Vacuum最新文献

英文中文

Study on surface integrity and crack propagation mechanism of Ti/Al composite plates enhanced based on water jet peening 基于喷水强化的钛铝复合板表面完整性和裂纹扩展机理研究

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-21 DOI: 10.1016/j.vacuum.2024.113818

Ping Zhang , Yeran Gao , Xiaomin Jiang , Yan Yu , Youqiang Wang

This study investigates the mechanisms through which water jet (WJ) enhancement affects surface integrity and crack propagation in Ti/Al composite plates. Finite element models for both WJ enhancement and crack propagation were developed using ABAQUS, complemented by experiments analyzing the influence of different jet velocities on surface integrity parameters, such as residual stress and surface roughness. These parameters were then examined for their effects on the stress intensity factor (SIF), fatigue crack propagation rate (FCP), and crack propagation path.The results demonstrated a positive relationship between jet velocity and both surface roughness and maximum residual compressive stress in specimens treated with WJ enhancement. Specifically, as jet velocity increased from 300 mm/s to 350 mm/s, surface roughness rose approximately 4.2-fold to around 0.95813 μm, while maximum residual compressive stress increased from 1109.9 MPa to 1472.5 MPa. The uniform distribution of residual compressive stress contributed significantly to the reduction in the stress intensity factor.Additionally, the crack propagation rate was inversely correlated with jet velocity. The residual compressive stress induced by higher jet velocities effectively slowed crack propagation. The theoretical interpretation of residual compressive stress as an equivalent damping layer further validated the effectiveness of WJ enhancement in reducing crack propagation in Ti/Al composites.

本研究探讨了水射流（WJ）增强对钛/铝复合板表面完整性和裂纹扩展的影响机制。研究人员使用 ABAQUS 建立了水射流增强和裂纹扩展的有限元模型，并通过实验分析了不同射流速度对残余应力和表面粗糙度等表面完整性参数的影响。结果表明，在经过 WJ 增强处理的试样中，射流速度与表面粗糙度和最大残余压应力之间存在正相关关系。具体来说，当喷射速度从 300 mm/s 增加到 350 mm/s，表面粗糙度增加了约 4.2 倍，达到约 0.95813 μm，而最大残余压应力则从 1109.9 MPa 增加到 1472.5 MPa。残余压应力的均匀分布在很大程度上降低了应力强度因子。较高的喷射速度引起的残余压应力有效地减缓了裂纹的扩展。残余压应力作为等效阻尼层的理论解释进一步验证了 WJ 增强在减少钛/铝复合材料裂纹扩展方面的有效性。

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引用次数: 0

Phase evolution and mechanical properties of AlxCrTaTi refractory medium entropy alloys AlxCrTaTi 难熔中熵合金的相变和机械性能

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-20 DOI: 10.1016/j.vacuum.2024.113847

Xiangxing Xiao , Jiadong Wen , Kechuan Wei , Xian Wang , Xingdong Zhao , Xingqiang Wang , Guixue Zhang , Ying Xu , Yan Wei , Hualong Ge , Hongzhong Cai , Xuehang Wang , Li Chen , Junmei Guo , Kunhua Zhang , Changyi Hu

In multi-principal refractory alloys (high-entropy alloys, medium-entropy alloys), the presence of the second phase has an important influence on the mechanical properties of the alloys. In this paper, AlxCrTaTi (x = 0, 0.25, 0.5, 1.0) refractory medium-entropy alloys were prepared by vacuum arc melting method, and the microstructure, density, and mechanical properties were investigated. The CrTaTi alloy consists of BCC dendritic and C15 Laves phases, whereas the Al_xCrTaTi alloys consist of a two-phase eutectic organization (BCC phase and C14 Laves phase). With the increase of Al content, the content of the second phase increases from 15.97 % to 42.19 %, resulting in an increase in the yield strength of the alloy from 1491 MPa to 2354 MPa at 25 °C, and from 253 MPa to 426 MPa at 1000 °C. The addition of Al element changes the enthalpy, elemental distribution, and solidification process of the alloy, resulting in the formation of Cr-rich and Ti-rich two-phase eutectic organizations in the alloy. With the increase of Al, the second phase strengthening is the main reason for the enhancement of alloy properties.

