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Microstructure and wear characterization of AA2124/4wt.%B4C nano-composite coating on Ti-6Al-4V alloy using friction surfacing

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Transactions of Nonferrous Metals Society of China 2019年第6期29卷 1263-1274页

作者： I. ESTHER I. DINAHARAN N. MURUGAN Department of Mechanical Engineering Anna University Chennai 600025 Tamil Nadu India Department of Robotics and Automation Engineering PSG College of Technology Coimbatore 641004 Tamilnadu India Department of Mechanical Engineering Science University of Johannesburg Auckland Park Kingsway Campus Johannesburg 2006 South Africa

This work is focused on developing AA2124/4 wt.%B4 C nano-composite coatings on Ti-6 A1-4 V using friction surfacing to improve the wear resistance. The composite was produced using conventional stir casting method and coatings were laid using an indigenously-developed friction surfacing machine. The rotational speed of the mechtrode was varied. The microstructure of the composite coating was observed using conventional and advanced microscopic techniques. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The coating geometry(thickness and width) increased with increased rotational speed. The interface was straight without thick intermetallic layer. Homogenous distribution of nano B4C particles and extremely fine grains was observed in the composite coating. The interfacial bonding between the aluminum matrix and B4C particles was excellent. The composite coating improved the wear resistance of the titanium alloy substrate due to the reduction in effective contact area,lower coefficient of friction and excellent interfacial bonding.

关键词： aluminum matrix composite titanium friction surfacing coating wear

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Experimental study of the removable assemblies with screws from high pressure injection pumps

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IOP Conference Series: Materials Science and engineering 2022年第1期1235卷

作者： D P Bistriceanu C Bujoreanu S G Pal 'Gheorghe Asachi' Technical University of Iasi Department of Mechanical Engineering Mechatronics and Robotics Blvd. Mangeron No. 43 700050 Iasi Romania

High pressure injection pumps use removable assemblies with screws. They allow the subsequent assembly and disassembly, without destroying the components and the entire assembly, whenever is necessary. Our paper is an experimental analysis highlighting the influence of tightening parameters on components deformations. We perform the study using controller, Janome screwdriver, ZEISS measurement system and SEM (Scanning Electron Microscope) used in the metallographic analysis. Various torques applied on the screws give us results that show the interactions and their impact on the pumps components, producing deformation on the screws, gaskets and even front plate. A trial was done to establish the upper limit for the torque of the screws. After applying several tightening's at different values, we conclude that the optimal upper limit for screws tightening between front plate and housing is 45 Nm. Applying a torque bigger than 50 Nm, the screws are destroyed, shear. This can generate numerous defects on the sealing gasket area and on the front plate in the screws holes area. The circularity of the front plate is impacted by the thickness of the wall and the inner / outer diameters.

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Solar-Powered Tri-Generation System Integrating Organic Rankine Cycle and Absorption Chiller for Passenger Train Energy Supply

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Energy and Built Environment 2025年

作者： Ehsanolah Assareh Aminhossein Jahanbin Nima Izadyar Mohammad Barati Neha Agarwal Built Environment and Engineering Program College of Sport Health and Engineering (CoSHE) Victoria University Melbourne VIC 3011 Australia School of Chemical Engineering Yeungnam University Gyeongsan 38541 South Korea Department of Architecture Construction and Design Polytechnic University of Bari 70126 Bari Italy Institute for Sustainable Industries and Liveable Cities Victoria University Melbourne VIC 3011 Australia Department of Mechanical Engineering Arvandan Non-profit Higher Education Institute Khorramshahr Iran

This study investigates the potential of leveraging solar energy to establish an integrated multi-energy production system to supply heating, cooling, and electricity for passenger trains. The proposed tri-generation system combines photovoltaic-thermal (PVT) panels, an organic Rankine cycle (ORC), an absorption chiller, and a water heater unit. The interactions between system components are examined through an exergoeconomic model developed in EES software, supported by a detailed parametric analysis. A two-step multi-objective optimization framework is implemented, integrating response surface methodology (RSM) with an artificial neural network (ANN) to improve optimization accuracy. In this framework, five decision variables and two objective functions—exergy efficiency and system cost rate—are optimized. Economic analysis reveals that the ORC unit and PVT panels incur the highest cost rates, while exergy analysis indicates that the PVT panels, absorption chillers, and evaporators experience the most significant exergy destruction. The optimal system achieves an exergy efficiency of 10.87% and a cost rate of 1.491 $/h. The second optimization stage using the ANN method based on 100 RSM-optimized points, results in further refinement in both exergy efficiency and cost rate. A real-world case study evaluates the feasibility of implementing the proposed system on a modern passenger train along a route with high solar energy potential, analyzing its performance during a 17-hour journey across five stations and over four seasons under varying weather conditions. The findings contribute to the development of low-carbon rail transport solutions, highlighting the need for future research on energy storage, system scalability, and real-time performance optimization.

