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Elastic microphase separation produces robust bicontinuous materials

Nature materials 2024年第1期23卷 124-130页

作者： Fernández-Rico, Carla Schreiber, Sanjay Oudich, Hamza Lorenz, Charlotta Sicher, Alba Sai, Tianqi Bauernfeind, Viola Heyden, Stefanie Carrara, Pietro Lorenzis, Laura De Style, Robert W. Dufresne, Eric R. Department of Materials ETH Zürich Zürich Switzerland Department of Mechanical and Process Engineering ETH Zürich Zürich Switzerland Adolphe Merkle Institute University of Fribourg Fribourg Switzerland Department of Materials Science and Engineering Department of Physics Cornell University IthacaNY United States

Bicontinuous microstructures are essential to the function of diverse natural and synthetic systems. Their synthesis has been based on two approaches: arrested phase separation or self-assembly of block copolymers. The former is attractive for its chemical simplicity and the latter, for its thermodynamic robustness. Here we introduce elastic microphase separation (EMPS) as an alternative approach to make bicontinuous microstructures. Conceptually, EMPS balances the molecular-scale forces that drive demixing with large-scale elasticity to encode a thermodynamic length scale. This process features a continuous phase transition, reversible without hysteresis. Practically, EMPS is triggered by simply supersaturating an elastomeric matrix with a liquid, resulting in uniform bicontinuous materials with a well-defined microscopic length scale tuned by the matrix stiffness. The versatility of EMPS is further demonstrated by fabricating bicontinuous materials with superior mechanical properties and controlled anisotropy and microstructural gradients. Overall, EMPS presents a robust alternative for the bulk fabrication of homogeneous bicontinuous materials. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

关键词： Microphase separation

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Improving the strength and surface properties of TNTZ alloy through a combination of high-pressure torsion and laser surface treatment

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International Journal of Advanced Manufacturing Technology 2024年第5-6期134卷 2693-2704页

作者： Lin, Hsuan-Kai Hsieh, Tsai-Hsuan Cheng, Yi-Hong Bazarnik, Piotr Wang, Chuan Ting Huang, Yi Ye, Jing Abdelkader, Amor Langdon, Terence G. Department of Materials Engineering National Pingtung University of Science and Technology Pingtung912 Taiwan Faculty of Materials Science and Engineering Warsaw University of Technology Woloska141 02-507 Poland School of Mechanical Engineering Nanjing University of Science and Technology Jiangsu Nanjing210094 China Department of Design and Engineering Faculty of Science and Technology Bournemouth University Dorset PooleBH12 5BB United Kingdom Materials Research Group Department of Mechanical Engineering University of Southampton SouthamptonSO17 1BJ United Kingdom

The Ti–29Nb–13Ta–4.6Zr alloy (TNTZ) is a β-Ti alloy that has a potential for use in biomedical applications as an alternative to the less-compatible Ti64 alloys. Enhancing the strength and the surface finish of TNTZ is essential for biomedical applications. In this research, a combination of high-pressure torsion (HPT) and laser treatment was used to improve the TNTZ properties. The HPT-treated samples showed significantly enhanced mechanical properties when compared with the traditional solution-treated TNTZ. A laser surface treatment immediately forms a hydrophilic surface that transforms into a steady hydrophobic state after 14 days in air and the surface roughness increases with an increase in laser power and a slower scanning rate. The corrosion resistance of TNTZ improves significantly after laser treatment, with the corrosion current dropping from 1 × 10−8 to 1.2 × 10−9 A and the corrosion potential peak shifting to a more positive value from − 0.349 to − 0.158 V. The friction coefficient after laser treatment decreased from 0.134 to 0.093 and then further reduced to 0.082 after 14 days in air thereby suggesting an enhancement in the tribological properties. Overall, the results show that HPT processing combined with a post-HPT laser treatment is beneficial for enhancing the mechanical properties and the corrosion and wear performance of the TNTZ alloy. © The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature 2024.

关键词： Corrosion resistance

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Challenges and risks of using renewable energy sources 5

Challenges and risks of using renewable energy sources

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5th International Conference on Green Energy, Environment, and Sustainable Development, GEESD 2024

作者： Viktoriia, Kozechko Valentyn, Kozechko Department of Mechanical Engineering Technology and Materials Science Dnipro University of Technology Dnipro49000 Ukraine

