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Journal of Iron and Steel Research(International) 2023年第1期30卷 64-73页

作者： Chun-feng Bai Bo Wang Jie Ma Jie-yu Zhang Wan-ping Pan State Key Laboratory of Advanced Special Steel Shanghai UniversityShanghai 200072China School of Materials Science and Engineering Shanghai UniversityShanghai 200072China Anhui Jianzhu University Hefei 230601AnhuiChina

In the twin-roll strip casting process,molten steel solidifies by losing heat through its interface with the casting rollers.The heat extraction along this interface has an effect on the quality of the strips and should be affected by coating,rolls’material,and cooling water flow rate.It is necessary to understand the effect of these casting parameters on the solidification structure of twin-roll strip casting.A three-dimensional computational domain is set up to simulate the solidification process of molten steel and heat exchange between steel strip/air,coating,rolls,and cooling water in the channel of roll sleeves.The effect of the cooling water intensity and flow intensity of molten steel in the pool on the solidification structures is studied during the Thermal cycle of rolls in the twin-roll strip casting.These predicted results are helpful to optimize casting parameters and improve the strip quality in the twin-roll strip casting process.

关键词： Twin-roll strip casting Solidification structure Numerical simulation Thermal cycle Cellular automata finite element model

Microstructures and mechanical properties of Cu/Al compound materials during Thermal cycle

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Rare Metals 2022年第11期41卷 3911-3918页

作者： Bing Wang Ping Liu Xin-Kuan Liu Zi-Yan Wang Yan-Yan Wang Xiao-Hong Chen Xiao-Zhi Liu School of Materials Science and Engineering University of Shanghai for Science and TechnologyShanghai200093China Automobiles Science and Technology(Shanghai)Co. LtdShanghai200433China

Cu/Al compound materials,named as copperclad aluminum bus bars,are widely used in heat dissipation of modern engineering.The Thermal cycle tests were conducted at 200,250 and 300℃for different cycle times,respectively.Effects of Thermal cycle temperatures and Thermal cycle times on micro structures and mechanical properties of the interface were studied.The results show that the width of bonding layer and bond strength are significantly affected by Thermal cycle temperatures and times.Nonetheless,the variety or the quantity of intermediate compounds is scarcely influenced.Al_(2)Cu,Cu_(9) Al_(4)and CuAl were identified on the interface.With the increase in cycle times,grains of the material grew up.However,grains of the interface grew up more apparently than those of Cu and Al.The knowledge may be applied in the establishment of service condition and quality evaluation of material.

关键词： Copper-clad aluminum bus bars Thermal cycle Interface Bonding Microstructure Intermetallic

Thermal cycle and its influence on the microstructure of laser welded butt joint of 8 mm thick Ti-6Al-4V alloy

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China Welding 2019年第3期28卷 61-66页

作者：田德勇颜廷艳高奇玉王飞云占小红 National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 211106China College of Science Nanjing University of Aeronautics and AstronauticsNanjing 211106China

Ti-6Al-4V alloy is extensively used in the manufacture of components in aviation.In the current study,the laser welding process is adopted to joint the Ti-6Al-4V alloy plate which has the thick of 8 mm.A three-dimensional finite element model is established to simulate the temperature distribution of laser welding process.The Thermal cycle curves are produced on the strength of the simulation results.Meanwhile,the microstructure characteristics of the welded joint are investigated combined with simulation results.The results show that weld zone,heat affected zone and based metal experience similar Thermal cycles process and the cooling rate has an important influence on the formation of microstructure.Moreover,the simulation results are well matched with experiment results.

关键词： Ti-6Al-4V alloy laser welding temperature distribution Thermal cycle microstructure

Effects of Composition and Thermal cycle on Transformation Behaviors,thermal Stability and Mechanical Properties of CuAlAg Alloy

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Journal of Materials Science & Technology 2003年第5期19卷 431-434页

作者： Yunqing MA, Chengbao JIANG, Lifen DENG and Huibin XUDepartment of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China Dept. of Mat. Sci. and Eng. Beijing Univ. of Aero. and Astron. Beijing 100083 China

The phase transformation behavior, mechanical properties, and the thermal stability of CuAlAg alloy were studied and minor rare earth (0.1 wt pct La+Ce) was added to improve the mechanical property of the studied alloy. It was found that Ag addition in the CuAl binary alloy can improve the stability of martensitic transformation and high Al content leads to the disappearing of martensitic transformation. The tensile strength and strain of the Cu-10.6AI-5.8Ag (wt pct) alloy were measured to be 383.5 MPa and 0.86%, respectively. With rare earth addition, the tensile strain increased from 0.86% to 1.47%. The CuAlAg alloy did not exhibit martensitic transformation on the second heating process. Its poor thermal stability still needs to be improved.

