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Cover Feature: Free-Standing Pearl-Chains-like MoO2Hierarchical Nanowires with Enhanced Pseudocapacitive Energy Storage (Batteries & Supercaps 9/2022)

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Batteries & Supercaps 2022年第9期5卷

作者： Changwei Shi Shihao Feng Xinyuan Li Jianyong Zhang Prof. Liqiang Mai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of Technology Wuhan 430070 P. R. China Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory Xianhu hydrogen Valley Foshan 528200 P. R. China

Boosting the Alkali Metal Ions Storage Performance of Layered Nb2C with a Molecular Welding Strategy

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SSRN 2022年

作者： Liu, Maocheng Zhang, Dongting Liu, Bao Tian, Chenyang Zhao, Bei Wang, Yaqin Wang, Yuanyi Hu, Yuxia Kong, Lingbin Luo, Dan Chen, Zhongwei State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of Technology Lanzhou730050 China School of Materials Science and Engineering Lanzhou University of Technology Lanzhou730050 China School of Materials Science and Engineering Xiangtan University Hunan Xiangtan411105 China Department of Chemical Engineering Waterloo Institute for Nanotechnology University of Waterloo WaterlooONN2L 3G1 Canada Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices School of Information and Optoelectronic Science and Engineering South China Normal University Guangzhou510006 China

MXenes are promising 2D-layered anode materials for rechargeable batteries. However, MXenes suffer from severe volume expansion and sluggish ion diffusion kinetics during ions insertion/extraction, leading to inferior battery performance. Herein, we developed a molecular welding strategy to stabilize layered structure and enlarge interlayer spacing of Nb2C through a dehydration condensation reaction between the -COOH groups in 1,3,5-benzenetricarboxylic acid (BTC) molecules and -NH2 groups on the surface of the aminofunctionalized Nb2C, which enable the BTC to chemically weld into interlayers of Nb2C (named as Nb2C/BTC). The intercalation of BTC into Nb2C contributes both pillar and strain effects to the 2D-layered Nb2C, rendering its maximum utilization. Such Nb2C/BTC with enlarged interlayer spacing and inhibited volume variation could remarkably promote the rate capability and cycling stability of Nb2C when used as the electrodes of alkali metal ions batteries. A decent Li+/Na+ ions storage capacity-retention of 86.6% (0.1 A g-1)/93.5% (1.0 A g-1) can be presented. A much reduced ion diffusion barrier of 0.88 eV is also delivered in Nb2C/BTC through DFT theoretical calculations. This work provides a new strategy for broadening the interlayer spacing and inhibiting the severe volume variation of MXenes for enhanced alkali metal ions storage. © 2022, The Authors. All rights reserved.

关键词： Anodes

A Novel Low-Cost High-Strength Β Titanium Alloy Microstructure Evolution and Mechanical Behavior

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SSRN 2022年

作者： Li, C.C. Xin, Chao Wang, Qi Ren, Junqiang Zhao, B. Wu, J.P. Pan, X.L. Lu, Xuefeng State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals School of Materials Science and Engineering Lanzhou University of Technology Lanzhou730050 China Xi'an Rare Metal Materials Institute Co. Ltd Shaanxi Xi'An710016 China School of Energy Engineering Huanghuai University Zhumadian463000 China Xi’an Surface Material Protection Co. Ltd. Xi'An710200 China

A novel metastable β-titanium alloy (Ti-4.8Al-5.6Mo-3V-1.5Cr-1.6Fe) with low-cost and high-strength was designed using the d-electron theory approach. A multiscale structure composing of β matrix, primary αp (volume fraction of 21%) and the precipitates αs were obtained after solution at 780 °C and aging at 470, 500, and 530 °C. The density and average spacing of precipitates were dependence of the aging temperature. The dense αs with the average spacing (λ) less than 100 nm were precipitated aging at 470 °C due to the greater driving force for formation of αs. In contrast, the coarse αs with the average spacing (λ) greater than 100 nm were precipitated aging at 530 °C due to the greater driving force for growth of αs. The tensile properties were also sensitive to the density and spacing precipitates αs inside the β matrix. A tensile strength ranging from 1512 MPa to 1648 MPa and tensile elongation ranging from 1.8% to 7.8% were reported by controlling the density and average spacing of precipitates αs inside the β matrix. Particularly, an excellent combination of high tensile strength (1512 MPa) and relatively high elongation (7.8%) was obtained by aging at 530 °C. © 2022, The Authors. All rights reserved.