关键词： Multi-energy system Tri-generation exergoeconomic analysis response surface methodology (RSM) artificial neural network (ANN)

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Structural Optimization of Photoacoustic Transducer with Pdms/Csnps Nanocomposite for Laser-Induced Nonlinear Surface Wave and its Application in Fatigue Crack Detection

SSRN

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SSRN 2023年

作者： Yao, Zhijun Li, Yehai Lv, Gaolong Chen, Dan Yang, Jian Guo, Shifeng Shenzhen Key Laboratory of Smart Sensing and Intelligent Systems Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China Guangdong Provincial Key Lab of Robotics and Intelligent System Shenzhen Institute of Advanced Technology Chinese Academy of Sciences Shenzhen518055 China University of Chinese Academy of Sciences Beijing100049 China Institute of Intelligent Manufacturing Technology Shenzhen Polytechnic Shenzhen518055 China Department of Mechanical Materials and Manufacturing Engineering University of Nottingham Ningbo China Ningbo315100 China

Laser ultrasonics is a promising non-contact inspection technique but faces the challenges of low signal-to-noise ratio and low amplitude under the non-destructive thermoelastic regime. In this paper, an ultrasonic surface wave modulation method based on laser ultrasonics and photoacoustic transducer (PAT) is proposed and combined with nonlinear wave mixing technique to achieve non-contact detection of fatigue crack. The PAT comprised of candle soot nanoparticles and polydimethylsiloxane (PDMS) as well as a line-arrayed laser source modulated by a slit mask are firstly introduced to generate narrowband surface wave with high intensity and SNR under the thermoelastic regime. The thicknesses of the PDMS layers of PAT are thereafter optimized by analytical, numerical and experimental investigations to acquire narrowband surface wave with pure fundamental frequency component. Two modulated ultrasonic surface waves with frequencies of 2.1 MHz and 2.9 MHz are excited on a fatigued aluminum plate to generate nonlinear mixed components, and the ultrasonic responses over the fatigue crack regions are acquired by using a scanning laser Doppler vibrometer. The localization of fatigue crack with microscale is eventually acquired by mapping the nonlinear parameter of the mixed components, which proves it a reliable and nondestructive technique to inspect the fatigue crack. © 2023, The Authors. All rights reserved.

关键词： Transducers

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Large spin Hall effect in Si at room temperature

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Physical Review B 2020年第9期101卷 094435-094435页

作者： Paul C. Lou Anand Katailiha Ravindra G. Bhardwaj Tonmoy Bhowmick W. P. Beyermann Roger K. Lake Sandeep Kumar Department of Mechanical Engineering University of California Riverside California 92521 USA Department of Electrical Engineering and Computer Science University of California Riverside California 92521 USA Department of Physics and Astronomy University of California Riverside California 92521 USA Materials Science and Engineering Program University of California Riverside California 92521 USA

Silicon's weak intrinsic spin-orbit coupling and centrosymmetric crystal structure are a critical bottleneck to the development of Si spintronics, because they lead to an insignificant spin Hall effect (spin current generation) and inverse spin Hall effect (spin current detection). Here, we undertake current, magnetic field, crystallography dependent magnetoresistance, and magnetothermal transport measurements to study the spin transport behavior in freestanding Si thin films. We observe a large spin Hall magnetoresistance in both p−Si and n−Si at room temperature and it is an order of magnitude larger than that of Pt. One explanation of the unexpectedly large and efficient spin Hall effect is spin-phonon coupling instead of spin-orbit coupling. The macroscopic origin of the spin-phonon coupling can be large strain gradients that can exist in the freestanding Si films. This discovery in a light, earth abundant and centrosymmetric material opens a new path of strain engineering to achieve spin dependent properties in technologically highly developed materials.

