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1、郑州工业应用技术学院学生课程考核专业外文翻译原 文：Machinery Design And ManufacturingRelated MaterialsAnd PartsIs Introduced译 文：机械设计制造材料和零件的介绍 学 院： 机电工程学院 专 业： 机械设计制造及其自动化 班 级： 机械设计四班 课 程： 机械工程专业英语教程 学生姓名： 李东明 学 号： 1102130408 时 间： 2015年1月6日 成绩评定： Machinery Design And ManufacturingRelated MaterialsAnd PartsIs IntroducedTypes
2、ofMaterialsMaterialsmaybegroupedinseveralways.Scientistsoftenclassifymaterialsbytheirstate:solid,liquid,orgas.Theyalsoseparatethemintoorganic(onceliving)andinorganic(neverliving)materials.Forindustrialpurposes,materialsaredividedintoengineeringmaterialsornonengineeringmaterials.Engineeringmaterialsa
3、rethoseusedinmanufactureandbecomepartsofproducts.Nonengineeringmaterialsarethechemicals,fuels,lubricants,andothermaterialsusedinthemanufacturingprocess,whichdonotbecomepartoftheproduct.Metalsareelementsthatgenerallyhavegoodelectricalandthermalconductivity.Manymetalshavehighstrength,highstiffness,and
4、havegoodductility.Somemetals,suchasiron,cobaltandnickel,aremagnetic.Atlowtemperatures,Whatisthedifferencebetweenanalloyandapuremetal?Puremetalsareelementswhichcomefromaparticularareaoftheperiodictable.Examplesofpuremetalsincludecopperinelectricalwiresandaluminumincookingfoilandbeveragecans.Alloyscon
5、tainmorethanonemetallicelement.Theirpropertiescanbechangedbychangingtheelementspresentinthealloy.Examplesofmetalalloysincludestainlesssteelwhichisanalloyofiron,nickel,andchromium;andgoldjewelrywhichusuallycontainsanalloyofgoldandnickel.Somemetalalloys,suchasthosebasedonaluminum,havelowdensitiesandar
6、eusedinaerospaceapplicationsforfueleconomy.Manyalloysalsohavehighfracturetoughness,whichmeanstheycanwithstandimpactandaredurable.Densityisdefinedasamaterialsmassdividedbyitsvolume.Mostmetalshaverelativelyhighdensities,especiallycomparedtopolymers.Materialswithhighdensitiesoftencontainatomswithhighat
7、omicnumbers,suchasgoldorlead.However,somemetalssuchasaluminumormagnesiumhavelowdensities,andareusedinapplicationsthatrequireothermetallicpropertiesbutalsorequirelowweight.Fracturetoughnesscanbedescribedasamaterialsabilitytoavoidfracture,especiallywhenaflawisintroduced.Metalscangenerallycontainnicksa
8、nddentswithoutweakeningverymuch,andareimpactresistant.Afootballplayercountsonthiswhenhetruststhathisfacemaskwontshatter.Plasticdeformationistheabilityofbendordeformbeforebreaking.Asengineers,weusuallydesignmaterialssothattheydontdeformundernormalconditions.Youdontwantyourcartoleantotheeastafterastro
9、ngwestwind.However,sometimeswecantakeadvantageofplasticdeformation.Thecrumplezonesinacarabsorbenergybyundergoingplasticdeformationbeforetheybreak.Theatomicbondingofmetalsalsoaffectstheirproperties.Inmetals,theoutervalenceelectronsaresharedamongallatoms,andarefreetotraveleverywhere.Sinceelectronscond
10、uctheatandelectricity,metalsmakegoodcookingpansandelectricalwiresItisimpossibletoseethroughmetals,sincethesevalenceelectronsabsorbanyphotonsoflightwhichreachthemetal.Nophotonspassthrough.Alloysarecompoundsconsistingofmorethanonemetal.Addingothermetalscanaffectthedensity,strength,fracturetoughness,pl
11、asticdeformation,electricalconductivityandenvironmentaldegradation.Forexample,addingasmallamountofirontoaluminumwillmakeitstronger.Also,addingsomechromiumtosteelwillslowtherusting.process,butwillmakeitmorebrittle.Aglassisaninorganicnonmetallicmaterialthatdoesnothaveacrystallinestructure.Suchmaterial
12、saresaidtobeamorphous.GearsiEarevital5vaitlfactorsinmachinerymE5Fi:nEri.Oneofthefirstmechanism5mekEnizEminventedusinggearswastheclocks.Infact,aclockislittlemorethanatrainofgears.ConsiderablekEn5sidErEblstudyandresearchhavebeenmadeongearsinrecentyearsbecauseoftheirwideuseunderexactingi5zAktiNconditio
13、ns.TheyhavetotransmittrAnz5mitheavierloadsandrunathigherspeedsthaneverbefore.TheengineersandthemachinistsmE5Fi:nistallconsidergearingtheprimeelementinnearlyallclassesofmachinery.Spurgearsareusedtotransmitpowerandrotary5rEutErimotionbetweenparallel5pArElelshafts.Theteetharecutparalleltotheaxisoftheshaftonwhichthe
