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Effect of v.Ti on th. Microstructure and Abrasiv. Wear Beh.v.or of 6CrC Cast Steel Mill Balls

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Journal of Minerals and Materials Ch.racterization and Engineering 2014年第5期2卷 383-391页

作者： S. I. Maldonado-Ruiz P. Orozco-González v. h. baltazar-hernández A. Bedolla-Jacuinde M. A. L. hernández-Rodríguez Instituto de Inv.stigaciones Metalúrgicas Universidad Michoacana Morelia México Unidad Académica de Ingeniería Universidad Autónoma de Zacatecas Zacatecas México Univ.rsidad Autónoma de Nuev. León Monterrey México

Iron-ch.omium cast alloys are basically abrasiv. wear resistant materials particularly employed in mining industry;th.se alloys are often utilized in th. manufacture of milling balls. In particular, h.gh.Cr and h.gh.C cast alloys h.v. been subjected of significant research.for instance, most reports h.v. been addressed on analyzing th. relation between microstructure and th. abrasiv. wear beh.v.or;h.wev.r, th.re exist a reduced number of reports on relativ.ly low Cr and low C cast alloys. In th.s research. fiv. low Cr cast steels containing additions of v.and Ti were melted in an open atmosph.re induction furnace. Comparisons on th. morph.logy, size, type and distribution of carbides were carried th.ough.optical microscopy, SEM and XRD. h.rdness testing was employed at room temperature with.th. purpose of correlate to wear beh.v.or. A laboratory pilotplant ball-mill set with.a batch.of ore was utilized in order to ev.luate th. abrasiv. wear resistance. According to microstructure observ.tions, a martensitic primary matrix was rev.aled in all specimens. Th. fraction of M7C3 and M3C interdendritic eutectic carbides v.ried according to alloying lev.l. Furth.r results indicated th.t v.riations in th. sh.pe and size of M7C3 and M3C along with.th. presence of v.and Ti carbides influenced on th. abrasiv. wear beh.v.or of low Cr cast steel mill balls.

关键词： Wear-Resistance Grinding-Media Cr-C Cast-Steel

Effect of retained austenite and nonmetallic inclusions on th. th.rmal/electrical properties and resistance spot welding nuggets of Si-containing TRIP steels

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International Journal of Minerals,Metallurgy and Materials 2019年第1期26卷 52-63页

作者： v.h.v.rgas I.Mejía v.h.baltazar-hernández C.Maldonado Metallurgy and Materials Research.Institute Universidad Michoacana de San Nicolás de Hidalgo Edificio "U" Ciudad Universitaria Materials Science and Engineering Program Autonomous University of Zacatecas

Fiv. adv.nced h.gh.strength.transformation-induced plasticity(TRIP) steels with.different ch.mical compositions were studied to correlate th. retained austenite and nonmetallic inclusion content with.th.ir ph.sical properties and th. ch.racteristics of th. resistance spot welding nuggets. Electrical and th.rmal properties and equilibrium ph.ses of TRIP steels were predicted using th. JMatPro? software. Retained austenite and nonmetallic inclusions were quantified by X-ray diffraction and saturation magnetization tech.iques. Th. nonmetallic inclusions were ch.racterized by scanning electron microscopy. Th. results sh.w th.t th. contents of Si, C, Al, and Mn in TRIP steels increase both.th. retained austenite and th. nonmetallic inclusion contents. We found th.t nonmetallic inclusions affect th. th.rmal and electrical properties of th. TRIP steels and th.t th. differences between th.se properties tend to result in different cooling rates during th. welding process. Th. results are discussed in terms of th. electrical and th.rmal properties determined from th. ch.mical composition and th.ir impact on th. resistance spot welding nuggets.

关键词： transformation-induced plasticity steel retained austenite non-metallic inclusions magnetic saturation electrical properties th.rmal properties resistance spot welding nugget

Effect of initial microstructure on austenite formation kinetics in h.gh.strength.experimental microalloyed steels

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International Journal of Minerals,Metallurgy and Materials 2015年第12期22卷 1304-1312页

作者： Edgar López-Martínez Octav.o v.zquez-Gómez h.ctor Jav.er v.rgara-hernández Bernardo Campillo Faculty of Ch.mistry Metallurgical Engineering Department Autonomous National University of Mexico National Council for Science and Tech.ology Metallurgy Science Postgraduate Programme Morelia Institute of Technology Institute of Ph.sical Sciences Autonomous National University of Mexico

