Introductiontothedevice
Accordingtoitsfunction,vacuumelectronicdevicescanbedividedintoelectrostaticcontroltubesthatrealizetheconversionbetweenDCelectricenergyandelectromagneticoscillationenergy;convertDCenergyintoafrequencyof300MHz～3000GigahertzMicrowaveelectrontubeswithHertzelectromagneticoscillationenergy;electronbeamtubesthatusefocusedelectronbeamstorecord,store,convertanddisplaylightandelectricalsignals;photoelectrictubesthatusephotoelectronemissiontoachievephotoelectricconversion;X-raytubesthatgenerateX-rays;insidethetubeInflatabletubesfilledwithgasandgeneratinggasdischarge;vacuumquantumelectronicdevicesthatamplifyelectromagneticwavesusingvacuumandstimulatedradiationofparticlesinthegasastheworkingmechanism.Sincethe1960s,manyvacuumelectronicdeviceshavebeengraduallyreplacedbysolid-stateelectronicdevices.However,inthefieldofhighfrequencyandhighpower,vacuumelectronicdevicesstillhaveconsiderablevitality,whileelectronbeamtubesandphotoelectrictubeswillstillbewidelyusedandhaveDeveloped.Vacuumelectronicdevicesincludevacuumcircuitbreakers.Vacuumcircuitbreakershavemanyadvantages,sotheyarewidelyusedinsubstations.VacuumcircuitbreakershavebeenincludedinKuaiyiyou.Duetotheuseofspecialvacuumcomponents,withtheimprovementofthemanufacturinglevelinrecentyears,thefailureofthearcextinguishingchamberhasbeensignificantlyreduced.Thevacuuminterrupterdoesnotneedtoberepaired.Whenitisdamaged,itcanonlybereplaced.Theoperatingmechanismpartaccountsforalargerproportionofthefaultsthatoccurduringtheoperationofthevacuumcircuitbreaker,followedbytheprimaryconductivepartandthecontactconductiverod.
Manufacturing
Thepartsareprocessed,assembled,andmanufacturedintovacuumelectronicdevices,andthroughaging,adjustment,andtestingtomeettheperformancerequirementsspecifiedbythedesign,thisentireprocessandmethodThatisthemanufacturingprocessofvacuumelectronicdevices.
Themanufacturingprocessofvacuumelectronicdevicesvarieswiththetypesofdevices,butintermsoftheircommoncharacteristics,theygenerallyincludepartsprocessing,componentmanufacturingandtesting,assembly,exhaustandotherprocesses(figure1).Somedevices,suchascameratubesandpicturetubes,alsousesomespecialmanufacturingprocesses,suchasgasfillingprocess,coatingprocess,ionetchingandphosphorscreencoatingprocess.
Reasonsandmethodsforvacuumcircuitbreakerrefusaltoopen
1.Electricalcircuitfailure
①TheDCvoltageistoolow;②OperationinsuranceandtripcircuitcomponentsPoorcontactorshortwire;
③Thetripcoilisbroken;④Theswitchisunqualifiedunderlowvoltage;⑤Thetrolleyorswitchinterlockingcontactisinpoorcontact.
2.Mechanicalcircuitfailure
①Thethreepointsofthethreeconnectingplatesaretoolow;②Thetopbaroftheswitchisstuckorfallsoff;③Theclosingbufferoffset,therollerandthebufferbararestuckstrength.Findingmethod:Whentheelectrictripfails,youshouldfirstdeterminewhetheritisanelectricalcircuitfailureoramechanicalcircuitfailure.Whentheejectorcoredoesnotmove,itmeansthetripcircuit,otherwiseitisamechanicalcircuitfailure,andthenfurtherfindoutthecause.Whentheswitchisfoundtobeoutoforder,itshouldbeopenedmanually.
3.Reasonsforthevacuumcircuitbreaker’srefusaltocloseandjumpsandtreatmentmethods
3.1.Thelengthoftheclosingironcoreejectorrodoftheelectromagneticoperatingmechanismisnotenough,andthelengthoftheironcoreejectorrodshouldbeadjustedMakethegapbetweentherollerandthebracketmeettherequirementof2±0.5mm.
