检索结果-南通市图书馆

CHARACTERiZATiON OF si_(1-x-y)Ge_xC_y FiLMs GROWN By iON iMPLANTATiON AND sUBsEQUENT sOLiD PHAsE EPiTAXy

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica sinica(English Letters) 2002年第1期15卷 49-52页

作者： X.Q. Liu y.y. Wang W.j. Cheng j. Zhang s.y. Ma Department of Physics Lanzhou University Lanzhou 730000 China Department of Physics Lanzhou University Lanzhou 730000 China Department of physics Northwest Normal University Lanzhou 730030 China

si1-x-yGexCy ternary alloy films were grown on monocrystalline silicon substrates by C+ ion implantation and subsequent solid phase epitaxy (sPE). Two-step annealing technique was employed in the sPE. The structure and electrical properties of the alloy films were determined using Fourier transform infrared spectroscopy and van der Pauw Hall measurements, respectively. With the optimization of two-step annealing technique for the implanted si1-x-yGexCy layers, a certain amount of C atoms occupied substitutional sites and no siC was formed.

关键词： si1-x-yGexCu film ion implantation sPE

Effects of Alumina on Cristobalite Crystallization and Properties of silica-Based Ceramic Cores

在线全文

学校读者我要写书评

暂无评论

journal of Materials science & Technology 2017年第2期33卷 204-209页

作者： j.j.Liang Q.H.Lin X.Zhang T.jin y.Z.Zhou X.F.sun B.G.Choi i.s.Kim j.H.Do C.y.jo institute of Metal Research Chinese Academy of SciencesShenyang 110016China Korea institute of Materials science Changwon 642-831Republic of Korea

in this work, the influences of alumina addition on cristobalite crystallization and properties of injec- tion molded silica-based ceramic cores were investigated. X-ray diffraction （XRD） was used to characterize phase transformations in the samples, and the XRD result indicated that the addition of alumina pro- moted crystallization of fused silica during sintering at 1180-1220 ℃ and thus increases the amount of cristobalite. The increased amount of cristobalite as well as alumina addition led to much more thermal dilation due to their higher coefficients of thermal expansion than that of fused silica. The flexural strengths at room temperature and 1500 ~C were tested, and it was shown that alumina addition could not affect room temperature strength, but decreased the flexural strength at 1500 ℃. in addition, deflection resis- tance during heating to high temperatures was investigated, and the result indicated that alumina addition speeded up high temperature softening of the samples. XRD and scanning electron microscopy equipped with energy dispersive spectrometry （sEMjEDs） analysis suggested that this softening behavior was related with viscous flow sintering which could be accelerated by the reaction of alumina and silica with a product of mullite.

关键词： silica-based ceramic cores Alumina Cristobalite crystallization Properties

sample size Dependence of second Magnetizaion Peak in Type-Ⅱsuperconductors

在线全文

学校读者我要写书评

暂无评论

Tsinghua science and Technology 2003年第3期8卷 370-378页

作者： j.H.s.Torres y.Kopelevich institute de fisica"Gleb Wataghin" Universitade Estadual de CampinasUnicamp 13083-970CampinasSao PauloBrasilInstitute de fisica"Gleb Wataghin"Universitade Estadual de CampinasUnicamp 13083-970CampinasSao PauloBrasil

We show that the second magnetization peak(sMP),i.e.,an increase in the magnetization hysteresis loop width in type-11 superconductors,vanishes for samples smaller than a critical size,We argue that the sMP is not related to the critical current enhancement but can be well explainde within a frameword of the thermomagenetic flux-jump in stability theory,where flux jumps reduce the absolute irreversible magnetization relative to the isothermal critical state value at low enough magnetic *** recovering of the isothermal critical sate with increasing field leads to the *** low-field sMP takes place in both *** and high**** *** results show that the rsstoration of the isothermal critical state is rsponsible for the sMP occurrence in both cases.

