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Hot-pressed graphene nanoplatelets or/and zirconia reinforced hybrid alumina nanocomposites with improved toughness and mechanical characteristics

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Journal of Materials Science & Technology 2020年第5期40卷 135-145页

作者： Iftikhar Ahmad Mohammad Islam Nuha Al Habis Shahid Parvez Center of Excellence for Research in Engineering Materials Deanship of Scientific ResearchKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia Mechanical Engineering Department College of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia

This work explains the synergistic contribution of graphene nanoplatelets(GNP)and zirconia ceramic nanoparticles(ZrO2)on the microstructure,mechanical performance and ballistic properties of the alumina(Al2O3)ceramic hybrid nanocomposites.Over the benchmarked monolithic alumina,the hotpressed hybrid nanocomposite microstructure demonstrated 68%lower grain size due to grain pinning phenomenon by the homogenously distributed reinforcing GNP(0.5 wt%)and zirconia(4 wt%)inclusions.Moreover,the hybrid nanocomposite manifested 155%better fracture toughness(KIC)and 17%higher microhardness as well as 88%superior ballistic trait over the monolithic alumina,respectively.The superior mechanical and ballistic performance of the hybrid nanocomposites was attributed to the combined role of zirconia nanoparticles and GNP nanomaterial in refining the microstructure and inducing idiosyncratic strengthening/toughening mechanisms.Extensive combined electron microscopy revealed complicated physical interlocking of the GNP into the microstructure as well as excellent bonding of the GNP with alumina at their interface in the hybrid nanocomposites.We also probed the efficiency of the pull-out and crack-bridging toughening mechanisms through proven quantitative methods.Based on the information extracted from the in-depth SEM/TEM investigation,we outlined schematic models for understating the reinforcing ability as well as toughening mechanisms in the hybrid nanocomposites and meticulously discussed.The hot-pressed hybrid nanocomposites owning high toughness and hardness may have applications in advanced armor technology.

关键词： Graphene Alumina Zirconia Toughness hybrid nanocomposites

Large carotid body tumor successfully resected in hybrid operating theatre: A case report

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World Journal of Clinical Cases 2019年第16期7卷 2346-2351页

作者： Meng-Qi Li Yan Zhao Huai-Yu Sun Xin-Yu Yang Department of Neurosurgery Tianjin Medical University General HospitalTianjin 300052China Department of Neurosurgery TieMei General Hospital of Liaoning Health Company Affiliated Shenyang Medical CollegeTieling 112000Liaoning ProvinceChina

BACKGROUND Surgical treatment for large carotid body tumor (CBT),particularly the Shamblin III type,is challenging and rarely reported.CASE SUMMARY In July 2014,a 63-year-old woman presented to our hospital with a large CBT (130 mm × 60 mm × 70 mm).The lesion was hypervascular,spanned from the first to the seventh cervical vertebra,and adhered to the right common carotid artery (CCA),internal carotid artery (ICA) and external carotid artery (ECA).The resection was carried out in a hybrid operating theatre.First,we used Onyx gel to embolize the feeding artery.An ICA balloon was used to prevent gel entry into the ICA.After shrinkage and hardening of the CBT,we quickly resected the CBT as well as a part of the ECA that adhered to the CBT.A vascular shunt was inserted between CCA and ICA,and the part where the ICA was cut off from the CCA was directly sutured.A follow-up at four years later showed no neurological damage.CONCLUSION For large hypervascular CBT,embolization of the feeding artery prior to resection is helpful.The hybrid operating theatre is the ideal platform to carry out such operations.

