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11th ASPE-euspen Summer Topical Meeting on Advancing Precision in Additive Manufacturing

作者： Zhang, Heyang Zhao, Xiayun Department of Mechanical Engineering and Materials Science University of Pittsburgh PittsburghPA United States

ISBN: (纸本)9781887706605

Vat photo polymerization (VPP) is an additive manufacturing (AM) method that creates 3-dimensional parts by projecting 2-D grayscale images created by digital light processing (DLP) masks with digital micromirror devices (DMD) at photo-sensitive resin vats layer by layer. Recent advancement in the VPP method has been made by using multiple DLP systems at different wavelengths to selectively initiate different resins curing mechanisms or activate inhibition reactions. This expands the basic VPP method to allow for multi-material printing and increases geometry precision control. As multiwavelength VPP technologies advance, development of two-wavelength DLP light delivery technology needs to be documented and formalized. In this work, the current state-of-the-art applications of dual-wavelength VPP printers are examined, and an orthogonal VPP printer using custom optics and control is developed with the help of ray tracing simulations. The intensity distribution, geometrical accuracy, precision, and spatial distribution of each projected single-wavelength exposure mask, as well as the alignment of the two-wavelength exposure masks, are quantified using a high-resolution CMOS camera and power meter and compared with other systems in literature. The developed optics system aims to achieve two-wavelength optical exposures characterized by high resolution, precise alignment, and desired intensity distribution. Designed with compatibility in mind, this optics system will allow for integration with mechanized platform as well as customized metrology and process control technologies, thereby establishing a strong foundation for precise, reproducible, and robust 2-wavelength VPP for advanced applications. © 2024 2024 ASPE. All rights reserved.

关键词： Photopolymerization

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Droplet epitaxy of InGaN quantum dots on Si (111) by plasma-assisted molecular beam epitaxy

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Discover Nano 2023年第1期18卷 1-10页

作者： Nurzal, Nurzal Hsu, Ting-Yu Susanto, Iwan Yu, Ing-Song Department of Materials Science and Engineering National Dong Hwa University Hualien97401 Taiwan Department of Mechanical Engineering Institut Teknologi Padang Kp Olo Padang25143 Indonesia Department of Mechanical Engineering Politeknik Negri Jakarta Depok16424 Indonesia

The droplet epitaxy of indium gallium nitride quantum dots (InGaN QDs), the formation of In–Ga alloy droplets in ultra-high vacuum and then surface nitridation by plasma treatment, is firstly investigated by using plasma-assisted molecular beam epitaxy. During the droplet epitaxy process, in-situ reflection high energy electron diffraction patterns performs the amorphous In–Ga alloy droplets transform to polycrystalline InGaN QDs, which are also confirmed by the characterizations of transmission electron microscopy and X-ray photoelectron spectroscopy. The substrate temperature, In–Ga droplet deposition time, and duration of nitridation are set as parameters to study the growth mechanism of InGaN QDs on Si. Self-assembled InGaN QDs with a density of 1.33 × 1011 cm−2 and an average size of 13.3 ± 3 nm can be obtained at the growth temperature of 350 °C. The photoluminescence emissions of uncapped InGaN QDs in wavelength of the visible red (715 nm) and infrared region (795 and 857 nm) are observed. The formation of high-indium composition of InGaN QDs via droplet epitaxy technique could be applied in long wavelength optoelectronic devices. © 2023, The Author(s).

关键词： Photoluminescence

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Multi-scale investigation of short-range order and dislocation glide in MoNbTi and TaNbTi multi-principal element alloys

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npj Computational materials 2023年第1期9卷 1430-1442页

作者： Hui Zheng Lauren T.W.Fey Xiang-Guo Li Yong-Jie Hu Liang Qi Chi Chen Shuozhi Xu Irene J.Beyerlein Shyue Ping Ong Department of NanoEngineering University of California San DiegoLa JollaCA 92093-0448USA Materials Department University of CaliforniaSanta BarbaraCA 93106-5050USA Department of Materials Science and Engineering University of MichiganAnn ArborMI 48109USA Department of Materials Science and Engineering Drexel UniversityPhiladelphiaPA 19104USA Department of Mechanical Engineering University of CaliforniaSanta BarbaraCA 93106-5070USA

Refractory multi-principal element alloys(RMPEAs)are promising materials for high-temperature structural ***,we investigate the role of short-range ordering(SRO)on dislocation glide in the MoNbTi and TaNbTi RMPEAs using a multi-scale modeling *** carlo/molecular dynamics simulations with a moment tensor potential show that MoNbTi exhibits a much greater degree of SRO than TaNbTi and the local composition has a direct effect on the unstable stacking fault energies(USFEs).From mesoscale phase-field dislocation dynamics simulations,we find that increasing SRO leads to higher mean USFEs and stress required for dislocation *** gliding dislocations experience significant hardening due to pinning and depinning caused by random compositional fluctuations,with higher SRO decreasing the degree of USFE dispersion and hence,amount of ***,we show how the morphology of an expanding dislocation loop is affected by the applied stress.

