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- 저자 : Zhanwei Li (검색결과 4 건)
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Zhanwei Yuan,Shanglin Wang,Hao Zhang,Fuguo Li,Rui Ma,Jie Bai 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11
GH3536 nickel-based superalloy was prepared using selective laser melting (SLM) to study its hot deformation behavior,microstructure evolution, and recrystallization mechanism during hot compression. GH3536 superalloy was hot compressedby a Gleeble-3800 hot simulation testing machine. The compression temperature was 900℃~1050℃, and the strain rate was0.01s− 1~10s− 1. The results show that the deformation conditions will significantly affect the flow stress, dislocation density,and the development of grain boundary and subgrains boundary. The dynamic recrystallization (DRX) mechanism is alsoeasily affected by the deformation conditions and different deformation regions. The alloy has experienced work hardening(WH), dynamic recovery (DRV), and DRX in hot deformation and finally entered the steady-state rheological stage. Thedynamic softening effect is more evident at a low strain rate. The temperature will strongly affect the migration of dislocationsand limit the transformation from LAGB to HAGB, thus affecting the formation of grain boundaries and finally affectingthe DRX mechanism. It is found that DRX is not a single process, and discontinuous dynamic recrystallization (DDRX)and continuous dynamic recrystallization (CDRX) exist at the same time. DDRX is the primary nucleation mechanismcharacterized by grain boundary expansion. CDRX is an auxiliary nucleation mechanism characterized by gradual rotationof subgrains, and CDRX is easier to activate at low temperatures.
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Effects of different coupling models of a helical gear system on vibration characteristics
Qibin Wang,Zhanwei Li,Hui Ma,Bang-chun Wen 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5
Time-varying mesh stiffness (TVMS) and the dynamic coupling between the helical gears have a great influence on the vibration characteristics of a helical gear rotor system. Considering the effects of TVMS and adopting two coupling models (lateral-torsional coupling model and lateral-torsional-axial-swing coupling model), the dynamic behavior of a helical gear system was studied. First, an analytical model was used to analyze TVMS of a helical gear pair where the helical tooth is simulated by many spur tooth slices along the direction of the tooth width and the mesh stiffness of each slice is calculated using the energy method. Then, considering the effects of the TVMS excitation, the finite element model of a helical gear rotor system was established. Gear mesh was simulated by the above-mentioned two coupling models to investigate the effects of coupling forms on the system vibration characteristics. The strain energy was used to distinguish the dominant mode and dominant shaft of a gear system in natural characteristics analysis. The results show that the full coupling model can analyze accurately the vibration characteristics of the system and the axial and swing motions cannot be ignored in vibration analysis. Finally, the effects of helix angle on TVMS and vibration responses of a helical gear system were also studied.
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Yang Ling,Jiachen Li,Jiang Wu,Hailong Liu,Xu Mao,Yongfeng Qi,Qian Ma,Qizhen Liu,Zhanwei Qiao,Weiqun Chu 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.2
Elemental mercury removal in coal-fired power plants is the key to global mercury pollution control, and photocatalytic oxidation is an effective and stable method. As a typical bismuth-based photocatalyst, BiOIO3 has a large band gap which is not conducive to the absorption and utilization of visible light, and its specific surface area also limits the diffusion and adsorption of reactants. In this work, pink BiOIO3 (PB) was first prepared successfully via vacuum calcination under absolute pressure of 1*103 Pa. The specific surface area of pink BiOIO3 is significantly increased to 44.52m2/g, which is 1.5-times compared with the traditional BiOIO3 prepared by hydrothermal method (only 29.60 m2/g). Abundant oxygen vacancy defects exist on sample surface, and the formed local BiOI Zero-dimensional (0-D) nanodots provide heterojunction-like effect combined with the BiOIO3, obtaining better photocatalytic property in the oxidation of elemental mercury. The as-prepared pink BiOIO3 and the preparation technology also have strong application potential in the field of energy and environment.
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One-Step Solvothermal Synthesis of Tetranitro-Cobalt Phthalocyanine/Reduced Graphene Oxide Composite
Lijuan Zhang,Hejun Li,QIANGANG FU,Zhanwei Xu,Kezhi Li,Jianfeng Wei 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.3
Tetranitro-cobalt phthalocyanine/reduced graphene oxide (TNCoPc/RGO) composite was prepared using ethylene glycol as reducing agent and precursor. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the composite. The electrochemical performance of the composite was examined by cyclic voltammetry and rotating disk electrode. The SEM observation and UV-Vis absorption spectrophotometer reveal that TNCoPc nanoparticles are closely contacted with RGO. The results show that the composite has a larger peak current and a higher current density than TNCoPc for oxygen reduction in an alkaline medium. This work offers a simple and environmental route for the synthesis of metal phthalocyanine (MPc)/RGO, which is adaptable to a wide range of applications in fuel cells.
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