Advanced Engineering Materials Research Articles

Electron Sponge Effect by Dynamic-Regulated Electron Self-Flow toward Coupled Electrochemical Ammonia Synthesis.

A dynamic-regulated Pd-Fe-N electrocatalyst was effectively constructed with electron-donating and back-donating effects, which serves as an efficient engineering strategy to optimize the electrocatalytic activity. The designed PdFe3/FeN features a comprehensive electrocatalytic performance toward the nitrogen reduction reaction (NRR, yield rate of 29.94 μg h-1 mgcat-1 and FE of 38.43% at -0.2 V vs RHE) and oxygen evolution reaction (OER, 308 mV at 100 mA cm-2). Combining in situ ATR-FTIR, XAS, and DFT results, the role of the interstitial-N-dopant-induced electron sponge effect has been significantly elucidated in strengthening the electrocatalytic NRR process. Specifically, the introduction of a N dopant, an electron acceptor, initiates the generation of robust Lewis-acidic Fe sites, facilitating free N2 capture and bonding. Simultaneously, after NH3 adsorption, the N dopant can back-donate electrons to Fe sites, strengthening the NH3 deportation through weakening the Lewis acidity of Fe centers. Besides, the electron-deficient Fe sites contribute to the reconstruction of FeOOH, the real active species during the OER, which accelerates the four-electron reaction kinetics. This research offers a perspective on electrocatalyst design, potentially facilitating the evolution of advanced material engineering for efficient electrocatalytic synthesis and energy storage.

Imperfection-Enabled Strengthening of Ultra-Lightweight Lattice Materials.

Lattice materials are an emerging family of advanced engineering materials with unique advantages for lightweight applications. However, the mechanical behaviors of lattice materials at ultra-low relative densities are still not well understood, and this severely limits their lightweighting potential. Here, a high-precision micro-laser powder bed fusion technique is dveloped that enables the fabrication of metallic lattices with a relative density range much wider than existing studies. This technique allows to confirm that cubic lattices in compression undergo a yielding-to-buckling failure mode transition at low relative densities, and this transition fundamentally changes the usual strength ranking from plate > shell > truss at high relative densities to shell > plate > truss or shell > truss > plate at low relative densities. More importantly, it is shown that increasing bending energy ratio in the lattice through imperfections such as slightly-corrugated geometries can significantly enhance the stability and strength of lattice materials at ultra-low relative densities. This counterintuitive result suggests a new way for designing ultra-lightweight lattice materials at ultra-low relative densities.

Methods to achieve tissue-mimetic physicochemical properties in hydrogels for regenerative medicine and tissue engineering.

Hydrogels are water-swollen polymeric matrices with properties that are remarkably similar in function to the extracellular matrix. For example, the polymer matrix provides structural support and adhesion sites for cells in much of the same way as the fibers of the extracellular matrix. In addition, depending on the polymer used, bioactive sites on the polymer may provide signals to initiate certain cell behavior. However, despite their potential as biomaterials for tissue engineering and regenerative medicine applications, fabricating hydrogels that truly mimic the physicochemical properties of the extracellular matrix to physiologically-relevant values is a challenge. Recent efforts in the field have sought to improve the physicochemical properties of hydrogels using advanced materials science and engineering methods. In this review, we highlight some of the most promising methods, including crosslinking strategies and manufacturing approaches such as 3D bioprinting and granular hydrogels. We also provide a brief perspective on the future outlook of this field and how these methods may lead to the clinical translation of hydrogel biomaterials for tissue engineering and regenerative medicine applications.

