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Anomalous properties of spark plasma sintered boron nitride solids

materials Today 2025年 86卷 42-51页

作者： Biswas, Abhijit Serles, Peter Alvarez, Gustavo A. Schimpf, Jesse Hache, Michel Kong, Jonathan Demingos, Pedro Guerra Yuan, Bo Pieshkov, Tymofii S. Li, Chenxi Puthirath, Anand B. Gao, Bin Gray, Tia Zhang, Xiang Murukeshan, Jishnu Vajtai, Robert Dai, Pengcheng Singh, Chandra Veer Howe, Jane Zou, Yu Martin, Lane W. Clancy, James Patrick Tian, Zhiting Filleter, Tobin Ajayan, Pulickel M. Department of Materials Science and Nanoengineering Rice University HoustonTX77005 United States Department of Mechanical & Industrial Engineering University of Toronto 5 King's College Road TorontoM5S 3G8 Canada Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States Department of Materials Science and Engineering University of California Berkeley94720 United States Department of Materials Science and Engineering University of Toronto 184 College St TorontoM5S 3E4 Canada Department of Physics and Astronomy McMaster University HamiltonL8S 4M1 Canada Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Physics and Astronomy Rice University HoustonTX77005 United States Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley94720 United States

Hexagonal boron nitride (h-BN) is a brittle ceramic with a layered structure, however, recent experiments have suggested that inter-layer structural engineering could be key to new structural and functional properties. Here we report the scalable bulk synthesis of high-density crystalline h-BN solids, by using high-temperature spark plasma sintering (SPS) of h-BN powders, which show high values of mechanical strength, ductility, dielectric constant, thermal conductivity, and exceptional neutron radiation shielding capability. Through exhaustive characterizations we reveal that SPS induces non-basal plane crystallinity, twisting of layers, and facilitates inter-grain fusion with a high degree of in-plane alignment across macroscale dimensions, resulting in near-theoretical density and improved properties. Our findings highlight the importance of material design, via new approaches such as layer twisting and interlayer interconnections, to create novel ceramics with properties that could go beyond their intrinsic limits. © 2025

关键词： Ductility

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Scalable Arrays of Pneumatic Sensors for Multitouch Soft Skins

Scalable Arrays of Pneumatic Sensors for Multitouch Soft Ski...

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IEEE International Conference on Soft Robotics (RoboSoft)

作者： Xiaoran Zha Saurabh Jadhav Iman Adibnazari Yichen Zhai Michael T. Tolley Mechanical and Aerospace Engineering Department Materials Science and Engineering Program University of California San Diego San Diego CA USA

Soft robotic systems necessitate accurate and reliable sensor readings to detect environmental interactions and provide precise feedback for control. To be effective, soft sensors must exhibit sensitivity, reliability, repeatability, and flexibility. A versatile approach to sensing for soft robots uses soft air-filled deformable structures with pressure transducers to detect pressure changes due to applied forces. However, the common approach of employing one pressure transducer per sensing chamber limits the scalability of this sensing approach (e.g., for large arrays able to detect touch at many locations). Here we present an approach to the design of pneumatic sensor arrays that reduces the number of required transducers. We develop mathematical models to analyze the pressure variations within the sensor arrays in response to applied forces at various locations. We also introduce a method of rapidly fabricating sensor arrays by laminating elastomeric sheets patterned with laser-cut sacrificial layers. We then use our model to optimize the geometry of the sensors and evaluate the results experimentally. Finally, we devise an algorithm capable of determining the location of multiple touches anywhere within the sensor array. This work represents a step towards the practical application of soft pneumatic sensors, particularly for robotic sensing and haptic devices, enhancing the safety of human-robot interactions.

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Continuous Lithium-Ion Extraction From Seawater and Mine Water With a Fuel Cell System and Ceramic Membranes

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Energy & Environmental materials 2024年第6期 258-265页

作者： Cansu K?k Lei Wang Jean Gustavo A.Ruthes Antje Quade Matthew E.Suss Volker Presser INM-Leibniz Institute for New Materials Department of Materials Science & Engineering Saarland University Leibniz Institute for Plasma Science and Technology Faculty of Mechanical Engineering Technion-Israel Institute of Technology Wolfson Department of Chemical Engineering Technion-Israel Institute of Technology Grand Technion Energy Program Technion-Israel Institute of Technology Saarene-Saarland Center for Energy Materials and Sustainability

The demand for electronic devices that utilize lithium is steadily increasing in this rapidly advancing technological *** high-purity lithium in an environmentally friendly way is challenging by using commercialized ***,we propose the first fuel cell system for continuous lithium-ion extraction using a lithium superionic conductor membrane and advanced *** fuel cell system for extracting lithium-ion has demonstrated a twofold increase in the selectivity of Li+/Na+while producing electricity.

