济南大学专业英语考试.docx
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济南大学专业英语考试
1.Whatarecomposites?
Characteristics,types什么是复合材料?
特点、类型(p98)
Composites:
compositesarehybrid混合的creationsmadeoftwoormorematerialsthatmaintaintheiridentities(身份)whencombined.Theyarecombinationsofmaterialsassembled(组合的)togethertoobtainpropertiessuperiortothoseoftheirsingleconstituentcharacteristics.Theyareexpensivecompetewithmetalandpolymers(高分子)becausethemanufacturing(制造)ofcompositesinvolvesmanysteps.It’sdifficulttorecycle.
Characteristics:
(1)Thepropertiesofoneconstituent(成分)enhancethedeficient(不足)propertiesoftheother.
(2)Usually,agivenpropertyofacompositeliesbetweenthevaluesforeachconstituent.
(3)Sometimes,thepropertyofacompositeisclearlysuperiortothoseofeitheroftheconstituents.
(4)Becausemanufacturingofcompositesinvolvesmanystepsandislabourintensive(劳动力密集型产业),compositesmaybetooexpensivetocompetewithmetalsandpolymers,
(5)Compositesareusuallydifficulttorecycle.
Types(P96):
Compositesareclassifiedaccordingtothenatureoftheirmatrix:
metal,ceramic(陶瓷),polymercomposite,oftendesignated(指定的)MMCs金属基复合材料,CMCs陶瓷基复合材料,PMCs聚合物基复合材料
2.classificationofmaterials材料的分类?
Materials:
Natural、InorganicNon-MetallicMaterials,Ceramics、OrganicMaterials(Polymers,blends混纺)、Metals(Alloys)、Semiconductors、Composites、Biomaterials(生物材料)
Accordingtotheirproperties,materialscanbebroadlyclassifiedintothefollowinggroups:
Structuralmaterials、Functionalmaterials、Smartmaterials(智能材料)
Scale(数值范围)ofMaterials:
1.Nanoscale,sizesofabout1to100nanometers;
2.Microscale,relevantformicro-devicesandmicrosystemshavingsizesoftypically1to1000micrometers(微米);
3.Macroscalematerials(宏观材料)havethedimensionsofallcustomaryproducts,devicesandplants,rangingfromthemillimeter(毫米)tothekilometerscale。
3.Physicalproperties(names)物理性质(名称)
Themechanicalproperties(机械性质)ofmaterial:
bendtest(弯曲试验):
ductility(延展性),elasticity(弹性),brittleness(脆性).Tensiletest(抗拉试验):
yieldstrength(屈服强度),tensilestrength(抗张强度).Hardnesstest(硬度试验):
hardness.Impacttest(冲击试验):
toughness(韧性)undershock(冲击).Fatiguetest疲劳试验:
fatiguebehavior.Stiffness(硬度);Creeptest蠕变试验:
creep.
Thermalproperties:
thermalconductivity(热导率),specificheatcapacity(比热容);Opticalproperties(光学性质):
reflection(反射)refraction(折射)dispersion(散射);
Electricalproperties(电学性质):
conductivity(导电性),resistivity(电阻率),particle-wavedualityoflight;Magneticproperties:
perneabolity,susceptibility(敏感性),magneticinduction,
4.Howtogetthestress-straincurve?
Whataretheparameterscanwegetfromthiscurve?
如何得到应力-应变曲线?
我们从这个曲线得到什么参数?
Theresultofatensiletestiscommonlydisplayedinastress–straindiagram.
Y:
stress,tensilestress.X:
strain.Undertensilestress,therodbecomeslongerinthedirectionoftheappliedforce(andeventuallynarrowerperpendiculartothataxis),thechangeinlongitudinaldimensioninresponsetostressiscalledstrainε:
Parameters参数:
(1)yieldstrength屈服强度σy
(2)modulusofelasticity弹性模量E(3)tensilestrength抗张强度σt(4)necking(5)breakingStrength力量σb(6)Stress,压力σ;(7)strain,张力ε
5.whataretoughnessundershock,fatiguebehavior,creep?
什么是冲击韧性、疲劳行为、蠕变?
(p22)
Toughnessundershock:
Whensubjectedtoasuddenblow,somematerialsbreakatalowerstressthanthatmeasuredusingatensilemachine.Theimpacttesterinvestigatesthetoughnessofmaterialsbystrikingthematthecenterwhilefixingbothends.Toughnessisdefinedastheenergy(nottheforce)requiredtobreakamaterial.
Fatiguebehavior:
Materials,evenwhenstressedbelowtheyieldstrength,stillmayeventuallybreakifalargenumberoftensionandcompressioncyclesareapplied.Thefatiguetestmeasuresthenumberofbendingcyclesthatneedtobeappliedforaspecificloaduntilfailureoccurs.
Creep:
Thecreeptestmeasuresthecontinuousandprogressiveplasticdeformationofmaterialsathightemperatureswhileaconstantstressoraconstantloadbelowtheroomtemperatureyieldstrengthisapplied.
6.Whatarephonons?
Heatcapacity?
什么是声子?
热容?
(p272)
Theheatcapacity,C:
istheamountofheat,dQ,thatneedstobetransferredtoasubstanceinordertoraiseitstemperaturebyacertaintemperatureinterval.TheunitfortheheatcapacityisJ/K.
Photons:
Duringtheabsorptionoflightbyintrabandtransitions,anadditionalmechanismmaytakeplace.Itinvolveslatticevibrationquantacalledphonons.Theyarequantaoftheionicdisplacementfieldwhichrepresentclassicalsound;thewordphononconveystheparticlenatureofanoscillator(振子).