关键词： Titanium alloys

Core-Shell Fe3al@Polypyrrole Composites with Tunable Shell Thickness and Enhanced Microwave Absorption Performance

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SSRN 2023年

作者： Shen, Yongqian Song, Pengfei Zhang, Fan Cao, Jiafeng Gao, Feng Ma, Jiqiang Feng, Huixia Yang, Fulong Zhang, Wenjuan Liu, Chunli Du, Xueyan School of Materials Science & Engineering State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Lanzhou University of Technology Lanzhou730050 China Shouhang Hi-Tech Energy Technology Co. Ltd. Jiuquan735099 China College of Science Lanzhou University of Technology Lanzhou730050 China College of Petrochemical Technology Lanzhou University of Technology Lanzhou730050 China College of Electrical and Information Engineering Lanzhou University of Technology Lanzhou730050 China

Nowadays, core-shell structures have attracted considerable attention as microwave absorbers (MAs) due to the synergistic effect between dielectric and magnetic loss. Herein, core-shell Fe3Al@polypyrrole (Fe3Al@PPy) composites were successfully fabricated by the thermit reaction and chemical oxidation polymerization method with the assistance of ammonium persulfate and p-toluene sulfonic acid. Due to the regulation of the impedance matching by the electromagnetic coupling and core-shell structure, the Fe3Al@PPy composites showed the enhanced electromagnetic wave (EMW) absorption performance compared with the pure Fe3Al. Furthermore, the thickness of the PPy shell increased from 0.3 μm to 1.5 μm as the addition of pyrrole increased from 0.25 mL to 1.0 mL. Meanwhile, the Fe3Al@PPy composites exhibited the optimal wave absorption performance when the PPy shell thickness was 0.8 μm, the reflection loss (RL) could reach to -40.5 dB with the thickness of 2.0 mm at 13.3 GHz. This work provides a new idea for the design of large-scale electromagnetic coupled microwave absorbers with core-shell structures. © 2023, The Authors. All rights reserved.

关键词： Polypyrroles

Two-Part Linear Low Cycle Fatigue Life in Ta5 Alloy and the Associated Cyclic Deformation Mechanisms

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SSRN 2023年

作者： Qi, Wang Sang, Biao Ren, Junqiang Zhang, Yonghong Xin, Chao Ran, Jing Qiang, Yaochun Chen, Biqiang Wang, Bing School of Energy Engineering Huanghuai University Zhumadian463000 China School of Materials Science and Engineering Shaanxi University of Technology Hanzhong723001 China State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals School of Materials Science and Engineering Lanzhou University of Technology Lanzhou730050 China Xi'an Rare Metal Materials Institute Co. Ltd Shaanxi Xi’an710049 China Xi’an Thermal Power Research Institute Co. Ltd Shaanxi Xi’an710054 China School of Materials Science and Engineering Beijing University of Technology Beijing100022 China

Because the transition of cyclic deformation mechanism from dislocation slip to deformation twins (DTs) as the total strain amplitude ( Εt/2) increases, a phenomenon of two-part linear relationship between elastic strain amplitude ( Εe/2) and fatigue life (2Nf ) was observed in TA5 alloy, which is different from the reported two-part linear relationship between plastic strain amplitude ( Εp/2) and . A overall tendency of cyclic softening was observed, and the degree of cyclic softening gradually decreases as Εt/2 increases due to DTs boundaries as barriers to dislocations. Meanwhile, the degree of tension-compression asymmetry gradually decreased as the increasing of Εt/2, which is mainly attributable to the discrepancy of working hardening and the weakening of Bauschinger effect induced by the activation of DTs. In this study, the activation of DTs during cyclic deformation is beneficial to improve the low cycle fatigue life at high Εt/2. The main underlying reason is the decreasing cyclic elastic modulus due the re-orientation effect of DTs. © 2023, The Authors. All rights reserved.

