检索结果-南通市图书馆

EffEcTs Of la ON sTRUcTURE AND PROPERTIEs Of HEAVY RAIl sTEEl

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica sinica(English letters) 2005年第6期18卷 701-706页

作者： c.j. liu M.f. jiang Y.s. Wang j.j. chen c.l. li Northeastern University Shenyang 110004 China Baotou Iron and steel Group Gorporation Baotou 014010 Ghina

The mechanisms of la in heavy rail steel were studied by means of experimental measurements, microstructure observation and theoretical analysis in the present work. for heavy rail steel, the state and the content of la were measured, and the mechanisms and the effects of la on sulfide inclusions, microstracture and properties of steel were determined. strip-like sulfides disappear in heavy rail steel with la/（O＋s）〉3.50, which is shown that the metallurgical function of modifying sulfide inclusions has been achieved by la. la can fine the grain size of the austenite in heavy rail steel. Under the experimental condition, the plasticity and the impacting toughness of heavy rail steel with 0.005wt% la can evidently be improved.

关键词： rare earth heavy rail steel microscopic structure sulfide inclusion,property

MIcROsTRUcTURE Of BINARY Mg-Al EUTEcTIc AllOY WIREs PRODUcED BY THE OHNO cONTINUOUs cAsTING PROcEss

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica sinica(English letters) 2008年第4期21卷 275-281页

作者： Z.M. Zhang T. lü c.j. Xu X.f. Guo school of Materials science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

Directionally solidified binary Mg-Al eutectic alloy wires of approximately 5 mm in diameter were produced by the Ohno continuous casting （Occ） process and the microstructure was examined. It was found that the wires possess obvious unidirectional growth characteristic along its axial direction. The microstructure consists of parallel columnar grains that resulted from the competitive growth of equiaxed grains solidified on the head of dummy bar. Each columnar grain comprises regular eutectic a-Mg and β-Mg17 Al12 phases, which grew along the axial direction of the wires. The morphology of the eutectic is mainly lamellar, meanwhile rod eutectic exists. The formation of rod eutectic was attributed to the ＂bridging effect＂ caused by incidental elements in the alloy.

关键词： Mg-Al alloy Eutectic structure Directional solidification Occ process

Unusual f_(3)stacking fault in magnesium

在线全文

学校读者我要写书评

暂无评论

journal of Magnesium and Alloys 2023年第7期11卷 2404-2428页

作者： Y.Yue s.l.Yang c.c.Wu j.f.Nie Department of Materials science and Engineering Monash UniversityVictoria 3800Australia

An unusual f_(3)basal stacking fault resulting from twin-dislocation interaction in magnesium is observed in molecular dynamics *** f_(3)fault is produced in the twin lattice from the interaction between a migrating(1012)twin boundary and a partial dislocation of either a prismaticc>edge,or a prismaticc+a>mixed dislocation in the *** condition is that the partial dislocation needs to have a negative sign and lie on a plane intersecting a compression site of the twin *** f_(3)fault can also be generated when a positive basalmixed dislocation in the twin lattice,with slip plane intersecting a compression site of the twin boundary,interacts with a basal-prismatic twinning *** f_(3)fault comprises two I_(1) faults that have the same character but are separated by two basal *** has one end connected to the twin boundary,and the other end bounded by a lattice defect with a Burgers vector identical to that of a 30°shockley partial *** formation frequency of the f_(3)fault is higher at a lower shear stress(below∼400 MPa)and/or a lower temperature(100 K and 200 K).The f_(3)fault can decompose into a glissile 30°shockley and a T_(2) fault at a temperature above∼400 *** relationships between the f_(3)fault and other types of basal stacking faults such as I_(2),T_(2) or paired I_(1) faults that are separated by multiple basal layers are discussed.

关键词： Magnesium Basal stacking fault f3 fault Twin-dislocation interactions

Impact of land Degradation on soil Microbial Biomass and Activity in Northeast Brazil