关键词： High temperature shape memory alloys CuAlAg Transformation behavior Thermal cycle thermal stability Rare earth Mechanical property

The effect of Thermal cycle on joint of Ti/stainless steel phase transformation diffusion bonding

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China Welding 2001年第1期10卷 14-18页

作者：周荣林张九海田锡唐 NKLAWPT Harbin Institute of Technology Harbin 150001 China

The effects of Thermal cycle parameters on the tensile strength and fracture characteristics of phase transformation diffusion bonding(PTDB) joint of titanium and stainless steel (Ti/SS) were studied in this paper. With the maximum cyclic temperature of 1 173～1 223 K , the minimum cyclic temperature of 1 073～1 093 K , the heating velocity of 30～50 K/s , the cooling velocity of 15～20 K/s , the cycle numbers of 15～20 and bonding pressure is 13 MPa , the tensile strength of joint is more than 380 MPa , exceeding 80% of that of Ti.

关键词： Thermal cycle phases transformation diffusion bonding titanium stainless steel

In situ performance and stability tests of large-area flexible polymer solar cells in the 35-km stratospheric environment

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National Science Review 2023年第4期10卷 150-158页

作者： Zihan Xu Guoning Xu Qun Luo Yunfei Han Yu Tang Ying Miao Yongxiang Li Jian Qin Jingbo Guo Wusong Zha Chao Gong Kun Lu Jianqi Zhang Zhixiang Wei Rong Cai Yanchu Yang Zhaojie Li Chang-Qi Ma i-Lab & Printable Electronic Center Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of Sciences School of Nano-Tech and Nano-Bionics University of Science and Technology of China Aerospace Information Research Institute Chinese Academy of Sciences University of Chinese Academy of Sciences CAS Key Laboratory of Nanosystem and Hierarchical Fabrication National Center for Nanoscience and Technology

Flexible organic solar cells(FOSCs) are one of the most promising power sources for aerospace aircraft due to their atractive advantages with high power-per-weight ratio and excellent mechanical flexibility.Understanding the performance and stability of high-performance FOSCs is essential for the further development of FOSCs for aerospace applications. In this paper, after systematic investigations on the performance of the state-of-the-art high-performance solar cells under Thermal cycle and intensive UV irradiation conditions, in situ performance and stability tests of the solar cells in the 35 km stratospheric environment were carried out through a high-altitude balloon uploading. The encapsulated FOSCs with an area of 0.64 cm2gave the highest power density of 15.26 mW/cm2and an efficiency over 11%,corresponding to a power-per-weight ratio of over 3.32 k W/kg. More importantly, the cells showed stable power output during the 3-h continuous flight at 35 km and only 10% performance decay after return to the lab, suggesting promising stability of the FOSCs in the stratospheric environment.

关键词： flexible organic solar cells stratospheric environment 35-km altitude Thermal cycle reliability

Conductivity and Oxidation Behavior of Fe-16Cr Alloy as Solid Oxide Fuel Cell Interconnect Under Long-Stability and Thermal cycles

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Acta Metallurgica Sinica(English Letters) 2021年第5期34卷 668-674页

作者： Jianwu Zhou Qiangfeng Chen Junkang Sang Rongmin Wu Zhuobin Li Wanbing Guan Zhejiang Energy Group R&D Institute Co.LtdHangzhou311121China Ningbo Institute of Material Technology&Engineering Chinese Academy of SciencesNingbo315201China Zhejiang Energy Beilun Power Generation Co.Ltd Ningbo315800China

Conductivity and oxidation behavior of Fe-16Cr alloy were investigated under long-term stability operation at 750℃and Thermal cycles from room temperature to 750℃.The results showed that the area specific resistance(ASR)of Fe-16Cr alloy increased over time and reached about 56.29 mΩcm~(2)after 40,000 h of long-term stability operation at 750℃by theoretical calculation.The ASR of Fe-16Cr remained about 11 mΩcm~(2)after 52 Thermal cycles from room temperature to750℃.The analysis of structure showed that the oxidized phase on the surface of Fe-16Cr was mainly composed of Cr_(2)O_3and Fe Cr_(2)O_(4)spinel phase under long-term stability operation at 750℃.While the Cr_(2)O_(3)phase was mainly observed on the surface of Fe-16Cr alloy after 52 Thermal cycles,the oxidation rates of Fe-16Cr alloy were 0.0142μm h~(-1)and 0.06μm cycle~(-1)under long-term stability operation and under Thermal cycle,respectively.The property of Fe-16Cr alloy with 2.6 mm thickness met the lifespan requirement of interconnect for solid oxide fuel cell(SOFC)stacks.The Cr element all diff used onto oxidation surface,indicating that it was necessary to spray a coating on the surface to avoid poisoning cell cathode of SOFCs.Two 2-cell stacks were assembled and tested to verify the properties of Fe-16Cr alloy as SOFC interconnect under long-term stability operation and Thermal cycle condition.

