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Study on the Effect of Preheating Temperature on Residual Stress in Laser Arc Composite Welding of Dissimilar Aluminum Alloys

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JOM 2024年第7期76卷 3832-3839页

作者： Chen, Xiaowen Tang, Song Xie, Wanlin Zhang, Meng Song, Hao Ran, Qingzheng Zhang, Defen Southwest Petr Univ Sch New Energy & Mat Chengdu 610500 Sichuan Peoples R China

This study, based on the Simufact Welding analysis software, established a three-dimensional finite element computational model according to actual welding conditions. Using a combined volumetric heat source, we analyzed the magnitude and distribution of residual stress after laser arc composite welding of dissimilar aluminum alloys, and validated the results with experimental data. The influence of different preheating temperatures on the variation rule of residual stress in each part of the weldment was explored. The results showed that the calibration results of the combined volumetric heat source model were ideal, and that the simulation results of transverse and longitudinal residual stress were in good agreement with the actual results. The average residual stress in the heat-affected zone (HAZ) of the 5083-H112 aluminum alloy was about 190 MPa, which is close to the yield strength of the base metal at room temperature (193 MPa);the average residual stress at the weld seam was about 230 MPa;and the average residual stress in the HAZ of the 6063-T6 aluminum alloy was about 80 MPa. In addition, preheating before welding has a positive effect on reducing residual stress after welding. The optimal preheating temperature for the 5083-H112 aluminum alloy is about 170 degrees C, and for 6063-T6 aluminum alloy it is about 220 degrees C.

关键词： Residual stresses

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Enhancing Energy Storage Performance of 0.85Bi0.5Na0.5TiO3-0.15LaFeO3 Lead-Free Ferroelectric Ceramics via Buried Sintering

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MATERIALS 2024年第16期17卷 4019页

作者： Zhang, Yixiao Jia, Yuchen Yang, Jian Feng, Zixuan Sun, Shuohan Zhu, Xiaolong Wang, Haotian Yan, Shiguang Zheng, Ming China Univ Min & Technol Sch Mat Sci & Phys Xuzhou 221116 Peoples R China Chinese Acad Sci Shanghai Inst Ceram Key Lab Inorgan Funct Mat & Devices Shanghai 200050 Peoples R China East China Normal Univ Key Lab Polar Mat & Devices Minist Educ Shanghai 200241 Peoples R China

Bismuth sodium titanate (Bi0.5Na0.5TiO3, BNT) ceramics are expected to replace traditional lead-based materials because of their excellent ferroelectric and piezoelectric characteristics, and they are widely used in the industrial, military, and medical fields. However, BNT ceramics have a low breakdown field strength, which leads to unsatisfactory energy storage performance. In this work, 0.85Bi(0.5)Na(0.5)TiO(3)-0.15LaFeO(3) ceramics are prepared by the traditional high-temperature solid-phase reaction method, and their energy storage performance is greatly enhanced by improving the process of buried sintering. The results show that the buried sintering method can inhibit the formation of oxygen vacancy, reduce the volatilization of Bi2O3, and greatly improve the breakdown field strength of the ceramics so that the energy storage performance can be significantly enhanced. The breakdown field strength increases from 210 kV/cm to 310 kV/cm, and the energy storage density increases from 1.759 J/cm(3) to 4.923 J/cm(3). In addition, the energy storage density and energy storage efficiency of these ceramics have good frequency stability and temperature stability. In this study, the excellent energy storage performance of the ceramics prepared by the buried sintering method provides an effective idea for the design of lead-free ferroelectric ceramics with high energy storage performance and greatly expands its application field.

关键词： BNT-based ceramics buried sintering dielectric ferroelectric energy storage

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Study on the structure and corrosion resistance of MoS2/MgO micro-arc oxidation composite ceramic coating on the surface of ZK60 magnesium alloy

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ANTI-CORROSION METHODS AND MATERIALS 2024年第2期71卷 213-222页

作者： Chen, Xiaowen Xie, Wanlin Tang, Song Zhang, Meng Song, Hao Ran, Qingzheng Zhang, Defen Southwest Petr Univ Chengdu Peoples R China

Purpose - The purpose of this study is to examine the impact of MoS2 on the microstructure and characteristics of micro-arc oxidized (MAO) ceramic coatings created on ZK60 magnesium alloy through the addition of varying concentrations of MoS2 particles to the electrolyte, aiming to enhance the corrosion resistance of magnesium alloy. Design/methodology/approach - The surface morphology, roughness and phase composition of the coatings were analyzed using scanning electron microscopy, a hand-held roughness tester and an X-ray diffractometer, respectively, and the corrosion resistance of the MAO coatings prepared by the addition of different contents of MoS2 particles was tested and analyzed using an electrochemical workstation. Findings - The results demonstrate that MoS2/MgO composite coatings have been successfully prepared on the surface of magnesium alloys through micro-arc oxidation. Furthermore, the corrosion resistance of the ZK60 magnesium alloy prepared with the addition of 1.0 g/L MoS2 was the best compared to the other samples. Originality/value - MoS2 particles were able to penetrate the coatings successfully during the micro-arc oxidation process, acting as a barrier in the micropores to prevent the corrosion medium from touching the surface, thus improving the corrosion resistance of the sample. The electrochemical workstation was used to study the corrosion resistance of the MoS2/MAO coating on the ZK60 magnesium alloy.

