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CLEO: science and Innovations in CLEO 2024, CLEO: S and I 2024 - Part of Conference on Lasers and Electro-Optics

作者： Chin, Hsiao Hsuan Melton, Tristan Aldhafeeri, Alwaleed Rukh, Lala Colación, Gabriel M. Chen, Yujie Cheng, Xiang Chang, Kai-Chi Drake, Tara E. Wong, Chee Wei Mesoscopic Optics and Quantum Electronics Laboratory University of California Los AngelesCA90095 United States Optical Science & Engineering Program Center for High Technology Materials University of New Mexico 1313 Goddard SE AlbuquerqueNM87106 United States Dept. of Physics and Astronomy University of New Mexico AlbuquerqueNM87106 United States

We demonstrate the tuning of carrier envelope offset frequency in chip-scale micro-resonator and the effects on the spectrum, providing a pathway to f-2f stabilization. © Optica Publishing Group 2024

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Ultrafast evanescent heat transfer across solid interfaces via hyperbolic phonon-polaritons in hexagonal boron nitride

arXiv

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arXiv 2024年

作者： Hutchins, William Tomko, John A. Hirt, Dan M. Zare, Saman Matson, Joseph R. Diaz-Granados, Katja He, Mingze Pfeifer, Thomas Li, Jiahan Edgar, James Maria, Jon-Paul Caldwell, Joshua D. Hopkins, Patrick E. Department of Mechanical and Aerospace Engineering University of Virginia CharlottesvilleVA22904 United States Interdisciplinary Materials Science Program Vanderbilt University NashvilleTN37212 United States Department of Mechanical Engineering Vanderbilt University NashvilleTN37212 United States Tim Taylor Dept. of Chemical Engineering Kansas State University ManhattanKS United States Department of Materials Science and Engineering Pennsylvania State University University ParkPA16802 United States Department of Materials Science and Engineering University of Virginia CharlottesvilleVA22904 United States Department of Physics University of Virginia CharlottesvilleVA22904 United States

The efficiency of phonon-mediated heat transport is limited by the intrinsic atomistic properties of materials, seemingly providing an upper limit to heat transfer in materials and across their interfaces. The typical speeds of conductive transport, which are inherently limited by the chemical bonds and atomic masses, dictate how quickly heat will move in solids. Given that phonon-polaritons (PhPs), or coupled phonon-photon modes, can propagate at speeds approaching 1% of the speed of light – orders of magnitude faster than transport within a pure diffusive phonon conductor – we demonstrate that volume-confined, hyperbolic phonon-polariton (HPhP) modes supported by many biaxial polar crystals can couple energy across solid-solid interfaces at an order of magnitude higher rates than phonon-phonon conduction alone. Using pump-probe thermoreflectance with a mid-infrared, tunable, probe pulse with sub-picosecond resolution, we demonstrate remote and spectrally selective excitation of the HPhP modes in hexagonal boron nitride (hBN) in response to radiative heating from a thermally emitting gold source. Our work demonstrates a new avenue for interfacial heat transfer based on broadband radiative coupling from a hot spot in a gold film to hBN HPhPs, independent of the broad spectral mismatch between the pump (visible) and probe (mid-IR) pulses employed. This methodology can be used to bypass the intrinsically limiting phonon-phonon conductive pathway, thus providing an alternative means of heat transfer across interfaces. Further, our time-resolved measurements of the temperature changes of the HPhP modes in hBN show that through polaritonic coupling, a material can transfer heat across and away from an interface at rates orders of magnitude faster than diffusive phonon speeds intrinsic to the material, thus demonstrating a pronounced thermal transport enhancement in hBN via phonon-polariton coupling. © 2024, CC BY.

关键词： III-V semiconductors

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Characterization study of perovskite solar cells with incorporation of organic long persistent luminescence

Characterization study of perovskite solar cells with incorp...

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IEEE International Conference on Sensors and Nanotechnology

作者： Tejas Sharma H.K. Jun Dept. of Mechanical & Materials Engineering Lee Kong Chian Faculty of Engineering and Science Unviersiti Tunku Abdul Rahman Kajang Malaysia Centre for Photonics and Advanced Materials Research Universiti Tunku Abdul Rahman Kajang Malaysia

Organic/inorganic metal halide perovskites are receiving a lot of interest as next generation solar technology material due to their low-cost and good performance. In this work, we investigated perovskite solar cells (PSCs) with the incorporation of long persistence luminescence (LPL) material. Room temperature mixed-cation perovskite material FAMAPbI3 was prepared for application in PSCs. To enhance the PSC performance, LPL material was integrated externally to the cell structure. XRD, SEM, and photoluminescence (PL) spectroscopy were performed to reveal the phase, morphology, and emission spectra of the samples. The findings revealed that LPL material affected the performance of PSCs to a certain degree. The charge-transfer features occurring at the interface between the electron transport layer and perovskite film were further examined using electrochemical impedance spectroscopy technique. From the optical observation, when electron donating group of TMB molecules were mixed with the electron accepting group of PPT molecules, it resulted a better luminescence effect. The PSC performances highlight the potential for removing expensive hole-transport layer and costly high-vacuum deposition techniques from the fabrication processes.