在多本征难熔合金（高熵合金、中熵合金）中，第二相的存在对合金的力学性能有重要影响。本文采用真空电弧熔炼法制备了 AlxCrTaTi（x = 0、0.25、0.5、1.0）难熔中熵合金，并对其显微组织、密度和力学性能进行了研究。CrTaTi 合金由 BCC 树枝状相和 C15 Laves 相组成，而 AlxCrTaTi 合金则由两相共晶组织（BCC 相和 C14 Laves 相）组成。随着铝含量的增加，第二相的含量从 15.97 % 增加到 42.19 %，从而使合金在 25 °C 时的屈服强度从 1491 兆帕增加到 2354 兆帕，在 1000 °C 时的屈服强度从 253 兆帕增加到 426 兆帕。铝元素的加入改变了合金的焓、元素分布和凝固过程，使合金中形成了富铬和富钛的两相共晶组织。随着铝元素的增加，第二相强化是合金性能增强的主要原因。

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引用次数: 0

Synthesis and characterization of ammonia strengthened and ambient dried N-doped hydrophilic graphene aerogel with good electrical conductivity 具有良好导电性的氨强化和常温干燥 N 掺杂亲水石墨烯气凝胶的合成与表征

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-20 DOI: 10.1016/j.vacuum.2024.113846

Feng Xiong , Jiabin Wang , Neville Dickman , Yujing Liu , Michael R.C. Hunt , Lidija Šiller

We present a novel ‘one-pot’ approach for strengthening reduced graphene oxide (rGO) hydrogels by nitrogen doping. Ammonia is directly added to the precursor reaction mixture prior to hydrothermal gel formation, as opposed to treating as-synthesised rGO hydrogel by ammonia in a second hydrothermal process. This process ensures that the resulting hydrogels are sufficiently robust that aerogels may then be produced by natural drying under ambient temperture and pressure. The as-formed rGO aerogel possesses a Young's modulus as high as 28 kPa and exhibits superelasticity, withstanding strains of up to 95 %. Moreover, the strengthed graphene aerogel possesses an electrical conductivity of up to 1.5 S cm⁻¹ and a specific surface area of 280.0 m² g⁻¹. Although the rGO aerogel was sufficiently reduced to provide good electrical conductivity, it retains a water contact angle of 47 ± 1°, indicating hydrophilic behaviour.

我们提出了一种通过氮掺杂强化还原氧化石墨烯（rGO）水凝胶的新型 "一步法"。在水热凝胶形成之前，氨被直接添加到前驱体反应混合物中，而不是在第二个水热过程中用氨处理合成的 rGO 水凝胶。这种工艺可确保生成的水凝胶足够坚固，从而可以在环境温度和压力下通过自然干燥生产气凝胶。成型的 rGO 气凝胶具有高达 28 kPa 的杨氏模量和超弹性，可承受高达 95% 的应变。此外，强化石墨烯气凝胶的导电率高达 1.5 S cm-1，比表面积为 280.0 m2 g-1。虽然 rGO 气凝胶已被充分还原以提供良好的导电性，但它的水接触角仍保持在 47 ± 1°，这表明它具有亲水性。

引用次数: 0

Influence of oxygen on metastable pitting behavior of super 13Cr stainless steel in CO2-saturated environment 氧气对二氧化碳饱和环境中超 13Cr 不锈钢瞬态点蚀行为的影响

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-19 DOI: 10.1016/j.vacuum.2024.113845