Advancements in shape-memory alloys: Properties, applications, challenges, and future prospects

Shape-memory alloys (SMAs) are advanced engineering materials that have gained significant attention in recent years due to their unique properties and potential applications. SMAs have the remarkable ability to recover their original shape after deformation, making them invaluable in various fields, from biomedical devices to aerospace engineering. Despite their many advantages, SMAs also face several challenges, including the need for improved processing techniques and the development of more efficient actuation systems. To address these challenges, researchers have adopted various approaches, including using advanced fabrication methods and developing novel actuation systems. Recent research has yielded several notable achievements in the field of SMAs. For example, researchers have developed new processing techniques that allow the production of SMAs with improved properties, such as higher strength and better fatigue resistance. Additionally, researchers have developed new actuation systems that allow for more precise and efficient control of SMA behavior. Looking ahead, the future of SMAs looks promising. With continued research and development, SMAs have the potential to revolutionize various fields, from aerospace engineering to biomedical devices. However, further work is needed to overcome the remaining challenges and fully realize the potential of these remarkable materials. This article provides a comprehensive overview of SMAs, including their properties, fabrication methods, and various applications. It also discusses the challenges facing the field, the approaches to address them, and recent achievements.

Healable, Recyclable, and Upcyclable Gel Membranes for Efficient Carbon Dioxide Separation.

Ionic liquids (ILs) are prized for their selective dissolution of carbon dioxide (CO2), leading to their widespread use in ionogel membranes for gas separation. Despite their advantages, creating sustainable ionogel membranes with high IL contents poses challenges due to limited mechanical strength, leakage risks, and poor recyclability. Herein, we leverage copolymerized and supramolecularly bound ILs to develop ionogel membranes with high mechanical strength, zero leakage, and excellent self-healing and recycling capabilities. These membranes exhibit superior ideal selectivity for gas separation compared to other reported ionogel membranes, achieving a CO2/nitrogen selectivity of 61.7 and a CO2/methane selectivity of 24.6, coupled with an acceptable CO2 permeability of 186.4 Barrer. Additionally, these gas separation ionogel membranes can be upcycled into ionic skins for sensing applications, further enhancing their utility. This research outlines a strategic approach to molecularly engineer ionogel membranes, offering a promising pathway for developing sustainable, high-performance materials for advanced gas separation technologies.

Foreword

The Congress of Automotive and Transport Engineering is an annual scientific event initiated in 1990 by the Society of Automotive Engineers of Romania (SIAR) and various Romanian universities with an interest in Automotive and Transport Engineering. This Congress is endorsed by EAEC (European Automotive Engineers Cooperation). The XXXII-nd edition of SIARS’s International Congress with the theme “Automotive and Transport Engineering” and the XVII-th European Automotive Congress was organized for the third time by Department of Mechanical Machines, Equipment and Transportation from the Politehnica University Timisoara. The Congress purpose is to gather members from academia, industry and government affiliated presenting their possibilities for investigations and latest research, to achieve collaborations in the near future in the field of automotive and transport engineering. The Congress hosted 201 participants from Europe, United States of America, Moldova presenting their scientific achievements within plenary sessions and congress sections. Thus, the auditorium had the opportunity to: • Gain insight into the cutting edge automotive and transport industry and ideas for future developments; • Update their skills and knowledge by attending focused technical sessions; • Network with potential new partners, clients and suppliers; • View the latest technology products and services in the technical exhibition. The papers included in this volume were selected by the Scientific Committee amongst the ones presented within the Congress and are covering the latest issues such as advanced powertrain and propulsion, automotive design and testing, terrain vehicles, advanced engineering methods, materials, automotive technology and maintenance, road safety, mobility of things. EAEC-MVT 2022 Student Congress was integrated into the main congress and offered students from around the world the opportunity to participate at an international conference and to present their papers on the main congress topics. This was also the meeting place for the young students (SIAR junior’s members) in an International Congress. We hope that these papers will be of interest to experts from academia and industry around the world and we wish them to create a favourable framework for addressing key issues in the field of Automotive and Road Transport Engineering that concern contemporary society today. Yours faithfully, EAEC-MVT 2022 Proceedings Editors List of Acknowledgement, Organizing Committee, Sponsors are available in this Pdf.

