Vacuum最新文献_第2页

Effect of cumulative plastic deformation on microstructure and strengthening mechanism of extruded Al-Zn-Mg-Cu alloy

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-27 DOI: 10.1016/j.vacuum.2024.113894

Linlin Liu , Guoqun Zhao , Xingting Zhao , Yexu Li , Zhengfeng Lv

{"title":"Effect of cumulative plastic deformation on microstructure and strengthening mechanism of extruded Al-Zn-Mg-Cu alloy","authors":"Linlin Liu , Guoqun Zhao , Xingting Zhao , Yexu Li , Zhengfeng Lv","doi":"10.1016/j.vacuum.2024.113894","DOIUrl":"10.1016/j.vacuum.2024.113894","url":null,"abstract":"<div><div>Al-Zn-Mg-Cu alloy profiles are widely used as aircraft components because of lightweight and high strength. The section of thin-walled profile is easy to have unavoidable heterogeneous strain. However, the influence mechanism of different cumulative plastic strains (CPS) on the material properties at different cross-section locations needs to be further clarified. This study carried out an extrusion experiment to study the influence of CPS on the microstructure, properties, and strengthening mechanisms by TEM, SEM and XRD. Results show that the strength and micro-hardness are positively correlated with CPS, while the elongation exhibits an inverse correlation. The orientation relationships between different micro- and nano-scale precipitates and the matrix were characterized. The strengthening mechanisms under different CPS were clarified. It was found that the contribution of solid solution strengthening is 22.6 % under the maximum cumulative strain, while Orowan strengthening accounts for 20.3 %. In contrast, these contributions are 30.2 % and 11.9 % under lower cumulative strain, respectively. Specimens at low CPS have the precipitated phase bands parallel to the extrusion direction, while the high CPS induces smaller and dense precipitated phases in the matrix and grain boundaries, resulting in precipitate-free zones with a width of 200–500 nm at the sub-grain boundary, which reduces the strengthening effect at the grain boundary. The research findings can guide for optimizing the heat treatment processes of thin-walled profiles.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"232 ","pages":"Article 113894"},"PeriodicalIF":3.8,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effects of magnetic conduction sleeve on the performance of a multi-cusped field thruster

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113880

Peng Hu , Wei Mao , Hui Liu , Daren Yu

{"title":"Effects of magnetic conduction sleeve on the performance of a multi-cusped field thruster","authors":"Peng Hu , Wei Mao , Hui Liu , Daren Yu","doi":"10.1016/j.vacuum.2024.113880","DOIUrl":"10.1016/j.vacuum.2024.113880","url":null,"abstract":"<div><div>The multi-cusped field thruster is a type of plasma electric propulsion device. Several alternating polarity permanent magnets are employed to form a unique cusped magnetic field. The thruster exhibits many performance advantages such as long lifetime, extremely large range thrust throttle ability, and high thrust density. In this paper, a magnetic conduction sleeve has been designed in a multi-cusped field thruster. The experimental results show that the additional magnetic conduction sleeve can significantly reduce the plume divergence angle, shifting the peak of the ion current density towards the axis from 24.5° to 15.1°. The main reason for this is that in the exit acceleration region, the magnetic field lines near the axis bend upwards, causing the electric field to be deflected towards the axis. As a result, the ions are accelerated by this focused electric field to form a collimated plume. In addition, the magnetic conduction sleeve can also reduce the radial gradient of the magnetic field in the main ionization region, and the ionization rate is enhanced. All these effects resulting in a significant increase in both thrust and efficiency. This work presents a new solution for optimizing the performance of a multi-cusped field thruster.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"232 ","pages":"Article 113880"},"PeriodicalIF":3.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Diatomic nitrogen-fixation electrocatalysts supported on graphitic carbon nitride achieve significantly low over potentials