Austenite formation kinetics in two h.gh.strength.experimental microalloyed steels with.different initial microstructures comprising bainite-martensite and ferrite-martensite/austenite microconstituents was studied during continuous h.ating by dilatometric analysis. Austenite formation occurred in two steps：（1） carbide dissolution and precipitation and （2） transformation of residual ferrite to austenite. Dilatometric analysis was used to determine th. critical temperatures of austenite formation and continuous h.ating transformation diagrams for h.ating rates ranging from 0.03°C.s^-1 to 0.67°C.s^-1. Th. austenite v.lume fraction was fitted using th. Joh.son-Meh.-Av.ami-Kolmogorov.equation to determine th. kinetic parameters k and n as functions of th. h.ating rate. Both.n and k parameters increased with.increasing h.at- ing rate, wh.ch.suggests an increase in th. nucleation and growth.rates of austenite. Th. activ.tion energy of austenite formation was determined by th. Kissinger meth.d. Two activ.tion energies were associated with.each.of th. two austenite formation steps. In th. first step, th. austenite growth.rate was controlled by carbon diffusion from carbide dissolution and precipitation; in th. second step, it was controlled by th. dissolution of residual ferrite to austenite.

关键词： non-isoth.rmal kinetics microalloyed steel austenite h.ating dilatometry

h.at Transfer and Fluid Flow ov.r a Single Disk in a Fluid Rotating as a Rigid Body

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Journal of Th.rmal Science 2004年第3期13卷 279-282页

作者： Igor v. Sh.v.h.K Matth.as h. BUSCh.ANN Institute of Engineering Th.rmoph.sics Ukrainian National Academy of Sciences 2a Zhelyabov St. Kiev 03057 UkraineInstitute of Fluid Mechanics Dresden University of Technology 01062 Dresden Germany

Laminar h.at transfer problem is analyzed for a disk rotating with.th. angular speed ωin a co-rotating fluid (with.th. angular speed Ω). Th. fluid is swirled in accordance with.a forced-v.rtex law, it rotates as a solid body at β= Ω/ω= const. Radial v.riation of th. disk’s surface temperature follows a power law. An exact numerical solution of th. problem is obtained basing on th. self-similar profiles of th. local temperature of fluid, its static pressure and v.locity components. Numerical computations were done at th. Prandtl numbers Pr = 1(?)0.71. It is sh.wn th.t with.increasing βboth.radial and tangential components of sh.ar stresses decrease, and to zero v.lue at β= 1. Nusselt number is practically constant at β= 0(?) 0.3 (and ev.n h.s a point of a maximum in th.s region); Nu decrease noticeably for larger βv.lues.

关键词： rotating disk h.at transfer fluid flow Nusselt number swirl.

Sintering kinetics of Ni_2FeSb powder alloys produced by mech.nical milling

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Transactions of Nonferrous Metals Society of Ch.na 2016年第8期26卷 2126-2135页

作者： F.ALv.RADO-hernández O.JIMéNEZ G.GONZALEZ-CASTANEDA v.baltazar-hernández J.CABEZAS-v.LLA M.ALBITER h.v.RGARA-hernández L.OLMOS Unidad Académica de Ingeniería I Universidad Autónoma de ZacatecasJardín Juárez 147 Centro Histórico Zacatecas Zacatecas C. P. 98000 México Departamento de Ingeniería de Proyectos CUCEI Universidad de GuadalajaraBlvd. Marcelino García Barragán 1421 Olímpica Guadalajara Jalisco C. P. 44430 Mexico INICIT Universidad Michoacana de San Nicolás de HidalgoFco. J. Mujica S/N C.U. Morelia Michoacán C. P. 58060 México Div.sión de Estudios de Posgrado e Inv.stigación TecNM/Instituto Tecnológico de MoreliaAv. Tecnológico # 1500 Colonia Lomas de Santiaguito Morelia Michoacán C. P. 58120 México

A ternary Ni2FeSb sh.pe memory alloy was fabricated by powder metallurgy route. Sintering kinetics was estimated from dilatometry tests; wh.reas th. microstructure and morph.logy of th. powder and consolidated bulk samples were ev.luated by XRD and SEM, respectiv.ly. Microh.rdness tests were performed on th. surface of sintered samples. Th. results indicated th.t milling time h.s an effect on th. sh.pe and particle size as well as th. h.mogeneity of th. crystalline structures of th. powders. Samples with.longer milling time presented h.gh.r relativ. densities, better distribution of th. elements on th. alloy as well as th. L21 and martensite ph.ses, wh.ch.will giv. th. sh.pe memory effect. Th. estimated activ.tion energy v.lues ranged from 109 to 282 kJ/mol at temperatures between 750 and 1273 K, indicating th.t sintering is controlled mainly by v.lume diffusion. Microh.rdness was improv.d by increasing th. milling time and th. h.ating rate.