Effect of the Glass Fiber Orientation on Mechanical Performance of Epoxy based Composites

Composites are one of the most advanced and adaptable engineering materials. The strength of any composite depends upon volume/weight fraction of reinforcement, orientation angle and other factors. The present work focuses on the determination of the mechanical properties of pure epoxy and unidirectional glass fiber reinforced epoxy. Nowadays, glass fibers are being used in several engineering applications like electronics, aviation, automobile, sport industry etc. Glass fibers are having excellent properties like high strength, flexibility, stiffness, and resistance to chemical attack. With an increase in the content of unidirectional glass fiber volume the properties of unidirectional glass Fiber Reinforcement Polymer (GFRP) composite were improved. It may be used in different forms like chopped, woven mat, short fibers and long fibers etc. Each type of glass fiber has unique properties and is used for different applications. The mechanical and thermal properties of various polymer composites reinforced with glass fibers when subjected to mechanical loading have been studied and reported.

A robust, high-temperature-resistant, protective cellulose gel enabled by multiscale structural engineering

Given the escalating environmental and safety concerns, friendly protective materials with exceptional mechanical properties, biodegradability, and insensitivity to high temperature have received more and more attention. Here, we report a robust cellulosic gel through the multi-scale integration of cellulose molecular skeleton, nano-reinforced diatomite, and in situ polymerized polyacrylamide molecule. The bottom-up yet cross-scale approach facilitates the formation of cellulosic gel characterized by a highly interconnected hydrogen bond network and nano-enhanced domain, resulting in a tensile strength of up to 13.83 MPa, a Young's modulus exceeding 280 MPa, and an impact strength around 12.38 KJ m−1. Furthermore, this gel exhibits structural stability at temperatures up to 130 °C, good flame retardancy, and complete biodegradability within a span of 35 days. The robust cellulosic gel, acting as a pliable protector, demonstrates exceptional protection for human joints. Our study presents a highly efficient and scalable pathway towards the development of sustainable and robust biomass gels, holding immense potential in intelligent-protective wearables and advanced materials science and engineering.

Cleaner and Sustainable Production of Core-Sheath Polymer Fibres.

The amalgamation of sustainable practises throughout the fabrication process with advanced material engineering holds promise not only for eco-conscious manufacturing but also for promoting technological advancements in versatile material design and application. Moreover, technological innovation serves as a catalyst for sustainability initiatives, driving innovation and enabling the adoption of greener practises across industries. This study investigates redefining the production protocol of pressure spinning to produce core-sheath polymer fibres, deepening sustainable practises. It aims to explore innovative approaches such as modifying spinning parameters, optimising polymer solvent configurations and understanding fluid behaviour to curtail material wastage and maintain minimal energy consumption without compromising production efficiency. Utilising Polyvinylpyrrolidone (PVP) for the core and Polyethylene oxide (PEO) for the sheath, production rates of up to 64 g/h were achieved with a fibre diameter range of 3.2 ± 1.7 µm to 4.6 ± 2.0 µm. Energy consumption per mass of fibres produced showed a decreasing trend overall with increasing applied gas pressure. These findings highlight the potential for the efficient and scalable production of core-sheath fibres with applications in various advanced materials fields.