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Effect of Organic Long Persistent Luminescence on Hole Transport Material-Free Perovskite Solar Cell

Effect of Organic Long Persistent Luminescence on Hole Trans...

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Power and Renewable Energy engineering (PREE), International Conference on

作者： Tejas Sharma Yew Hang Soo Chai Yan Ng H.K. Jun Dept. of Mechanical & Materials Engineering Lee Kong Chian Faculty of Engineering & Science Universiti Tunku Abdul Rahman Kajang Malaysia Centre for Photonics and Advanced Materials Research Universiti Tunku Abdul Rahman Kajang Malaysia

This work focuses on the study of perovskite materials as the active component in perovskite solar cells (PSCs). Hole transport material-free PSCs consisting of perovskite MAPbI3 and FAMAPbI 3 were fabricated under ambient conditions. To enhance the functionality of PSCs, a mixture of organic long persistent luminescence (LPL) materials, namely TMB and PPT, and an inorganic LPL material, strontium aluminate doped with europium and dysprosium (SrAl 2 O 3 ), were integrated into the cell structure, allowing operation in the low light conditions. The afterglow effect observed in the LPL materials was investigated in relation to its impact on the solar cell performance. Specifically, the influence of mixed organic LPL materials on the optical properties was examined. The results showed that an LPL mixture with TMB:PPT = 7:3 (by mass) exhibited the highest photoluminescence (PL) response. The integration of LPL materials presents a novel approach to enable PSCs to operate with improved performances. Additionally, the power conversion efficiency of three different setups of PSCs was evaluated. The findings revealed that PSCs with the inorganic LPL material achieved improved performance attributed to the light down-conversion effect.

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The correlation between non-linear acoustic and magnetic properties and local misorientation induced by plastic strain in metastable austenitic stainless steel

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Zairyo/Journal of the Society of materials science, Japan 2021年第2期70卷 191-198页

作者： Ohtani, Toshihiro Ishii, Yutaka Kamada, Yasuhiro Kamaya, Masayuki Dept. Mechanical Engineering Shonan Inst. of Tech. Tsujido-Nishikaigan Fujisawa251-8511 Japan Dept. Physical Science & Materials Engineering Iwate University Ueda Morioka020-8551 Japan Institute of Nuclear Safety System Inc. Sata Mihama-cho Mikata-gun Fukui919-1205 Japan

We studied the correlation between the evolutions of non-linear acoustic and magnetic properties and local misorientation on strain-induced martensitic transformation (SIMT) behavior in SUS 304 metastable austenitic stainless steel during tensile test. Two nonlinear acoustic characterizations;resonant frequency shift and high harmonic components with electromagnetic acoustic resonance (EMAR), parameters in magnetic hysteresis loops were measured. Furthermore, the evolution of microstructure was observed with electron backscatter diffraction (EBSD) was examined. EMAR is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method enables not only to measure exact ultrasonic attenuation of measured sample but also to eliminate nonlinear acoustic effect between the sample and transducer. We used two type of axial SH wave EMATs, which transmit and receive axially polarized shear wave along a cylindrical surface of a circular rod, for ferromagnetic and non-ferromagnetic materials. The changes in non-linear acoustic and magnetic properties have good correlations with microstructural observations. They successfully capture SIMT behavior in a metastable austenitic stainless steel. © 2021 Society of materials science Japan. All rights reserved.