关键词： Low-cycle fatigue

Nanophase Transformation and Strengthening - Toughening Mechanism of the Cu-15ni-8sn Alloy During Aging

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SSRN 2023年

作者： Jiang, Kai-Xuan Zhou, Yan-Jun Yang, Ran Song, Ke-Xing Liu, Yahui Zhang, Yan-Min Yang, Shao-Dan Zhou, Fei Huang, Kuan Liu, Dong Yang, Wen-Hao School of Materials Science and Engineering Henan University of Science and Technology Luoyang471023 China Provincial and Ministerial Co-construction Collaborative Innovation Center of Nonferrous New Materials and Advanced Processing Technology Luoyang471023 China Henan Key Laboratory of Advanced Nonferrous Metals Luoyang471023 China School of Medical Technology and Engineering Henan University of Science and Technology Luoyang471023 China Henan Academy of Sciences Zhengzhou450046 China School of Mechatronics Engineering Henan University of Science and Technology Henan Luoyang471023 China School of Material Science & Engineering Zhengzhou University Zhengzhou450001 China

The Cu-15Ni-8Sn alloy ingot was prepared in the medium-frequency induction melting furnace. The hot extruded alloy was treated by solid solution at 840 °C for 60 min and aging at 400 °C for different times. The effect of aging time on the evolution of the nanophase of Cu-15Ni-8Sn alloy and the strengthening-toughening mechanism were studied. The results show that at the beginning of aging, the alloy undergoes spinodal decomposition, the wavelength of the modulated structure is approximately 3~7 nm, the ordered phase transformation of D022 and L12 occurs simultaneously, and the ordered phase size is approximately 5 nm. With the extension of aging time, the modulated structure became coarser, and the wavelength of the modulated structure increased to 5~9 nm. At the same time, the D022 ordered phase changed to the L12 ordered phase, and a continuous distribution of elliptical discontinuous precipitation appeared at the grain boundary. The ratio of the long and short axes of the discontinuous precipitation was approximately 4.7. In the late aging period, the D022 ordered phase was basically transformed into the L12 ordered phase, and discontinuous precipitation, which is incompatible with the matrix, extended into the crystal. After 120 min of aging at 400 °C, the hardness, strength, and elongation of the alloy are 105.4 HRB, 839.8 MPa and 9.6%, respectively. The peak-aging states D022 and L12 coexist in an orderly phase at the nanoscale, and this nanoscale strengthening phase is completely integrated with the matrix, which improves the strength and toughness of the alloy. © 2023, The Authors. All rights reserved.

关键词： Tin alloys

Deformation Temperature Impacts on the Microstructure Evolution and Mechanical Properties of a Novel Medium-Heavy Alloy (Mha)

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SSRN 2022年

作者： Xiong, Yi Shu, Kang-Hao Li, Yong Chen, Zheng-Ge Zha, Xiao-Qin He, Tian-Tian Han, Shun Wang, Chun-Xu School of Materials Science and Engineering Henan University of Science and Technology Luoyang471023 China Collaborative Innovation Center of New Nonferrous Metal Materials Advanced Processing Technology Jointly Established by the Ministry of Science and Technology Henan Luoyang471023 China Central Iron and Steel Research Institute Beijing100081 China State Key Laboratory of Laser Interaction with Matter Northwest Institute of Nuclear Technology Shaanxi Xi’an710024 China Luoyang Ship Material Research Institute Henan Luoyang471000 China