High Optical Abropsion from Thin Film MoS2 Nano-Flakes

Due to their distinctive electronic and optical characteristics, transition metal dichalcogenides (TMDs) have become significant materials in optoelectronics. Molybdenum disulfide (MoS2) flakes have received significant interest due to their potential applications. The unique bandgap properties exhibited by MoS2 flakes render them highly appealing for applications in optoelectronic devices [1]. A direct bandgap in this material enables effective interactions between light and matter, which is significant for various applications, including transistors, photodetectors, and light-emitting diodes [2].In this work, we synthesized our MoS2 flakes by exfoliating MoS2 powder following [3]’s recipe. We disperse 500 mg of MoS2 powder into 50 mL of N-Methyl-2-pyrrolidone (NMP)and then use a probe sonicator for the exfoliation process that runs continuously for 6 hours while keeping the sample cooled by a 0 °C ice bath. We later centrifuged at 1500 rpm for 60 min to remove any unexfoliated particles and then centrifuged again at 7500 rpm for 30 min to remove soluble impurities. After removing NMP, the acquired MoS2 flakes dispersed in 50 mL isopropyl alcohol. To study the optical properties of these MoS2 flakes, we prepared 3 x 3 cm2 fused silica substrate rinsed with acetone and DI water, respectively. Before deposition, we sonicate our MoS2 solution for 60 minutes in a bath sonicator. A precise pipet is used to drop-cast 20 uL of MoS2 on the fused silica substrate and wait 120 seconds to let it spread and settle. Afterward, we spin the sample at a low 150 rpm for 40 seconds, ensuring no spillovers. The sample was then carried to a UV-Vis Lambda 1050 spectrometer tool to measure the transmittance and reflectance of the sample over a range of wavelengths 250 to 1200 nm. Subsequently, we calculated absorbance values from this data. We repeat this on the same sample in steps of 20 uL of MoS2, acquiring spectrometer data for 20 to 200 uL of MoS2 on fused silica. The absorbance data showed a slope increase of absorption around 830 nm wavelength, reaching a peak around 660 nm, and It continues to absorb to 250 nm wavelength of the UV range.Moreover, as we increased the MoS2 amount, the overall absorbance increased. At the same time, reflectance increased; however, the change slowed after 60 uL of MoS2. We suspect that the former is due to the increase in the overall thickness of the deposited material, which increases the chance of photons traversing the material to be absorbed. The latter effect could be attributed to texturing, as these deposited MoS2 flakes do not seem to fall flat and create a uniform film and additional reflection from the MoS2 surface. To study that, we prepared five other 3x3 cm2 MoS2 on silicon (Si) samples with 20-100 uL in steps of 20 uL using the same process described earlier. Looking at the morphology using an optical microscope and SEM images of MoS2 on Si, the images show random settlement of MoS2 flakes, leading to uneven coating and witnessing MoS2 flakes arranged and aggregated into islands similar to results reported by others [4]. Also, we found similar dips in reflectivity as reported by literature due to absorption of A and B excitons[5]. Additionally, we measured the electrical conductivity using a hall measurement system of 100 uL MoS2 sample and found that it exhibited n-type behavior with an average sheet resistance value of 2.91x102 Ω/sq. We aim to investigate further the properties and potential applications of these MoS2 flakes.[1] K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically Thin MoS2: A New Direct-Gap Semiconductor,” Phys. Rev. Lett., vol. 105, no. 13, p. 136805, Sep. 2010, doi: 10.1103/PhysRevLett.105.136805.[2] H. J. Jin, C. Park, H. H. Byun, S. H. Park, and S.-Y. Choi, “Electrically Modulated Single/Multicolor High Responsivity 2D MoTe2/MoS2 Photodetector for Broadband Detection,” ACS Photonics, vol. 10, no. 9, pp. 3027–3034, Sep. 2023, doi: 10.1021/acsphotonics.3c00143.[3] X. Yu et al., “Hybrid Heterojunctions of Solution-Processed Semiconducting 2D Transition Metal Dichalcogenides,” ACS Energy Lett., vol. 2, no. 2, pp. 524–531, Feb. 2017, doi: 10.1021/acsenergylett.6b00707.[4] N. Zebardastan et al., “2D MoS2 Heterostructures on Epitaxial and Self-Standing Graphene for Energy Storage: From Growth Mechanism to Application,” Advanced Materials Technologies, vol. 7, no. 4, p. 2100963, 2022, doi: 10.1002/admt.202100963.[5] “Layer-number dependent reflection spectra of MoS2 flakes on SiO2/Si substrate.” Accessed: Nov. 23, 2023. [Online]. Available: https://opg-optica-org.libconnect.ku.ac.ae/ome/fulltext.cfm?uri=ome-8-10-3082&id=398132 Figure 1

Scalable Synthesis of Single Crystal Ni-Rich Cathodes for Advanced Lithium-Ion Batteries