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Towards a new avenue for rapid synthesis of electrocatalytic electrodes via laser-induced hydrothermal reaction for water splitting

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International Journal of Extreme Manufacturing 2024年第1期6卷 340-351页

作者： Yang Sha Menghui Zhu Kun Huang Yang Zhang Francis Moissinac Zhizhou Zhang Dongxu Cheng Paul Mativenga Zhu Liu Department of Materials School of Natural SciencesThe University of ManchesterOxford RoadManchester M139PLUnited Kingdom Laser Processing Research Centre Department of MechanicalAerospace and Civil EngineeringSchool of EngineeringThe University of ManchesterOxford RoadManchester M139PLUnited Kingdom National Graphene Institute The University of ManchesterOxford RoadManchester M139PLUnited Kingdom Department of Chemical Engineering and Analytical Science School of EngineeringThe University of ManchesterOxford RoadManchester M139PLUnited Kingdom Research Centre for Laser Extreme Manufacturing Ningbo Institute of Materials Engineering and TechnologyChinese Academy of SciencesNingboPeople’s Republic of China

Electrochemical production of hydrogen from water requires the development ofelectrocatalysts that are active,stable,and low-cost for water *** address these challenges,researchers are increasingly exploring binder-free electrocatalytic integratedelectrodes (IEs) as an alternative to conventional powder-based electrode preparation methods,for the former is highly desirable to improve the catalytic activity and long-term stability for large-scale applications of ***,we demonstrate a laser-inducedhydrothermal reaction (LIHR) technique to grow NiMoO4nanosheets on nickel foam,which is then calcined under H2/Ar mixed gases to prepare the IE *** electrode exhibits superior hydrogen evolution reaction performance,requiring overpotentials of 59,116 and143 mV to achieve current densities of 100,500 and 1000 mA·*** the 350 h chronopotentiometry test at current densities of 100 and 500 m A·cm-2,the overpotentialremains essentially *** addition,NiFe-layered double hydroxide grown on Ni foam is also fabricated with the same LIHR method and coupled with IE-NiMo-IR to achieve water *** combination exhibits excellent durability under industrial current *** energy consumption and production efficiency of the LIHR method are systematicallycompared with the conventional hydrothermal *** LIHR method significantly improves the production rate by over 19 times,while consuming only 27.78%of the total energy required by conventional hydrothermal methods to achieve the same production.

关键词： electrocatalytic electrode laser-induced hydrothermal reaction NiFe layered double hydroxides hydrogen evolution reaction water splitting energy consumption production rate

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A FINITE ELEMENT ANALYSIS-BASED DIGITAL TWIN FOR INVESTIGATING THE mechanical BEHAVIOR OF TI–6AL–4V AT HIGH AND MODERATE TEMPERATURES

A FINITE ELEMENT ANALYSIS-BASED DIGITAL TWIN FOR INVESTIGATI...

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ASME 2024 International mechanical engineering Congress and Exposition, IMECE 2024

作者： Xu, Dong Frame, Lesley D. Kim, Jeongho Tang, J. School of Mechanical Aerospace and Manufacturing Engineering University of Connecticut StorrsCT06269 United States Department of Materials Science & Engineering University of Connecticut StorrsCT06269 United States Department of Civil & Environmental Engineering University of Connecticut StorrsCT06269 United States

ISBN: (纸本)9780791888612

The titanium alloy Ti-6Al-4V is widely used across various applications, such as aircraft structural components, machinery parts, and particularly in parts for medical devices. Understanding the deformation behavior and microstructural changes of this material during thermal processing is essential for achieving the required product dimensions and ultimate mechanical properties. The transformation of Ti-6Al-4V's crystal structure from the beta phase (body-centered cubic structure) to the alpha phase (hexagonal close-packed structure) occurs over a temperature range of 980°C to 650°C. Therefore, investigating the mechanical behavior of Ti-6Al-4V within this temperature spectrum is crucial for optimizing the heat treatment process and improving the alloy's mechanical properties. Existing studies have revealed that in this temperature range, the increase in flow stress of Ti-6Al-4V as the temperature decreases exhibits a unique non-linear behavior. Utilizing a Finite Element Analysis (FEA)-Based Digital Twin enables precise simulations of complex behaviors, offering deep insights into stress distribution and deformation patterns under various thermal conditions. This predictive model plays a crucial role in enhancing heat treatment methodologies, crafting components with improved mechanical properties, and reducing both the cost and time associated with experimental procedures. The utilization of the Gleeble 3500 physical simulator emerges as a cornerstone in this study for the systematic collection of experimental data, specifically targeting a range of predefined temperatures and strain rates. This investigation notably pioneers the use of a variable temperature tensile test, a methodological innovation aimed at an in-depth exploration of the phase transformation dynamics inherent to the Ti-6Al-4V alloy. This technique is distinguished by its gradual temperature reduction strategy, enabling a nuanced analysis of thermal effects on material properties. In the realm of

