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Low-thermal-conductivity thermal barrier coatings with a multi-scale pore design and sintering resistance following thermal exposure

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Rare Metals 2020年第4期39卷 352-367页

作者： wei-wei zhang Zhi-Yuan wei Li-Yuan zhang Ya-Zhe Xing Qiang zhang School of Materials Science and Engineering Chang'an UniversityXi'an 710064China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi'an 710049China College of Chemistry and Chemical Engineering Neijiang Normal UniversityNeijiang 641112China AECC Beijing Institute of Aeronautical Material Beijing 100095China

High-insulation,long-life thermal barrier coatings(TBCs)decrease the service temperature of superalloys and improve the service life of gas *** in the thermal insulation properties of the coating mainly depends on the optimization of the TBC *** important challenge for TBCs is maintaining a high performance during thermal exposure without degradation,as the pore-rich structure of the topcoat would inevitably be transformed by sintering.A low-thermalconductivity anti-sintering coating can overcome the tradeoff between thermal insulation and sinter *** this review,the design,preparation,and serviceability evaluation of a low-thermal-conductivity anti-sintering coating will be ***,directions for potential development are *** paper provides a comprehensive understanding of the structured tailoring of TBCs for better thermal insulation and anti-sintering performance.

关键词： Thermal barrier coatings Multi-scale pore Sintering resistance Low thermal conductivity

Determination of Water Sorption in Freestanding Epoxy Film by Capacitance Method Using EIS

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Journal of Materials Science & Technology 2006年第1期22卷 108-112页

作者： Yinghua wei Lixin zhang wei KE State Key Laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Electrochemical impedance spectra （EIS） technique was adopted to evaluate the water sorption behaviour of an epoxy freestanding film in a 0.5 mol/L sodium chloride solution at 20℃. The methods for obtaining the capacitance data from EIS data were compared. The Brasher-Kingsbury （BK） and corresponding modified version （Modi-BK） models were used to calculate the water uptake in film and the gravimetric results were presented for comparisons. According to the discussion of the discrepancy of water content in film obtained from two models, a new method was proposed to indicate the organic film structure.

关键词： Epoxy Capacitance Water sorption EIS

Artificial intelligence in fluid mechanics

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Acta Mechanica Sinica 2021年第12期37卷 1715-1717页

作者： wei-wei zhang Bernd R.Noack School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China Center for Turbulence Control Harbin Institute of Technology(Shenzhen)Shenzhen 518055China

The rapid generation of high-quality flow data and the development of increasingly powerful artificial intelligence methods foster novel highly fruitful research paradigms for solving big challenge problems in fluid *... 详细信息

关键词： Fluid mechanics Machine learning Articificial intelligene

Element Segregation and Solidification Behavior of a Nb, Ti, Al Co-Strengthened Superalloy ЭК151

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Acta Metallurgica Sinica(English Letters) 2019年第10期32卷 1298-1308页

作者： Yuan-Guo Tan Fang Liu An-Wen zhang Da-wei Han Xiao-Yu Yao wei-wei zhang Wen-Ru Sun Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China University of Science and Technology of China Hefei 230026 China

The as-cast microstructure, element segregation and solidification behavior of a multi-alloyed superalloy ЭК151 have been investigated. The results show that the severe element segregation leads to the complicated precipitations at the inter-dendritic region, including η-Ni3(Ti, Nb), eutectic(γ + γ’) and Laves, which shows the characteristics of both Ti, Al-strengthened and Nb-strengthened alloys. Differential thermal analysis, heating and quenching tests reveal the solidification sequence as follows: Liquids →γ matrix →(Nb, Ti)C →η-Ni 3(Ti, Nb) →eutectic( γ+γ’) → Laves. The melting points are between 1250 and 1260 °C for(Nb, Ti)C, between 1200 and 1210 °C for η phase, between 1180 and 1190 °C for eutectic(γ+γ’) and Laves. γ’ initially precipitates from matrix at 1150 °C and achieves the maximum precipitation at 1130 °C. According to the microstructure evolution captured during solidification and composition analysis by an energy dispersive spectrometer and electron probe microanalyzer,(Nb, Ti)/Al ratio is put forward to explain the formation of η-Ni3(Ti, Nb) and eutectic( γ+γ’). The solidification of γ matrix increased the Nb, Ti concentration in the residual liquids, so the high(Nb, Ti)/Al ratio would result in the formation of η-Ni3(Ti, Nb); the precipitation of the phase consumed Nb and Ti and decreased the(Nb, Ti)/Al ratio in the liquid, which led to the precipitation of eutectic(γ + γ’). Laves formed by the sides of η-Ni3(Ti, Nb) and in front of the eutectic( γ + γ’) after Al, Ti were further depleted by the two phases and Cr, Co, Mo were rejected to liquids.