关键词： alloys dislocation element

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Sintering characteristics, phase transitions, and microwave dielectric properties of low-firing [(Na_(0.5)Bi_(0.5))_(x)Bi_(1-x)](W_(x)V_(1-x))O_(4) solid solutionceramics

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Journal of Advanced Ceramics 2023年第6期12卷 1178-1188页

作者： Xian Xue Xiaomeng Li Changli Fu Yan Zhang Jing Guo Hong Wang State Key Laboratory for Mechanical Behavior of Materials Faculty of Electronic and Information EngineeringXi'an Jiaotong UniversityXi'an 710049China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an 710049China Department of Materials Science and Engineering&Shenzhen Engineering Research Center for Novel Electronic Information Materials and Devices Southern University of Science and TechnologyShenzhen 518055China Department of Physiology and Pathophysiology Shaanxi Engineering and Research Center of VaccineKey Laboratory of Environment and Genes Related to Diseases of Education Ministry of ChinaSchool of Basic Medical SciencesXi'an Jiaotong UniversityXi'an 710061China

A series of high-k[(Na_(0.5)Bi_(0.5))_(x)Bi_(1-x)](W_(x)V_(1-x))O_(4)(abbreviated as NBWV(x value))solid solution ceramics with a scheelite-like structure are synthesized by a modified solid-state reaction method at the temperature range of 680-760 C.A monoclinic(0≤x<0.09)to tetragonal scheelite(0.09≤x≤1.0)structural phase transition is confirmed by X-ray difraction(XRD),Raman,and infrared(IR)*** effect of structural deformation and order-disorder caused by Na^(+)/Bi^(3+)/W^(6+) complex substitution on microwave dielectric properties is investigated in *** compositional series possess a wide range of variable relative permittivity(er=24.8-80)and temperature coefficient of resonant frequency(TCF value,-271.9-188.9 ppm/℃).The maximum permittivity of 80 and a high Qxf value of~10,000 GHz are obtained near the phase boundary at x=***,the temperature-stable dielectric ceramics sintered at 680 C with excellent microwave dielectric properties of ε_(r)=80.7,Qxf=9400 GHz(at 4.1 GHz),and TCF value=-3.8 ppm/℃ are designed by mixing the components of x=0.07 and *** summary,similar sinterability and structural compatibility of scheelite-like solid solution systems make it potential for low-temperature co-fired ceramic(LTCC)applications.

关键词： structural phase transition order-disorder phenomena microwave ceramics dielectric behavior low sintering temperatures

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Reveal Hydrogen Behavior at Grain Boundaries in Fe-22Mn-0.6C TWIP Steel via In Situ Micropillar Compression Test

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1095-1104页

作者： Xu Lu Dong Wang Di Wan Xiaofei Guo Roy Johnsen Department of Mechanical and Industrial Engineering Norwegian University of Science and Technology7491 TrondheimNorway School of Materials Science and Engineering Shanghai UniversityShanghai 200444China Steel Institute(IEHK) RWTH Aachen University52072 AachenGermany

In this study,the effect of hydrogen on dislocation and twinning behavior along various grain boundaries in a high-manganese twinning-induced plasticity steel was investigated using an in situ micropillar compression *** compressive stress in both elastic and plastic regimes was increased with the presence of *** investigation by transmission electron backscatter diffraction and scanning transmission electron microscope demonstrated that hydrogen promoted both dislocation multiplication and twin formation,which resulted in higher stress concentration at twin-twin and twin-grain boundary intersections.

