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译文:
镁合金电动车轮毂微弧氧化生产研究
指导教师:
张清郁职称:
讲师
学生姓名:
陈孟丽学号:
1002130301
专业:
机械设计制造及其自动化
院(系):
机电工程学院
2015年4月10日
Magnesiumalloyelectricwheelhubmicro-arcoxidationproductionresearch
Mostelectricvehiclesathomeandabroadisconfiguredtoaluminumalloywheelhub,itsquality,energysaving,shockabsorption,noisereductionandvehicledynamicscharacteristicsindexismuchlowerthanmagnesiumalloys.Magnesiumalloyis30%lighterthanaluminumalloy,thedampingeffectis30timesthatofaluminumalloy.Replacethealuminumalloywithmagnesiumalloywheelhub,drivingthedevelopmentofmagnesiumalloymaterialdevelopmentanddeepprocessingtechnology,toreduceelectricvehicleweightandpowerconsumption,energyconservationandenvironmentalprotection;
Toreducevibrationandnoise;
Improveridecomfortandelectricvehicledynamiccharacteristicssuchasobjective(transportationqualityeachreduce10%,energyconsumptionwillbereduced8%~10%).Butitscorrosionresistanceispoor,seriouslylimitstheapplication.Commonlyusedchemicaloxidationandanodeoxidationformationofoxidefilmonmagnesiumalloyhascertainprotectiveeffect,butitscorrosionresistance,environmentalfriendliness,appearanceisnotsatisfactory,bebadlyinneedofthedevelopmentofnewsurfacetreatment.Inrecentyears,peopletryingtodevelopavarietyofnewtechnologies,suchasmicroarcoxidationtechnology,thebetter
OneMicro-arcoxidationmechanism
Micro-arcoxidationtechnologyisanewsurfacetreatmenttechnologyofgreenenvironmentalprotection,cangrowinlightmetalsurfaceinsituceramiclayerdirectly.Itstechnologicalcharacteristics,surfacetreatment,aswellastheperformanceofthesincethetechnologywasinventedbythefavourofpeople,itsmechanismistolightmetalssuchasaluminum,magnesium,titaniumanditsalloyputinelectrolyteaqueoussolutionasanode,usingthemethodofelectrochemicalsparkdischargespotsonthesurfaceofthematerial,thethermalchemistry,plasmachemistryandelectrochemistry,underthejointactionofmetaloxideceramiclayersofasurfacemodificationtechnology
Tworesearchmethodsandtechnology
Thistopicintheresearchonmagnesiumalloyelectricwheelhub,higherrequirementsonthetoughnessofthealloy,sochooseAM60B,meltandinitialtemperatureof468℃,themeltingendtemperatureis596℃,theliquidustemperaturerangeof165℃.Thechemicalcompositionasshownintable1.
Table1AM60Balloychemicalcomposition(WB/%)
Al
Zn
Mn
Si
Cu
Ni
Fe
杂质
余量
5.6~6.4
≤0.20
0.26~0.5
≤0.05
≤0.008
≤0.001
≤0.004
0.02
Mg
Becauseofthemagnesiumalloyelectricwheelhubsurfaceareaislarger,generalabove0.4m2,requiremicro-arcoxidationpowersupplyisbigger,thissubjectadoptsthelanzhouuniversityoftechnologyinstituteofmaterialsanddevelopmentofMAO-300typencmicro-arcoxidationproductiondevice(figure1)micro-arcoxidationonmagnesiumalloywheelcastingprocessing,itssimilartoordinaryanodicoxidationequipment,includingspecialhigh-voltagepowersupply,micro-arcoxidationalkalinesolutionofelectrolytictank,mixingsystem,coolingsystem,workpiecewithstainlesssteelplateforpeerelectrode.
Withmicro-arcoxidationmethodinsodiumsilicateandsodiumhydroxideelectrolytefluidsysteminthepreparationofmagnesiumalloywheelcastingoxideceramicmembrane,theconcretetechnologicalprocessfirstsetoxidationprocessparametersandthealkalinetanksodiumsilicatesolution,thecleaningaftermicro-arcoxidationofmagnesiumalloywheelcastingintocell15~20min,cleanwithclearwatertank2~4min,addhotwaterinhotwater(80℃,10~15min),closed,thencoolinthecoldwatertank2min,hoistedoutdrainage,drying,examinethehub.Aftermicro-arcoxidationtreatmentmustbeclosedbyhotwater,formedbymicro-arcoxidationdischargeholessothedistributionofthechannelandthesurroundingalargenumberofmicrocrackswillbeclosed,preventoxygentocauseoxidation.Aftercompletionofmicro-arcoxidation,fromaftermicro-arcoxidationonmagnesiumalloywheelcastinginterceptfilmsamplewereanalyzed,andtofacilitatetestanalysis,requestsamplesmadeofcircularplate,sothesampleinterceptionlocationchoiceamongwheels,mostisshowninfigure2.Usingscanningelectronmicroscopeanalysisofoxidefilm
Figure1MAO-300typencmicro-arcoxidationpowersupply
Figure2aftermicro-arcoxidationmagnesiumalloywheelhubcastingandinterceptionofmembranelayeranalysissample
Threemicro-arcoxidationprocessparametersonthequalityofthefilm
Basedontheresearchofthesampleandanalysisofmicro-arcoxidationtechnologyis,infact,thesubstratemagnesiummagnesiumoxide.Figure3forthedimensionofsamplesbeforeandafteroxidationappearanceschematicsimulation,whichissuitableforceramicoxidefilmaoutwardgrowth,namelytheincreaseofsizepart,bisthedepthoftheinternaloxidationtothematrix,aandbinterfaceforinitialsamplesurfaceposition,hforthetotalthicknessofoxidefilm.