3.2.Theauxiliaryswitchisdisconnectedtooearly.Atthistime,adjustthelengthoftheauxiliaryswitchlevertomakeitopenafterthecircuitbreakercontactsareclosed.
3.3.Theclosingspringlimitofthespringenergystorageoperatingmechanismisunreliableandtheclosingisnotinplace.Theclosingspringenergystorageisover,butthemotorpotentialcannotbecutoff.
4.Thespringenergystorageswitchcannotbeclosed
4.1Thepoweroftheclosingspringisnotenough,replacetheclosingspring.
4.2Whentheswitchisclosed,itisinahalf-openandhalf-closedstate.Adjustthegapbetweenthecamandtherollertoincreaseit,andadjusttheovertraveltodecreaseit.
Partsprocessing
Thepartsareprocessedfirstbeforeassemblingandmanufacturingthedevice,thepurposeistomakethepartitselfclean,havelessaircontent,andeliminateinternalstress.
Cleaning
Metalpartsareusuallycleanedwithgasoline,trichloroethylene,acetoneorsyntheticdetergentsolutionstoremoveoilstainsonthesurface,andthentreatedwithacidsandalkalis.Removetheoxidelayerorrustonthesurface.Sometimesultrasoniccleaningcanbeperformedintheaboveliquidtoobtainbetterresults.Theglassshellorpartscanbetreatedwithmixedacid.Allpartsafterchemicalcleaningmustbethoroughlywashed.Aftertheceramicpartsaredegreasing,chemicallycleanedandwashedwithwater,theycanbefiredinamufflefurnaceforabout1,000tomakethesurfacecleaner.
Annealing
Thecleanedpartsareheatedtoacertaintemperaturebelowtheirmeltingpointandkeptforacertainperiodoftime,andthenslowlycooledtoeliminatethepartsintheprocessingprocessThestresscausedin.Mostmetalsshouldbeannealedinaprotectivegasorvacuumtoavoidoxidation,whilealsopurifyingthesurfaceandremovingthegascontainedinside.Theglasspartscanbeannealedinanairfurnaceafterprocessing.
Surfacecoating
Inordertoavoidoxidationduringthemanufacturingprocess,facilitateweldingorreducehigh-frequencylossduringuse,somepartsmustbecoatedonthesurfaceNickel,copper,goldorsilver,etc.Somepartsmustbepre-coatedwithaspecialcoating.Forexample,theattenuatorusedinthemicrowavetubecanbecoatedwithalayerofhigh-frequencyattenuatingmaterialbycarbonization,graphitespraying,vacuumevaporation,sputtering,andothermethods.Somepartsalsoneedtobecoatedwithacertainmaterial,suchastantalumcarbide,toincreasethesurfaceworkfunctionandreducethesecondaryemission.
Manufacturingandtesting
Inordertoensurethattheelectrodesofthedevicecanbeassembledaccuratelyandreliablyaccordingtothedesignrequirements,severalpartsandcomponentsarepre-made.Somecomponentsmustbetestedforelectricalparameters(alsocalledcoldtest),andthecomponentsthatmakeupthetubeandshellmustbetestedforairtightnessandcanbeassembledonlyaftertheyarequalified.Themainmanufacturingprocessesincludemounting,sealing,weldingandtesting.
Mountingframe
Assemblepartsintocomponentssuchascathode,electrongun,grid,slowwavecircuit,anodeorcollector,orfurtherassembleintowaitingSealedtube.Theweldingmethodsusedwhenmountingtherackarespotwelding,atomichydrogenwelding,laserweldingandultrasonicwelding.Sometimesmicro-beamplasmawelding,electronbeamweldinganddiffusionweldingarealsoused.
Glasssealingprocess
Thefusionsealingbetweenglassandbetweenglassandmetalisoneofthecommonlyusedprocesses,andmostofthemhavebeenautomated.Usethistechnologytomakeelectrodeleadsorstems,andsealtheshellandstemtogether.