关键词： superconductor flux pinning and creep peekeffect phase transityons

THERMAL iMAGiNG sTUDy OF sCALAR TRANsPORT iN sHALLOW WAKEs

在线全文

学校读者我要写书评

暂无评论

journal of Hydrodynamics 2012年第1期24卷 17-24页

作者： CHONG K.j.y UKTHUsyANTHAN N.i. LiANG Dong-fang TANG Hong-wu Department of Engineering University of CambridgeCambridge KW Ltd FetchamSurreyUK College of Water Conservancy and i tydropowcr Engineering Hohai University Nanjing 210098 China

The thermal imaging technique relies on the usage of infrared signal to detect the temperature *** temperature as a flow tracer,thermography is used to investigate the scalar transport in the shallow-water wake generated by an emergent circular *** imaging is demonstrated to be a good quantitative flow visualization technique for studying turbulent mixing phenomena in shallow waters.A key advantage of the thermal imaging method over other scalar measurement techniques,such as the Laser induced Fluorescence（LiF）and Planar Concentration Analysis（PCA）methods,is that it involves a very simple experimental *** dispersion characteristics captured with this technique are found to be similar to past studies with traditional measurement techniques.

关键词： environmental hydraulics shallow wake turbulent mixing thermal imaging vortex street

Giant magnetocaloric effect in the Gd_5 Ge_(2.025)si_(1.925)in_(0.05) compound

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第3期19卷 517-522页

作者： E.yzak i.Dincer y.Elerman Department of Engineering Physics Faculty of EngineeringAnkara University06100 BesevlerAnkaraTurkey

The magnetocaloric properties of the GdsGe2.025si1.925in0.05 compound have been studied by x-ray diffraction, magnetic and heat capacity measurements. Powder x-ray diffraction measurement shows that the compound has a dominant phase of monoclinic Cd5Ge2si2-type structure and a small quantity of Gds（Ge,si）3-type phase at room temperature. At about 270 K, this compound shows a first order phase transition. The isothermal magnetic entropy change （△sM） is calculated from the temperature and magnetic field dependences of the magnetization and the temperature dependence of MCE in terms of adiabatic temperature change （△Tad） is calculated from the isothermal magnetic entropy change and the temperature variation in zero-field heat-capacity data. The maximum △sM is -13.6 j·kg^-1.K^- 1 and maximum ATad is 13 K for the magnetic field change of 0 5 T. The Debye temperature （θD） of this compound is 149 K and the value of DOs at the Fermi level is 1.6 states/*** from the low temperature zero-field heat-capacity data. A considerable isothermal magnetic entropy change and adiabatic temperature change under a field change of 0-5 T jointly make the Gd5Ge2.025si1.925in0.05 compound an attractive candidate for a magnetic refrigerant.

关键词： magnetic properties magnetocaloric effect isothermal magnetic entropy change adia-batic temperature change

Microstructure and mechanical properties of new Mg-Zn-y-Zr alloys with high castability and ignition resistance

在线全文

学校读者我要写书评

暂无评论

international journal of Minerals,Metallurgy and Materials 2024年第12期31卷 2714-2726页

作者： T.A.Koltygina V.E.Bazhenov A.V.Koltygin A.s.Prosviryakov N.y.Tabachkova i.i.Baranov A.A.Komissarov A.i.Bazlov National University of science and Technology Misis Moscow 119049Russia A.M.Prokhorov General Physics institute Russian Academy of SciencesMoscow 119991Russia Moscow state University of Medicine and Dentistry Moscow 127473Russia

Complex studies of new Mg-Zn-y-Zr system alloys have been carried *** content range for the formation of the two-phase structure Mgss(Mg solid solution)+LPsO(long-period stacking ordered)in alloys of the Mg-Zn-y-Zr system was determined by thermodynamic *** effect of heat treatment regimes on microstructure,mechanical,and corrosion properties was *** fluidity,hot tearing tendency,and ignition temperature of the alloys were *** best combination of castability,mechanical,and corrosion properties was found for the Mg-2.4Zn-4y-0.8Zr *** alloys studied are superior to their industrial counterparts in terms of technological properties,while maintain high corrosion and mechanical *** increased level of pro-perties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPsO phase.

