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Peng Han,Jia Lin,Wen Wang,Zhihao Liu,Yating Xiang,Ting Zhang,Qiang Liu,Xiaohu Guan,Ke Qiao,Yingchun Xie,Kuaishe Wang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.3
The high-entropy alloy particles reinforced 6061Al composite was prepared by cold spray (CS) and then modified by frictionstir processing (FSP). The microstructure evolutions, corrosion, and wear behaviors of the composites were investigated. Results showed that numerous micro-pores and cracks were distributed in the Al matrix due to adiabatic shear instability andinsufficient deformation of the deposited particles for CSed samples. The average size of uniformly distributed HEA particleswas ~ 24 μm, and the geometric necessary dislocation (GND) density reached 17.1 × 1015m−2 due to large plastic deformationduring CS. Comparatively, the micro-pores and cracks were eliminated, and many fragmented HEA particles dispersed inthe Al matrix with an average size of ~ 4 μm for FSPed sample. Note that the GND density reduced to 9.8 × 1015m−2 due todynamic recrystallization during FSP. The formation rate of the oxide film was gradually greater than that of the dissolutionrate with the samples immersion in 3.5 wt% NaCl solution from 12 to 36 h, and the main corrosion mechanism was particledissolution around micro-pores and pitting for CSed and FSPed samples, respectively. In the polarization process, the FSPedsamples exhibited low corrosion tendency and high corrosion rate due to the dense and uniform microstructure, low GNDdensity, and dispersed HEA particles. The FSPed samples had better wear resistance than the CSed samples at 25 °C and200 °C. The dominant wear mechanisms of CSed and FSPed samples were abrasion at 25 °C, while the wear mechanismsof these samples were adhesion accompanied by abrasion at 200 °C.
Peng Han,Jia Lin,Wen Wang,Zhihao Liu,Yating Xiang,Ting Zhang,Qiang Liu,Xiaohu Guan,Ke Qiao,Yingchun Xie,Kuaishe Wang 대한금속ᆞ재료학회 2023 METALS AND MATERIALS International Vol.29 No.2
The high-entropy alloy particles reinforced 6061Al composite was prepared by cold spray (CS) and then modified by frictionstir processing (FSP). The microstructure evolutions, corrosion, and wear behaviors of the composites were investigated. Results showed that numerous micro-pores and cracks were distributed in the Al matrix due to adiabatic shear instability andinsufficient deformation of the deposited particles for CSed samples. The average size of uniformly distributed HEA particleswas ~ 24 μm, and the geometric necessary dislocation (GND) density reached 17.1 × 1015m−2 due to large plastic deformationduring CS. Comparatively, the micro-pores and cracks were eliminated, and many fragmented HEA particles dispersed inthe Al matrix with an average size of ~ 4 μm for FSPed sample. Note that the GND density reduced to 9.8 × 1015m−2 due todynamic recrystallization during FSP. The formation rate of the oxide film was gradually greater than that of the dissolutionrate with the samples immersion in 3.5 wt% NaCl solution from 12 to 36 h, and the main corrosion mechanism was particledissolution around micro-pores and pitting for CSed and FSPed samples, respectively. In the polarization process, the FSPedsamples exhibited low corrosion tendency and high corrosion rate due to the dense and uniform microstructure, low GNDdensity, and dispersed HEA particles. The FSPed samples had better wear resistance than the CSed samples at 25 °C and200 °C. The dominant wear mechanisms of CSed and FSPed samples were abrasion at 25 °C, while the wear mechanismsof these samples were adhesion accompanied by abrasion at 200 °C.
Hui-Bo He,Wen-Qiang Han,Hua-Ying Li,Dong-Yang Li,Jun Yang,Tao Gu,Tao Deng 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
TiAlN coatings were deposited on the YT15 tungsten carbide inserts by magnetron sputtering technique. The TiAlN coated tools weredeep cryogenic treatment (DCT) at -196oC for 30 h. The dry turning tests of 40Cr steel were carried out to evaluate performancesof uncoated, no cryogenically treated (NCT) and DCT coated tools on the CA6140A lathe. The effect of the three kinds of tools oncutting forces, cutting temperature, surface qualities and tool wear had been investigated to assess the performance of DCT coatedtools. Results of the investigation showed that the cutting forces and cutting temperature obtained by DCT coated tools weresignificantly decreased in comparison with the uncoated and NCT coated tools, especially at higher cutting speeds. Flank wear ofthe DCT coated inserts was less than that of the NCT coated inserts under the same cutting conditions. The DCT coated insertsproduced a good surface finish and yield a tool life of about 65 min. The wear mechanisms of the DCT coated carbide tools are mainlyabrasive and adhesive wear, accompanied with diffusion and oxidation wear.