关键词： Hydrogen TWIP steel Micropillar compression Grain boundary t-EBSD

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Spintronic filter via p-typed polaron state in photoelectron conversion integrating devices

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Sustainable Energy and Fuels 2023年第16期7卷 3993-4001页

作者： Lai, Yi-Sheng Huang, Dao-Jing Zhang, Xiu-Xuan Su, Yen-Hsun Department of Mechanical Engineering National Chung Cheng University Chiayi621301 Taiwan Department of Materials Science and Engineering National Cheng Kung University Tainan70101 Taiwan

In response to the initiative of the 2021 United Nations Conference of the Parties (COP26) on Climate Change and the Group of Twenty (G20), high-performance water-splitting energy conversion integrated devices are the best solution to addressing climate change, environmental pollution, and energy deficiency. Intrinsic defects of Cu2O enhance the performance of water-splitting via p-typed polaron surface state-induced high charge mobility and spintronic injection system. With the defect from the unfilled electron orbital, 3d9, in Cu, spin-orbital coupling effects are achieved by coherent ħ/−ħ angular momentum circular polarization laser light excited spintronic and spintronic injection systems. With the support of a 473 nm laser and ħ/−ħ angular momentum modulated 808 nm circular polarization laser light irradiation, the population of spintronic systems drastically increases and responds to the current density of the devices. Furthermore, the p-typed polaron surface state corresponding to combined laser light of 473 and 808 nm induced a high spin polarization rate of over 35% at a low bias. Cu defects induce p-typed polaron surface states that are successfully applied in spintronic injection water-splitting energy conversion integrated electronic systems, which will lead the energy conversion devices in green industries and advance quantum electronics. At the optimal operating conditions for water-splitting (1 atm, 25 °C), over 2 L of hydrogen gas were generated from a 1 m2 device, and the charge mobility was as high as 1.08 × 1015 m2 V−1 s−1 © 2023 The Royal Society of Chemistry.

关键词： Surface states

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Design and development of an integrated enset processing machine suitable for central highland farmers of west shewa zone Ethiopia

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Discover Agriculture 2025年第1期3卷 1-26页

作者： Jima, Beka Adugna Kolhe, Kishor Purushottam Jiru, Moera Gutu Agricultural Machinery Engineering Program Department of Mechanical Engineering School of Mechanical Chemical and Materials Engineering at Adama Science and Technology University Adama Ethiopia Department of Mechanical Engineering School of Mechanical Chemical and Materials Engineering at Adama Science and Technology University Adama Ethiopia

The development of Integrated Enset processing technology is significant for the easy availability of stable food in the current condition for fulfilling the pangs of hunger in Ethiopia, currently; individual manual technologies such as decortication, corm granting, bulla extraction, and fermenting techniques eventually contribute to utilizing food security such as Kocho, which is not affordable for the marginal farmers of Ethiopia. However, there is a lack of integrated compromise of the all-function process of corm granting, decortication, and pulverization in one machine wholesome of the product such as Kocho, and bulla within consuming time and labor. Therefore, it is decided to design and develop an integrated enset processing machine for central high land of Ethiopian farmers with high-quality production. The physical and mechanical properties of the enset is studied to get an efficient and robust design of the various components. The overall design and development of proposed machine components were carried out at Adama science and Technology University, Ethiopia by using ANSYS 2023 R1 software by considering the engineering economics and material specifications as per ASTM standards. The process parameters of the proposed machine are identified as feed rate, drum speed, concave to drum clearance, power requirement, etc. Also, the enset characteristics were considered as decorticating and granting, fiber cutting resistance, fiber length, dimension, shape, and weight. The overall developed enset integrated machine assembles are analyzed for granting and decorticating with drum clearance and bulla extraction throughput capacity, reliability, simplicity, safety, and overall cost. The machine's safety from a Design Perspective is checked and validated by a simulation study on the critical parts subjected to higher stresses. The cost of available individual decorticators, granting, pulverized, and bulla squeezer machines is costly to the farmer’s community. Theref

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Surface Modification and Corrosion Performance of Laser Cladded Co–Ni on Ti–6Al–4 V in 0.5 M H2SO4 Environment

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Journal of Bio- and Tribo-Corrosion 2024年第4期10卷 1-14页

作者： Adesina, Olanrewaju Seun Popoola, Abimbola Patricia Farotade, Gabriel Ayokunle Sanyaolu, Olufemi Oluseun Obadele, Babatunde Abiodun Ikubanni, Peter Pelumi Adediran, Adeolu Adesoji Adeleke, Adekunle Akanni Department of Mechanical Engineering Redeemers University Ede Nigeria SDG 9 Industry Innovation and Infrastructure Redeemer’s University Ede Nigeria Department of Chemical Metallurgical and Materials Engineering Tshwane University of Technology P.M.B. X680 Pretoria0001 South Africa Department of Chemical Materials and Metallurgical Engineering Botswana International University of Science and Technology Palapye Botswana Department of Mechanical Engineering Landmark University Omu - Aran Nigeria Department of Mechanical Engineering Nile University of Nigeria Abuja Nigeria