Medium-heavy alloys (MHAs) were rolled under different temperatures to characterize the microstructural evolution and mechanical properties by using optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, electron backscattered diffraction, tensile testing and microhardness testing. The results show that with an increase in the degree of deformation, the equiaxed grains are elongated along the rolling direction. A large number of slip bands are generated to coordinate intense plastic deformation, which leads to the formation of a fibrous texture. The sharp increase in dislocation density promotes significantly the dislocation interaction, which, in turn, refines the grain size of the MHAs to the nanometer level. Compared with the room-temperature rolling specimens, the cryorolling specimens underwent intense deformation. After 90% cryorolling deformation, the MHA grains were refined to 16.1 nm. The strength and hardness of the cryorolling specimens were significantly higher than those of the room-temperature rolling specimens, though the elongation was slightly lower. The fracture morphology of both specimens changed from ductile fracture (before deformation) to a mixed ductile–brittle fracture (after deformation). © 2022, The Authors. All rights reserved.

关键词： Cold rolling

Structure Design and Analysis of a Novel Forward-folding Rotor used in a Downwind Horizontal-axis Turbine

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IOP Conference Series: materials Science and Engineering 2020年第1期825卷

作者： Haoran Meng Pan Zeng Liping Lei Key Laboratory for Advanced Materials Processing Technology of MOE Department of Mechanical Engineering Tsinghua University Beijing 100084 China

To alleviate the stiffness constraints of the conventional blade and thus reduce the rotor mass, a novel forward-folding rotor (Downwind Forward-folding Rotor, DFFR) used in a downwind horizontal-axis turbine is presented. This novel rotor is designed to align the combination of gravitational, centrifugal, and thrust forces along the blade path, resulting in primarily tensile loads instead of cantilever loads on the blades. The DFFR blades fold forward at a power-limited condition, which induces the change of the blade pitch angle and cone angle and thus maintains a constant power output. To quantify the mass savings, a 5-MW DFFR was designed based on the NREL 5-MW reference rotor. According to the results calculated by an improved BEM method, the rotor power and torque of the 5-MW DFFR have a slight increase compared with those of the NREL-5MW reference rotor, while the rotor thrust of the 5-MW DFFR is smaller than that of the NREL-5MW reference rotor. Furthermore, based on the finite element analysis, the blade of the 5-MW DFFR had an 18.9% mass saving and an 8.4% peak stress reduction compared with the blade of the NREL-5MW reference rotor, over a range of operating wind speeds and azimuthal angles.

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Structure Analysis of an Innovative Vertical Axis Wind Turbine with Inclined Pitch Axes using Finite Element Method

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IOP Conference Series: materials Science and Engineering 2020年第1期825卷

作者： Jia Guo Pan Zeng Liping Lei Key Laboratory for Advanced Materials Processing Technology of MOE Department of Mechanical Engineering Tsinghua University Beijing 100084 China

Pitch regulation is critical to power performance of wind turbines. However, the complexity of the conventional pitch system of vertical axis wind turbines (VAWTs) retards its appliance. In the present study, an innovative pitch system of a VAWT with inclined pitch axes was proposed where a slider in the main shaft actuated upwards or downwards drives blades to be folded by linkage mechanisms. Effect of design parameters of the pitch system on blade folding movement control sensitivity was evaluated. Loads of pitch hinge, deformation of blades and stresses of components were analyzed as well as natural frequencies of the wind turbine with various azimuth and fold angles under rated operational conditions by finite element method and effect of design parameters on structural performance of the wind turbine was investigated. It was found that deformation of blades and stresses of supporting arms deteriorated but natural frequencies of the wind turbine increased when blades were folded in the negative direction. In addition, the increasing arm interval height improved structural performance with the increasing natural frequencies. In the contrary, the decreasing blade linkage length, shaft linkage length and slider height improved structural performance with the decreasing natural frequencies. This study laid the foundation for the further design optimization of the novel pitch system.

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