关键词： ZK60 magnesium alloy Micro-arc oxidation MoS2 particles Electrochemical corrosion Corrosion Electrochemistry Materials

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Determination of optimal holding time for brazing Cu-Sn-Ti/ diamond composites

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DIAMOND AND RELATED MATERIALS 2024年 141卷

作者： Wang, Cong Li, Haodong Fan, Yonggang Northeastern Univ Sch Met Key Lab Ecol Met Multimet Mineral Minist Educ Shenyang 110819 Peoples R China Cent South Univ State Key Lab Powder Met Changsha 410083 Peoples R China

Diamond particles are brazed by Cu-Sn-Ti active filler metals under vacuum at 1213 K. The impact of different holding times on wettability, interfacial reaction layer characteristics, and wear resistance of Cu-Sn-Ti/diamond composite has been systematically investigated. The results show that the complete encapsulation of diamond particles can only be observed after holding for 30 min or further. The interfacial reaction layer is composed of TiC, and the change of the reaction layer thickness follows a parabolic growth rate within 30 min, reaching a maximum of 1.73 mu m at 30 min and then remaining almost stable thereafter. It is further shown that when the holding time approaches 30 min, the main phase of the metal matrix changes from Cu41Sn11 to Cu3Sn, and the wear resistance of Cu-Sn-Ti/diamond composite reaches the maximum value. However, further prolonging the holding time results in slight graphitization of the diamond in the sample, which will reduce the wear resistance of the brazed sample. It is recommended that the holding time shall be limited <30 min for optimized bonding strength and grinding capability.

关键词： Cu -Sn -Ti Diamond Holding time Interfacial reaction Wetting

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Quasi-Solid Composite Polymer Electrolyte-Based Structural Batteries with High Ionic Conductivity and Excellent Mechanical Properties

SMALL STRUCTURES

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SMALL STRUCTURES 2024年第8期5卷

作者： Wang, Zeru Hou, Yue Li, Sen Xu, Zhuang Zhu, Xiaotao Guo, Bing Lu, Dong Wang, Ke Southern Univ Sci & Technol Sch Syst Design & Intelligent Mfg Shenzhen Key Lab Intelligent Mfg Continuous Carbon Shenzhen 518055 Peoples R China Southern Univ Sci & Technol Dept Mat Sci & Engn Shenzhen 518055 Guangdong Peoples R China Harbin Inst Technol Sch Sci Shenzhen Key Lab Flexible Printed Elect Technol Shenzhen Key Lab Adv Funct Carbon Mat Res & Compre Shenzhen 518055 Peoples R China Hong Kong Univ Sci & Technol Guangzhou Lab Future Technol Guangzhou 511458 Peoples R China

Structural lithium batteries integrated with energy storage and mechanical load-bearing capabilities hold great promise to revolutionize lightweight transport vehicles. However, the current development of structural batteries faces critical challenges in balancing the electrochemical and mechanical properties of the electrolytes. Herein, a super strong quasi-solid composite polymer electrolyte (QCPE) is successfully fabricated by reinforcing polyelectrolyte with 3D in situ self-assembled metal-organic framework-modified glass fiber (MOF@GF) soaking a small amount of liquid electrolyte, which provides continuous ion conductive pathways for fast Li+ transport and contributes to the high ambient ionic conductivity of 1.47 x 10-3 S cm-1. The micropores and abundant polar functional groups selectively restrict the transport of anions to afford a homogeneous Li+ flux and a high Li+ transference number (0.56). Simultaneously, the MOF@GF provides more effective reinforcement and a remarkably high tensile strength of 48.6 MPa, and Young's modulus of 1.66 GPa is achieved. Furthermore, the lithium metal batteries fabricated with this QCPE exhibit a long, stable operation lifespan of 2000 h and excellent cycling performance with LiFePO4 and NCM811 cathodes. This design strategy generally opens a new avenue for structural batteries with high ionic conductivity and outstanding mechanical properties, which holds great promise for industrial translation. A super strong quasi-solid composite polymer electrolyte with excellent ionic conductivity is successfully designed and fabricated by reinforcing polyelectrolyte with 3D in situ self-assembled metal-organic framework-modified glass fiber (MOF@GF). The MOF@GF enhances Li+ transport and mechanical strength, showcasing promise for structural batteries with superior ionic conductivity and mechanical properties in industrial *** (c) 2024 WILEY-VCH GmbH