关键词： Spin Hall magnetoresistance Spintronics Doped semiconductors

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Compositional-structural inhomogeneity and multi-layered oxide film formation on high-entropy alloys

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Acta Materialia 2025年

作者： Huaqing Yi Mengtian Liang Jinpeng Zhang Bingbing Yin Jianyu Huang Fugang Qi Zhenhua Yang Guangwen Zhou Qianqian Jin Jian Chen Yi Yang School of Materials Science and Engineering Xiangtan University Xiangtan Hunan 411105 P.R. China Department of Mechanical Engineering & Materials Science and Engineering Program State University of New York Binghamton NY 13902 USA Materials Science and Engineering Research Center Guangxi University of Science and Technology Liuzhou 545006 China Department of Chemistry and Surface Science Western University of Western Ontario London Ontario N6A5B7 Canada

The wide compositional range and diverse elemental combinations in high-entropy alloys give rise to complex oxide scales, posing significant challenges in understanding the mechanisms governing local compositional and structural evolution during oxidation. This work investigates the mechanisms underlying the formation of the multi-layered oxide scale on the AlCoFeNiTi high-entropy alloys. The results show that the thermodynamic predominance for the formation of protective Al 2 O 3 and TiO 2 , coupled with the insufficient conditions for the establishment of a continuous oxide film, results in the development of a mixed inner oxide layer. This mixed layer facilitates the outward diffusion of alloying elements. Incomplete filling of the cavities at the forefront of the inner oxide layer by oxide growth leads to partial backfilling of Ni, thereby creating a localized Ni-rich layer. The formation of multiple oxide layers is governed by the interplay of thermodynamic driving force, elemental diffusivities, and the homogeneity of oxygen distribution. Additionally, kinetically captured solute atoms can alter the formation energy of oxides, influencing the spatial arrangement of different phases within the scale. The enrichment of Ni and Fe—driven by extended structural defects in the oxide scale—further leads to the precipitation of NiO x and FeO x clusters within the TiO 2 lattice. These insights provide a broader understanding of multi-layer oxide formation in Ti-containing high-entropy alloys and other alloys incorporating 3d transition metals, contributing to the design of oxidation-resistant high-entropy materials.

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Core packing of well-defined x-ray and NMR structures is the same

arXiv

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arXiv 2022年

作者： Grigas, Alex T. Liu, Zhuoyi Regan, Lynne O’Hern, Corey S. Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Institute of Quantitative Biology Biochemistry and Biotechnology Centre for Synthetic and Systems Biology School of Biological Sciences University of Edinburgh United Kingdom Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

Numerous studies have investigated the differences and similarities between protein structures determined by solution NMR spectroscopy and those determined by x-ray crystallography. A fundamental question is whether any observed differences are due to differing methodologies, or to differences in the behavior of proteins in solution versus in the crystalline state. Here, we compare the properties of the hydrophobic cores of high-resolution protein crystal structures and those in NMR structures, determined using increasing numbers and types of restraints. Prior studies have reported that many NMR structures have denser cores compared to those of high-resolution x-ray crystal structures. Our current work investigates this result in more detail, and finds that these NMR structures tend to violate basic features of protein stereochemistry, such as small non-bonded atomic overlaps and few Ramachandran and side chain dihedral angle outliers. We find that NMR structures solved with more restraints, and which do not significantly violate stereochemistry, have hydrophobic cores that have a similar size and packing fraction as their counterparts determined by x-ray crystallography at high-resolution. These results lead us to conclude that, at least regarding the core packing properties, high-quality structures determined by NMR and x-ray crystallography are the same, and the differences reported earlier are most likely a consequence of methodology, rather than fundamental differences between the protein in the two different environments. Significance: Dense packing of hydrophobic residues is key to protein structure and stability. Previously, it has been noted that structures solved by NMR spectroscopy have denser cores than x-ray crystal structures. Here, we calculate the core size and packing fraction of NMR structures with experimental restraints in the PDB. Their cores are typically smaller, but denser. However, NMR structures with accurate stereochemistry possess core pa

关键词： X ray crystallography

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Preface

Mechanisms and Machine Science

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Mechanisms and Machine Science 2023年 127卷 ix-x页

作者： Doroftei, Ioan Nitulescu, Mircea Pisla, Doina Lovasz, Erwin-Christian Department of Mechanical Engineering Mechatronics and Robotics "Gheorghe Asachi" Technical University of Iaşi Iaşi Romania Department of Computers and Electronics Mechatronics and Robotics Faculty of Automation University of Craiova Craiova Romania CESTER Technical University of Cluj-Napoca Cluj-Napoca Romania Department of Mechatronics Polytechnic University of Timisoara Timisoara Romania

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Corrigendum to "3D printed biomimetic composite scaffolds with sequential releasing of copper ions and dexamethasone for cascade regulation of angiogenesis and osteogenesis" [Chem. Eng. J. 496 (2024) 153662] (Chemical engineering Journal (2024) 496, (S1385894724051519), (10.1016/***.2024.153662))

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Chemical engineering Journal 2025年 511卷