关键词： Strain rate

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MODEL UPDATING OF CONSTITUTIVE RELATION OF TI64 ALLOY BASED ON GLEEBLE TESTING

MODEL UPDATING OF CONSTITUTIVE RELATION OF TI64 ALLOY BASED ...

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ASME 2024 International Design engineering Technical Conferences and Computers and Information in engineering Conference, IDETC-CIE 2024

ISBN: (纸本)9780791888346

This study investigates the mechanical behavior of Ti64 alloy at high temperature (750°C) using digital twinning technology based on finite element analysis in combination with Gleeble testing. In the realm of high-temperature alloy materials, empirical constitutive models, such as the Johnson-Cook constitutive relation, have conventionally been utilized to delineate the mechanical behavior of metallic substances under conditions of elevated temperatures and strain rates. This research applies a modified Johnson-Cook model tailored specifically for characterizing the unique strength hardening mechanisms inherent to Ti64 alloy. Subsequently, computational simulation is conducted to implement the modified Johnson-Cook model within finite element analyses. Furthermore, to address the computational challenge inherent in finite element simulation based inverse analysis through optimization, a multi-response Gaussian process model is constructed as a surrogate model to replicate thermomechanical analyses, thereby facilitating efficient simulation. Finally, the parametric identification is cast into an optimization problem, that minimizes the difference between Gleeble testing results and the model prediction in the parametric space, to determine the model parameters of the modified Johnson-Cook model. This framework is successfully applied to the model updating of Ti64 alloy. The algorithms, including the custom user subroutines and the parameter identification process, provide valuable tools for exploring the constitutive relations of various alloys. © 2024 by ASME.

关键词： Strain rate

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Experimental Investigation of the Nonlocal Dynamic Damage Mechanism in Shale

Experimental Investigation of the Nonlocal Dynamic Damage Me...

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SEM Annual Conference and Exposition on Experimental and Applied Mechanics, 2022

作者： Fahem, Ali F. Guthai, Achyuth Thumbalam Singh, Raman P. Department of Materials Science and Engineering College of Engineering Architecture and Technology Oklahoma State University TulsaOK United States Department of Mechanical Engineering University of Al-Qadisiyah Al-Qadisiyah Iraq Department of Mechanical and Aerospace Engineering College of Engineering Architecture and Technology Oklahoma State University TulsaOK United States

ISBN: (纸本)9783031174520

Understanding the dynamic failure mechanisms of shale is critical for optimizing oil and gas extraction from unconventional resources. This work presents the experimental investigation of the mechanism of nonlocal damage distribution in shale material under dynamic loading conditions. A circular disk specimen is subjected to local biaxial loading conditions and tested under two different experimental configurations. First, dynamic damage is investigated when the material is under tensile load along the bedding direction and compressive load perpendicular to the bedding direction. Second, the disk is rotated 90°, and the damage is investigated when a compressive load is applied in the bedding direction and a tensile load in the perpendicular direction. The specimens are dynamically loaded using a split Hopkinson pressure bar (SHPB). A noncontact optical technique, digital image correlation, is utilized to monitor the full-field strain and nonlocal damage initiation. As a result, two different dynamic damages are observed and discussed. The experimental setup and the nonlocal damage as a function of the bedding direction are also discussed. © 2023, The Society for Experimental Mechanics, Inc.

关键词： Image correlation

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Microwave synthesis of high-entropy alloy catalysts on graphene oxide sheets for oxygen reduction and evolution reactions

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International Journal of Hydrogen Energy 2024年 53卷 999-1008页

作者： Khan, Jala Bib Panda, Pradeep Kumar Yang, Po-Chih Hsieh, Chien-Te Gandomi, Yasser Ashraf Liu, Wei-Ren Chang, Jeng-Kuei Department of Chemical Engineering and Materials Science Yuan Ze University Taoyuan 32003 Taiwan Department of Mechanical Aerospace and Biomedical Engineering University of Tennessee Knoxville 37996 TN United States Department of Chemical Engineering Massachusetts Institute of Technology Cambridge 02142 MA United States Department of Chemical Engineering R&D Center for Membrane Technology Center for Circular Economy Chung Yuan Christian University Taoyuan 32023 Taiwan Department of Materials Science and Engineering National Yang Ming Chiao Tung University Hsinchu 30010 Taiwan