关键词： Carotid body tumor Paraganglioma hybrid operating theatre Interventional embolization Case report

Performance evaluation of hybrid constructed wetlands for the treatment of municipal wastewater in developing countries

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Chinese Journal of Chemical Engineering 2020年第6期28卷 1717-1724页

作者： Sajjad Haydar Mehwish Anis Misbah Afaq Institute of Environmental Engineering&Research(IEER) University of Engineering&Technology(UET)LahorePakistan

In developing countries,high cost of conventional wastewater treatment is a major hindrance in its application.Constructed wetlands(CWs)offer low-cost and effective solution to this issue.The current study aimed to evaluate an innovative maneuver of CWs i.***.hybrid flow constructed wetlands(HCWs)for municipal wastewater(MWW).The HCWs included two lab scale CWs;one horizontal and one vertical,in series.Local plant species were used.HCWs were operated in both,batch and continuous mode.Batch mode was used to(1)optimize detention time and(2)find pollutants removal efficiency.Continuous operation(at batch optimized retention time)was carried out for the evaluation of mass removal rate,r(g·m-2·d-1),volumetric rate constant,Kv(per day)and areal rate constant,Ka(m·d-1).Among two local plants tested,Pistia stratiotes gave better removal efficiency than Typha.Optimum detention time in HCWs was found to be 8 days(4+4 each).The optimum COD,BOD,TSS,TKN and P removal observed for Pistia stratiotes planted HCWs was 80%,84%,82%,71%and88%respectively.Effluent standards for COD,BOD and TSS were met at optimum conditions.The values of Kaand Kv demonstrated that more removal occurred in vertical flow as compared to horizontal flow CW.

关键词： Constructed wetlands Municipal wastewater hybrid Pistia Typha Batch mode Continuous mode

hybrid Laser-GMAW Welding of High Strength Quenched-Tempered Steels

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稀有金属材料与工程 2011年第S4期40卷 102-105页

作者： Radovan Kovacevic Research Center for Advanced Manufacturing Southern Methodist UniversityTexas 75205United States

High-strength quenched and tempered (HSQT) steels have been widely used in structural applications where light weight is of primary design interest.Gas metal arc welding is a common way to join QT steels.When GMAW is used to join the HSQT steel,multi-pass is usually required to achieve full penetration.In addition,weld crack is often observed because of HSQT steel's high susceptibility to hydrogen embrittlement.In addition,due to the large amount of heat input from the arc,the heat affected zone is often softened.This reduces the ductility and strength of welds and makes the weld weaker than the base metal.In this study,a hybrid laser/GMAW process is proposed to produce butt joint for 6.5mm thick HSQT A514 steel plate.Hydrogen diffusion mechanism is first discusses for GMAW and hybrid laser-GMAW welding processes.Metal transfer mode during the hybrid laser/GMAW welding process is also analyzed.A high speed CCD camera with 4000 frame/second is used to monitor the welding process in real time.Welds obtained by GMAW and hybrid laser/GMAW techniques are compared and tested by static lap shear and dynamic impact.Effects of gap between two metal plates and laser beam/GMAW torch spacing on weld property are studied.By appropriately choosing these two parameters,crack-free butt joints with full penetration can be successfully obtained by the hybrid laser/GMAW welding process for HSQT A514 steel plate.

关键词： hybrid laser-GMAW welding high strength quenched and tempered steels hydrogen induced cracking

AC fault ride through control strategy on inverter side of hybrid HVDC transmission systems

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Journal of Modern Power Systems and Clean Energy 2019年第5期7卷 1129-1141页

作者： Zexin ZHOU Zhengguang CHEN Xingguo WANG Dingxiang DU Guosheng YANG Yizhen WANG Liangliang HAO China Electric Science Research Institute Co. Ltd.BeijingChina State Key Laboratory for Power Grid Safety and Energy Conservation BeijingChina School of Electrical Engineering and Automation Tianjin UniversityTianjinChina College of Electrical Engineering Beijing Jiaotong UniversityBeijingChina