Long-range electrical vehicles require high energy density lithium-ion batteries that utilize stable, high-energy cathode materials. Among various cathodes, Ni-rich NMC cathodes with a layered structure, knows for their high capacity, high voltage, and cost-effectiveness, stand out as one of the most promising cathodes. Traditional polycrystalline Ni-rich NMC encounter issues such as pulverization, gas generation and moisture sensitivity, limiting their widespread use in EV batteries on large scale. The single crystal format of Ni-rich cathode can effectively eliminate and mitigate these issues. However, synthesizing of high-performance single crystal Ni rich NMC, especially when Ni ≥0.8, presents a significant challenge.We’ve explored an innovative phase separation approach for direct synthesis of high-performance single crystal NMC811. The comprehensive investigation into the reaction mechanism of single crystal growth was conducted to understand the relationship between synthesis, morphology, and performance in growing single crystal NMC811. The enhanced performance of these materials was realized through the precise morphological and structural control of precursors and has been confirmed in practical 2Ah pouch cells. The developed approach is readily adaptable to current industry manufacturing processes and provides valuable new insights that can be broadly applied to cost-efficient large-scale synthesis of single crystals and various advanced battery materials technologies.

Viruses and Non‐Woven Polymers: Surface Properties and Future Perspectives in Sampling for Wastewater‐Based Epidemiology

AbstractEnvironmental disease monitoring initiatives such as wastewater‐based epidemiology can offer a unique perspective on the health status of a population. Such efforts are being increasingly utilized to guide public health initiatives and to aid in controlling the spread of infectious diseases. Key to these approaches is the sampling and identification of viruses, bacteria, and other pathogens. Advanced material technologies can be explored for the development of materials suitable for sampling, leading to the retention and detection of viruses. Here, how the surface interactions between viruses and adsorbent materials can inform the future development of effective, novel materials to aid in sampling viruses for wastewater‐based epidemiology are considered. This review provides a summary of the surface properties of viruses along with their physiochemical interactions with adsorbent materials at the solid‐water interface. Also discussed are the properties of non‐woven polymer membranes, a newer material technology being employed for the retention of viruses, with a focus on virus‐capture applications in aqueous environments.

Preface

The 2024 4th International Conference on Advanced Materials and Mechatronics (ICAMM 2024) was held via virtual form in Xi’an, China from May 10th to 12th, 2024. Previous conferences in the past three years of this series have been successfully held and it was agreed to hold the conference once a year, with the aim to establish and develop a constant international collaboration. In recent years, interest in advanced materials and mechatronics has been flourishing all over the globe due to both theoretical and practical requirements. Considering the trend, the fourth conference of ICAMM series was organized in order to provide an international academic forum for developing research cooperation and to promote research and other academic activities in related fields. We entertained about 80 participants at ICAMM 2024 and arranged various speeches and presentations which cover a wide range of topics related to the Conference theme. Many scholars and researchers all over the world have contributed to the emerging technology and application of advanced materials and mechatronics. The wonderful keynote speeches included Semiconductor Lighting and Display: Design and Manufacturing Technology for High Efficiency GaN-based LED Chips (by Prof. Shengjun Zhou, Wuhan University, China), Materials, Processing and Reliability of Low Temperature Bonding in 3D Chip Stacking (by Prof. Liang Zhang, Xiamen University of Technology, China), Monitoring Applications of Electronic Devices in the Shipbuilding Industry (by Assoc. Prof. Fengming Du, Dalian Maritime University, China), and Addictive Manufacturing and Intelligent Processing Control of Advanced Metal Materials (by Prof. Kun Li, Chongqing University, China). ICAMM 2024 has been endorsed and supported by many national and international engineering-related universities and organizations and was a complete success. The topics of papers collected and undergone rigorous peer review in the Proceedings of ICAMM 2024 can be classified as follows: Semiconductor Materials, Mechanics of Materials, Material Forming Process and Equipment, Advanced Electromagnetism, Laser Physics and Technology, Irradiation electronics, etc. Last but not the least is our gratitude. We would like to express our sincere thanks to all the keynote speakers, authors, committee members for the success of the Conference, which has given rise to this present volume of selected papers. We would also like to acknowledge the staff of Journal of Physics: Conference Series for their effective work to make this Proceedings published. The Committee of ICAMM 2024 List of Committee Member is available in this Pdf.