ISBN: (纸本)9781510683006

The article provides a comprehensive analysis of the transition from traditional energy sources to renewable energy. The article begins by addressing the necessity for stable and cost-effective energy generation while mitigating environmental impacts. Despite the advantages, renewable energy sources often present accessibility and cost challenges compared to fossil fuels, primarily due to lower energy returns and high capital investments. The classification of renewable energy sources into five main types: wind, solar, hydro, bioenergy, and geothermal energy, highlighting their respective advantages and operational limitations. For instance, wind energy is effective in coastal regions but has high initial costs and transmission challenges, while solar energy’s efficiency is weather-dependent. The article delves into barriers to green energy adoption, such as high capital expenditures, decentralized location requirements, transmission costs, grid integration complexities, and the intermittency of renewable sources. It emphasizes the need for significant energy storage solutions to ensure a stable energy supply. Furthermore, the discussion extends to the economic, logistical, and regulatory challenges of decentralized renewable energy systems. The complexities of production, recycling, and disposal of renewable energy components are highlighted, stressing the environmental and economic costs. Also it examines the Energy Return on Investment (EROI) for both traditional and renewable energy sources. Traditional sources like coal, natural gas, hydropower, and nuclear energy exhibit high EROI values, making them more efficient compared to renewable sources, which often have lower EROI due to the energy-intensive processes involved in their production and maintenance. In conclusion, while renewable energy offers significant long-term benefits, the article underscores the need for overcoming initial financial, logistical, and technical challenges to achieve a sustainable en

关键词： Clean energy

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Circular Economy in Healthcare Sector: Cloud-based HST with GT to Minimize Healthcare-associated Infections

Circular Economy in Healthcare Sector: Cloud-based HST with ...

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2024 IEEE International Conference on Industrial engineering and engineering Management, IEEM 2024

作者： Alfina, Kartika Nur Chandima Ratnayake, R.M. Bandung Indonesia Department of Mechanical and Structural Engineering and Materials Science University of Stavanger Stavanger Norway

ISBN: (纸本)9798350386097

Healthcare-associated infections (HAIs) pose a significant challenge to the quality of care, leading to patient complications, extended hospital stays, and high consumable costs. Cloud-based technologies have become essential for overcoming barriers to circularity in healthcare, offering transformative opportunities for healthcare systems. Measuring the impact of linear consumption is crucial for circularity, however the healthcare industry lacks focus on measuring the impact of HAIs, particularly related to hand hygiene. Integrating cloud-based hand sanitizer and group technology offers potential to prevent the spread of HAIs and minimize linear consumption, aligning with Circular Economy Goals (CEGs). This study examines the potential of integrating cloud-based HST with group technology (GT) to minimize the impact of HAIs caused by poor hand hygiene. Using the Opitz Code classification system, a coding system is created to measure the impact of poor hand hygiene, serving as a control and improvement tool aligned with CEGs. This article presents an illustrative case to demonstrate the HST coding classification to facilitate predictive analysis for HAIs prevention and control. These findings contribute to reducing HAIs by improving hand hygiene performance in healthcare facilities. Furthermore, by aligning technological advances with CEGs, this study offers a proactive strategy to mitigate environmental degradation by reducing carbon dioxide (CO2) emissions and strengthening the resilience of healthcare systems. © 2024 IEEE.

关键词： Circular economy

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On the Free Vibration of 3D-Printed Structural Elements 14

On the Free Vibration of 3D-Printed Structural Elements

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14th International Conference on Recent Advances in Structural Dynamics, RASD 2024

作者： Virgin, Lawrie Department of Mechanical Engineering and Materials Science Duke University DurhamNC27708 United States

This paper focuses on using 3D-printing to produce relatively simple, flexible structural components such as cantilevers, rings and plane frames. The relatively high resolution of modern 3D-printers facilitates the production of small-scale but slender structures, and thus provides an opportunity to exploit geometric parameter variations to enhance a practical understanding of stiffness and vibration. This approach has proved successful in both the classroom via demonstration models, as well as in the research lab in which elementary facilities can be utilized to acquire data. An especially useful facet of this approach is the assessment and justification for modeling simplifications, e.g., estimating flexural modulus, or judging the circumstances under which the familiar sway assumption is valid in portal frames. Non-simple structural geometries, for example circular rings, can also be conveniently produced and tested for natural frequencies and vibration mode shapes. We then extend this approach to forced vibration, with examples including the vibrating reed tachometer and sympathetic resonance. The advantage of this approach obviates the need for any external sources of excitation. © 2024 Institute of Physics Publishing. All rights reserved.