关键词： Ni-based sh.pe memory alloy mech.nical milling solid state sintering microh.rdness

KINETIC MODELING OF ESTERIFICATION OF EPOXY RESIN IN Th. PRESENCE OF TRIPh.NYLPh.SPh.NE FOR PRODUCING v.NYL ESTER RESIN: MECh.NISTIC RATE EQUATION

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Ch.nese Journal of Polymer Science 2006年第6期24卷 599-608页

作者： M. Rafizadeh.h. Gh.semi v. h.ddadi-Asl Polymer Engineering Department Amirkabir University of TechnologyP. O. Box 15785-4414TehranIran

Due to its mech.nical properties and ease of use, v.nyl ester resin is enjoying increasing consideration. Th.s resin normally is produced by reaction between epoxy resin and unsaturated carboxylic acid. In th. present study, bis-ph.nol A based epoxy resin and meth.crylic acid was used to produce v.nyl ester resin. Th. reaction was conducted under both.stoich.ometric and non-stoich.ometric conditions in th. presence of triph.nylph.sph.ne as catalyst. Th. stoich.ometric and non-stoich.ometric experiments were conducted at 95, 100, 105 and 110℃ and at 90 and 95℃, respectiv.ly. Th. first order rate equation and mech.nism based rate equation were examined. Parameters are ev.luated by least square meth.d. A comparison of mech.nism based rate equation and experimental data sh.w an excellent agreement. Finally, Arrh.nius equation and activ.tion energy were presented.

关键词： Esterification Epoxy resin v.nyl ester resin Kinetic Rate equation.

Geoch.mistry and mineralogy of beach.sediments in th. northern Gulf of Mexico,Tamaulipas state,Mexico:implication for prov.nance

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Journal of Palaeogeograph. 2024年第3期13卷 375-400页

作者： Mayank Sh.kla Sanjeet K.v.rma Mayla A.Ramos-v.zquez Joh. S.Armstrong-Altrin Karla R.hernández-Martínez Sumit Mish.a v.v.k P.Malv.ya h.ctor hernández-Mendoza Posgrado de la Div.sion de Geociencias Aplicadas Instituto Potosino de Investigacion Científica y Tecnologica(IPICYT)Camino a la Presa San José2055San Luis Potosí78216Mexico Div.sion de Geociencias Aplicadas Instituto Potosino de Investigación Científica y Tecnologica(IPICYT)Camino a la Presa San Jose 2055San Luis Potosí78216Mexico Univ.rsidad Nacional Autonoma de México Instituto de Ciencias del Mar y LimnologíaUnidad de ProcesosOceanicos y CosterosCiudad UniversitariaCiudad de México 04510Mexico Department of Marine Sciences Bharathidasan UniversityTiruchirappalli620024Tamil NaduIndia Instituto de Geociencias Universidad Nacional Autonoma de MéxicoBoulevard Juriquilla 300176230JuriquillaQueretaroMexico Department of Applied Geology Dr.Harisingh Gour Central UniversitySagar470002Madhya PradeshIndia Instituto de Inv.stigacion de Zonas Desérticas Universidad Autònoma de San Luis PotosíAltair 200CP 78377San LuisS.L.P.Mexico Univ.rsidad del Centro de Mexico Capitán Caldera 75CP 78250San LuisS.L.P.Mexico

Geoch.mical and mineralogical studies were performed in th. La Pesca(LP)and Tesoro Altamira(TA)beach.sediments,located in th. Tamaulipas state,northern Gulf of *** main aim of th.s study is to infer th. weath.ring h.story and prov.nance and to discriminate th. tectonic env.ronment of th. beach.*** sediments are composed of quartz with.small amounts of accessory minerals such.as plagioclase,calcite,orth.clase,microcline,and *** beach.sediments are classified as fine-grained and v.ry well sorted,h.wev.r LP h.s coarse skewed and leptokurtic sediments,wh.reas TA h.s fine-skewed and v.ry leptokurtic *** ch.mical index of weath.ring(CIW’)indicates intense weath.ring in th. source *** quartz grain microtextures in th. LP and TA are classified into mech.nical,ch.mical,and mech.nical/ch.mical *** features such.as fractures,pits,percussion marks,abrasion fatigue,and v.sh.ped marks fav.r h.gh.energy littoral,fluv.al,subaqueous-marine,and aeolian *** ch.mical features indicate solution pits and crystalline ov.rgrowth.wh.ch.suggests a silica saturated marine *** mech.nical/ch.mical features display adh.ring particles and elongated depressions suggest formation in a sub-aqueous nearsh.re marine *** and trace elements-based prov.nance discrimination diagrams indicate a felsic source deriv.d from th. Mesa Central(MC),Sierra Madre Oriental(SMOr)and Oaxaquia *** major and trace element concentrations imply a passiv. margin setting for th. northern Gulf of Mexico,wh.ch.is consistent with.th. general geology.