Synthesis of hierarchical porous carbon scaffold derived from red kidney bean peels for advanced Li–Se and Na–Se batteries

Incorporating selenium into high-surface-area carbon with hierarchical pores, derived from red kidney bean peels via simple carbonization/activation, yields a superior Li–Se battery cathode material. This method produces a carbon framework with 568 m2 g−1 surface area, significant pore volume, and improves the composite’s electronic conductivity and stability by mitigating volume changes and reducing lithium polyselenide dissolution. The Se@ACRKB composite, containing 45 wt% selenium, shows high discharge capacities (609.13 mAh g−1 on the 2nd cycle, maintaining 470.76 mAh g−1 after 400 cycles at 0.2 C, and 387.58 mAh g−1 over 1000 cycles at 1 C). This demonstrates exceptional long-term stability and performance, also applicable to Na–Se batteries, with 421.36 mAh g−1 capacity after 200 cycles at 0.1 C. Our study showcases the potential of using sustainable materials for advanced battery technologies, emphasizing cost-effective and scalable solutions for energy storage.

Achieving excellent mechanical and robust lubrication behavior in the CoCrNi medium-entropy alloy via in-situ graphite

The unsatisfactory wear resistance and lubrication performance of CoCrNi multi-principal elements alloys (MPEAs) have emerged as critical challenges, impeding their extensive utilization as advanced engineering materials, despite their desirable mechanical and physical properties. Incorporating graphite to obtain MPEAs-based self-lubricating composites is believed to improve the wear resistance. However, it is challenging to prepare composites with high strength, large plasticity, and excellent anti-friction performance simultaneously. The present study reports the fabrication of novel CoCrNi MPEA-based self-lubricating composites, consisting of in-situ graphite and high-hardness silicides/carbides as reinforcement, prepared by powder metallurgy and reactive sintering. The 20.6 vol% Gr@CoCrNi–SiC composite exhibits an optimal trade-off between strength and ductility, along with anti-friction and wear resistance which is superior to the reported composites with different solid lubricants. The wear mechanism is attributed to the coordinated deformation mechanism between the CoCrNi FCC matrix and silicides/carbides, and the stabile lubrication effect supported by the structural transformation from the original polycrystalline lattice structure to core-shell nanocomposite structure (similar to diamond-like carbon) of the in-situ graphite. This simple, economical and practical strategy contributes to the development of MPEA self-lubricating composites with excellent comprehensive properties.

Influence of aluminium in wetting characteristics of Zn-Al alloy

In this article, the effect of aluminium in Zn-5 wt%Al alloy is studied after heat treatment at 375 ⁰C focusing particularly on its effect at grain boundaries or grain boundary junctions. The understanding of such behaviour is crucial for microstructural controlling during alloy processing, ensuring better alloy performance for various applications. Using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), the microstructural and crystallographic study of the alloy was carried out. The SEM results of the annealed sample show a lenticular-shaped wetting layer corresponding to the lower energy of the grain boundary. It was observed that Zn is distributed throughout the sample, while the concentration of Al is increased at the grain boundaries as evidenced by the elemental spectra. XRD result confirms that no new phases are formed thereby confirming the formation of an Al-rich solid solution at the grain boundary. The absence of new phases indicates that aluminium in the alloy tends to lower grain boundary energy by occupying grain boundary positions, rather than forming a new compound, thereby reaching thermodynamic equilibrium. This study is important for developing advanced engineering materials with solid-state lubrication capabilities, for diverse industrial applications.

Nanostructured Titanium with Ultrafine‐Grained Structure as Advanced Engineering Material for Biomedical Application

Titanium and its alloys are popular materials for medical application, particularly in implant devices, where high mechanical properties and osseointegration are critical factors for successful implantation. In this work, the progress in the studies of nanostructured commercially pure Grade 4 titanium (nanoTi) is demonstrated, in which an ultrafine‐grained structure with nanoscale grain size is formed using severe plastic deformation processing. Nanostructured Grade 4 Ti has a very high strength, and its physical nature and strengthening mechanisms are analyzed herein. NanoTi proved also to have very high osseointegration during in vivo experiments. At the same time, the highest biofunctionality is demonstrated by the etched nanoTi samples with pronounced surface roughness, the latter being revealed from precise roughness measurements. The present study provided convincing evidence of accelerated bone formation on nanoTi, which is very promising for manufacture of dental and maxillofacial implants.