hybrid high-voltage direct current(HVDC)transmission systems employ a new type of HVDC transmission topology that combines the advantages of the linecommutated converter system and the voltage-source converter system.They can improve the efficiency and reliability of long-distance power transmission.However,realizing alternating-current(AC)grid-fault ride through on the inverter side of a hybrid HVDC transmission system is a challenge considering that a voltage-source converter based HVDC(VSC-HVDC)is used on the inverter side.In this study,a control strategy for an overvoltage fixed trigger angle based on the power-balance method is developed by fully utilizing the operation characteristics of a hybrid HVDC transmission system.The strategy reduces the inverter-side overvoltage of the HVDC system under a fault in the inverter-side AC system.Simulations based on Gezhou Dam are conducted to validate the effectiveness of the proposed strategy.

关键词： hybrid HVDC transmission Fault crossing Control strategy Inverter side

Designing new work-hardenable ductile Ti-based multilayered bulk metallic glass composites with ex-situ and in-situ hybrid strategy

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Journal of Materials Science & Technology 2020年第15期47卷 128-138页

作者： Shifeng Lin Zhengwang Zhu Shaofan Ge Long Zhang Dingming Liu Yanxin Zhuang Huameng Fu Hong Li Aimin Wang Haifeng Zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China School of Material Science and Engineering Northeastern UniversityShenyang 110819China

To overcome the trade-off between the devisable micro structure and the excellent tensile ductility of bulk metallic glass composites(BMGCs),a novel ex-situ and in-situ hybrid strategy is successfully proposed to design a series of the work-hardenable ductile Ti-based multilayered BMGCs(ML-BMGCs).The asprepared ML-BMGCs,consisting of α-phases,β-phases and amorphous phases,exhibit a controllable multilayered structure of the Ti layers and the amorphous layers with alternative distribution.The size and volume fraction of the crystalline phases are tuned by Nb microalloying.It is found that the ML-BMGCs possess a suitable size and volume fraction of the crystalline phases when Nb microalloying content are5%(at.) or 8%(at.),and they obtain an optimum combination of the specific strength of 243 MPa g kg-1 or 216 MPa g kg-1,and tensile plasticity of 4.33%±0.1 % or 5.10%±0.1%.The deformation mechanism of the as-prepared ML-BMGCs during tension is also revealed.The ex-situ Ti layers and in-situ dendrites together effectively serve as absorbers to suppress the propagation of shear bands and multiply shear bands.And the defo rmation of ex-situ α-Ti phases by dislocation slip and the transformation from in-situ metastable β-Ti phase to orthorhombic α-Ti during tension impart significant work-hardening capability to the ML-B MGCs.The present study provides a guidance of developing novel high-performance BMGCs with a controllable micro structure.

关键词： hybrid Strategy ML-BMGCs Tensile property Deformation Mechanism

Development and strengthening mechanisms of a hybrid CNTs@SiCp/Mg-6Zn composite fabricated by a novel method

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Journal of Magnesium and Alloys 2021年第4期9卷 1370-1379页

作者： Chao Ding Xiaoshi Hu Hailong Shi Weimin Gan Kun Wu Xiaojun Wang National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of Technology92 West Dazhi StreetHarbinHeilongjiang 150001PR China GEMS at Heinz Maier-Leibnitz Zentrum(MLZ) Helmholtz-Zentrum GeesthachtLichtenbergstr.1D-85748 GarchingGermany

The hybrid addition of CNTs was used to improve both the strengths and ductility of SiCp reinforced Mg matrix composites.A novel method was developed to simultaneously disperse SiCp and CNTs in Mg melt.Firstly,new CNTs@SiCp hybrid reinforcements were synthesized by CVD.Thus,CNTs were well pre-dispersed on the SiCp surfaces before they were added to Mg melt.Therefore,the following semisolid stirring and ultrasonic vibration dispersed the new hybrid reinforcements well in Mg-6Zn melt.The hybrid composite exhibits some unique features in microstructures.Although the distribution of SiCp was very uniform in the Mg-6Zn matrix,most CNTs distributed along the strips in the state of micro-clusters,in which CNTs were bonded very well with Mg matrix.Most of the CNTs kept their structure integrity during fabrication process.All these factors ensure that the hybrid composite have much higher strength and elongation than the mono SiC/Mg-6Zn composites.The dominant strengthening mechanism is the load transfer effect of CNTs.Apart from grain refinement,the CNTs toughen the composites by impeding the microcrack propagation inside the material.Thus,the hybrid CNTs@SiCp successfully realizes the reinforcing advantage of“1+1>2”.