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113888

Zheng-Yun Xiong , Wen-qing Hong , WangDong Zeng , Zhi-Min Ao , Ying Xu

{"title":"Diatomic nitrogen-fixation electrocatalysts supported on graphitic carbon nitride achieve significantly low over potentials","authors":"Zheng-Yun Xiong , Wen-qing Hong , WangDong Zeng , Zhi-Min Ao , Ying Xu","doi":"10.1016/j.vacuum.2024.113888","DOIUrl":"10.1016/j.vacuum.2024.113888","url":null,"abstract":"<div><div>The construction and screening of diatomic catalysts (DAC), as well as the exploration of intrinsic descriptors, are attracting increasing attention. In this work, using graphitic carbon nitride (g-CN) as the substrate, we assembled W, Mo, Cr, Mn, Fe, Co, and Ni atoms into DAC and conducted a systematic exploration of the catalytic capabilities of these systems for nitrogen reduction reaction (NRR) using first-principles calculations. Our research demonstrates that MoMn@g-CN exhibits outstanding catalytic activity and selectivity among the investigated 28 catalysts. The overpotential for NRR on MoMn@g-CN along the enzymatic pathway is merely 0.10 V, which is lower than most of the reported catalysts. By conducting in-depth electronic structure calculations, the catalytic mechanism of the DAC is investigated. N<sub>2</sub> adsorption and activation are influenced by the <em>σ</em>-acceptor-<em>π</em>∗-donor mechanism. The enhanced activation of nitrogen molecules is attributed to the synergistic effect of two hetero-diatomic species. Moreover, we have identified an new intrinsic descriptor for NRR related to the electronegativity of the two transition metal atoms. This descriptor correlates with the volcano plot of NRR's limiting potential. Our findings can provide valuable insights for the design and high-throughput screening of DAC.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"232 ","pages":"Article 113888"},"PeriodicalIF":3.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Internal cylindrical cathode arc deposited Cr coatings on the interior of slender tube: The influence of arc currents

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113883

Benfu Wang, Xiubo Tian, Chunzhi Gong, Huiyuan Geng, Tianshi Hu

{"title":"Internal cylindrical cathode arc deposited Cr coatings on the interior of slender tube: The influence of arc currents","authors":"Benfu Wang, Xiubo Tian, Chunzhi Gong, Huiyuan Geng, Tianshi Hu","doi":"10.1016/j.vacuum.2024.113883","DOIUrl":"10.1016/j.vacuum.2024.113883","url":null,"abstract":"<div><div>In this study, a novel internal cylindrical cathode arc device with electric-field assistance is proposed to address the issue of uniform coating on the interior of a slender tube. The relative average deviation of Cr coating thickness has been reduced to as low as 0.53 %, indicating high uniformity in axial thickness of the coatings. The effect of different arc currents (25–55 A) on the structure and surface properties of the coatings is investigated. The thickness, micro-structure, surface roughness, nano-hardness, friction and wear, adhesion between the coating and substrate as well as corrosion resistance of the deposited coatings are measured by a scanning electron microscopy, atom force microscopy, X-ray diffraction spectrometer, nano indenter, friction and wear instrument, scratch and indentation apparatus and electrochemical instrument, respectively. The results suggest that the proportion of macroparticles increases with arc current. Additionally, the macroparticles exhibit an atypical oblate pattern. This may lead to weaker, more fragile regions that are prone to flaking. Consequently, larger arc current gives rise to the deterioration in the tribological properties, adhesion between the coating and substrate, and electrochemical properties of the coatings. This study provides a feasible solution to obtain extremely uniform Cr coatings on the interior of slender tube by using the axially cylindrical cathode arc ion plating. At the same time, minimizing the arc current is beneficial to improve the performance of the coatings.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"232 ","pages":"Article 113883"},"PeriodicalIF":3.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Kinetic study of a-Si crystallization induced by an intermetallic compound

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113877

Evgeny T. Moiseenko , Vladimir V. Yumashev , Roman R. Altunin , Leonid A. Solovyov , Sergey M. Zharkov

{"title":"Kinetic study of a-Si crystallization induced by an intermetallic compound","authors":"Evgeny T. Moiseenko , Vladimir V. Yumashev , Roman R. Altunin , Leonid A. Solovyov , Sergey M. Zharkov","doi":"10.1016/j.vacuum.2024.113877","DOIUrl":"10.1016/j.vacuum.2024.113877","url":null,"abstract":"<div><div>The problem under study is concerned with amorphous silicon (a-Si) crystallization which is induced by an intermetallic compound, with this compound chosen to be Al<sub>2</sub>Cu, formed by a solid-state reaction between nanolayers of aluminum and copper in a Cu/Al/a-Si multilayer system. In the case of crystallization initiated by the intermetallic compound Al<sub>2</sub>Cu, the crystallization temperature of amorphous silicon was found to be ≈ 300°С (upon heating at a rate of 5–10 °C/min), which was significantly higher than in the case of pure Al (≈170°С), but lower as compared to using pure Cu (≈485°С). The higher crystallization temperatures in comparison with aluminium-induced crystallization are assumed to be caused by a decrease in the number of free electrons due to the presence of copper and formation of the Al<sub>2</sub>Cu phase. By kinetic modeling, it was revealed that the mechanism of a-Si crystallization induced by the intermetallic compound Al<sub>2</sub>Cu was similar to the mechanism of Al-induced crystallization of a-Si in multilayer (Al/a-Si)<sub>n</sub> films, i.e the process of a-Si crystallization occurred in two subsequent stages: Cn-X→Fn. Kinetic parameters of silicon crystallization for each reaction step were obtained. The enthalpy of a-Si crystallization initiated by Al<sub>2</sub>Cu was estimated to be ΔH = 12.3 ± 0.5 kJ/mol.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"232 ","pages":"Article 113877"},"PeriodicalIF":3.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Labyrinth seal design for space applications