7.illustrateslightinteractionwithmatter说明(举例说明)光与物质的相互作用。
Absorptionoflight;Emissionoflight;refractionoflight;dispersionoflight;reflectionoflight;transmissionoflight;diffractionoflight;interferenceoflight.
8.luminescenceandmechanism?
发光和机制(p259)Whatarelasers?
什么是激光?
Howtheyareobtained?
如何获得激光(P261)?
Luminescence:
Theemissionoflightduetoreversionofelectronsfromahigherenergystateiscalledluminescence.
Mechanism:
Anelectron,onceexcited,musteventuallyrevertbackintoalower,emptyenergystate.Thisoccurs,asarule,spontaneouslywithinafractionofasecondandisaccompaniedbytheemissionofaphotonand/orthedissipationofheat---phonons.
Laser:
lightamplificationbystimulatedemissionofradiation.
Stimulatedemissionoflightoccurswhenelectronsareforcedbyincidentradiationtoaddmorephotonstoanincidentbeam.
9.Thermoelectricityandpiezoelectricity?
Examplesandapplications?
热电和压电?
举例和应用(p220/p212)
Piezoelectricity:
Thepressureisappliedtoaferroelectricmaterial,achangeinthejust-mentionedpolarizationmayoccurwhichresultsinasmallvoltageacrossthesample.Theslightchangeindimensionscausesavariationinbondlengthsbetweencationsandanions.Thiseffectiscalledpiezoelectricity.
Examples:
Quartz(石英),BaTiO3,inZnO,inPbZrTiO6;
applications:
Piezoelectricityisutilizedindevicesthataredesignedtoconvertmechanicalstrainintoelectricity.Thosedevicesarecalledtransducers.Applicationsincludestraingages,microphones,sonardetectors,andphonographpickups,tomentionafew.
Thermoelectricity:
Assumetwodifferenttypesofmaterials(e.g.,acopperandanironwire)whichareconnectedattheirendstoformaloop.Oneofthejunctionsisbroughttoahighertemperaturethantheother.Thenapotentialdifference,△V,betweenthesetwothermocouplesisobservedwhichisessentiallyproportionaltothetemperaturedifference,△T,where:
△V/△T=Siscalledthethermoelectricpower.
Examplesandapplications:
Thermocouplesmadeofmetalwiresareutilizedasrigid,inexpensive,andfastprobesformeasuringtemperaturesevenatotherwisenoteasilyaccessibleplaces.Thermoelectricpowergenerators(utilizingtheabove-mentionedsemiconductors)areusedparticularlyinremotelocationsoftheearth(Siberia,Alaska,etc.).
10.Influenceoftemperatureandimpurityonresistenceofmetals?
Explanations温度和杂质对金属电阻的影响?
(P187)解释.
Theresistivityofmetalsessentiallyincreaseslinearlywithincreasingtemperatureaccordingtotheempiricalequation(经验方程):
ρ2=ρ1[1+α(T2-T1)]whereαisthelineartemperaturecoefficientofresistivity,andT1andT2aretwodifferenttemperatures.
Explanation:
Athighertemperatures,thelatticeatomsincreasinglyoscillateabouttheirequilibriumpositionsduetothesupplyofthermalenergy,thusenhancingtheprobabilityforcollisionsbythedriftingelectrons.Asaconsequence,theresistanceriseswithhighertemperature.Atnear-zerotemperature,theelectricalresistancedosenotcompletelyvanishandtheresidualresistivityisessentiallytemperature-independent.
11.bandstructureofsemiconductors半导体的能带结构?
Intrinsicsemiconductorhasthreeelectronbandswhicharevalenceband,conductionbandandforbiddenband.Thereiscompletelyfilledwithvalenceelectronsinvalencebandandconductionbandcontainsnoelectrons.Theforbiddenbandisnotallowedtheelectronsresideinthegap.Sincethefilledvalencebandpossessesnoallowedemptyenergystatesinwhichtheelectronscanbethermallyexcited(andthenacceleratedinanelectricfield),andsincetheconductionbandcontainsnoelectronsatall,silicon,at0K,isaninsulator.
Twoelectronbands,thelowerofwhich,at0K,iscompletelyfilledwithvalenceelectronscalledthevalenceband.Itisseparatedbyasmallgapfromtheconductionband,which,at0K,containsnoelectrons.Further,quantummechanicsstipulatesthatelectronsessentiallyarenotallowedtoresideinthegapbetweenthesebands(calledtheforbiddenband).Sincethefilledvalencebandpossessesnoallowedemptyenergystatesinwhichtheelectronscanbethermallyexcited(andthenacceleratedinanelectricfield),andsincetheconductionbandcontainsnoelectronsatall,silicon,at0K,isaninsulator.
12.types,application,machenismsofmagneticmaterials(names,differences)磁性材料的类型、应用和机理。
(名字、差异)
paramagnetics,diamagnetics,ferromagnetics,ferriamgnetics,andantiferromagnetics.
AqualitativeaswellasaquantitativedistinctionbetweenthesetypescanbeachievedinarelativelysimplewaybyutilizingamethodproposedbyFaraday.
Magneticmaterialtobeinvestigatedissuspendedfromoneofthearmsofasensitivebalanceandisallowedtoreachintoaninhomogeneousmagneticfield.Diamagneticmaterialsareexpelledfromthisfield,wherepara-,ferro-,antiferro-,andferrimagneticsareattractedindifferentdegrees.
FIGURE12.2.Schematicrepresentationofmagneticfieldlinesinandarounddifferenttypesofmaterials.(a)Para-orferromagnetics铁磁体.Themagneticinduction(B)磁感应强度insidethematerialconsistsofthefree-spacecomponent(0H)plusacontributionbythem