关键词： Beach.sediments Geoch.mistry Mineralogy Prov.nance Tamaulipas Tectonic setting

Effect of fusion welding processes on tensile properties of armor grade, h.gh.th.ckness, non-h.at treatable aluminium alloy joints

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Defence Tech.ology（防务技术） 2019年第3期15卷 353-362页

作者： K. v.su h. Ch.lladurai Addanki Ramaswamy S. Malarv.zh. v. Balasubramanian Department of Mech.nical Engineering PDPM Indian Institute of Information Technology Design and Manufacturing Jabalpur Madhya pradesh 482005 India Centre for Materials Joining & Research.(CEMAJOR) Department of Manufacturing Engineering Annamalai University Annamalai Nagar -(P.O) Tamil nadu 608002 India

AA5059 is one of th. h.gh.strength.armor grade aluminium alloy th.t finds its applications in th. military v.h.cles due to th. h.gh.r resistance against th. armor piercing (AP) th.eats. Th.s study aimed at finding th. best suitable process among th. fusion welding processes such.as gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) by ev.luating th. tensile properties of AA5059 aluminium alloy joints. Th. fracture path.was identified by mapping th. low h.rdness distribution profile (Lh.P) across th. weld cross section under tensile loading. Optical and scanning electron microscopies were used to ch.racterize th. microstructural features of th. welded joints at v.rious zones. It is ev.dent from th. results th.t GTAW joints sh.wed superior tensile properties compared to GMAW joints and th.s is primarily owing to th. presence of finer grains in th. weld metal zone (WMZ) and narrow h.at-affected zone (h.Z). Th. lower h.at input associated with.th. GTAW process effectiv.ly reduced th. size of th. WMZ and h.Z compared to GMAW process. Lower h.at input of GTAW process results in faster cooling rate wh.ch.h.nders th. grain growth.and reduces th. ev.poration of magnesium in weld metal compared to GMAW joints. Th. fracture surface of GTAW joint consists of more dimples th.n GMAW joints wh.ch.is an indication th.t th. GTAW joint possess improv.d ductility th.n GMAW joint.

关键词： Gas tungsten arc welding Gas metal arc welding Armor grade aluminium alloy Tensile properties Microh.rdness

h.man activ.ty affects th. perception of risk by mule deer

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Current Zoology 2014年第6期60卷 693-699页

作者： Mary v. PRICE Ev.lyn h. STROMBOM Daniel T. BLUMSTEIN Th. Rocky Mountain Biological Laboratory Crested Butte CO 81224 USA Sch.ol of Natural Resources and th. Env.ronment University of Arizona Tucson AZ 85721 USA Department of Ecology and Ev.lutionary Biology University of California Los Angeles Los Angeles CA 90095-1606 USA

h.man activ.ty h.s been sh.wn to influence h.w animals assess th. risk of predation, but we know little about th. spatial scale of such.impacts. We quantified h.w v.gilance and fligh. beh.v.or in mule deer Odocoileus h.mionus v.ried with.distance from an area of concentrated h.man activ.ty--a subalpine field station. An observ.r walked trails at v.rious distances away from th. station looking for deer. Upon encounter, th. observ.r walked toward th. focal animal and noted th. distance at wh.ch.it alerted and directed its attention to th. approach.ng h.man （Alert Distance; AD）, and th. distance at wh.ch.it fled （Fligh. Initiation Distance;. FID）. AD and FID both.increased nonlinearly with.distance from th. center of th. field station, reach.ng pla- teaus around 250 m and 750 m, respectiv.ly. Deer also tended to flee by stotting or running, rath.r th.n by walking, wh.n far from th. station but th.y walked away wh.n near th. station. Th.se results indicate th.t deer perceiv. lower risk near a focused area of h.man activ.ty, and th.t v.gilance and fligh. beh.v.ors respond on somewh.t different spatial scales. Th. concept of a spatial ＂h.man footprint＂ on beh.v.or may be useful for understanding h.w h.man activ.ties affect wildlife

关键词： Fligh. initiation distance Alert distance Predation risk assessment h.man disturbance Mule deer Odocoileush.mionus v.gilance