 - 2620 2023.11

ISSN 02683768

Due to its exceptional performance, the Ti6Al4V alloy finds extensive use in aviation, biomedical, and petrochemical sectors. Nonetheless, its limited machinability and subpar wear resistance have hindered its widespread application. Therefore, this study underlooks a novel approach by employing nitrogen (N2) gas–assisted electrical discharge machining (NA-EDM) to machine Ti6Al4V. In this context, N2 gas serves a dual purpose. On the one hand, the flow of N2 has a beneficial impact on enhancing the surface properties of the workpiece. On the other hand, N2 reacts with titanium (Ti) to create titanium nitride (TiN), enhancing the component’s performance. Also, this study focuses on investigating how peak current, pulse-on time, electrode rotation speed, and gas pressure influence various aspects, including surface morphology, surface roughness, the microstructure of the recast layer, the microhardness of the recast layer, the thickness of the recast layer, and material removal rate (MRR). Experimental findings show that the NA-EDM process results in a smoother surface morphology, a uniform recast layer, and a reduced MRR. The microhardness in NA-EDM exceeds that of EDM by 42.1%, attributed to the formation of TiN and martensite. Ra is decreased by 21.2% compared to EDM. This study offers novel insights into machining Ti6Al4V alloy, opening up possibilities for broader-scale applications.

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Tool wear and surface integrity in liquid nitrogen clean cutting of cobalt-based superalloy GH605 with AlTiN coated tools

Li X., Zheng G., Yan J., Cheng X., Li Y., Cui E.

Wear (Wear) 530-531 2023.10

ISSN 00431648

The tool wear is severe and the machined surface quality is low in dry cutting of cobalt-based superalloy. The traditional coolant is harmful to the environment and not in line with sustainable development. The liquid nitrogen (LN2) clean cutting of cobalt-based superalloy GH605 using AlTiN coated tools is proposed in this work. The tool wear mechanism and the machined surface integrity are investigated. The results show that, with the decrease of LN2 injection temperature, the sharp wear stage of the tool can be delayed. The injection temperature directly affects the tool life. Compared with dry cutting, the tool life is increased by 42.5% at LN2 injection of −190 °C. Under the lower liquid nitrogen condition, the coating peeling is reduced on the rake face. The decrease of LN2 injection temperature can effectively reduce the damaged area of the flank face and inhibit the oxidation wear. The injection temperature between −30 °C and −150 °C can significantly reduce the surface roughness. The minimum surface roughness value at the injection temperature of −90 °C is 0.486 μm, which is 39.4% lower than that at dry cutting condition. When the LN2 injection temperature is below −90 °C, the thickness of the white layer is less than half of that in dry cutting condition. The hardness of the machined surface is enhanced and the residual stress is reduced at injection temperature below −150 °C. This work demonstrates the possibility of improving the machinability of cobalt-based superalloy by optimizing the LN2 injection temperature.

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Nanosecond laser coloration of Ti-based metallic glass under various laser parameters and irradiation atmospheres

Zhang H., Wang C., Huang H., Zhang L., Yan J.

Journal of Non-Crystalline Solids (Journal of Non-Crystalline Solids) 618 2023.10

ISSN 00223093

Laser coloration is an emerging technique for surface functionalization of metallic glasses (MGs). Understanding the influence of laser parameters on surface color of MGs will accelerate their commercialization. Herein, surface coloration was conducted on a Ti-based MG, and the hue–saturation–intensity (HSI) color space was employed to evaluate color variation. Various colors were achieved by varying the average power and scanning speed in an ambient atmosphere. The results indicated that the overlap rate and number of repetitive scans had a negligible effect on the color and significantly changed the microscopic morphology. The irradiated surfaces were yellowish and colorless in nitrogen and argon atmospheres. Furthermore, the effect of morphology on the surface color and the mechanism of surface coloration were examined. This study demonstrates that nanosecond laser irradiation is an effective method for achieving surface coloration of MGs, which is expected to enrich the surface functionality of MG products.

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Grain visualization of FeCoCrMnNi and AlCoCrFeNi<inf>2.1</inf> high-entropy alloys by nanosecond pulse laser irradiation

Wang C., Huang H., Zhang H., Zhang L., Yan J.

Vacuum (Vacuum) 216 2023.10

ISSN 0042207X

Characterizing grains is the most common method in materials science research, but the existing techniques for grain characterization are generally expensive and time-consuming. In this study, nanosecond pulse laser irradiation with low laser fluence is attempted to visualize the grains of two typical high-entropy alloys (HEAs) with different crystal structures and elemental compositions. The effects of laser parameters and gas atmospheres on the laser visualization of grains are comparatively investigated. Under specific laser irradiation conditions, the grains of these two HEAs could be well visualized by producing different surface nanostructures. By experiments and analysis, the underlying mechanisms of laser visualization of grains under different conditions are elucidated, and the role of O element on the promotion of the visualization of grain boundaries is confirmed. This study provides a simple and efficient method to visualize the grains of HEAs, and on the other hand, enhances the understanding of nanosecond laser-HEA interaction.

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Achieving superhydrophobicity of the FeCoCrMnNi surface via synergistic laser texturing and low temperature annealing

Wang C., Huang H., Cui M., Zhang Z., Zhang L., Yan J.