Indiumsealingprocess
Thevacuumsealingbetweentwokindsofglassorglassandvariouscrystals,glassandmetalwithverydifferentexpansioncoefficientscanbeusedwithhighPureindiumiscoldpressedassolder.Thisprocessisoftenusedforthesealingbetweenthecameratubewindowandthetubeshell.Itissuitableforvacuumsealingofpartsthatcannotwithstandhightemperatures,andindiumcanbeusedasanelectrodeleadwire.
Ceramicmetalsealing
Inordertorealizethesealingofceramicinsulatorsandmetalpartstoformparts,sinteredmetalpowdermethodandactivemetalmethodarewidelyusedTwoprocesses.Theformeristocoatmolybdenum,manganeseandothermetalpowders(sometimesaddasmallamountofoxidesasactivators)onthesurfaceoftheceramictobesealed,andthensinteritintoametalizedlayeratatemperatureintherangeof900to1600inahydrogenfurnace.Afternickelplating,itissealedwithsolderandmetal.Theactivemetalmethodusesactivemetalssuchastitaniumandzirconiumandsolderoralloysoldercontainingactivemetalstoheatupinavacuumfurnacetoatemperatureslightlyhigherthanthemeltingpointofthesoldertoformaliquid-phaseactivealloytowettheceramicandmetaltocompletethesealing..Inadditiontothesetwoprocesses,therearealsoprocessessuchasoxidesoldering,diffusionsealing,andsealingusingevaporationorsputteringmetallization.Figure2showssomecommonlyusedceramic-metalsealingstructures.
Brazingandargonarcwelding
Themetal-to-metalconnectionoftenadoptstheprocessofbrazinginahydrogenfurnaceoravacuumfurnace.Ifthepartsneedtobebrazedmultipletimes,highmeltingpointsoldersshouldbeusedfirstandthenlowmeltingpointsoldersshouldbeusedforstepwisebrazing.Ifthepartsaredesignedtohaveaflangedflangestructure,theycanbeconnecteddirectlybyargonarcwelding.
Test
Somehigh-frequencysystemcomponents,suchasresonators,slow-wavecircuits,etc.,shouldbe"coldtest"aftertheyaremanufactured.Checkitselectricalperformance.Someadjustmentscanbemadetothecomponentsifnecessary.Foroptoelectronicdevices,afterthetargetsurfaceismade,itneedstoundergodynamictestingtoverifyitsperformance.Sealed,brazedorargonarcweldedparts,suchaspartoftheshell,mustusealeakdetector(suchasheliummassspectrometer,etc.)totestthesealingperformanceoftheweldseam,andcanbeusedinthefinalassemblyafterbeingqualified.
Assembly
Thecomponentsthathavepassedtheinspectioncanbeassembledintothewholetubebyhigh-frequencyconcentratedwelding,brazingorargonarcwelding.gas.Ifitisaglasstubeshell,thetubecoreandtheshellshouldbeassembled,andthejointshouldbesealedbyflame,thatis,theseal.Sometimes,afterthefinalassembly,anoverallleakcheckisperformedbeforeexhausting.
Exhaust
Theprocessofextractingthegasinsidetheassembleddevicetomakethepressurereach10-5Paorlessiscalledexhaust.Intheexhaustprocess,itisnecessarytocarryoutdegassingofthetubeshell,degassingoftheelectrode,decompositionandactivationofthecathode,etc.,toensurethenormaloperationofthetube.Theexhaustsystemisusuallyasysteminwhichamechanicalpumpandanoildiffusionpumpareconnectedinseries.Inrecentyears,anoil-freeexhaustsystemhasbeengraduallyadopted,whichhelpstoimprovetheperformanceofthedevice(seevacuumacquisitiontechnology).
Baking
Intheexhaustprocess,externalheatingmethodsarecommonlyusedtobakeanddegastheshellandparts,andthenexhaustbytheexhaustsystemOutsidethetube.Inordertopreventoxidationofthemetalpartofthetubeandshell,avacuumdryinghoodisofteninstalledoutsidethevacuumdeviceforbakinginavacuumenvironment,whichisalsocalled"dualvacuumexhaust".
Electrodedegassing
Inadditiontoexternalbakinganddegassing,theelectrodesysteminthetubecanalsobeheatedbyhighfrequency,electronbombardmentanddirectelectricheating,etc.Methodfordegassing.Theheatingtemperatureshouldbehigherthantheusetemperature.