High-entropy alloys (HEAs) are commonly synthesized through solid-state reactions and solution-mediated techniques. In this work, HEA nanoparticles were synthesized using an ultra-efficient pulse microwave (PM) method at relatively low temperatures (∼100 °C) with superior catalytic activities. During the PM synthesis process, the precursors of the reaction activate and accelerate the reaction owing to the release of localized and excessive energy. This leads to the formation of a crystallized high-entropy alloy (HEA). Pt₃₀Al₁₅Mn₁₅Co₁₀Ni₁₅Cu₁₅ and Pt₃₀Al₁₅Mn₁₅Co₁₀Ni₁₅Fe₁₅ HEA nanoparticles were synthesized without requiring additional external heat treatments. Furthermore, the synthesized entropically stable HEA nanoparticles showed excellent dispersion behavior towards graphene oxide (GO) sheets (particle size: 4–10 nm), this enhanced dispersion resulted in improved catalytic activity and long-term durability for various processes including H₂ adsorption/desorption, oxygen reduction reaction (ORR), and oxygen evolution reaction (OER). The robust design of Cu-HEA-GO catalytic nanoparticles leads to increased synergistic interactions, which play a critical role in enhancing the ORR/OER activity. We firmly believe that the framework established in this study paves the way for the development of various high-performance catalysts based on HEAs for applications in fuel cells, metal-air batteries, and other electrochemical devices. © 2023 Hydrogen Energy Publications LLC

关键词： Electrochemical catalysts Graphene oxide High entropy alloy Oxygen reduction reaction Pulse microwave approach

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Automated classification of big X-ray diffraction data using deep learning models

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npj Computational materials 2023年第1期9卷 169-180页

作者： Jerardo E.Salgado Samuel Lerman Zhaotong Du Chenliang Xu Niaz Abdolrahim Materials Science program University of RochesterRochesterNew York 14627USA Department of Computer Science University of RochesterRochesterNew York 14627USA Department of Mechanical Engineering University of RochesterRochesterNew York 14627USA Laboratory for Laser Energetics University of RochesterRochesterNew York 14627USA

In current in situ X-ray diffraction(XRD)techniques,data generation surpasses human analytical capabilities,potentially leading to the loss of *** techniques require human intervention,and lack the performance and adaptability required for material *** the critical need for high-throughput automated XRD pattern analysis,we present a generalized deep learning model to classify a diverse set of materials’crystal systems and space *** our approach,we generate training data with a holistic representation of patterns that emerge from varying experimental conditions and crystal *** also employ an expedited learning technique to refine our model’s expertise to experimental *** addition,we optimize model architecture to elicit classification based on Bragg’s Law and use evaluation data to interpret our model’s *** evaluate our models using experimental data,materials unseen in training,and altered cubic crystals,where we observe state-of-the-art performance and even greater advances in space group classification.

关键词： Automate classify cubic

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Mechanistic modeling of copper corrosions in data center environments

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Building Simulation 2024年第3期17卷 483-492页

作者： Rui Zhang Jianshun Zhang Roger Schmidt Jeremy L.Gilbert Department of Mechanical and Aerospace Engineering College of Engineering and Computer ScienceSyracuse UniversitySyracuseNY13244USA Buildings and Transportation Science Division Oak Ridge National LaboratoryOak RidgeTN37830USA SyracuseCoE-New York Center of Excellence in Environmental and Energy Systems Syracuse University727 E.Washington StreetSyracuseNY13244USA Department of Bioengineering Clemson UniversityClemson-Medical University of South Carolina Bioengineering ProgramCharlestonSC29425USA

Air-side economizers are increasingly used to take advantage of“free-cooling”in data centers with the intent of reducing the carbon footprint of ***,they can introduce outdoor pollutants to indoor environment of data centers and cause corrosion damage to the information technology *** evaluate the reliability of information technology equipment under various thermal and air-pollution conditions,a mechanistic model based on multi-ion transport and chemical reactions was *** model was used to predict Cu corrosion caused by Cl_(2)-containing pollutant *** also accounted for the effects of temperature(25℃and 28℃),relative humidity(50%,75%,and 95%),and *** also identified higher air temperature as a corrosion barrier and higher relative humidity as a corrosion accelerator,which agreed well with the experimental *** average root mean square error of the prediction was 13.7Å.The model can be used to evaluate the thermal guideline for data centers design and operation when Cl_(2)is present based on pre-established acceptable risk of corrosion in data centers’environment.

关键词： chloride pollutant mixture copper corrosion model data center temperature relative humidity synergistic effect

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