磁学量经常使用单位换算

磁学量经常使用单位换算磁学量名称SI符号和单位CGS符号和单位单位换算磁通量韦伯（Wb）麦克斯韦（Mx）1Mx=10-8Wb磁感应强度B特斯拉（T）B高斯（Gs）1Gs=1O-4T磁场强度H安/米(A/m)H奥斯特（Oe）1Oe=1O3/4A/m磁化强度M安/米(A/m)M高斯（Gs）1Gs=103A/m磁极化强度J特斯拉（T）4M高斯（Gs）1Gs=1O-4T磁能积BH焦/米3（J/m3）BH高•奥（GOe）1MGOe=1O2/4kJ/m3真空磁导率4・10jH/m-1-注二在園际标淮单位制（31）中B=+J：.J=在高斯单位制CCGS5中5=磁概念永磁材料：永磁材料被外加磁场磁化后磁性不消失，可对外部空间提供稳固磁场。钕铁硼永磁体经常使用的衡量指标有以下四种：剩磁（Br）单位为特斯拉（T）和高斯（Gs）1Gs=将一个磁体在闭路环境下被外磁场充磁到技术饱和后撤消外磁场，现在磁体现的磁感应强度咱们称之为剩磁。它表示磁体所能提供的最大的磁通值。从退磁曲线上可见，它对应于气隙为零时的情形，故在实际磁路中磁体的磁感应强度都小于剩磁。钕铁硼是现今发觉的Br最高的有效永磁材料。磁感矫顽力（Hcb）单位是安/米（A/m）和奥斯特（Oe）或1Oe^m处于技术饱和磁化后的磁体在被反向充磁时，使磁感应强度降为零所需反向磁场强度的值称之为磁感矫顽力（Hcb）。但现在磁体的磁化强度并非为零，只是所加的反向磁场与磁体的磁化强度作用彼此抵消。（对外磁感应强度表现为零）现在假设撤消外磁场，磁体仍具有必然的磁性能。钕铁硼的矫顽力一样是llOOOOe以上。内禀矫顽力（Hcj）单位是安/米（A/m）和奥斯特（Oe）1Oe^m使磁体的磁化强度降为零所需施加的反向磁场强度，咱们称之为内禀矫顽力。内禀矫顽力是衡量磁体抗退磁能力的一个物理量，若是外加的磁场等于磁体的内禀矫顽力，磁体的磁性将会大体排除。钕铁硼的Hcj会随着温度的升高而降低因此需要工作在高温环境下时应该选择高Hcj的牌号。磁能积(BH)单位为焦/米3(J/ms)或高•奥(GOe)1MGOeT.96kJ/ms退磁曲线上任何一点的B和H的乘积既BH咱们称为磁能积，而BxH的最大值称之为最大磁能积(BH)max。磁能积是恒量磁体所贮存能量大小的重要参数之一，(BH)max越大说明磁体包括的磁能量越大。磁路时要尽可能使磁体的工作点处在最大磁能积所对应的B和H周围。各向同性磁体：任何方向磁性能都相同的磁体。各向异性磁体：不同方向上磁性能会有不同；且存在一个方向，在该方向取向时所得磁性能最高的磁体。烧结钕铁硼永磁体是各向异性磁体。取向方向：各向异性的磁体能取得最正确磁性能的方向称为磁体的取向方向。也称作“取向轴”，“易磁化轴”。磁场强度：指空间某处磁场的大小，用H表示，它的单位是安/米(A/m)。磁化强度：指材料内部单位体积的磁矩矢量和，用M表示，单位是安/米(A/m)。磁感应强度：磁感应强度B的概念是：B=p°(H+M)，其中H和M别离是磁化强度和磁场强度，而p0是真空导磁率。磁感应强度又称为磁通密度，即单位面积内的磁通量。单位是特斯拉(T)。磁通:给定面积内的总磁感应强度。当磁感应强度B均匀散布于磁体表面A时，磁通①的一样算式为①=BxA。磁通的SI单位是麦克斯韦。相对磁导率：媒介磁导率相关于真空磁导率的比值，即人=P/P。。在CGS单位制中川。=1。另外，空气的相对磁导率在实际利用中往往值取为1，另外铜、铝和不锈钢材料的相对磁导率也近似为1。磁导：磁通①与磁动势F的比值，类似于电路中的电导。是反映材料导磁能力的一个物理量。磁导系数Pc:又为退磁系数，在退磁曲线上，磁感应强度Bd与磁场强度Hd的比率，即Pc=Bd/Hd，磁导系数可用来估量各类条件下的磁通值。关于孤立磁体Pc只与磁体的尺寸有关，退磁曲线和Pc线的交点确实是磁体的工作点，Pc越大磁体工作点越高，越不容易被退磁。一样情形下关于一个孤立磁体取向长度相对越大Pc越大。因此Pc是永磁磁路设计中的一个重要的物理量。GlossaryofMagnetTerminologyAirGap-The"external"distaneefromonepoleofthemagnettotheotherthoughanonmagneticmaterial(usuallyair).Anisotropic-Ananisotropicmaterialhasdifferentpropertiesindifferentdirections.Forexample,woodwhichhasagrainisstrongerinsomeonedirectionthananother.Likewood,neodymiummagnetsarealsoanisotropic.Evenbeforeitismagnetized,aneodymiummagnethasa"preferred"magnetizationdirection.Seeourarticleformoreinfo.Neodymiummagnetsaremadewithapreferredmagnetizationdirectionwhichcannotbechanged.Thesematerialsareeithermanufacturedintheinfluenceofstrongmagneticfieldsorpressedaspecificway,andcanonlybemagnetizedthroughthepreferredNeodymium(IronBoron)andSamariumCobaltmagnetsareanisotropic.B/HCurve-Theresultofplottingthevalueofthemagneticfield(H)thatisappliedagainsttheresultantfluxdensity(B)achieved.Thiscurvedescribesthequalitiesofanymagneticmaterial.Agraphicexplanationcanbefound.BHma)(MaximumEnergyProduct)-TheMaximumEnergyProductatthepointontheB/HCurvethathasthemoststrength,expressedinMGOe(MegaGaussOersteds).Whendescribingthegradeofaneodymiummagnet,thisnumberiscommonlyreferredtoasthe"N"number,asinGradeN52magnets.Inthepictureatright,itistheareainsidethebox,underthecurve.Brmax(ResidualInduction)-Alsocalled"ResidualFluxDensity".Themagneticinductionremaininginasaturatedmagneticmaterialafterthemagnetizingfieldhasbeenremoved.ThisisthepointatwhichthehysteresisloopcrossestheBaxisatzeromagnetizingforce,andrepresentsthemaximumfluxoutputfromthegivenmagnetmaterial.Bydefinition,thispointoccursatzeroairgap,andthereforecannotbeseeninpracticaluseofmagnetmaterials.-Abbreviationforthe"Centimeter,Grams,Second"systemofmeasurement.CoerciveForce(He)-Thedemagnetizingforce,measuredinOersteds,necessarytoreduceobservedinduction,B,tozeroafterthemagnethaspreviouslybeenbroughttosaturation.CurieTemperature(Tc)-Thetemperatureatwhichamagnetlosesallofitsmagneticproperties.DemagnetizationCurve-Thesecondquadrantofthehysteresisloop,generallydescribingthebehaviorofmagneticcharacteristicsinactualuse.AlsoknownastheB-HCurve.Findthesecurvesforsomeofourmostpopularmagnetgradesonourpage.DemagnetizationForce-Amagnetizingforce,typicallyinthedirectionoppositetotheforceusedtomagnetizeitinthefirstplace.Shock,vibrationandtemperaturecanalsobedemagnetizingforces.Dimensions-Thephysicalsizeofamagnetincludinganyplatingorcoating.DimensionalTolerance-Anallowanee,givenasapermissiblerange,inthenominaldimensionsofafinishedmagnet.Thepurposeofatoleraneeistospecifytheallowedleewayforvariationsinmanufacturing.(Magnetic)DipoleMoment(m)-aquantitythatdescribesthetorqueagivenmagnetwillexperienceinanexternalmagneticfield.Somefolks(likephysicists)useamagneticdipolemodeltosimulateormathematicallymodelamagnetorgroupofmagnets.Mathematically,it'seasierthanconsideringthecomplexitiesofweirdmagnetshapes.It'snottheoreticallyperfect.Usingitwon'talwaysmatchmeasuredfieldstrengthsnearaneodymiummagnet.Itworksgreatforasphere,butisn'tcorrectnearothershapeslikediscsorblocks.It'sagreatapproximationwhenyou'remeasuringfarawayfromamagnet,butnotsogoodcloseup,especiallyneartheedgesofamagnet.Calculatethedipolemomentusingtheformulam=dipolemomentinAm2=BrxV/po,where:BrisBrmax,theResidualFluxDensity,expressedinTesla.Visthevolumeofthemagnet,expressedincubicmeters.A。isthepermeabilityofavacuum,or4nx10-7N/A2.Electromagnet-Amagnetconsistingofasolenoidwithanironcore,whichhasamagneticfieldonlyduringthetimeofcurrentflowthroughthesolenoid.Learnmoreinourarticle.FerromagneticMaterial-Amaterialthateitherisasourceofmagneticfluxoraconductorofmagneticflux.Mostferromagneticmaterialshavesomecomponentofiron,nickel,orcobalt.Gauss-Unitofmagneticinduction,B.Linesofmagneticfluxpersquarecentimeterinthesystemofmeasurement.EquivalenttolinespersquareinchintheEnglishsystem,andweberspersquaremeterorteslainthe.system.10,000gaussequals1tesla.Gaussmeter-Aninstrumentusedtomeasuretheinstantaneousvalueofmagneticinduction