Cathodedecompositionactivation
Foroxidecathodes,thecathodemustbeheatedduringtheexhaustprocesstodecomposecarbonateintooxides.Inordertoimprovetheemissioncapabilityofthecathode,thecathodetemperatureshouldbefurtherincreasedoractivatedbyamethodofdrawingalargercurrent.Thedecompositionandactivationofthecathodeisalsocarriedoutafterthetubeissealedoff,suchasthe"under-stagedecomposition"ofapicturetube.
Sealingoff
Attheendofthedeviceexhaustprocess,whenthegaspressureinthetubeisbelow10-5Pa,separatethedevicefromtheexhaustsystemandkeepitThesealingprocessiscalledFengLi.Fordevicesusingglassexhaustpipes,flamesprayexhaustpipesareusedtofusetheglassandseparateitfromtheexhaustsystem.Fordevicesthatusemetalexhaustpipes,specialclampsareusedtodirectlyclampthemetalpipe,andtheclampingmouthfunctionsasasealtomaintainthevacuumstateinthepipe.Devicescontaininggettermaterialsoftenusehigh-frequencyinductionheatingtoevaporatetheevaporativegetteroractivatethenon-evaporablegettertoabsorbresidualgasinthedevicetofurtherimprovethevacuum.
Aging
Theprocessofelectricaltreatmentofexhausteddevicestoobtainstableelectricalperformanceiscalledaging.
First,undertheconditionofcathodeheating,anormalorslightlyhighervoltageisappliedtoeachelectrodeforacertainperiodoftimetofurtherdegastheelectrodeandstabilizethecathodeemissioncurrentandotherparameters.Forhigh-voltagedevices,beforeaging,withoutheatingthecathode,applyahighervoltagethantheworkingvoltagebetweentheelectrodes,andusethedischargephenomenontoremoveburrs,dustandstainsonthesurfaceoftheinsulatingpartsontheelectrodesinthedevice.Etc.,soastoavoidflashoverwhenthedeviceisinuse.Inordertomaintainsufficientvacuuminthedevice,somedevicesarealsoequippedwithtitaniumpumps.
Test
Theperformanceofthedeviceneedstobetestedafteraging,andthemainparametersshouldreachthepredeterminedindex.Thiskindoftestisalsocalled"thermaltest".Inordertobereliableinuse,routinetestssuchasdynamiccharacteristictest,lifetest,impactresistancetest,earthquakeresistancetest,andcold-heatcyclemustbesampled.
Inflationprocess
Somedevices,suchaszenertubes,thyratronsandiondisplaydevices,mustbefilledwithacertainspecialgassuchashydrogen,Helium,neon,argon,etc.Thegasisfilledattheendoftheexhaustprocess.Theinflatedgasmustbeverypure,socertainmeasuresmustbetakenandcarefullycontrolledduringtheinflatingprocess.
Coatingprocess
Inthemanufacturingprocessofmodernvacuumelectronicdevices,thecoatingprocessiswidelyused.Thecoatingprocessincludesvacuumevaporation,sputtering,ioncoatingandchemicalvapordeposition.Whenmakingcameratubesandphotomultipliertubes,varioustransparentconductivefilms,photocathodesandlightguidetargetsurfacematerialsaremadebyvacuumevaporation.Theinnersurfaceofthefluorescentfilmofthepicturetubeisoftensteamedwithaluminumfilmtopreventthefluorescentfilmfrombeingburned,anditcanalsoimprovethebrightnessandcontrastofthetube.Moderncoatingtechnologyisalsousedtochangethesurfacestateofcertainmaterials,tomakecathodes,tometalizethesurfaceofceramicsorotherdielectricsatlowtemperature,andtoachievehigh-frequencyandlow-losssealing.
Ionetching
Thisisanewtypeofmicrofabricationmethodthatusesionenergytograduallypeelsolidatomsormoleculesfromthesurfacelayer.Theuseofmaskscanproduceprecisepatterns.Thisprocesscanbeusedtopeeloffthesurfaceofthedeviceparts,removetheorganicfilm,andcleanthetargetsurfaceofthecameratubecrystalormakethefinemeshofthetargetsurface(seeelectronbeamandionbeammicroprocessing).