Journal of Laser Applications (Journal of Laser Applications) 35 ( 3 ) 2023.08

ISSN 1042346X

Superhydrophobic surfaces are highly desirable due to their remarkable water-repellent behavior. Laser texturing with subsequent low surface energy modification is a versatile strategy for creating such surfaces. In this study, via synergistic laser texturing and low temperature annealing, superhydrophobicity was first attempted to be achieved on the FeCoCrMnNi surface. By optimizing the laser parameters, the arrays with large depth-to-width ratios were constructed. Subsequently, by annealing at a low temperature, the transition process from superhydrophilicity to superhydrophobicity was successfully achieved on the FeCoCrMnNi surface. The effects of the hatching interval on the wettability were investigated, and the mechanism of wettability transition for FeCoCrMnNi was discussed. According to the experimental results and analysis, the textured surfaces exhibited excellent superhydrophobicity at different hatching intervals and a maximum contact angle of 165° was obtained. Furthermore, the created superhydrophobic surfaces possessed good liquid capture and self-cleaning capabilities and enabled magnification for optical imaging. The wettability transition after low temperature annealing was attributed to the absorption of airborne organic compounds. This study provides an efficient, clean, and versatile strategy to achieve superhydrophobicity of the FeCoCrMnNi surface by laser processing.

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Laser repairing of FeCoCrNiV high-entropy alloy and its mechanical and cutting characteristics

Wang C., Huang H., Zhang H., Zhang L., Yan J.

Journal of Materials Processing Technology (Journal of Materials Processing Technology) 317 2023.08

ISSN 09240136

High-entropy alloys (HEAs) are promising structural and functional materials owing to their superior mechanical and chemical properties. High surface quality and good machinability are essential for micro-machining high-end precision equipment. Here, laser repairing (LR) was firstly employed to eliminate surface defects and improve the machinability of FeCoCrNiV. After LR, the microstructures and mechanical properties of FeCoCrNiV were investigated. The results show that the surface morphology and chemical composition uniformity of FeCoCrNiV were significantly improved after LR, in which the high melting-point V-rich precipitates concentrated on the original surface were homogeneously distributed throughout the substrate. The surface hardness decreased from 10.5 to 4.5 GPa due to the growth of grains, and the hardness distribution became more homogeneous after LR, providing the opportunity to improve its machinability. In ultrasonic vibration diamond turning tests, the machined surface quality, tool wear, and cutting chips indicated that the laser-repaired material exhibited superior machinability. A sinusoidal free-form surface with high surface quality was then constructed by ultrasonic vibration-assisted diamond turning on the laser-repaired surface. This study provides a method to repair surface defects of HEAs and improve their machinability, which is beneficial to their practical applications.

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Mechanisms of tool-workpiece interaction in ultraprecision diamond turning of single-crystal SiC for curved microstructures

Huang W., Yan J.

International Journal of Machine Tools and Manufacture (International Journal of Machine Tools and Manufacture) 191 2023.07

ISSN 08906955

Single-crystal silicon carbide (SiC) is one of the most attractive materials for electronics and optics but extremely difficult to cut owing to its hard and brittle properties. While in previous studies, the focus has been placed on machining flat surfaces, in this study, the mechanisms of tool-workpiece interaction in cutting curved microstructures on 4H–SiC (0001) were explored through the ultraprecision diamond turning of micro-dimples. The surface/subsurface of both machined workpieces and used diamond tools were characterized, and the machining characteristics, such as chip formation and cutting forces, were also investigated. It was found that microcracks occurred easily in the feed-in/cut-in area of the dimples, which is caused by a large friction-induced tensile stress due to a large thrust force. The dimples located on the secondary cleavage directions <10−10> (S-dimples) were easy to produce crack-free surfaces, while the dimples located on the primary cleavage directions <−12−10> (P-dimples) were very prone to cause cracks on surfaces, even though the chips were formed in a ductile mode. The dimples located on the in-between direction (I-dimples) were moderately prone to surface cracking. It was also found that although the S-dimple has a crack-free surface, it has the thickest subsurface damage (SSD) layer containing a disordered layer, dislocations, and stacking faults; the SSD layer of the P- and I-dimples do not contain stacking faults; and the SSD layer of the I-dimple is the thinnest. Flank wear with nanoscale grooves on the diamond tool was significant without edge chipping and diamond graphitization detected. By optimizing the cutting conditions, a crack-free micro-dimple array was fabricated with nanometric surface roughness. The findings from this study provide guidance for the manufacture of curved SiC parts with high surface integrity, such as molds for replicating microlens arrays and other freeform surfaces on glass.

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A theoretical and deep learning hybrid model for predicting the surface roughness of diamond-turned polycrystalline materials

He Chunlei, Yan Jiwang, Wang Shuqi, Zhang Shuo, Chen Guang, Ren Chengzu

International Journal of Extreme Manufacturing (International Journal of Extreme Manufacturing) 5 ( 3 ) 2023.06

ISSN 2631-8644

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Antireflective structured surface of chalcogenide glass fabricated using glass to glass molding

Zhu Z., Zhou T., He Y., Yu Q., Wang X., Yan T., Yan J., Ruan H.

Ceramics International (Ceramics International) 49 ( 17 ) 28216 - 28223 2023.06

ISSN 02728842

Chalcogenide (ChG) glasses with micro-nano structure arrays are increasingly demanded in infrared optical systems owing to their excellent antireflective properties, and can be mass-produced by precision glass molding (PGM). Nickel-phosphorus (Ni–P) plated molds are commonly used in the PGM process, but the Ni atoms tend to react with the ChG glass at high temperatures. In this study, we propose a novel two-step PGM process. A Ni–P mold is used to transfer antireflective micro-nano structure array to silicate glass. Then the silicate glass, which has a higher glass transition temperature (Tg) than the ChG glass, is used as the mold to replicate the antireflective structured surface to the ChG glass. The results show that the ChG glass micro-nano structure array has high forming accuracy and favorable infrared optical transmission characteristics. The silicate glass is proved to be an appropriate mold material for the ChG glass molding process. This work provides a novel type of the PGM techniques for ChG glass materials.

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