Periodic spinodal decomposition in double–strengthened medium–entropy alloy

Achieving an optimal balance between strength and ductility in advanced engineering materials has long been a challenge for researchers. In the field of material strengthening, most approaches that prevent or impede the motion of dislocations involve ductility reduction. In the present study, we propose a strengthening approach based on spinodal decomposition in which Cu and Al are introduced into a ferrous medium–entropy alloy. The matrix undergoes nanoscale periodic spinodal decomposition via a simple one-step aging procedure. Chemical fluctuations within periodic spinodal decomposed structures induce spinodal hardening, leading to a doubled strengthening effect that surpasses the conventional precipitation strengthening mechanism. Notably, the periodic spinodal decomposed structures effectively overcome strain localization issues, preserving elongation and doubling their mechanical strength. Spinodal decomposition offers high versatility because it can be implemented with minimal elemental addition, making it a promising candidate for enhancing the mechanical properties of various alloy systems.

Development and parametric study of reversible motion-wire electrochemical spark machining (RM-WECSM) setup for micro-width curve profile cutting on Al2O3 epoxy nanocomposites

The development of wire electrochemical spark machining setup is always challenging in the form of industrial viable for machining advanced engineering materials such as polymer nanocomposites, quartz, glass, ceramics, etc. Because of some drawbacks associated with it, like irregularity in kerf width, poor surface finish, no spark formed at high wire velocity, wire breaking at high voltage, etc. In the present work, a newly developed hybrid machining process that is reversible motion-wire electrochemical spark machining (RM-WECSM) has been developed for curve profile cutting, especially on non-conducting workpieces such as aluminum oxide epoxy nanocomposite of 3.5 mm thickness. The effect of NaOH concentration, applied voltage, reversible wire velocity, pulse on-and-off time, on material removal rate and average surface roughness have been studied using a one-parameter-at-a-time approach. Sparking occurred from the electrolyte surface to 10 mm above the electrolyte surface to cut the workpiece. The spark length is equal to the workpiece thickness. A continuous, stable spark has been formed at a high reversible wire velocity (19.8 m/min). Simultaneously, self-electrolyte flow has been generated, due to which melted materials have been washed out of the cut-surface and provided the smooth (1.987 µm) cut-surface of the workpiece. The maximum MRR is found as 1.63 mg/min. Thermal cracks, heat-affected zones and recast layers were not found on the curve cut-surface, and it was analyzed by a field emission scanning electron microscope.

Simulation and experimental study for enhancing surface integrity of micro-slots processed on Nimonic-263 super alloy via electrochemical machining

ABSTRACT The potential of micro electrochemical slotting is significant due to its adaptability and usefulness across diverse manufacturing applications. This technique holds potential, particularly for handling advanced engineering materials like superalloys, with a focus on applications requiring high strength, i.e., micro-cutting for gas-turbine parts, biomedical applications, etc. With this view, this article has been attempted to explore the influence of various considered machining factors, namely as; applied potential difference, tool feed rate (TFR), pulse supply, and modes of tool insulation on the performance measures, i.e. material removal rate (MRR) and surface roughness (Ra) while attempting micro-slotting in Nimonic-263 superalloy work samples. The entire experimentation was conducted on the in-house fabricated 3-axis micro-electrochemical setup designed for performing various complex machining operations at a miniature scale. Furthermore, this study has also been focused toward investigating the impact of varying the electrical conductivity by employing different tool materials (i.e. copper and SS304) on the process characteristics measured. The observed effects of the tool electrode’s conductivity have also been expressed and supported by performing the simulation for electric field distribution using COMSOL Multiphysics software. The experimental results have revealed that the process input variables remarkably influence MRR and Ra, mainly applied voltage and TFR. The best values of MRR and Ra attained with SS304 and copper tool electrodes were 1.521 mg/min and 0.721 mg/min, and 0.038 µm and 0.029 µm, correspondingly. The microstructure analysis has further been conducted on machined micro-slotted work samples that provided detailed insights into various surface integrity aspects, which are essential for microdevice applications.