关键词： Superalloy ЭК151 Solidification Eutectic(γ+γ’) η-Ni3(Ti,Nb) Laves

Comprehensive damage evaluation of localized spallation of thermal barrier coatings

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Journal of Advanced Ceramics 2017年第3期6卷 230-239页

作者： wei-wei zhang Guang-Rong LI Qiang zhang Guan-Jun YANGa State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 ChinaInstitute of Publication Science Chang'an University Xi'an 710064 ChinaSchool of Materials Science and Engineering Chang'an University Xi'an 710064 China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and Engineering Xi'an Jiaotong University Xi'an 710049 ChinaAECC Beijing Institute of Aeronautical Material Beijing 100095 China

Thermal barrier coatings (TBCs) enable the hot section part to work at high temperatures owing to their thermal barrier effect on the base metal components. However, localized spallation in the ceramic top-coat might occur after long duration of thermal exposure or thermal cycling. To comprehensively understand the damage of the top-coat on the overall hot section part, effects of diameter and tilt angle of the spallation on the temperature redistribution of the substrate and the top-coat were investigated. The results show that the spallation diameter and tilt angle both have a significant effect on the temperature redistribution of the top-coat and the substrate. In the case of the substrate, the maximum temperature increment is located at the spallation center. Meanwhile, the surface (depth) maximum temperature increment, having nothing to do with the tilt angle, increases with the increase of the spallation diameter. In contrast, in the case of the top-coat, the maximum temperature increment was located at the sharp corner of the spallation area, and the surface (depth) maximum temperature increment increases with the increase of both the spallation diameter and the tilt angle. Based on the temperature redistribution of the substrate and the top-coat affected by the partial spallation, it is possible to evaluate the damage effect of spalled areas on the thermal capability of TBCs.

关键词： thermal barrier coatings (TBCs) thermal property localized spallation damage evaluation

Topological quantum walks:Theory and experiments

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Frontiers of physics 2019年第6期14卷 3-8页

作者： Jizhou Wu wei-wei zhang Barry C·Sanders Shanghai Branch National Laboratory for Physical Sciences at MicroscaleUniversity of Science and Technology of ChinaShanghai 201315China CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Centre for Engineered Quantum Systems School of PhysicsThe University of SydneySydneyNew South Wales 2006Australia Institute for Quantum Science and Technology University of CalgaryCalgaryAB T2N 1N4Canada

Inspired by recent breakthroughs with topological quantum materials,which pave the way to novel,high-efficiency,low-energy magnetoelectric devices[1-3]and fault-tolerant quantum information processing[4],inter alia,topological quantum walks have emerged as an exciting topic in its own right,especially due to the theoretical and experimental simplifications this approach offers[5-14].Motivated by impressive progress in topological quantum walks,we provide a perspective on theoretical studies and experimental investigations of topological quantum walks focusing on current explorations of topological properties arising for single-walker quantum walks.

关键词： quantum topological walk

Bimodal TBCs with low thermal conductivity deposited by a powder-suspension co-spray process

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Journal of Materials Science & Technology 2018年第8期34卷 1293-1304页

作者： wei-wei zhang Guang-Rong Li Qiang zhang Guan-Jun Yang Guo-Wang zhang Hong-Min Mu State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi'an Jiaotong UniversityXi'an 710049China School of Materials Science and Engineering Chang'an UniversityXi'an 710064China Institute of Publication Science Chang'an UniversityXi'an 710064China AECC Beijing Institute of Aeronautical Material Beijing 100095China