Fluorescentscreencoating
Theinnersurfaceofthepicturetubeandoscilloscopescreenmustbecoatedwithauniformlayeroffluorescentmaterial.Themethodofcoatingthescreenshouldtrytokeepthefluorescentpropertiesofthematerial.Therequirementsforthecoatingareuniform,particlesizedistributionmustmeetcertainrequirements,goodvacuumperformance,smalloutgassing,andsufficientadhesionstrength.Screencoatingmethodsmainlyincludeprecipitationmethod,slurrymethodanddrymethod.
Precipitationmethod
Blackandwhitepicturetubesandoscilloscopetubesarecommonlyusedtocoatscreensbyprecipitationmethod.Cleantheglassscreenfirst,injecttheworkingsolutioncontainingpotassiumsilicate,andtheninjectthesuspensioncontainingphosphor.Afteracertainperiodofstandingandsettling,pourouttheremainingliquid,passinaflowofhotairofabout60,andatthesametimeuseinfraredlampsorhotairtoevenlyheatitfromtheoutsidetomakeitdry.Itisfiredat400-450toremoveorganicimpuritiesintroducedduringthecoatingprocess.
Powdermethod
Thephosphorscreenofcolorpicturetubeismostlycoatedwiththephosphorpowdermethod,thatis,thephosphorpowdercontainingwater-solublephotosensitiveglueisusedtoinjectthescreenSpincoatingonthesurfacetomakethephosphorpasteevenlydistributed,andthenitismanufacturedthroughthestepsofopticalexposureanddevelopment(washingwithwarmpurewater).
Threekindsoffluorescentmaterialsneedtobeappliedthreetimesinsuccessiontofixthemonthecorrespondingpositions.Sometubetypesneedtobecoatedwithgraphiteblackinadvanceinthepositionbetweenthethreetoners.Thefluorescentfilmshouldbecoatedwithalayeroforganicfilmbythesolutionmethodfirst,andthenthealuminumfilmshouldbevaporizedtoensurethatthesurfaceofthealuminumfilmisbright,andtheorganicfilmwillbeburnedoffinthesubsequentfiring.Becausethescreeniscoatedwithphosphorpowderandcannotwithstandthehightemperatureofglassmelting,lowmeltingglasssoldermustbeusedtosealthescreenandtheneckconeassemblyataround440.
Drymethod
Thisisanewlydevelopedopticalbondingprocess,whichbelongstothedryprocessofcoatingscreen.
Firstapplyahydrophobicpre-coatingfilmonthescreensurface,andthenapplyalightadhesive.Sincethephoto-adhesiveisstickywhenexposedtolight,aftersprinklingdryphosphorpowder,aircanbeusedtoblowthescreentoblowoffthepowderintheunexposedparttoachievethepurposeofcoatingthescreen.Thephosphorsofthethreecolorsofthecolortubeareappliedinthreetimes.Theprocessissimple,lowincost,fluorescentfilmhashighbrightnessandhighresolution,andcanmeettherequirementsofultra-high-precisiontubesforcoatingscreens.
Mainproductclassification
Productsmainlyinclude:
——Electronictubes:receivingamplifiertube,transmittingtube,locktube,UHFtube,stabilizerTubes(stabilizertube,constantcurrenttube,constantamplitudetube),etc.;
——Microwavetube:magnetron,klystron,backwardwavetube,travelingwavetube,gas-filledmicrowaveswitchtube,frontDirectionalwavequadraturesoundfieldamplifiertube,noisetube,microwave
Bibliography
EditedbyMoChunchangandChenGuoping:"ElectricVacuumTechnology",NationalDefenseIndustryPress,Beijing,1980.
LiuLianbao,editorinchief:"BrazingandCeramic-MetalSealingofElectricVacuumDevices",NationalDefenseIndustryPress,Beijing,1980.
H.KohlWalter,TheHandbookofMaterialsandTechniquesforVacuumDevices,ReinholdPub.Corp.,NewYork,1967.