关键词： composite polymer electrolytes glass fiber-reinforced composites lithium metal batteries metal-organic frameworks structural batteries

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Numerical Simulation Study of Laser-arc Hybrid Welding of 6063/5083 Aluminum Alloy

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JOURNAL OF MATERIALS engineering AND PERFORMANCE 2024年 1-10页

作者： Chen, Xiaowen Tang, Song Xie, Wanlin Zhang, Defen Southwest Petr Univ Sch New Energy & Mat Chengdu 610500 Sichuan Peoples R China

This study numerically simulates the laser-arc hybrid welding of 6-mm-thick 6063/5083 dissimilar aluminum alloy plates using Simufact welding simulation software. The changes in workpiece stress and deformation are calculated from the fixture clamping state, pre-welding heating, and post-welding heat treatment. The results indicate that unloading the fixture at an appropriate time is beneficial for reducing residual stress in the workpiece, especially on the 5083 aluminum alloy side, where it can decrease by up to 43 MPa. However, unloading the fixture can increase the amount of workpiece deformation and cause significant angular deformation. Increasing the preheating temperature has a positive effect on reducing residual stress on both sides of the base material. When the preheating temperature is between 70 and 170 degrees C, the high residual stress area on the 5083 aluminum alloy side decreases most significantly, ultimately reaching 128 MPa. Meanwhile, within this preheating temperature range, the total deformation of the workpiece is relatively small, and its effect on the weld position is not significant. Excessively high preheating temperatures can increase the lateral shrinkage of the workpiece. The annealing temperature after welding mainly affects the rate of workpiece heating. After annealing treatment, the stress at the weld position decreases significantly, and its lateral shrinkage improves, which is beneficial for improving dimensional accuracy.

关键词： dissimilar aluminum alloys distortion laser-arc hybrid welding numerical simulation residual stresses

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Study on Preparatory Stage of Sheath During the Interruption of Vacuum Interrupters

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IEEE TRANSACTIONS ON PLASMA SCIENCE 2021年第5期49卷 1621-1626页

作者： Shi, Jing Zang, Yina Liu, Liming Chen, Hongkun Wuhan Univ Sch Elect Engn & Automat Wuhan 430072 Peoples R China State Grid Jiangsu Elect Power Co Ltd Suzhou Operat & Maintenance Stn Suzhou 215131 Peoples R China Huazhong Univ Sci & Technol Sch Elect & Elect Engn Wuhan 430072 Peoples R China

During the breaking process of a vacuum interrupter, there is a time interval between current zero and generation of recovery voltage. This time interval is variable and matters to the calculation of continuous transition model, but always simplified as a constant. In this article, we put forward the concept of preparatory stage of sheath, analyze the production mechanism and influence on breaking ability, and give the computation method for the duration of this stage. In order to verify the rationality of the theoretical analysis and calculation method proposed in this article, experimental measurement is conducted. The experimental results are in good agreement with the values of duration calculated by the theoretical formula in this article in terms of magnitude and variation law.

关键词： Ions Plasmas Cathodes Electric breakdown Dielectrics Anodes Polarization Dielectric hysteresis dielectric polarization high-voltage direct current (HVdc) insulation plasma sheaths vacuum interrupters (VIs)

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Hot oscillating pressing sintered AlCoCrFeNi/nanodiamond high-entropy alloy composites

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INTERMETALLICS 2024年 172卷

作者： Gao, Ka Wu, Ziqian Zhang, Zixiang Ren, Chunyang Sun, Dejian Gao, Yang Dang, Li Shang, Yan An, Linan Univ Shanghai Sci & Technol Sch Mech Engn Shanghai 200093 Peoples R China Chongqing Univ Technol Minist Educ Key Lab Adv Manufacture Technol Automobile Parts Chongqing 401135 Peoples R China Zhengzhou Univ Aeronaut Sch Mat Sci & Engn Zhengzhou 450015 Peoples R China Changhai Hosp Dept Gen Med Shanghai 200000 Peoples R China Dongguan Univ Technol Sch Mech Engn Dongguan 523808 Peoples R China

AlCoCrFeNi/nanodiamond high-entropy alloy composites were successfully prepared by hot oscillating pressing (HOP) at different sintering temperatures in this work. The microstructures of the HOPed composites consisted of the FCC phase, BCC phase and nanocarbide phase uniformly distributed in the particles interstices. With the temperature increasing, the original powder particle boundaries gradually disappeared, the density progressively increased, and the microstructure defects decreased. At 1100 degrees C, its maximum density reached to 99.7 %. Moreover, the FCC phase volume fraction and carbide content further increased without significant microstructure coarsening. The hardness and corrosion resistance of the HOPed samples were better than the hot pressing (HP) samples because the original particle boundaries and pores became smaller, and a small number of nanocarbides were uniformly distributed. Then its maximum hardness reached to 566.48 HV 1 , and the minimum corrosion current density and corrosion rate was 2.916 mu m/cm 2 and 0.013 mm/year, respectively, which was better than other alloys reported.