关键词： Research laboratories

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Gradient CNT/PVDF piezoelectric composite with enhanced force-electric coupling for soccer training

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Nano Research 2023年第8期16卷 11312-11319页

作者： Wanghong Zeng Weili Deng Tao Yang Shenglong Wang Yue Sun Jieling Zhang Xiarong Ren Long Jin Lihua Tang Weiqing Yang Key Laboratory of Advanced Technologies of Materials(Ministry of Education) School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China Department of Mechanical and Mechatronics Engineering University of AucklandAuckland 1010New Zealand Research Institute of Frontier Science Southwest Jiaotong UniversityChengdu 610031China

Real-time monitoring of ball–shoe interactions can provide essential information for high-quality instruction in personalized soccer training,yet existing monitoring systems struggle to reflect specific forces,loci,and durations of ***,we design a self-powered piezoelectric sensor constructed by the gradient carbon nanotube/polyvinylidene fluoride(CNT/PVDF)composite to monitor the interactions between the ball and the ***-dimensional Raman mapping demonstrates the gradient structure of CNT/PVDF prepared by programmable electrospinning combined with a hot *** from the synergistic effect of local polarization caused by the enrichment of CNT and the reduced diffusion of silver patterns in gradient structure,the as-prepared composite exhibits enhanced force-electric coupling with an excellent sensitivity of 80 mV/N and durability over 15,000 *** this basis,we conformally attach a 3×3 sensor array to a soccer shoe,enabling real-time acquisition of kick position and contact force,which could provide quantitative assessment and personalize guidance for the training of soccer *** self-powered piezoelectric sensor network system offers a promising paradigm for wearable monitoring under strong impact forces.

关键词： mechanical and electrical performance pressure sensor carbon nanotube/polyvinylidene fluoride(CNT/PVDF)composite soccer training

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Solvothermal growth of Zn_(2)SnO_(4) for efficient dye-sensitized solar cells

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Rare Metals 2022年第3期41卷 942-950页

作者： Yu-Fen Wang Hui Feng Yi-Rui Deng Fei-Fei Xin De-Jun Li Zhuo-Fan Hu Lei Zhang Rui-Ping Liu Energy and Materials Engineering Centre College of Physics and Materials ScienceTianjin Normal UniversityTianjin 300387China Department of Materials Science and Engineering China University of Mining and Technology(Beijing)Beijing 100083China Department of Mechanical Engineering University of AlaskaFairbanksAlaska 99775-5905USA

Zn_(2)SnO_(4)plates,particles and spheres are suc-cessfully prepared via a facile synthesis way by carefully adjusting the solvothermal conditions,which are further applied as photoanodes in dye-sensitized solar cells(DSSCs)to explore the relationships between the pho-toanode nanostructure and the photovoltaic *** a result,the DSSCs based on Zn_(2)SnO_(4)spheres pho-toanode showcased the best power conversion efficiency(PCE,4.85%),compared to Zn_(2)SnO_(4)plates(3.80%)and particles(4.13%).It is found that Zn_(2)SnO_(4)spheres exhibit the highest light-scattering abilities,as evidenced by ultraviolet–visible(UV–Vis)diffuse reflectance ***,investigations on dynamic electron transport and recombination properties via intensity-modulated photovoltage/photocurrent spectroscopy(IMVS/IMPS),and electrochemical impedance spectroscopy(EIS)mea-surements demonstrate that the Zn_(2)SnO_(4)spheres-based DSSCs possess the fastest electron transport rate,the longest electron lifetime,the highest electron collection efficiency(ηc c),and the largest charge recombination resistance,compared with the Zn_(2)SnO_(4)plates and particles,all of which are highly beneficial for the powder conversion efficiency enhancements.

关键词： Dye-sensitized solar cell Zn_(2)SnO_(4) Plates Particles Spheres

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In-situ observation of microcrack initiation and damage nucleation modes on the HAZ of laser-welded DP1180 joint

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Journal of materials science & Technology 2023年第17期148卷 138-149页

作者： Junliang Xue Wei Guo Jin Yang Mingsheng Xia Guang Zhao Caiwang Tan Zhandong Wan Jiaxuan Chi Hongqiang Zhang School of Mechanical Engineering and Automation Beihang UniversityBeijing100191China School of Materials Engineering Shanghai University of Engineering ScienceShanghai201620China R&D Center TANGSTEEL CompanyHBIS GroupTangshan063016China Shandong Provincial Key Laboratory of Special Welding Technology Harbin Institute of Technology at WeihaiWeihai264209China Department of Mechanical Engineering Tsinghua UniversityBeijing100084China School of Materials Science and Engineering Beihang UniversityBeijing100191China

In-situ SEM can intuitively observe the changes in microstructure and microcrack initiation during the deformation process of the *** this paper,the microstructural evolution,mechanical properties,and damage nucleation modes of DP1180 laser welded joints were systematically discussed by the trans-mission electron microscope(TEM),focused ion beam(FIB),and in-situ tensile *** precipitation of carbides and disappearance of dislocations tangles deteriorated the mechanical properties of tempered martensite in the sub-critical heat affected zone(SCHAZ),which caused its microhardness slightly de-creased(∼27 HV)and also called the softened *** joints fractured in the SCHAZ during the tensile and Erichsen cupping tests and microcracks initiated from the tempered martensite,while the microc-rack initiation of base material(BM)occurred at the ferrite/martensite *** dominant damage nucleation mode of the joint was tempered martensite cracking,and that of BM was ferrite/martensite interface decohesion during tests.