关键词： Shear waves

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In-Situ Observation of ‘Chemical’ Strengthening Induced by Compositional Fluctuations in Nb-Mo-Ta-W

SSRN

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SSRN 2023年

作者： Pozuelo, Marta Marian, Jaime Dept. of Materials Science and Engineering University of California Los Angeles Los AngelesCA90095 United States Dept. of Mechanical and Aerospace Engineering University of California Los Angeles Los AngelesCA90095 United States

The mechanical response of refractory high-entropy alloys (RHEA) can be greatly influenced by local chemical fluctuations. Here, we perform in-situ transmission electron microscopy (TEM) nanocompression tests at room temperature of body-centered cubic Nb-Mo-Ta-W RHEA single-crystal nanopillars to understand the reasons behind this at atomic scale. We find that (i) chemical composition is not uniform in space, following certain oscillatory patterns and (ii) that specimen near-surface regions with local ‘soft’ spots favor dislocation nucleation over ‘hard’ ones. Under stress these dislocations glide inwardly, inevitably running into hard local regions adding hardening stresses of up to 400 MPa to the nominal yield stress. These hard local regions act as ‘chemical’ obstacles as revealed by the occurrence of double cross-slip and the formation of prismatic loops. Using electron dispersive spectroscopy along with atomic resolution TEM, we demonstrate that the obstacles correspond to atomic environments rich in W surrounded by misfit edge dislocations. © 2023, The Authors. All rights reserved.

关键词： High resolution transmission electron microscopy

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On Importance of Start Transient Current Measurement for Health Monitoring of Aerospace Solenoid Valves

On Importance of Start Transient Current Measurement for Hea...

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Silchar Subsection Conference (SILCON), IEEE

作者： P A V Sidhartha Arnika Verma Venkata Sunil Sai N Subrata Chakrabarti Balaram Sahoo Aloke Kumar Liquid Propulsion Systems Centre Indian Space Research Organisation Trivandrum India Materials Research Centre Indian Institute of Science Bangalore India Dept. of Mechanical Engineering Indian Institute of Science Bangalore India

ISBN: (数字)9798331540821

ISBN: (纸本)9798331540838

Solenoid valves form an integral part of aerospace systems. They primarily find application as thruster on-off valves for propellant flow control during steady state and pulse width modulation (PWM) operation of spacecraft thrusters. Electromechanical transient characteristics (ETC) of the sole-noid valves decide the overall system response of the thruster. ETC can be a powerful tool for performance characterization, prediction, health monitoring and failure analysis in solenoid valves. Several tools are used for deducing the ETC in solenoid valves. Important among them are finite element method (FEM) based and analytical multi-physics based models to name a few. FEM can be time consuming. Multi-physics based models are generally very exhaustive. However, simulations need to be validated by elaborate mechanical measurements of plunger stroke, velocity, electromagnetic force etc. This calls for high accuracy measurement arrangements to be made. It turns out that measurement of coil current alone can be an ideal replacement for all the above which can help in correctly characterising the performance of a solenoid valve.

关键词： Coils Attitude control Current measurement Pulse width modulation Valves Finite element analysis Velocity measurement Transient analysis Solenoids Monitoring

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Investigation on cutting fluid use in finish milling of polylactide (PLA) 3D-printed parts 20

Investigation on cutting fluid use in finish milling of poly...

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20th CIRP Conference on Modeling of Machining Operations in Mons, CIRP CMMO 2025

作者： Lorenzoni, Margaux Spitaels, Laurent Rivière-Lorphèvre, Edouard Odent, Jérémy M'Saoubi, Rachid Cloëz, Liam Fontaine, Michaël Ducobu, François Machine Design and Production Engineering Lab Research Institute for Materials Science and Engineering University of Mons Place du Parc 20 Mons7000 Belgium University of Mons Place du Parc 20 Mons7000 Belgium R&D Material and Technology Development Seco Tools AB Björnbacksvägen 2 FagerstaSE-737 82 Sweden Department of Mechanical Engineering Sciences Division of Production and Materials Engineering Lund University Ole Römers väg 1 LundSE-221 00 Sweden FEMTO-ST Institute-Applied Mechanics Dept. Université de Franche-Comté-SUPMICROTECH-CNRS Rue de l'épitaphe 24 BesançonF-25000 France

Fused Filament Fabrication (FFF) is an additive manufacturing process based on Material Extrusion (MEX) of polymeric filament. This manufacturing technology is commonly used for personalized production applications and prototyping, allowing to obtain customized parts with complex geometries at a low cost. However, this production technique has its limitations regarding dimensional accuracy and surface roughness of the final parts. To overcome these limitations, finish milling is considered to be a promising technique as it is widely used for metallic parts. Yet, the specific thermal properties of polymers such as low thermal conductivity and low melting temperature are adding a challenge in the determination of optimal cutting conditions. In this context, the use of cutting fluid could be the key to keep the material from melting during milling. Therefore, this paper proposes to compare the impact of using a compressed air flow to dry conditions on the cutting forces and the surface quality obtained on 3D-printed polylactide (PLA) parts. The qualification test of the tool-material couple standard (NF E 66-520-6) will be used as a guideline to determine the relevance of cutting fluid use for cutting conditions varying around an operating point. Moreover, simulated cutting forces using a mechanistic model will be compared to experimental data to evaluate the applicability of the model. © 2025 The Authors.