Xue-Song Sun,Di-Han Liu,Sai-Lan Liu,Qiu-Yan Chen,Shan-Shan Guo,Yue-Feng Wen,Li-Ting Liu,Hao-Jun Xie,Qing-Nan Tang,Yu-Jing Liang,Xiao-Yun Li,Jin-Jie Yan,Ming-Huang Hong,Jun Ma,Lin-Quan Tang,Hai-Qiang M 대한암학회 2019 Cancer Research and Treatment Vol.51 No.4
Purpose The purpose of this study was to investigate the survival trends and patterns of failure in patients with stage II nasopharyngeal carcinoma (NPC) treated with radiotherapy (RT) and chemotherapy over the last 20 years. Materials and Methods Thirty-eight hundred and eight patients diagnosed with stage II NPC between January 1990 and December 2012 were involved in this retrospective cohort study. All patients were treated with RT. According to the main imaging techniques and RT technology, we categorized these patients into four calendar periods: 1990-1996, 1997-2002, 2003-2007, and 2008-2012. Overall survival (OS), progression-free survival (PFS), locoregional relapse-free survival (LRFS), and distant metastasis–free survival (DMFS) were served as the clinical outcome. Results After a median follow-up period of 84.7 months, we observed increasing trends in survival and disease control. The 3- and 5-year OS rates increased from 87.1% and 78.7% in the first calendar period to 97.4% and 94.5% in the last calendar period, respectively (p < 0.001). Additionally, significant increasing trends could be seen in the PFS and LRFS during the four calendar periods. In the subgroup analysis, the LRFS in patients older than 50 years at diagnosis showed greater improvement than younger patients. However, the rate of distant metastasis was stable and relatively low, as the 5-year DMFS ranged from 90.5% to 94.7% among the four calendar periods. Conclusion The survival rates in patients with stage II NPC showed increasing trends from 1990 to 2012. The advance of RT provided excellent locoregional control and enhanced OS.
Seismic resistant design of highway bridge with multiple-variable frequency pendulum isolator
Xu Liang,Jianian Wen,Qiang Han,Xiuli Du 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.2
Multiple variable frequency pendulum isolator (MVFPI) has been recently developed as a superior alternative to the traditional friction pendulum bearing (FPB) especially for the seismic isolation in near-fault regions. The MVFPI is characterized by its variable frequency and self-adaptability, which are achieved by piecewise function of sliding surface and shape memory alloy (SMA). The objective of this study is to propose the design algorithm of the MVFPIs in highway bridge as an extension of the direct displacement-based design (DDBD) framework. The nonlinearities of the structural components are taken into account in the design procedure, and the corresponding damage states satisfy the two-stage design philosophy. The accuracy and robustness of the design procedure are verified by an isolated four-span highway bridge through nonlinear time history (NLTH) analyses. The analytical results indicate that the proposed design procedure can predict the profile of deck displacement and amplitude, as well as the damage states of the piers. From statistic aspect, the fragility analyses illustrate that the bridge isolated by MVFPIs exhibits better seismic performance than that of the bridge isolated by FPBs.
Mechanism of heterogeneous mercury oxidation by HCl on V2O5(001) surface
Li Zhao,Yu Liu,Yang-wen Wu,Jian Han,Song-lin Zhang,Qiang Lu,Yong-ping Yang 한국물리학회 2018 Current Applied Physics Vol.18 No.6
The selective catalytic reduction (SCR) system for NOX removal in coal-fired power plants has a promoting effect on the oxidation and removal of elemental mercury. In this study, basic mechanism of mercury oxidation by V2O5-based SCR catalyst is investigated via density functional theory method and the periodic slab models. Calculations are conducted to determine the adsorption energies and geometries of Hg0, HgCl, HgCl2 and HCl on V2O5(001) surface, and to reveal the energy profile of oxidation reaction and the structures of relative transition states and intermediates. The results indicate that HCl can significantly promote Hg0 oxidation on V2O5(001) surface, by forming an intermediate HgCl-surface which is important for Hg0 oxidation. The Hg0 oxidation goes through Hg0→HgCl→HgCl2, and the two stages of the reaction follow Eley–Rideal mechanism and Langmuir- Hinshelwood mechanism, respectively. The formation of HgCl2 is the rate-determining step due to its high energy barrier. Three detailed reaction pathways are obtained, and the related energy profiles and structures are analyzed in detail. The Hg0 oxidation reaction can take place through all three pathways even if differences exist in each other, while pathways I and II have relatively low energy barriers.