关键词： hybrid CVD Mg matrix composites Strengthening mechanism Ultrasonic vibration

Thermal conductivity of natural rubber nanocomposites with hybrid fillers

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Chinese Journal of Chemical Engineering 2019年第4期27卷 928-934页

作者： Junping Song Xiteng Li Kaiyan Tian Lianxiang Ma Wei Li Shichune Yao Key Laboratory of Rubber-plastics Ministry of Education Shandong Provincial Key Laboratory of Rubber-plastics Chinese and German School of Science and Technology College of Electromechanical Engineering Qingdao University of Science and Technology Qingdao 266061 China Department of Energy Engineering Zhejiang University Hangzhou 310027 China Department of Mechanical Engineering Carnegie Mellon University Pittsburgh PA 15213-3890 USA

Natural rubber nanocomposites filled with hybrid fillers of multi-walled carbon nanotubes(CNTs) and carbon black(CB) were prepared. CNTs were ultrasonically modified in mixture of hydrogen peroxide(H2O2) and distilled water(H2O). The functional groups on the surface of CNTs, changes in nanotube structure and morphology were characterized by Fourier transform infrared spectroscopy(FT-IR), Raman Spectroscopy, and transmission electron microscopy(TEM). It shows that hydroxyl(OH·) is successfully introduced. The surface defects of modified CNTs were obviously higher than those of original CNTs, and the degree of agglomeration was greatly reduced. Thermal conductivity of the composites was tested by protection heat flow meter method. Compared with unmodified CNTs/CB filling system, the thermal conductivity of hybrid composites is improved by an average of 5.8% with 1.5 phr(phr is parts per hundred rubber) of hydroxyl CNTs and 40 phr of CB filled. A three-dimensional heat conduction network composed of hydroxyl CNTs and CB, as observed by TEM, contributes to the good properties. Thermal conductivity of the hybrid composites increases as temperature rises. The mechanical properties of hybrid composites are also good with hydroxyl CNTs filled nanocomposites;the tensile strength, 100% and 300% tensile stress are improved by 10.1%, 22.4% and 26.2% respectively.

关键词： Modified carbon nanotube Carbon black hybrid filler Natural rubber Thermal conductivity

Manipulation of multi-transparency windows and fast-slow light transitions in a hybrid cavity optomechanical system

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Science China(Physics,Mechanics & Astronomy) 2019年第5期62卷 75-83页

作者： Ming-Hua Zheng Tie Wang Dong-Yang Wang Cheng-Hua Bai Shou Zhang Cheng-Shou An Hong-Fu Wang Department of Physics College of Science Yanbian University Department of Physics Harbin Institute of Technology

We study the generation of quadruple-transparency windows and the implementation of a conversion between slow and fast light in a hybrid optomechanical system. By demonstrating the generation of these transparency windows one by one, we analyze the physical mechanism through which each transparency window forms in detail. Additionally, we discuss how the system parameters affect the formation of transparency windows and conclude that the location, width, and absorption of each transparency window can be arbitrarily manipulated by varying the appropriate parameters. Moreover, when the pump field is changed from red to blue detuning, conversions between slow and fast light occur in the output field. These interesting properties of the output field can be applied to achieve the coherent control and manipulation of light pulses using cavity optomechanical system.

关键词： hybrid cavity optomechanical system optomechanical induced transparency fast-slow light