关键词： metals and alloys liquid-solid reactions microstructure fluidity mechanical properties corrosion transmission electron mi-croscopy

Effect of site amplification on inelastic seismic response

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2019年第3期18卷 535-554页

作者： Adhikary s singh y Department of Civil Engineering Visvesvaraya National Institute of Technology Nagpur-440010 Maharashtra India Department of Earthquake Engineering Indian Institute of Technology Roorkee-247667 Uttarakhand India

The available models for eff ective periods of site and structure are reviewed in context of frequency tuning in the inelastic seismic response of soil-structure system. The eff ect of seismic intensity and ductility demand, on the eff ective periods, is investigated, and inelastic site amplifi cation is shown to be strongly correlated to the normalized eff ective period. Two non-dimensional parameters, analogous to the conventional site amplifi cation factors in codes, are defi ned to quantify the inelastic site amplifi cation. it is shown that the inelastic site amplifi cation factor (i.e. ratio of constant ductility spectral ordinates at soil site to those at rock outcrop) is able to represent the site eff ects more clearly, as compared to the inelastic site amplifi cation ratio (i.e. ratio of inelastic spectral ordinates at soil site to the corresponding elastic spectral ordinates at rock outcrop). Further, the peak in the amplifi cation factor corresponding to the eff ective site period diminishes rapidly with increasing ductility demand.

关键词： site amplifi cation normalized response spectra eff ective period inelastic seismic response inelastic site amplifi cation factor

Designing hetero-structured ultra-strong and ductile Zr-2.5Nb alloys:Utilizing the grain size-dependent martensite transformation during quenching

在线全文

学校读者我要写书评

暂无评论

journal of Materials science & Technology 2022年第30期125卷 198-211页

作者： s.y.Liu j.y.Zhang j.Kuang X.y.Bao D.D.Zhang C.L.Zhang j.K.yang G.Liu j.sun state Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

To further improve the service performance of Zr-2.5Nb alloy worked as pressure tubes in pressurized heavy water reactors,more investigation about the microstructure and thermomechanical processing route of Zr-2.5Nb alloy need to be *** this work,a hetero-structured Zr-2.5Nb alloy was prepared by applying a novel *** analysis reveals that the alloy exhibits a grain sizedependent martensite substructure transition during post-rolling *** hetero-structure consists of equiaxed primaryαgrains and the lamellae groups containing both parallelα’dislocation martensite andα’twin *** with the previously reported Zr-Nb alloys,the present Zr-2.5Nb alloys manifest the highest yield strength(∼710 MPa),together with a high ultimate tensile strength(∼844 MPa)and good ductility(∼17.1%).The enhanced mechanical properties are found to arise from the properly controlled fraction/size of the two types of martensite,which not only significantly strengthens the alloy but also contributes to a stronger strain hardening.A model based on the grain-size-dependent critical resolved shear stress for dislocation slip and twinning has been proposed to explain theα’martensite substructures transition at a critical grain size dc=3.3μ*** this size,the critical resolved shear stress(CRss)for twinning is higher than that for the***,theα’dislocation martensite is more favorable to ***,theα’twin martensite would exhibit a high *** present work indicates that making use of the grain size-dependent martensite transformation to tailor the heterostructure in Zr alloys is an effective strategy to overcome the strength–ductility trade-off in the material.

关键词： Zr-Nb alloys Heterogeneous structure Martensitic transformation Grain size strength

Preparation and photocatalytic property of Fe_(2)O_(3)/ZnO composites with superhydrophobicity

在线全文

学校读者我要写书评

暂无评论

international journal of Minerals,Metallurgy and Materials 2021年第6期28卷 1072-1079页

作者： Muntadher i.Rahmah Raad s.sabry Wisam j.Aziz Physics Department College of ScienceMustansiriyah UniversityBaghdad 10052Iraq

A facile approach was developed to construct Fe_(2)O_(3)-modified ZnO micro/nanostructures with excellent superhydrophobicity and photocatalytic *** effects of stearic acid(sA)and Fe_(2)O_(3) on the morphological characteristics,water contact angle(WCA),and photocatalytic degradation were *** results showed that WCA increased from 144°±2°to 154°±2°when the weight of sA increased from 5 to 20 mg because of the formation of a hierarchical or rough ***,Fe_(2)O_(3)-modified ZnO micro/nanostructure surfaces before and after sA treatment(20 mg)were chosen to evaluate the photodegradation of methylene blue(MB)dye under the support of visible *** degraded after 80 min of irradiation,and its photodegradation efficiencies were 91.5%at the superhydrophobic state and 92%at the hydrophilic *** improvement in photocatalytic activity at both states might be attributed to an increase in surface area and improvement in charge carrier separation.

关键词： nano composites stearic acid superhydrophobic photocatalytic self-cleaning