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2012年第1期22卷 88-95页

作者： j.s.NUNEs A.s.f.ARAUjO l.A.P.l.NUNEs l.M.lIMA R.f.V.cARNEIRO A.A.c.sAlVIANO s.M.TsAI soil Quality lab. Agricultural Science CenterFederal University of PiauíTeresinaPI(Brazil) center of Nuclear Energy in Agriculture University of Sao PauloPiracicabaSP(Brazil)

land degradation causes great changes in the soil biological *** process of degradation may decrease soil microbial biomass and consequently decrease soil microbial *** study was conducted out during 2009 and 2010 at the four sites of land under native vegetation(NV),moderately degraded land(lDl),highly degraded land(HDl) and land under restoration for four years(Rl) to evaluate changes in soil microbial biomass and activity in lands with different degradation levels in comparison with both land under native vegetation and land under restoration in Northeast *** samples were collected at 0-10 cm *** organic carbon(sOc),soil microbial biomass c(MBc) and N(MBN),soil respiration(sR),and hydrolysis of fluorescein diacetate(fDA) and dehydrogenase(DHA) activities were *** two years of evaluation,soil MBc,MBN,fDA and DHA had higher values in the NV,followed by the *** decreases of soil microbial biomass and enzyme activities in the degraded lands were approximately 8-10 times as large as those found in the ***,after land restoration,the MBc and MBN increased approximately 5-fold and 2-fold,respectively,compared with the *** results showed that land degradation produced a strong decrease in soil microbial ***,land restoration may promote short-and long-term increases in soil microbial biomass.

关键词： land restoration microorganisms soil quality soil respiration

sTUDY ON REDUcING THE cORE lOss Of GRAIN ORIENTED sIlIcON sTEEl AND IMPROVING ITs AGING PROPERTY BY lAsER NITRIDING TEcHNIQUE IN ATMOsPHERIc AMBIENT

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica sinica(English letters) 2005年第4期18卷 533-538页

作者： Y.l. Yang c.s. liu f.j. sun D. Zhang college of science Northeastern University Shenyang 110004 China college of Material ＆ Metallurgy Northeastern University Shenyang 110004China

cW-cO2 laser nitriding technique was applied to improve the properties （such as aging property and the core loss） of grain oriented silicon steel. The samples were nitrided with regular space. laser power density and scanning speed were chosen as 7.8×10^5W·cm^-2 and 100mm·min^-1. By some laser irradiation, fe4N and fe3N were formed in the nitrided zone. The nitrided samples were annealed at the temperatures ranged from 100 to 90℃. The core loss of some interested samples was tested. The results show that the core loss of the nitrided samples with different thickness of 0.23 and 0.30mm decreased by 14.9% and 9.4% respectively, and the aging property were improved up to 800℃. The mechanism of laser nitriding to improve the properties of grain oriented silicon steel is discussed.

关键词： laser nitriding grain oriented silicon steel sheet core loss aging property

Tracing changes in the Microbial community of a Hydrocarbon-Polluted soil by culture-Dependent Proteomics

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2010年第4期20卷 479-485页

作者： f.BAsTIDA c.NIcOls j.l.MORENO T.HERNNDEZ c.GARcIA Department of soil and Water conservation Centro de Edafologia y Biologia Aplicada del Segura(CEBAS-CSIC)Campus Universitario de Espinardo

Hydrocarbon contamination may affect the soil microbial community, in terms of both diversity and function. A laboratory experiment was set-up, with a semi-arid control soil and the same soil but artificially contaminated with diesel oil, to follow changes in the dominant species of the microbial community in the hydrocarbon-polluted soil via proteomics. Analysis of the proteins extracted from enriched cultures growing in luria-Bertani （lB） media showed a change in the microbial community. The majority of the proteins were related to gIycolysis pathways, structural or protein synthesis. The results showed a relative increase in the complexity of the soil microbial community with hydrocarbon contamination, especially after 15 days of incubation. species such as Ralstonia solanacearum, synechococcus elongatus and different clostridium sp. were adapted to contamination, not appearing in the control soil, although Bacillus sp. dominated the growing in lB in any of the treatments. We conclude that the identification of microbial species in soil extracts by culture-dependent proteomics is able to partially explain the changes in the diversity of the soil microbial community in hydrocarbon polluted semi-arid soils, but this information is much more limited than that provided by molecular methods.

关键词： culture dependent hydrocarbon contamination microbial diversity proteomics semiarid soil

Rietveld refinement and optical properties of srWO_4:Eu^(3+) powders prepared by the non-hydrolytic sol-gel method

在线全文

学校读者我要写书评

暂无评论

journal of Rare Earths 2015年第2期33卷 113-128页

作者： P.f.s.Pereira I.c.Nogueira E.longo E.j.Nassar I.l.V.Rosa l.s.cavalcante chemistry Institute University of the State of Sao Paulo Julio de Mesquita Filho-UNESP Francisco DegniAraraquara-SP 14800-900 Brazil lIEc-chemistry Department Federal University of Sao Carlos Via Washington Luis Km 235Sao Carlos-SP 13565-905 Brazil University of franca-UNIfRAN Via Dr.Armando Sales de OliveiraNo.201 Franca-SP 14404-600 Brazil ccN-DQ-GERATEc University of the State of Piauí Joao Cabral 2231 P.O.Box 391Terezina PI 64002-150 Brazil