Lv Naixin , Fu Anqing , Chen Chao , Bai Haitao , Zhao Zaipeng , Li Xuanpeng , Xu Zhengyi , Guozhe Meng

This study investigates the effect of oxygen on the metastable pitting corrosion behavior of Super 13Cr martensitic stainless steel in a CO₂-saturated environment, which is pertinent to challenging extraction conditions of oil and gas industry. Potentiostatic polarization and comprehensive statistical analysis to assess the corrosion dynamics. The results indicate that the presence of oxygen significantly influences the initiation and progression of metastable pitting. In the 50 % O₂ + 50 % CO₂ environment, a decrease in the frequency and size of metastable pitting events was observed, along with a reduction in the peak current, pit radius, and stable product, suggesting that oxygen inhibits the transition from metastable to stable pitting.

本研究探讨了氧气对超级 13Cr 马氏体不锈钢在二氧化碳饱和环境中的转移点腐蚀行为的影响，这与石油和天然气工业的挑战性开采条件有关。通过恒电位极化和综合统计分析来评估腐蚀动态。结果表明，氧气的存在极大地影响了易生点蚀的发生和发展。在 50%O2 + 50% CO2 的环境中，观察到可迁移点蚀事件的频率和大小有所下降，峰值电流、点蚀半径和稳定产物也有所减少，这表明氧气抑制了从可迁移点蚀到稳定点蚀的转变。

引用次数: 0

Modelling and working process mechanism of a double-claw vacuum pump with novel double-claw rotors 带有新型双爪转子的双爪真空泵的建模和工作过程机理

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-19 DOI: 10.1016/j.vacuum.2024.113844

Min Wei, Haibin Liu, Lezhi Ye, Yanfeng Wei, Yue Chang

Double-claw rotors can significantly increase the pumping speed of the claw vacuum pump. In order to develop new claw rotors with higher comprehensive performance, in this study, a novel type of two intermeshing double-claw rotors consisting of the elliptical arc, line segment, circular arc and their conjugate curves was proposed. A geometric model of the proposed double-claw rotor was established, and profile equations were also derived. The effects of its independent geometric parameters of the proposed double-claw rotors on the performance were analyzed, and then a corresponding double-claw vacuum pump with these novel rotors was designed. Meanwhile, its the working process was studied and numerically simulated. Results indicate that the proposed double-claw rotor offers several significant advantages, including a higher pumping speed, improved profile meshing characteristics, and enhanced dynamic balance performance. The working process of the double-claw vacuum pump includes 5 processes: suction process, isometric delivery process, compression process, discharge process and mixing process. The contents of this study will provide theoretical basis for the development of the double-claw vacuum pump and promote its application.

双爪转子能显著提高爪式真空泵的抽气速度。为了开发综合性能更高的新型爪式转子，本研究提出了一种由椭圆弧、线段、圆弧及其共轭曲线组成的新型双啮合双爪转子。建立了双爪转子的几何模型，并推导了轮廓方程。分析了所提出的双爪转子的独立几何参数对其性能的影响，然后设计出了采用这些新型转子的相应双爪真空泵。同时，对其工作过程进行了研究和数值模拟。结果表明，所提出的双爪转子具有几个显著的优点，包括抽气速度更高、轮廓啮合特性更好以及动平衡性能更强。双爪真空泵的工作过程包括 5 个过程：吸气过程、等距输送过程、压缩过程、排气过程和混合过程。本研究的内容将为双爪真空泵的开发提供理论依据，并促进其应用。

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引用次数: 0

Diagnostic study of atmospheric pressure inductively coupled plasma temperature field based on image and relative spectral line method 基于图像和相对谱线方法的大气压电感耦合等离子体温度场诊断研究

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-19 DOI: 10.1016/j.vacuum.2024.113841

Xingyue Jin , Peng Zhao , Lin Li , Chengzhou Liu , Chuanwen Geng , Qifu Lin , Liqun Hu