关键词： Compressed air

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Design rules for the thermal and elastic properties of rare-earth disilicates

arXiv

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arXiv 2023年

作者： Toher, Cormac Ridley, Mackenzie J. Tomko, Kathleen Q. Olson, David Hans Curtarolo, Stefano Hopkins, Patrick E. Opila, Elizabeth J. Dept. Materials Science and Engineering Dept. Chemistry and Biochemistry University of Texas at Dallas RichardsonTX75080 United States Center for Autonomous Materials Design Duke University DurhamNC27708 United States Dept. Materials Science and Engineering University of Virginia CharlottesvilleVA22904 United States Materials Science and Technology Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Laser Thermal Inc. CharlottesvilleVA22904 United States Dept. Mechanical Engineering and Materials Science Duke University DurhamNC27708 United States Dept. Mechanical and Aerospace Engineering University of Virginia CharlottesvilleVA22904 United States Dept. Physics University of Virginia CharlottesvilleVA22904 United States

Rare-earth silicates are the current standard material for use as environmental barrier coatings for SiC-based ceramic matrix composites as hot-section components in gas-turbine engines. Expanding the design space to all available rare-earth elements to facilitate optimizing functionality requires an understanding of systematic trends in RE2Si2O7 properties. In this work, we combine first-principles calculations with experimental measurements of Young’s modulus, coefficient of thermal expansion, and thermal conductivity for a range of different RE2Si2O7 compositions and phases. Clear trends are observed in these properties as a function of the radius of the rare-earth cation. In the case of Young’s modulus and thermal expansion, these trends also hold for multi-component systems;while the thermal conductivity of multi-component systems is noticeably lower, indicating the potential of such materials to also act as thermal barriers. These results provide design rules for developing new thermal and environmental barrier coatings with stiffness and thermal expansion engineered to match that of the substrate, while simultaneously having reduced thermal conductivity. © 2023, CC BY.

关键词： Thermal expansion

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Evolution of Creep Deformation near Tips of Sharp Notches and Cracks in CM247LC-DS Ni-Base Superalloy

Evolution of Creep Deformation near Tips of Sharp Notches an...

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2021 ASTM International Symposium on Advances in Accelerated Testing and Predictive Methods in Creep, Fatigue, and Environmental Cracking

作者： Towner, Zachary B. Smith, Kyle V. Shinde, Sachin R. Narasimhachary, Santosh B. Neu, Richard W. Muhlstein, Christopher L. Saxena, Ashok Woodruff School of Mechanical Engineering Georgia Institute of Technology 801 Ferst Dr. AtlantaGA30313 United States Formerly with Siemens Energy Inc. 11842 Corporate Blvd. OrlandoFL32817 United States Siemens Corporate Technology 1505 Westinghouse Blvd. CharlotteNC28273 United States School of Materials Science and Engineering Georgia Institute of Technology 771 Ferst Dr. NW AtlantaGA30313 United States Dept. of Mechanical Engineering College of Engineering University of Arkansas 1 University of Arkansas FayettevilleAR72701 United States

ISBN: (纸本)9780803177338

Finite element analyses were performed for varying crack tip or notch geometries and temperatures in C(T) specimens of CM247LC-DS Ni-base superalloy used in gas turbine blades to understand the accumulation of creep strains at notches. The constitutive models used considered elastic-primary-secondary creep deformation behavior. Simulations were performed under 2D plane stress, 2D plane strain, and 3D conditions for temperatures of 750°C, 850°C, and 950°C The estimated load-line displacements as a function of time from finite element analyses and from analytical expressions were validated using results from experiments conducted on notched and fatigue precracked C(T) specimens. Differences in the development of the creep zone size due to the notch tip geometry diminish in time under plane stress conditions, but they do not for plane strain conditions. Over short periods of time, small-scale creep plays a significant role in the evolution of the notch tip creep zones. The 3D analysis results show that creep zones grow at a faster rate on the surface of the specimen than in the midthickness region, and these differences are exacerbated as the notch root radius decreases. This work can potentially be the basis for formulating a theory for creep crack formation from notches in CM247LC-DS alloys. © 2023 by ASTM International.

关键词： Creep

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