We investigated the effect of annealing time on the structure and optical properties of sr WO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 *** and differential thermal analyses revealed that sr WO4：Eu^3＋ powders were obtained at about 800 ℃.X-ray diffraction patterns and Rietveld refinement data confirmed that all powders had a scheelite-type tetragonal ***-Raman and fourier transform infrared spectra indicated structural order at short range and anti-symmetric stretching vibrations of O-W-O bonds associated with tetrahedral[WO4]*** properties were investigated by ultraviolet-visible（UV-vis）diffuse reflectance,and photoluminescence（Pl）data which provided the evolution of quantum efficiency（η）and lifetime（τ）.UV-vis spectroscopy evidenced intermediate energy levels within the band gap of sr WO4：Eu^3＋ *** properties validated that the Eu^3＋ electric-dipole（^5D0→^7f2）transition in Pl emission spectra was dominant which proved that Eu^3＋ ions were positioned in a site without an inversion center.[（^5D0→^7f2）/（^5D0→^7f1）]band ratios showed that Eu^3＋ ions were located in a low symmetry *** Pl emission,ηandτproved the dependence on the annealing time in the behavior of sr WO4：Eu3＋powders with a higher relative emission Pl intensity as well as higherηandτvalues related to other samples when heat treated at 800℃ for 8 h.

关键词： srWO4 Rietveld refinement optical band gap Eu^(3+) +-rare earth luminescence

An Experi mental study on Wave-Induced Dynamic stresses in seabed

在线全文

学校读者我要写书评

暂无评论

china Ocean Engineering 2006年第1期20卷 27-44页

作者： s.c.chang l.K.chien j .G.lin Y.f.chiu Department of Harbor and River Engineering National Taiwan Ocean University Taiwan China Harbor and Marine Technology center Taiwan China

A series of hydraulic model tests with horizontal movable seabed under regular wave actions have been carried out to investigate the dynamic interactions between water waves and seabed soil. seabed dynamic stresses from experiments are, tound to differ from theoretical resuhs. The response of p0 in permeable seabed has a small decay and phase shift to the nonlinear wave actions, and the dynamic stresses, σs/p0, σh/p0 and u/p0, contain different phase shift characteristics. such phenomena will strongly affect the dynamic stress path in seabed. If the phase shifts of σs. and σh are neglected, the stress path will become a straight line; otherwise, it will become an elliptical curve. In phase shift cases, the long axis of the p - q diagram will be shortened when the depth increases, and the short axis will become longer when the phase shift increases. for the p＇ - q＇ diagram, the larger the phase lag of u, the longer the short axis. Relative results offer useful information for the analysis of seabed stability.

关键词： wave-induced dynamic stresses movable seabed hydraulic model test stress path

sTRUcTURE, MEcHANIcAl PROPERTIEs AND THERMAl sTABIlITY Of DIAMOND-lIKE cARBON fIlMs PREPARED BY ARc ION PlATING

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica sinica(English letters) 2005年第3期18卷 331-338页

作者： Y.s.Zou j.D.Zheng j.Gong c.sun R.f.Huang l.s.Wen DivisionofsurfaceEngineeringofMaterials InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China DivisionofsurfaceEngineeringofMaterials InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China／／ShenyangResearchCenterforInterfacialMaterialsShenyang110016China

Diamond-like carbon (Dlc) films have been prepared on si(100) substrates by arc ion plating in conjunction with pulse bias voltage under H2 atmosphere. The depo sited films have been characterized by scanning electron microscopy and atomic f orce microscopy. The results show that the surface of the film is smooth and den se without any cracks, and the surface roughness is low. The bonding characteris tic of the films has been studied by X-ray photoelectron spectroscopy (XPs) and Raman spectroscopy. It shows the sp3 bond content of the film deposited at -200V is 26.7%. The hardness and elastic modulus of the film determined by nanoindent ation technique are 30.8 and 250.1GPa, respectively. The tribological characteri stic of the films reveals that they have low friction coefficient and good wear- resistance. After deposition, the films have been annealed in the range of 350-7 00℃ for 1h in vacuum to investigate the thermal stability. Raman spectra indica te that the ID/IG ratio and G peak position have few detectable changes below 50 0℃. further increasing the annealing temperature, the hydrogen can be released, the structure rearranges, and the phase transition of sp3 configured carbon to sp2 configured carbon appears.

关键词： diamond-like carbon arc ion plating microstructure mechanical