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113882

Josef Pouzar , David Kostal , Lars-Göran Westerberg , Erik Nyberg , Ivan Krupka

{"title":"Labyrinth seal design for space applications","authors":"Josef Pouzar , David Kostal , Lars-Göran Westerberg , Erik Nyberg , Ivan Krupka","doi":"10.1016/j.vacuum.2024.113882","DOIUrl":"10.1016/j.vacuum.2024.113882","url":null,"abstract":"<div><div>Labyrinth seals, extensively used in space applications, serve to prevent the loss of liquid lubricants and shield satellite subsystems from contamination. These seals are essential for the reliable functioning of bearings and for protecting satellite subsystems from contamination. This study compares analytical predictions of lubricant loss against experimental measurements and computer simulations to optimize labyrinth seal configurations. Analytical models tend to overestimate mass loss by 5–8 times compared to experimental data, indicating limited reliability for complex seal geometries. Simulations using MolFlow+ and COMSOL Multiphysics align closely with experimental results, providing accurate mass loss predictions. Key findings highlight that labyrinth length, width, and surface roughness are critical factors in minimizing evaporative mass loss. Notably, stepped labyrinth seals with relief grooves and optimized step positioning effectively reduce molecular beaming effects and improve sealing performance compared to straight geometries. Effective sealing not only reduces mission failures but also helps to minimize space debris, thereby promoting safer satellite missions.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"232 ","pages":"Article 113882"},"PeriodicalIF":3.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Microstructure and temperature-dependent fretting wear behaviour of AA7075/MoS2/Red-Mud Hybrid composites via vacuum-assisted stir casting route

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113884

Priyeshiv Kumar Gurmaita , Virendra Pratap Singh , Rosang Pongen

引用次数: 0

Effects of pressure on the electronic and optical properties of defect-free and defect-containing fused silica: A first-principles study 压力对无缺陷和含缺陷熔融石英的电子和光学特性的影响：第一原理研究

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113881

Rongqi Shen , Yi Lu , Zhongxi Zhang

引用次数: 0

Micro milling mechanism and tool wear of Unidirectional HfZrTiTaNbCu0.2 fiber reinforced aluminum matrix composites

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113886

Ping Zhang , Shunxiang Wang , Xiaomin Jiang , Yan Yu

{"title":"Micro milling mechanism and tool wear of Unidirectional HfZrTiTaNbCu0.2 fiber reinforced aluminum matrix composites","authors":"Ping Zhang , Shunxiang Wang , Xiaomin Jiang , Yan Yu","doi":"10.1016/j.vacuum.2024.113886","DOIUrl":"10.1016/j.vacuum.2024.113886","url":null,"abstract":"<div><div>This study delves into the micro milling and tool wear mechanisms of 2A97 aluminum matrix composites reinforced with HfZrTiTaNbCu<sub>0.2</sub> fibers. Finite element analysis models the fibers as uniformly distributed cylindrical entities within the matrix, applying various material constitutive laws, failure, and evolution criteria to simulate milling at three specific angles (45°, 90°, 135°). The research examines the effects of milling parameters, fiber orientations, and tool coating thickness on cutting forces, temperatures, surface roughness, and tool wear. Key findings include: These forces escalate with both cutting speed and depth of cut. Notably, at a feed rate of 68 μm/z, the cutting force is 1.5 times higher compared to 58 μm/z.An increase in milling parameters leads to higher cutting temperatures. Differences of 12 °C and 10 °C were noted at varying depths of cut (10–25 μm) and cutting speeds (1000–1200 mm/s), respectively. As the fiber angle increases, cutting forces first decrease and then rise, with fibers oriented at 90° experiencing only 53 % of the force compared to those at 135°. Similarly, cutting temperatures follow this trend, with a 26 °C difference between 45° and 90° fibers. This factor is positively correlated with depth of cut and fiber angle. Surface roughness at a 55 μm depth is 4.3 times that at 10 μm, and 135° fibers show 2.7 times the roughness of 45° fibers. However, within feed rates of 48–58 μm/z and cutting speeds of 800–1200 mm/s, there is a notable decrease in surface roughness. Variations in cutting parameters, fiber orientations, and tool coating thickness significantly influence peak tool stress. Stress concentration at the central groove tends to reduce tool wear, whereas stress concentration at the peripheral edge or strain concentration at the bottom edge exacerbates it.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"232 ","pages":"Article 113886"},"PeriodicalIF":3.8,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748344","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Fast prediction of the melting of FeHx in planetary interiors

IF 3.8 2区材料科学

Vacuum Pub Date : 2024-11-26 DOI: 10.1016/j.vacuum.2024.113857

Tran Dinh Cuong , Anh D. Phan

引用次数: 0