Atmospheric pressure inductively coupled plasma (ICP) is widely applied in the production of high-purity coatings and powders. This paper innovatively presents a dual-band imaging ICP temperature diagnostic system that integrates visible light image processing technology and relative spectral line method. The system utilizes a dual-band imaging unit to simultaneously acquire monochromatic grayscale images of ICP at two different wavelengths using a single CCD camera. By establishing the correspondence between the emission intensity received by the emission spectrometer and the grayscale images recorded by the CCD camera, the two-dimensional (2D) electron excitation temperature (EET) field distribution of ICP is obtained by the relative spectral line method. The experimental results demonstrate that the maximum EET is located near to the center line of the RF-driven coil. Additionally, the EET in ICP decreases gradually from the center of the induction coil to the periphery. As the radio frequency (RF) power increases, the maximum EET also increases, and the high-temperature region expands. The accuracy of this method is validated by comparing it with the results obtained from the Boltzmann plot method. Therefore, this method can quickly obtain the transient EET field distribution of ICP, which is significant for optimizing the application of ICP in material processing.

常压电感耦合等离子体（ICP）广泛应用于高纯涂层和粉末的生产。本文创新性地提出了一种双波段成像 ICP 温度诊断系统，该系统集成了可见光图像处理技术和相对谱线方法。该系统利用双波段成像装置，使用单个 CCD 相机同时获取两个不同波长的 ICP 单色灰度图像。通过建立发射光谱仪接收到的发射强度与 CCD 相机记录的灰度图像之间的对应关系，利用相对谱线法获得了 ICP 的二维（2D）电子激发温度（EET）场分布。实验结果表明，最大 EET 位于射频驱动线圈中心线附近。此外，ICP 中的 EET 从感应线圈中心向外围逐渐减小。随着射频（RF）功率的增加，最大 EET 也随之增加，高温区也随之扩大。通过与波尔兹曼图法得出的结果进行比较，验证了该方法的准确性。因此，该方法能快速获得 ICP 的瞬态 EET 场分布，这对优化 ICP 在材料加工中的应用意义重大。

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引用次数: 0

Synthesis and spark plasma sintering of Ti5Si3-Mo powders with core-shell structure 具有核壳结构的 Ti5Si3-Mo 粉末的合成与火花等离子烧结

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-19 DOI: 10.1016/j.vacuum.2024.113843

Ievgen Solodkyi , Vadim Mosiichuk , Oleksandr Kucher , Manja Krüger

Core-shell Ті₅Si₃-Mo powders were successfully synthesized by reducing of ammonium molybdate (para) tetrahydrate with hydrogen and glycerol, respectively. As a result, the Ti₅Si₃ core was coated with submicron and nanosized Mo particles. The morphology and microstructure of the synthesized powders were studied scanning electron microscopy along with local chemical analysis. Phase analysis was performed using X-ray diffraction. The synthesized powders were densified by spark plasma sintering (SPS) at a temperature of 1500 °C. It was shown that powders with a core-shell structure are densified up to a temperature of 1330 °C, while the mechanical mixture of commercial powders at this temperature only begins to densify. The hardness (HV20) of the obtained composites was also investigated. Compressive strength investigation at room temperature shows 5.5 % plastic strain and ultimate strength of about 3 GPa as well as fractographic studies have shown the presence of a pseudo-brittle fracture mechanism for the metal matrix composite (MMC), which was sintered by SPS of the core-shell Ti₅Si₃-Mo powder synthesized by reduction with glycerol.

