材料科学与工程 专业外语

1,TheScienceandEngineeringofMaterials,Chapter2IntroductiontoMaterialsScienceandEngineering,2,ObjectivesofSection1,HistoryofmaterialsIntroducethefieldofmaterialsscienceandengineering(MSE)Provideintroductiontotheclassificationofmaterials,3,ChapterOutline,1.1WhatisMaterialsScienceandEngineering?1.2ClassificationofMaterials1.3FunctionalClassificationofMaterials1.4ClassificationofMaterialsBasedonStructure1.5EnvironmentalandOtherEffects1.6MaterialsDesignandSelection,4,WhatareMaterials?,Thatseasy!Lookaround.Ourclothesaremadeofmaterials,ourhomesaremadeofmaterials-mostlymanufactured.Glasswindows,vinylsiding,metalsilverware,ceramicdishesMostthingsaremadefrommanydifferentkindsofmaterials.,5,6,HistoryofMaterials,EvenourhistoryhasbeendefinedbythematerialsweuseThestoneageThecopperageThebronzeageTheironageWhatwouldbeagoodmaterialnamefortoday?(MSECRC,2006),7,HistoryofMaterials,Manhasbeenstudyingmaterialssincebeforeleavingthecave.Duetolackofcommunication,earlymanspenthundredsofmillenniaexperimentingwithstonetools.Thefirstmetaltoolsappearedperhapsonlysixthousandyearsago.,8,Section1.1WhatisMaterialsScienceandEngineering?,MaterialsScienceandEngineeringCompositionmeansthechemicalmake-upofamaterial.Structuremeansadescriptionofthearrangementsofatomsorionsinamaterial.Synthesisistheprocessbywhichmaterialsaremadefromnaturallyoccurringorotherchemicals.Processingmeansdifferentwaysforshapingmaterialsintousefulcomponentsorchangingtheirproperties.,9,MaterialsScienceandEngineering,Aninterdisciplinarystudythatcombinesmetallurgy,physics,chemistry,andengineeringtosolvereal-worldproblemswithreal-worldmaterialsinanacceptablesocietalandeconomicalmanner,ThefollowingelementsandtheirinteractiondefineMaterialsScienceandEngineering:PerformancePropertiesStructureandcompositionSynthesisandprocessing,10,2003Brooks/ColePublishing/ThomsonLearning,IntroductiontoChapter1,11,2003Brooks/ColePublishing/ThomsonLearning,Figure1.1Applicationofthetetrahedronofmaterialsscienceandengineeringtoceramicsuperconductors.Notethatthemicrostructure-synthesisandprocessing-compositionareallinterconnectedandaffecttheperformance-to-costratio,12,Figure1.2Applicationofthetetrahedronofmaterialsscienceandengineeringtosheetsteelsforautomotivechassis.Notethatthemicrostructure-synthesisandprocessing-compositionareallinterconnectedandaffecttheperformance-to-costratio,2003Brooks/ColePublishing/ThomsonLearning,13,2003Brooks/ColePublishing/ThomsonLearning,Figure1.3Applicationofthetetrahedronofmaterialsscienceandengineeringtosemiconductingpolymersformicroelectronics,14,Section1.2ClassificationofMaterials,MetalsandAlloysCeramics,Glasses,andGlass-ceramicsPolymers(plastics),ThermoplasticsandThermosetsSemiconductorsCompositeMaterials,15,KindsofMaterials,Metals:arematerialsthatarenormallycombinationsofmetallicelements.Metalsusuallyaregoodconductorsofheatandelectricity.Also,theyarequitestrongbutmalleableandtendtohavealustrouslookwhenpolished.Ceramics:aregenerallycompoundsbetweenmetallicandnonmetallicelements.Typicallytheyareinsulatingandresistanttohightemperaturesandharshenvironments.,16,KindsofMaterials,Plastics:(orpolymers)aregenerallyorganiccompoundsbaseduponcarbonandhydrogen.Theyareverylargemolecularstructures.Usuallytheyarelowdensityandarenotstableathightemperatures.Semiconductors:haveelectricalpropertiesintermediatebetweenmetallicconductorsandceramicinsulators.Also,theelectricalpropertiesarestronglydependentuponsmallamountsofimpurities.,17,KindsofMaterials,Composites:consistofmorethanonematerialtype.Fiberglass,acombinationofglassandapolymer,isanexample.Concreteandplywoodareotherfamiliarcomposites.Manynewcombinationsincludeceramicfibersinmetalorpolymermatrix.,18,NewerBranchesofMaterialsScience,Nanotechnology:arelativelynewareagrownoutoftechniquesusedtomanufacturesemiconductorcircuits.Machinescanbeproducedonamicroscopiclevel.Example-miniaturerobotstodosurgeryinsidethebodyorminiaturechemicallaboratoriesandinstrumentsthatwillcontinuouslyanalyzebloodanddispensemedicationsinsidethebody.,19,Table1.1Representativeexamples,applications,andpropertiesforeachcategoryofmaterials,ExampleofApplicationsPropertiesMetalsandAlloysGraycastironAutomobileengineblocksCastable,machinable,vibrationdampingCeramicsandGlassesSiO2-Na2O-CaOWindowglassOpticallytransparent,thermallyinsulatingPolymersPolyethyleneFoodpackagingEasilyformedintothin,flexible,airtightfilm,20,ExampleofApplicationsPropertiesSemiconductorsSiliconTransistorsandintegratedUniqueelectricalcircuitsbehaviorCompositesCarbidecuttingtoolsforHighhardness,yetTungstencarbidemachininggoodshockresistance-cobalt(WC-Co),Table1.1Continued,21,2003Brooks/ColePublishing/ThomsonLearning,Figure1.4Representativestrengthsofvariouscategoriesofmaterials,22,Figure1.5Asectionthroughajetengine.Theforwardcompressionsectionoperatesatlowtomediumtemperatures,andtitaniumpartsareoftenused.Therearcombustionsectionoperatesathightemperaturesandnickel-basedsuperalloysarerequired.Theoutsideshellexperienceslowtemperatures,andaluminumandcompositesaresatisfactory.(CourtesyofGEAircraftEngines.),Figure1.6Avarietyofcomplexceramiccomponents,includingimpellersandblades,whichallowturbineenginestooperatemoreefficientlyathighertemperatures.(CourtesyofCertech,Inc.),23,2003Brooks/ColePublishing/ThomsonLearning,Figure1.7Polymerizationoccurswhensmallmolecules,representedbythecircles,combinetoproducelargermolecules,orpolymers.Thepolymermoleculescanhaveastructurethatconsistsofmanychainsthatareentangledbutnotconnected(thermoplastics)orcanformthree-dimensionalnetworksinwhichchainsarecross-linked(thermosets),24,Figure1.8Polymersareusedinavarietyofelectronicdevices,includingthesecomputerdipswitches,wheremoistureresistanceandlowconductivityarerequired.(CourtesyofCTSCorporation.),Figure1.9Integratedcircuitsforcomputersandotherelectronicdevicesrelyontheuniqueelectricalbehaviorofsemiconductingmaterials.(CourtesyofRogersCorporation.),Figure1.10TheX-wingforadvancedhelicoptersreliesonamaterialcomposedofacarbon-fiber-reinforcedpolymer.(CourtesyofSikorskyAircraftDivisionUnitedTechnologiesCorporation.),25,Section1.3FunctionalClassificationofMaterials,AerospaceBiomedicalElectronicMaterialsEnergyTechnologyandEnvironmentalTechnologyMagneticMaterialsPhotonicorOpticalMaterialsSmartMaterialsStructuralMaterials,26,2003Brooks/ColePublishing/ThomsonLearning,Figure1.11Functionalclassificationofmaterials.Noticethatmetals,plastics,andceramicsoccurindifferentcategories.Alimitednumberofexamplesineachcategoryisprovided,27,Section1.4ClassificationofMaterials-BasedonStructure,Crystallinematerialisamaterialcomprisedofoneormanycrystals.Ineachcrystal,atomsorionsshowalong-rangeperiodicarrangement.Singlecrystalisacrystallinematerialthatismadeofonlyonecrystal(therearenograinboundaries).Grainsarethecrystalsinapolycrystallinematerial.Polycrystallinematerialisamaterialcomprisedofmanycrystals(asopposedtoasingle-crystalmaterialthathasonlyonecrystal).Grainboundariesareregionsbetweengrainsofapolycrystallinematerial.,28,Section1.5EnvironmentalandOtherEffects,Effectsoffollowingfactorsmustbeaccountedforindesigntoensurethatcomponentsdonotfailunexpectedly:TemperatureCorrosionFatigueStrainRate,29,2003Brooks/ColePublishing/ThomsonLearning,Figure1.12Increasingtemperaturenormallyreducesthestrengthofamaterial.Polymersaresuitableonlyatlowtemperatures.Somecomposites,specialalloys,andceramics,haveexcellentpropertiesathightemperatures,30,2003Brooks/ColePublishing/ThomsonLearning,Figure1.13Skinoperatingtemperaturesforaircrafthaveincreasedwiththedevelopmentofimprovedmaterials.(AfterM.Steinberg,ScientificAmerican,October,1986.),31,Figure1-14SchematicofaX-33planeprototype.Noticetheuseofdifferentmaterialsfordifferentparts.ThistypeofvehiclewilltestseveralcomponentsfortheVenturestar(FromASimplerRidein