Advanced thermal harrier coatings （TBCs） with better thermal barrier performance are required by both advanced gas turbine and air engine. In this work, novel bimodal TBCs with low thermal conductivity were deposited and characterized by a novel co-spray approach with both solid powder and suspension. Experimental and finite element analyses were used to optimize the process parameters to prepare the specific morphology nanostructure features. With a comprehensive understanding on the influence of spraying parameters on the morphology ofnano-particles, homogeneous nano-particle heaps with a large aspect ratio were introduced to conventional layered coatings by plasma co-spraying with suspension and solid powder. Co-sprayed bimodal microstructure composite coatings resulted from both wet suspension droplets and molten particle droplets exhibited low thermal conductivity. The thermal conductivity of the composite coating was 1/5 lower than that of the counterpart coatings by conventional plasma spraying with solid powder. This study sheds light to the structural tailoring towards the advanced TBCs with low thermal conductivity.

关键词： Thermal barrier coatings Aspect ratioBimodal microstructure Thermal conductivity Co-spray process

EXPERIMENTAL RESEARCH ON THE SHAPE CHARACTERS OF NATURAL AND VENTILATED SUPERCAVITATION

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Journal of Hydrodynamics 2007年第5期19卷 564-571页

作者： zhang Xue-wei wei Ying-jie zhang Jia-zhong WANG Cong YU Kai-ping School of Astronautics Harbin Institute of Technology Harbin 150001 China

A series of projectile and water-tunnel experiments were conducted to investigate the shape characters of natural and ventilated supercavitation. It was found that the shape and dimensions of both the natural supercavitation and the ventilated supercavitation are similar through the comparison of them when the cavitation number is small and equal, and the contour of both the natural supercavitation and the ventilated supercavitation can be calculated effectively with the Savchenko formula. The gravity effect can induce the asymmetry of ventilated supercavitation, and the asymmetry is more apparent as the Froude number is smaller. The empirical formula for calculating the axial deformation of ventilated supercavitation was corrected and expanded based on experiment data. The evolution rules of both the natural supercavitation and the ventilated supercavitation were described, and the vortex frequency of natural cavitation was obtained. In addition, the hysteretic aspect was observed between the development and the fall process of ventilated cavitation.

关键词： natural cavitation ventilated cavitation shapecharacters water tunnel experiment projectile experiment

Major complications after radiofrequency ablation for liver tumors:Analysis of 255 patients

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World Journal of Gastroenterology 2009年第21期15卷 2651-2656页

作者： Wen-Tao Kong wei-wei zhang Yu-Dong Qiu Tie Zhou Jun-Lan Qiu wei zhang Yi-Tao Ding Department of Hepatobiliary Surgery Drum Tower Hospital Medical College of Nanjing University Nanjing 210008 Jiangsu Province China

AIM:To investigate the major complications after radiofrequency ablation(RFA) for the treatment of liver tumors and analyze possible risk factors that precipitate these ***:From March 2001 to April 2008,255 patients with liver tumors(205 male,50 female;age range,18-89 years;mean age,56.0 years) who received RFA were enrolled in this *** these patients,212 had hepatocellular carcinoma,39 had metastatic liver tumors and four had cholangiocellular *** hundred and forty eight patients had a single tumor,and 107 had multiple *** diameter of the tumors ranged 1.3-20 cm(mean,5.1 cm).All patients were treated with a cooled-tip perfusion electrode attached to a radiofrequency generator(Radionics,Burlington,MA,USA).RFA was performed via the percutaneous approach(n = 257),laparoscopy(n = 7),or open surgical treatment(n = 86).The major complications related to RFA were *** resultant data were analyzed to determine risk factors associated these ***:Among the 255 patients,425 liver tumors were treated and 350 RFA sessions were ***-seven(10%) major complications were observed which included 13 cases of liver failure,10 cases of hydrothorax requiring drainage,three casesof tumor seeding,one case of upper gastrointestinal bleeding,one case ofintrahepatic abscess,one case of bile duct injury,one case of cardiac arrest,and five cases of *** patients had more than two *** failure was the most severe complication and was associated with the highest *** patients died due to worsening liver ***-Pugh classification(P = 0.001) and choice of approach(P = 0.045) were related to post-treatment liver failure,whereas patient age,tumor size and number were not significant factors precipitating this ***:RFA can be accepted as a relatively safe procedure for the treatment of liver ***,attention should be paid to possible com

关键词： Complication Hepatocellular carcinoma Metastatic liver tumor Radiofrequency ablation Liverfailure