,B,usuallymeasuredinGaussAlsocalledaDCmagnetometer.Gilbert-Theunitofmagnetomotiveforce,F,inthesystem.HysteresisLoop-Aplotofmagnetizingforceversusresultantmagnetization(alsocalledaB/Hcurve)ofthematerialasitissuccessivelymagnetizedtosaturation,demagnetized,magnetizedintheoppositedirectionandfinallyremagnetized.Withcontinuedrecycles,thisplotwillbeaclosedloopwhichcompletelydescribesthecharacteristicsofthemagneticmaterial.Thesizeandshapeofthis"loop"isimportantforbothhardandsoftmaterials.Withsoftmaterials,whicharegenerallyusedinalternatingcircuits,theareainsidethis"loop"shouldbeasthinaspossible(itisameasureofenergyloss).Butwithhardmaterialsthe"fatter"theloop,thestrongerthemagnetwillbe.Thefirstquadrantoftheloop(thatis+Xand+Y)iscalledthemagnetizationcurve.Itisofinterestbecauseitshowshowmuchmagnetizingforcemustbeappliedtosaturateamagnet.Thesecondquadrant(-Xand+Y)iscalledtheDemagnetizationCurve.Agraphicexplanationcanbefound.Induction,(B)-Themagneticfluxperunitareaofasectionnormaltothedirectionofflux.MeasuredinGauss,inthesystemofunits.IntrinsicCoerciveForce(Hc)-Indicatesamaterials'resistancetodemagnetization.Itisequaltothedemagnetizingforcewhichreducestheintrinsicinduction,Bi,inthematerialtozeroaftermagnetizingtosaturation;measuredinoersteds.IrreversibleLosses-Partialdemagnetizationofthemagnet,causedbyexposuretohighorlowtemperatures,externalfields,shock,vibration,orotherfactors.Theselossesareonlyrecoverablebyremagnetization.Magnetscanbestabilizedagainstirreversiblelossesbypartialdemagnetizationinducedbytemperaturecyclesorbyexternalmagneticfields.IsotropicMaterial-Amaterialthatcanbemagnetizedalonganyaxisordirection(amagneticallyunorientedmaterial).TheoppositeofAnisotropicMagnet.Keeper-Asoftironpiecetemporarilyaddedbetweenthepolesofamagneticcircuittoprotectitfromdemagnetizinginfluences.Alsocalledashunt.KeepersaregenerallynotneededforNeodymiumandothermodernmagnets.TheyaremorecommonlyusedwitholderAlnico.Kilogauss-OneKilogauss=1,000Gauss=Maxwellspersquarecentimeter.Magnet-Amagnetisanobjectmadeofcertainmaterialswhichcreateamagneticfield.Everymagnethasatleastonenorthpoleandonesouthpole.Byconvention,wesaythatthemagneticfieldlinesleavetheNorthendofamagnetandentertheSouthendofamagnet.Thisisanexampleofamagneticdipole("di"meanstwo,thustwopoles).Ifyoutakeabarmagnetandbreakitintotwopieces,eachpiecewillagainhaveaNorthpoleandaSouthpole.Ifyoutakeoneofthosepiecesandbreakitintotwo,eachofthesmallerpieceswillhaveaNorthpoleandaSouthpole.Nomatterhowsmallthepiecesofthemagnetbecome,eachpiecewillhaveaNorthpoleandaSouthpole.IthasnotbeenshowntobepossibletoendupwithasingleNorthpoleorasingleSouthpolewhichisamonopole("mono"meansoneorsingle,thusonepole).MagneticCircuit-Consistsofallelements,includingairgapsandnon-magneticmaterialsthatthemagneticfluxfromamagnettravelson,startingfromthenorthpoleofthemagnettothesouthpole.MagneticField(B)-Whenspecifiedonoursite,thesurfacefieldormagneticfieldreferstothestrengthin.Foraxiallymagnetizeddiscsandcylinders,itisspecifiedonthesurfaceofthemagnet,alongthecenteraxisofmagnetization.Forblocks,itisspecifiedonthesurfaceofthemagnet,alsoalongthecenteraxisofmagnetization.Forrings,youmayseetwovalues.Bycenterspecifiestheverticalcomponentofthemagneticfieldintheairatthecenterofthering.Byringspecifiestheverticalcomponentofthemagneticfieldonthesurfaceofthemagnet,mid-waybetweentheinnerandouterdiameters.SomedepictionsofmagnetfieldscanbefoundMagneticFieldStrength(H)-Magnetizingordemagnetizingforce,isthemeasureofthevectormagneticquantitythatdeterminestheabilityofanelectriccurrent,oramagneticbody,toinduceamagneticfieldatagivenpoint;measuredinOersteds.MagneticFlux-Isacontrivedbutmeasurableconceptthathasevolvedinanattempttodescribethe“flow”ofamagneticfield.Whenthemagneticinduction,B,isuniformlydistributedandisnormaltothearea,A,theflux,0=BA.MagneticFluxDensity-Linesoffluxperunitarea,usuallymeasuredinGaussOnelineoffluxpersquarecentimeterisoneMaxwell.MagneticInduction(B)-Themagneticfieldinducedbyafieldstrength,H,atagivenpoint.Itisthevectorsum,ateachpointwithinthesubstanee,ofthemagneticfieldstrengthandtheresultantintrinsicinduction.Magneticinductionisthefluxperunitareanormaltothedirectionofthemagneticpath.MagneticLineofForce-Animaginarylineinamagneticfield,which,ateverypoint,hasthedirectionofthemagneticfluxatthatpoint.MagneticPole-Anareawherethelinesoffluxareconcentrated.MagnetomotiveForce(Formmf)-Themagneticpotentialdiffereneebetweenanytwopoints.Analogoustovoltageinelectricalcircuits.Thatwhichtendstoproduceamagneticfield.Commonlyproducedbyacurrentflowingthroughacoilofwire.MeasuredinGilbertsorAmpereTurns.).MaterialGrade-Neodymium(NdFeB)magnetsaregradedbythemagneticmaterialfromwhichtheyaremanufactured.Generallyspeaking,thehigherthegradeofmaterial,thestrongerthemagnet.WefindthatthePullForceofamagnetrelatesdirectlytothe"N"number.NeodymiummagnetscurrentlyrangeingradefromN35toN52.ThetheoreticallimitforNeodymiummagnetsisgradeN64,thoughitisn'tcurrentlyfeasibletomanufacturemagnetsthisstrong.ThegradeofmostofourstockmagnetsisN42becausewefeelthatN42providestheoptimalbalaneebetweenstrengthandcost.WealsostockawiderangeofsizesingradeN52forcustomerswhoneedthestrongestpermanentmagnetsavailable.MaximumEnergyProduct(BHmaX-Themagneticfieldstrengthatthepointofmaximumenergyproductofamagneticmaterial.ThefieldstrengthoffullysaturatedmagneticmaterialmeasuredinMegaGaussOersteds,MGOe.MaximumOperatingTemperature(TMaX-Alsoknownasmaximumservicetemperature,isthetemperatureatwhichthemagnetmaybeexposedtocontinuouslywithnosignificantlong-rangeinstabilityorstructuralchanges.Maxwell-Unitofmagneticfluxintheelectromagneticsystem.Onemaxwellisonelineofmagneticflux.MagnetizationCurve-Thefirstquadrantportionofthehysteresisloop(B/H)Curveforamagneticmaterial.MagnetizingForce(H)-Themagnetomotiveforceperunitofmagnetlength,measuredinOerstedsorampere-turnspermeter.Maxwell-Theunitfortotalmagneticflux,measuredinfluxlinespersquarecentimeter.MGOe-Mega(million)GaussOersteds.Unitofmeasuretypicallyusedinstatingthemaximumenergyproductforagivenmaterial.SeeMaximumEnergyProduct.NorthPole-Thenorthpoleofamagnetistheoneattractedtothemagneticnorthpoleoftheearth.Thisnorth-seekingpoleisidentifiedbytheletterN.Byacceptedconvention,thelinesoffluxtravelfromthenorthpoletothesouthpole.Oersted(Oe)-Theunitformagnetizingforce.TheEnglishsystemequivalentisAmpereTurnsperInch(1OerstedequalsA/m).The.unitisAmpereTurnsperMeter.Orientation-Usedtodescribethedirectionofmagnetizationofamaterial.OrientationDirection-Thedirectioninwhichananisotropicmagnetshouldbemagnetizedinordertoachieveoptimummagneticproperties.ParamagneticMaterials-Materialsthatarenotattractedtomagneticfields(wood,plastic,aluminum,etc.).Amaterialhavingapermeabilityslightlygreaterthan1.PermanentMagnet-Amagnetthatretainsitsmagnetismafteritisremovedfromamagneticfield.Apermanentmagnetis"alwayson".Neodymiummagnetsarepermanentmagnets.Permeance(P)-Ameasureofrelativeeasewithwhichfluxpassesthroughagivenmaterialorspace.Itiscalculatedbydividingmagneticfluxbymagnetomotiveforce.Permeanceisthereciprocalofreluctance.PermeanceCoefficient(Pc)-Alsocalledtheload-line,B/Hor"operatingslope"ofamagnet,thisisthelineonthewhereagivenmagnetoperates.Thevaluedependsonboththeshapeofthemagnet,andit'ssurroundingenvironment(somewouldsay,howit'susedinacircuit).Inpracticalterms,it'sanumberthatdefinehowharditisforthefieldlinestogofromthenorthpoletothesouthpoleofamagnet.AtallcylindricalmagnetwillhaveahighPc,whileashort,thindiscwillhavealowPc.PermeanceCoefficient1斗1210B6斗2□■归芒CD-16-1斗-1210-eH(We>OuronlinecancalculatePcforcommonshapes.Itassumesasinglemagnetinfreespace.Othernearbymagnetsorferromagneticmaterialscanchangematters.Permeability(卩)-Theratioofthemagneticinductionofamaterialtothemagnetizingforceproducingit(B/H).Themagneticpermeabilityofavacuum(叮is4nx10jN/Amp2.Pole-Anareawherethelinesofmagneticfluxareconcentrated.Plating/Coating-Mostneodymiummagnetsareplatedorcoatedinordertoprotectthemagnetmaterialfromcorrosion.Neodymiummagnetsaremostlycomposedofneodymium,iron,andboron.Theironinthemagnetwillrustifitisnotsealedfromtheenvironmentbysomesortofplatingorcoating.Mostoftheneodymiummagnetsthatwestockaretripleplatedinnickel-copper-nickel,butsomeareplatedingold,silver,orblacknickel,whileothersarecoatedinepoxy,plasticorrubber.Polarity-Thecharacteristicofaparticularpoleataparticularlocationofapermanentmagnet.DifferentiatestheNorthfromtheSouthPole.PullForce-Theforcerequiredtopullamagnetfreefromaflatsteelplateusingforceperpendiculartothesurface.Thelimitoftheholdingpowerofamagnet.Thepullforcelistedisactualdataacquiredbytestingusingourstate-of-the-artforceteststand.Acomprehensivetableofthepullforceforallofourstockmagnetsisavailablehere:.Wetestfortwodifferentvaluesofpullforceusingtwodifferentsetups.Readmoreaboutthesetwopullforces.RareEarth-CommonlyusedtodescribehighenergymagnetmaterialsuchasNdFeB(Neodymium-Iron-Boron)andSmCo(Samarium-Cobalt).RelativePermeability-Theratioofpermeabilityofamediumtothatofavacuum.Inthesystem,thepermeabilityisequalto1inavacuumbydefinition.Thepermeabilityofairisalsoforallpracticalpurposesequalto1inthesystem.Reluctance(R)-Ameasureoftherelativeresistaneeofamaterialtothepassageofflux.Itiscalculatedbydividingmagnetomotiveforcebymagneticflux.Reluctanceisthereciprocalofpermeance.Remanence,(Bd)-Themagneticinductionthatremainsinamagneticcircuitaftertheremovalofanappliedmagnetizingforce.ResidualFluxDensity(Br)-See.maxResidualInduction但r)-See.maxReturnPath-Conductionelementsinamagneticcircuitwhichprovidealowreluctaneepathforthemagneticflux.ReversibleTemperatureCoefficient-Ameasureofthereversiblechangesinfluxcausedbytemperaturevariations.Saturation-Thestatewhereanincreaseinmagnetizingforceproducesnofurtherincreaseinmagneticinductioninamagneticmaterial.Shunt-Asoftironpiecetemporarilyaddedbetweenthepoleofamagneticcircuittoprotectitfromdemagnetizinginfluences.Alsocalledakeeper.NotneededforNeodymiumandothermodernmagnets..-Abbreviationfor"SystemeInternational”.ReferstotheInternationalStandardSystemofunits.ItisalsoknownastheMKSsystem.SouthPole-Thesouthpoleofamagnetistheoneattractedtothesouthpoleoftheearth.Thissouth-seekingpoleisidentifiedbytheletterS.Byacceptedconvention,thelinesoffluxtravelfromthenorthpoletothesouthpole.Stabilization-Theprocessofexposingamagnetoramagneticassemblytoelevatedtemperaturesorexternalmagneticfieldstodemagnetizeittoapredeterminedlevel.Oncedonethemagnetwillsuffernofuturedegradationwhenexposedtothatlevelofdemagnetizinginfluenee.SurfaceField(SurfaceGauss)-ThemagneticfieldstrengthatthesurfaceofthemagnetasmeasuredbyaGaussmeter.Acomprehensivetableofthesurfacefieldforallofourstockmagnetsisavailablehere:.TemperatureCoefficient-Afactorthatisusedtocalculatethedecreaseinmagneticfluxcorrespondingtoanincreaseinoperatingtemperature.Thelossinmagneticfluxisrecoveredwhentheoperatingtemperatureisdecreased.Tesla-The.unitformagneticinduction(fluxdensity).OneTeslaequals10,000Gauss.Weber-The.unitfortotalmagneticflux.Thepracticalunitofmagneticflux.Itistheamountofmagneticfluxwhich,whenlinkedatauniformratewithasingle-turnelectriccircuitduringanintervalof1second,willinduceinthiscircuitanelectromotiveforceof1volt.Weight-Theweightofasinglemagnet