通过氢气和甘油分别还原四水钼酸铵（对位），成功合成了核壳Ті5Si3-Mo粉末。因此，Ti5Si3 内核被覆上了亚微米和纳米级的 Mo 粒子。通过扫描电子显微镜和局部化学分析研究了合成粉末的形态和微观结构。利用 X 射线衍射进行了相分析。合成粉末通过火花等离子烧结（SPS）在 1500 ℃ 的温度下进行致密化。结果表明，核壳结构粉末的致密化温度可达 1330 °C，而商品粉末的机械混合物在此温度下才开始致密化。此外，还对所获复合材料的硬度（HV20）进行了研究。室温下的抗压强度调查显示，其塑性应变为 5.5%，极限强度约为 3 GPa，断裂力学研究表明，通过甘油还原法合成的核壳 Ti5Si3-Mo 粉末经 SPS 烧结而成的金属基复合材料（MMC）存在伪脆性断裂机制。

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引用次数: 0

Monte Carlo simulation of the magnetic properties of a multilayer mixed-spin system (5/2, 3/2) 多层混合自旋系统（5/2，3/2）磁特性的蒙特卡罗模拟

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-18 DOI: 10.1016/j.vacuum.2024.113781

H. Saadi , A. Al-Rajhi , E.M. Jalal , O. Hachem , M. Madani , M. El Bouziani

A Monte Carlo simulation has been employed to investigate the critical behavior of a multilayer system composed of two blocks: the upper block A with spin-5/2 and the bottom one B with spin-3/2. In the first instance, the effect of number of layers is studied in order to determine the optimal number of layers to select. The influence of exchange coupling and crystal fields constants on total and sublattice magnetizations, susceptibilities, and internal energy is deduced for specific parameters. The phase diagrams under the effect of different parameters have also been established. Moreover, We analyzed the hysteresis cycles for selected values of temperature, exchange coupling interaction and the crystal fields. At last, we noticed that our findings are comparable with the results of theoretical and experimental studies carried out by others.

蒙特卡洛模拟被用来研究由两个区块组成的多层系统的临界行为：上层区块 A 具有自旋-5/2，下层区块 B 具有自旋-3/2。首先研究了层数的影响，以确定选择的最佳层数。在特定参数下，推导了交换耦合和晶体场常数对总磁化和亚晶格磁化、电感和内能的影响。还建立了不同参数影响下的相图。此外，我们还分析了温度、交换耦合作用和晶体场选定值下的磁滞周期。最后，我们注意到，我们的研究结果与其他人的理论和实验研究结果具有可比性。

引用次数: 0

Interfacial electric field of CdIn2S4/CuS heterostructure induced S-scheme charge transfer for efficient photoelectrochemical water splitting CdIn2S4/CuS 异质结构的界面电场诱导 S 型电荷转移，实现高效光电化学水分离

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-17 DOI: 10.1016/j.vacuum.2024.113838

Zonghan Hu , Qi Wang , Zihang Wang , Lanlan Zhang , Chengwei Hu , Yuanhu Lei , Yupei Qiao , Bing Lv

Currently, the two predominant heterojunction types, namely type II and S-scheme heterojunctions, are extensively employed in photoelectrochemical (PEC) water splitting for hydrogen production. However, type II heterojunctions suffer from the drawback of diminished oxidation-reduction capability. In this work, S-scheme CdIn₂S₄/CuS (CIS/CuS) heterojunction nanoblocks (NBs) photoanode is constructed for the first time by a hydrothermal and the successive ionic layer adsorption and reaction (SILAR) methods. The heterojunction achieves a photocurrent density of up to 4.0 mA/cm² at 0 V vs. Ag/AgCl, 2.37 times that of the pure CIS NBs photoanode. X-ray photoelectron spectroscopy (XPS), Tauc plots, Mott-Schottky (M − S) tests and density functional theory (DFT) calculations reveal the formation of S-scheme band structure between the interface of CIS and CuS. As a result, the significantly enhanced PEC water splitting performance of CIS/CuS NBs photoanode is attributed to the superior light absorption ability of CuS and the effective charge separation achieved by S-scheme band structure between the interface of CIS and CuS. This work also provides new ideas and strategies for designing efficient S-scheme heterostructures for efficient PEC water splitting.