This study investigates the laser cladding of Co and Ni powders onto Ti–6Al–4 V substrates, varying the admixed percentages while adjusting laser processing parameters. The influence of nickel and cobalt contents on the microstructure, phase composition, and electrochemical behavior of the laser-clad Ti–6Al–4 V coatings were analyzed. Coating morphology and phases were characterized using scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS), and X-ray diffractometry (XRD), respectively. The corrosion resistance of Ti–6Al–4 V, both with and without Ni–Co additions, in 0.5 M H2SO4 was evaluated using potentiodynamic polarization technique. Results indicated that the coatings exhibited excellent metallurgical compatibility with the substrate. Additionally, the high scan speed laser-clad samples showed enhanced corrosion resistance compared to those processed at low speeds. The potentiodynamic polarization analysis revealed passive behavior in all specimens, with higher cobalt content notably enhancing passivity and corrosion resistance by suppressing the anodic reaction. © The Author(s) 2024.

关键词： Corrosion resistance

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PHOTOINHIBITION-AIDED VAT PHOTOPOLYMERIZATION ADDITIVE MANUFACTURING OF BIO-COMPOSITES 11

PHOTOINHIBITION-AIDED VAT PHOTOPOLYMERIZATION ADDITIVE MANUF...

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11th ASPE-euspen Summer Topical Meeting on Advancing Precision in Additive Manufacturing

作者： Bensouda, Yousra Zhao, Xiayun Department of Mechanical Engineering and Materials Science University of Pittsburgh PittsburghPA United States

ISBN: (纸本)9781887706605

Vat photopolymerization (VPP) additive manufacturing (AM) has emerged as a promising and versatile technique for producing intricate and complex 3D components with precision and efficiency. This innovative approach has garnered significant attention in the AM community and beyond. Among the various technologies used, digital light processing (DLP) is a mainstream process with higher print speed and resolution than other VPP processes, such as continuous liquid interface production and two-photon polymerization. The rapid development of polymer- and metal-based structures has led to a significant surge in the utilization of printing suspensions. While pure resins like epoxy and acrylate have been widely used for VPP, they have limited mechanical properties and can only be used for a limited number of applications due to chemical safety concerns associated with their toxicity. Bio-composites, made of biopolymer matrices, have gained prominence lately, since they originate from renewable sources and often require less energy than petrochemically derived resins to produce. However, they also present challenges related to the printability and resolution of the final build. Research on Polylactic acid (PLA) based bio-composites has been substantial and well documented within the fused deposition modeling domain, yet a research gap becomes apparent when considering the use of VPP. DLP allows to print parts with higher speed and resolution thanks to the ability to rapidly project high-definition optical masks. DLP also enables good surface smoothness and relatively isotropic material properties in final prints due to curing each entire layer simultaneously and printing all layers in a continuous manner. However, most of the currently available resins lack biodegradability and exhibit poor properties, highlighting the need for further study. © 2024 2024 ASPE. All rights reserved.

关键词： Photopolymerization

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A review of current understanding in tribochemical reactions involving lubricant additives

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Friction 2023年第4期11卷 489-512页

作者： Yan CHEN Peter RENNER Hong LIANG Department of Materials Science and Engineering Texas A&M UniversityCollege Station 77843USA J.Mike Walker’66 Department of Mechanical Engineering Texas A&M UniversityCollege Station 77843USA

Lubricants have played important roles in friction and wear reduction and increasing efficiency of mechanical *** optimize tribological performance,chemical reactions between a lubricant and a substrate must be designed *** reactions are chemical reactions enabled or accelerated by mechanical *** activated lubricant additives play important roles in these *** this review,current understanding in mechanisms of chemical reactions under shear has been *** such as oil-soluble organics,ionic liquids(ILs),and nanoparticles(NPs)were analyzed in relation to the tribochemical reaction routes with elements in metallic *** results indicated that phosphorus,sulfur,fluorine,and nitrogen are key elements for tribochemical *** resulting tribofilms from zinc dithiophosphates(ZDDP)and molybdenum dithiocarbamate(MoDTC)have been widely reported,yet that from ILs and NPs need to investigate *** review serves as a reference for researchers to design and optimize new lubricants.

关键词： lubricant additives tribochemical reactions oil-soluble organics ionic liquids(ILs) nanoparticles(NPs)

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