关键词： Fe-16Cr Interconnect Long-term stability Thermal cycle Solid oxide fuel cell

Effect of Thermal cycles on microstructure of reduced activation steel fabricated using laser melting deposition

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Journal of Iron and Steel Research(International) 2021年第3期28卷 316-326页

作者： Qian An Zhi-xin Xia Chi Zhang Zhi-gang Yang Hao Chen School of Material Science and Engineering Tsinghua UniversityBeijing100084China Shagang School of Iron and Steel Soochow UniversitySuzhou215021JiangsuChina

Reduced activation steel was successfully fabricated by laser melting deposition employing a Gaussian and a ring-shaped laser.The microstructure evolution of the reduced activation steel was investigated using the scanning electron microscope,transmission electron microscope and electron backscatter diffraction.The experimental results showed that the grains close to the substrate were smaller than the grains in the upper layers.Compared to those deposited using a Gaussian laser,the samples deposited using a ring-shaped laser showed a more homogeneous microstructure.Furthermore,a finite element analysis(FEA)model was applied to reveal the thermal history during laser melting deposition.The simulation results were well validated with the experimental results.FEA results indicate that the peak temperature increases and the cooling rate decreases,as the layer gets further from the substrate.Additionally,the temperature and the cooling rate resulting from the Gaussian laser model were higher at the midline of the samples and lower around the edges,whereas those of the ring-shaped laser model were consistent with both at the center and around the edges.

关键词： Laser melting deposition Reduced activation steel Microstructure evolution Thermal cycle Finite element analysis

A theoretical and 1-D numerical investigation on a valve/valveless air-breathing pulse detonation engine

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Chinese Journal of Aeronautics 2021年第1期34卷 68-78页

作者： Hua QIU Cha XIONG Jianling LI School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

The important operating characteristics of pulsed Pressure Gain Combustion(PGC)propulsion are the pressure gain of the combustor component and the propulsive performance gain of the engine.A ramjet-type valve/valveless air-breathing pulsed detonation engine with a supersonic internal compression inlet is investigated.Based on an ideal Thermal cycle,the ideal equivalent pressure ratios(pcb)of the Pulsed Detonation Combustor(PDC)are obtained theoretically which are directly related with the propulsive performance of the engine.By introducing an orifice loss model into the cycles,the critical pressure drop ratios through the orifice for the PDC achieving pressure gain and the engine achieving thrust gain are studied.More influencing factors are investigated by the use of a one-dimensional(1-D)numerical simulation model.The operating characteristics of the pulse detonation engine are investigated with changes of the valve type,the inlet/outlet area ratio of the PDC,the nozzle area ratio,and flight conditions.All these factors can affect pcbof the PDC,and pcbcan be optimized by changing the geometry of the engine.The most important influence parameter is the valve type.When using an orifice-type aerodynamic valve,simulation results show that the PDC cannot achieve the pressure gain characteristics.When a supersonic internal compression inlet is introduced to the engine,whether the Pulse Detonation Engine(PDE)can achieve thrust gain comparable with that of an ideal Brayton cycle engine not only is related to the pressure gain of the combustor,but also needs to optimize the engine structure to reduce the total pressure loss.

关键词： Detonation Pressure gain characteristics Propulsive performance Supersonic internal compression inlet Valve/valveless Thermal cycle

Effect of Thermal cycles on the thermal Expansion Behavior of T700 Carbon Fiber Bundles

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Chemical Research in Chinese Universities 2018年第3期34卷 451-456页

作者： GENG Guohang MA Xiaofei GENG Hongbin WU Yiyong School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 P. R. China CAST-Xi 'an Institute of Space Radio Technology Xi 'an 710100 P. R. China

The relationships between the coefficient of thermal expansion（CTE） of T700 carbon fiber bundles（CFBs） and the Thermal cycles were investigated. The microstructure of T700 CFBs was analyzed with Raman spectra and XRD before and after the thermomechanical test. The results indicated that the T700 CFBs exhibited negative expansion in the direction of parallel fibers in the temperature range of-150-150 ℃ The thermal strain that occurred during the heating and the cooling Thermal cycle had an unclosed curve that served as the loop. When the experimental load was the same, the position of strain loop tended to move upward, and the length of the specimen increased continuously with the Thermal cycles increasing. The microstructural analysis suggested that the degree of structural order and the degree of orientation along the fiber axis were improved with the increase of Thermal cycles. The change of microstructure parameters could be the primary cause of the negative CTE＇s variation within the T700 CFBs.

关键词： T700 carbon fiber bundle Thermal cycle Coefficient of thermal expansion Microstructural analysis