关键词： In-situ tensile test DP steel Laser welded Damage nucleation modes

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Design of protective and high sensitivity encapsulation layers in wearable devices

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science China(Technological sciences) 2023年第1期66卷 223-232页

作者： WANG XiuFeng HUANG JieLong LIU YangChengYi TAN JinYuan CHEN ShangDa AVILA Raudel XIE ZhaoQian School of Materials Science and Engineering Xiangtan UniversityXiangian 41105China Department of Mechanical Engineering Northwestern UniversityEvanstonIL 60208USA State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of TechnologyDalian116024China

Elastomeric encapsulation layers are widely used in soft, wearable devices to physically isolate rigid electronic components from external environmental stimuli(e.g., stress) and facilitate device sterilization for reusability. In devices experiencing large deformations, the stress-isolation effect of the top encapsulation layer can eliminate the damage to the electronic components caused by external forces. However, for health monitoring and sensing applications, the strain-isolation effect of the bottom encapsulation layer can partially block the physiological signals of interest and degrade the measurement accuracy. Here, an analytic model is developed for the strain-and stress-isolation effects present in wearable devices with elastomeric encapsulation layers. The soft, elastomeric encapsulation layers and main electronic components layer are modeled as transversely isotropicelastic mediums and the strain-and stress-isolation effects are described using isolation indexes. The analysis and results show that the isolation effects strongly depend on the thickness, density, and elastic modulus of both the elastomeric encapsulation layers and the main electronic component layer. These findings, combined with the flexible mechanics design strategies of wearable devices, provide new design guidelines for future wearable devices to protect them from external forces while capturing the relevant physiological signals underneath the skin.

关键词： strain-isolation effect stress-isolation effect elastomeric encapsulation transversely isotropic medium wearable devices

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Dual nanoprecipitation and nanoscale chemical heterogeneity in a secondary hardening steel for ultrahigh strength and large uniform elongation

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Journal of materials science & Technology 2024年第18期185卷 245-258页

作者： Shidong Wang Jinhua Wang Shijie Zhang Daixiu Wei Yang Chen Xuequan Rong Wu Gong Stefanus Harjo Xiaochun Liu Zengbao Jiao Zhigang Yang Gang Sha Chunxu Wang Guang Chen Hao Chen Key Laboratory for Advanced Materials of Ministry of Education School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China School of Materials Science and Engineering/Herbert Gleiter Institute of Nanoscience Nanjing University of Science and TechnologyNanjing 210094China National Key Laboratory of Advanced Casting Technologies MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials TechnologyEngineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China J-PARC Center Japan Atomic Energy AgencyIbaraki 319-1195Japan Institute of Metals College of Materials Science and EngineeringChangsha University of Science&TechnologyChangsha 410114China Department of Mechanical Engineering Research Institute for Advanced ManufacturingThe Hong Kong Polytechnic UniversityHong Kong 999077China Central Iron and Steel Research Institute Beijing 100081China

Nanoprecipitates and nanoscale retained austenite(RA)with suitable stability play crucial roles in deter-mining the yield strength(YS)and ductility of ultrahigh strength steels(UHSSs).However,owing to the kinetics incompatibility between nanoprecipitation and austenite reversion,it is highly challenging to si-multaneously introduce high-density nanoprecipitates and optimized RA in *** this work,through the combination of austenite reversion treatment(ART)and subsequent flash austenitizing(FA),nanoscale chemical heterogeneity was successfully introduced into a low-cost UHSS prior to the aging *** chemical heterogeneity involved the enrichment of Mn and Ni in the austenite *** resulting UHSS exhibited dual-nanoprecipitation of Ni(Al,Mn)and(Mo,Cr)_(2)C and nanoscale austenite stabilized via Mn and Ni *** hard martensitic matrix strengthened by high-density dual-nanoprecipitates con-strains the plastic deformation of soft RA with a relatively low fraction of-15%,and the presence of relatively stable nanoscale RA with adequate Mn and Ni enrichment leads to a marginal loss in YS but keeps a persistent transformation-induced plasticity(TRIP)*** a result,the newly-developed UHSS exhibits an ultrahigh YS of-1.7 GPa,an ultimate tensile strength(UTS)of-1.8 GPa,a large uniform elongation(UE)of-8.5%,and a total elongation(TE)of-13%.The strategy of presetting chemical heterogeneity to introduce proper metastable phases before aging can be extended to other UHSSs and precipitation-hardened alloys.

关键词： Ultrahigh strength steels Dual-nanoprecipitation Austenite stability TRIP effect Phase transformation

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