关键词： AlCoCrFeNi/Nanodiamond high-entropy alloy composites Hot oscillating pressing Microstructure Property

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High-Performance Olefin Thermoplastic Elastomer Based on Dynamically Cross-Linking Crystalline Macromers and Elastic Backbones

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MACROMOLECULES 2024年第4期57卷 1788-1794页

作者： Xiao, Yangke Wang, Wen-Jun Li, Bo-Geng Liu, Pingwei Zhejiang Univ Coll Chem & Biol Engn State Key Lab Chem Engn Hangzhou 310058 Peoples R China Inst Zhejiang Univ Quzhou Quzhou 324000 Peoples R China

Developing novel olefin thermoplastic elastomers (TPE-Os) that outperform those with well-defined block or grafted chain structures is both highly attractive and challenging. Here, we report the preparation of high-performance TPE-Os in a combinatorial way. Semicrystalline ethylene/1-octene/diene copolymers with pendant vinyl groups and crystalline polyethylene macromers with terminal double bonds are synthesized, and they are dynamically linked with a dithiol-based cross-linker containing a boronic ester bond to form a new TPE-O. Due to the synergy between physical crystallization and dynamic cross-linking, it exhibits a significantly increased Young's modulus (E), elongation at break (epsilon), ultimate strength (sigma), and tensile toughness (U-T) of up to 27.2 +/- 3.8 MPa, 902 +/- 28%, 26.7 +/- 1.1 MPa, and 120.1 +/- 9.5 MJ center dot m(-3), respectively, which are among the highest levels of the dynamically cross-linked elastomers and traditional well-defined TPE-Os. It also has good elasticity with a 10-cycle elastic recovery ratio of up to 71.4%;a high melting point of nearly 123.8 degree celsius and the sigma can even maintain 0.14-0.42 MPa at 200 degree celsius. The new TPE-O also offers high reprocessing performance with a recovery ratio of 113.2% for E, 98.5% for epsilon, 95.8% for sigma, and 92.5% for U-T. We believe that our study will facilitate the development of next-generation TPE-Os with higher performance.

关键词： Crystallization Elastomers Nucleic acid structure Organic compounds Vinyl

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Self-regulating shielding layer induces (002) plane directional deposition of zinc metal anode

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ENERGY STORAGE MATERIALS 2024年 71卷

作者： Fan, Changchun Meng, Weijia Han, Jun Li, Tongheng Zuo, Dapeng Deng, Shengxiang Li, Diansen Jiang, Lei Beihang Univ Sch Chem Key Lab Bioinspired Smart Interfacial Sci & Techno Minist Educ Beijing 100191 Peoples R China Changan Univ Sch Energy & Elect Engn Shaanxi Key Lab New Transportat Energy & Automot E Xian 710061 Peoples R China Beijing Univ Chem Technol State Key Lab Organ Inorgan Composites Beijing 100029 Peoples R China

Rechargeable aqueous zinc batteries (AZIBs) are ideal for grid-scale energy storage due to their safety and economic characteristics. However, uncontrollable side reactions and dendrite growth severely affect the reversibility of zinc anodes. In the interfacial reaction, inducing smooth deposition of dominant planes is crucial for stabilizing the zinc anodes. Herein, we report a highly concentrated 1-butyl-3-methylimidazolium ion (BMIM+) modified electrolyte to improve the diffusion and deposition behavior of Zn2+. Thanks to the strong adsorption effect of BMIM+ at the zinc anode interface, the self-regulating shielding layer inhibits water-induced parasitic reactions. Under the action of BMIM+, Zn2+ has the lowest diffusion energy barrier towards the (002) plane, thus transforming the electrodeposition from a randomly stacked sheet to a dense deposited layer in the Zn (002) plane. The results showed that the symmetric cell composed of the modified electrolyte had a cycle life of 3200 h at 1 mA cm-2, and the average coulombic efficiency (CE) of the asymmetric cell was as high as 99.8 %. The full cell assembled with ZnxV2O5 & sdot;nH2O still provided 86 % capacity retention at 2 A g- 1 after 500 cycles. This electrolyte modification strategy provides a promising option for modulating the anode/electrolyte interface chemistry to achieve high-performance AZIBs.

关键词： Electrolyte additive Zinc anode Electrostatic shielding Directed diffusion (002) plane-edge deposits

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