目前，两种主要的异质结类型，即 II 型异质结和 S 型异质结，被广泛用于光电化学（PEC）水分离制氢。然而，II 型异质结存在氧化还原能力减弱的缺点。本研究首次采用水热法和连续离子层吸附和反应（SILAR）法构建了 S 型 CdIn2S4/CuS（CIS/CuS）异质结纳米块（NBs）光阳极。该异质结在 0 V 对 Ag/AgCl 时的光电流密度高达 4.0 mA/cm2，是纯 CIS NBs 光阳极的 2.37 倍。X 射线光电子能谱（XPS）、陶氏图、莫特-肖特基（M - S）测试和密度泛函理论（DFT）计算揭示了 CIS 与 CuS 界面之间形成的 S 型带结构。因此，CIS/CuS NBs 光阳极的 PEC 水分离性能的显著提高归功于 CuS 优异的光吸收能力以及 CIS 和 CuS 界面之间的 S 型带结构实现的有效电荷分离。这项研究还为设计高效 S 型异质结构以实现高效 PEC 水分离提供了新的思路和策略。

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引用次数: 0

Effect of preheating treatment in Ar atmosphere on oxidation resistance of Mg-Y alloys and formation of oxide film 氩气环境中的预热处理对 Mg-Y 合金抗氧化性和氧化膜形成的影响

IF 3.8 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Vacuum

Pub Date : 2024-11-17 DOI: 10.1016/j.vacuum.2024.113836

S.Y. Liu , J. Apell , B. Li , Z.H. Liu , G.J. Liu , X.Y. Lang , Y.F. Zhu , Q. Jiang

Magnesium and its alloys occupy a vital role in the aerospace, automotive and communications industries due to their low density, high specific strength and electromagnetic shielding capabilities. However, due to the strong affinity of Mg for O and the fact that MgO is generally not protective, application of Mg and its alloys at high temperature often results in catastrophic oxidation. One promising approach is based on the addition of Y in combination with a suitable pretreatment to achieve a protective oxide. Therefore, the oxidation resistance (OR) of Mg-xY (x = 0.5, 2.5 and 5.5 wt%) was investigated after using a preheating treatment in Ar atmosphere. The oxidation resistance of preheated Mg-xY alloys is greatly improved compared to unpreheated alloys and pure Mg, particularly for x = 2.5. This improvement is attributed to the enrichment of Y to the surface caused by outward diffusion of Y, and subsequent selective oxidation of Y under low oxygen partial pressure to generate a dense and compact protective film, composed of an outer thin MgO/Y₂O₃ composite layer and an inner thick Y₂O₃ layer. Some flocculent MgO/Y₂O₃ composites were observed on the surface of preheated Mg-5.5Y during the oxidation process, lowering the OR of this alloy.

镁及其合金具有密度低、比强度高和电磁屏蔽能力强的特点，在航空航天、汽车和通信行业中发挥着重要作用。然而，由于镁与 O 的亲和力很强，而且氧化镁通常不具有保护作用，因此在高温下使用镁及其合金往往会导致灾难性的氧化。一种可行的方法是在添加 Y 的同时进行适当的预处理，以获得保护性氧化物。因此，在氩气环境中进行预热处理后，对 Mg-xY（x = 0.5、2.5 和 5.5 wt%）的抗氧化性（OR）进行了研究。与未加热的合金和纯镁相比，预热 Mg-xY 合金的抗氧化性大大提高，尤其是 x = 2.5 时。这种改善归因于 Y 的向外扩散使 Y 富集到表面，随后 Y 在低氧分压下发生选择性氧化，生成一层致密而紧凑的保护膜，该保护膜由外层薄 MgO/Y2O3 复合层和内层厚 Y2O3 层组成。在氧化过程中，在预热的 Mg-5.5Y 表面观察到一些絮状 MgO/Y2O3 复合材料，从而降低了这种合金的 OR。

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