作者： Song, Yongteng Hu, Qingxi Liu, Suihong Wang, Yahao Jia, Lijun Hu, Xinli Huang, Changjin Zhang, Haiguang Rapid Manufacturing Engineering Center School of Mechatronic Engineering and Automation Shanghai University Shanghai200444 China Shanghai Key Laboratory of Intelligent Manufacturing and Robotics Shanghai University Shanghai200072 China National Demonstration Center for Experimental Engineering Training Education Shanghai University Shanghai200444 China School of Mechanical and Aerospace Engineering Nanyang Technological University Singapore Engineering Science and Mechanics Department Penn State University University ParkPA16802 United States Department of Orthopedics Changzheng Hospital Naval Medical University Shanghai China School of Health Science and Engineering University of Shanghai for Science and Technology Shanghai China

(1) The authors regret the error in Fig. 9(C) of the published article, where the unit of BMD on the y-axis was incorrectly given as "g/mm2". The correct unit should be "g/cm3".(2) The authors also regret the error in the calculation of Tb.N in Fig. 9(E), which has now been *** the above errors, in section 3.1.4, the SHG-MSNs@DEX compression modulus should be "22.88 ± 2.50 MPa" instead of "22.88 ± 22.50 MPa." The authors sincerely apologize for any inconvenience this may have caused. This correction does not affect the interpretation of the results or the conclusions of the study, and the updated figure is shown below as Fig. 9 (Updated).[Figure presented] Fig. 9 (Updated) Bone regeneration of rat skull defects in vivo. (A) Schematic diagram of the use of prepared bone scaffolds to repair skull defects. (B) Representative 3D reconstructed micro-CT images depicting skull defect sites 4 weeks and 8 weeks after scaffold implantation. (C-E) BMD, BV/TV, and Tb.N analysis results were obtained from micro-CT images at 4 weeks and 8 weeks post-surgery. (F, G) Results of histological analysis of skull sections at 4 weeks and 8 weeks after surgery: H&E staining (F) and Masson staining (G). Error bars indicate the standard deviation (n = 3), with statistical significance defined as **p © 2024 Elsevier B.V.

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Tailoring the Microstructure of a Cu-0.7cr-0.07zr Alloy Submitted to Ecap at Cryogenic Temperature for Improved Thermal Stability

SSRN

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SSRN 2022年

作者： Oliveira, Pedro H.F. Magalhães, Danielle Cristina Camilo Unti, Luiz Fernando K. Cintho, O.M. Kliauga, Andrea M. Sordi, Vitor Luiz Federal University of São Carlos Graduate Program in Materials Science and Engineering Rod. Washington Luís km 235 São Carlos SP CEP 13565-905 Brazil Federal University of São Carlos Department of Materials Engineering Rod. Washington Luís km 235 São Carlos SP CEP 13565-905 Brazil Department of Mechanical Engineering Aeronautics Institute of Technology Praça Marechal Eduardo Gomes 50 SP São José dos CamposCEP 12228-900 Brazil Department of Materials Engineering State University of Ponta Grossa Av. General Carlos Cavalcanti PR Ponta GrossaCEP 84030-900 Brazil

Severe Plastic Deformation (SPD) routes, such as Equal Channel Angular Pressing (ECAP), are capable of producing ultrafine-grained (UFG) materials with outstanding mechanical properties. Although grain refinement and the increase in mechanical processing could be enhanced through ECAP processing at cryogenic temperatures, this route presents the drawback of microstructural instability, which is responsible for reversing the gain in mechanical properties and microstructural refinement when the material is stored at room temperature or submitted to relatively high temperatures. Aiming to design severely deformed and stable microstructures, this study investigated pure copper (Cu) and a commercial ITER-grade Cu-0.7Cr-0.07Zr alloy submitted to ECAP at 298 and 123 K followed by annealing heat treatments. ECAP processing introduced a high density of dislocations and vacancy concentration in the materials assessed. Pure Cu showed poor microstructural stability when long-term stored at room temperature after ECAP processing at cryogenic temperatures, and when submitted to annealing post-ECAP processing. In contrast, the Cu-0.7Cr-0.07Zr alloy submitted to cryo-ECAP showed outstanding thermal stability even when submitted to annealing at 673 K for 120 min. For this alloy, the fine Cr-rich precipitates were responsible for preventing static recovery and preserving a grain size of ~6.6 μm and an area fraction of recrystallized grains of 6.2%. Finally, it was possible to pave the way for the design of refined and stable microstructures after cryo-SPD processing. © 2022, The Authors. All rights reserved.

关键词： Equal channel angular pressing

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