Figure3samplesdimensionchangesbeforeandaftermicro-arcoxidationdiagram
Largerinfluenceontesthasapositivevoltage,frequency,dutycycle,currentdensityandoxidationtimeontheprocessparameters.Duetotheelectriccastingofmagnesiumalloysurfaceareaislarger,micro-arcoxidationmicro-arcdischargemustbeformedinthesurfacecanoccurafteracertainthicknessofoxidefilm,sotheformationoftheoxidefilmisneededforthevoltagedoesn'
tneedmuch,thecurrentislarger,theoxidefilmformationandtheprocessofthickening,oftenaccompaniedbycurrentandvoltagemutation.Whentheoxidefilmthicknessreachesacertaindegree,theneedtoincreasethevoltageonbothendsoftheworkpiece,usuallyataround150Vinthemicroarcdischargebetweentheworkpieceandtheelectrolyte.Increasedwiththeincreaseofvoltage,current,micro-arcdensityismoreandmoreclose,moreandmorebright,andmicro-arcconstantlybeating,basically,thecurrentandvoltage,linearincreaseabout180Vvoltage,thedensityofmicro-arcbasicallymeetthetechnologicalrequirements,thecurrentgrowthslowly.Whenthethicknessofoxidefilmreachesacertainelectricity
Fromelectriccastingmagnesiumalloysisnothardtofindinthemicro-arcoxidationtestresultanalysis,micro-arcoxidationintheprocesscanbedividedintotwosteps,namelytheoxidefilmformationstageandthestageofmicro-arcoxidationfilmdischarge,theformationofoxidefilmphaseastheinitialstage,thestageofthesupplyvoltageissmall,andafterthefilmtoproducemicro-arcdischargerequireshighvoltage,formagnesiumalloyelectriccastingthelargeworkpiecewithmicro-arcoxidationprocessingsurfaceareaislarger,thefilmforalongtime,toalargeextentaffectedtheproductionefficiency.
Experimentalresultsalsofoundthatthedcpowerofoxidefilmfasterthanpulsepower,intheabsenceofmicroarcdischarge,oxidefilmlayerisnotdense,itcanbeseenfromappearance,needagainwithpulsepowersupplyformicro-arcoxidationdischarge,theoxidefilmbecomemoredense.Inordertoimprovetheproductionefficiency,tomeettheneedsofindustrialproduction,suggestearlylowvoltageadjustabledcconstantvoltagepowersupplyareavailabletosetuptheinitialoxidationfilm,formingacompleteinsulationfilminplacetoensurethatthefirstphase,andtheoxidefilminthelatedischargecanusedigitalpulsetypeadjustablepowersupply,itcanshortentheartifactsofmicro-arcoxidationtime.
Thesizeofthecurrentdensityinacertainextentreflectstheintensityofmicro-arcoxidation,stronglyaffecttheresultingperformanceofthemicroarcoxidationceramiclayer.Thedurationofoxidationalsoseriouslyaffectsthecoatingcorrosionresistance:
oxidationtimeistooshort,althoughgeneratedmainlythedenselayer,butthefilmistoothin,don'
thavegoodcorrosionresistance;
Afteroxidationtimeistoolong,atsometime,withtheincreaseoftime,althoughtheoverallfilmthicknessincreases,buttheincreaseisalooselayer,layerdensityandthinningtrend,doesnotfavorthecoatingcorrosionresistance,alsonoteconomic.Thedensityofmicroarcalsorelatedwiththepulsefrequency,whenthepulsefrequencyincreases,thedensityofmicroarcalsograduallyincreased.Willhavetheelectricfieldsetupsuddenly,canproducemicroarc.Inthebasicprocessparameterssuchaselectrolyteconcentration,dutyratioandpulsenumberofuncertain,thearcvoltageisconstantcommonly,sowhenthefrequencyincreases,thesustainmicro-arcvoltagefrequencyincreases,themicro-arcdensitywillincrease
Fourmicro-arcoxidefilmlayerstructurecharacteristics
Aftermicro-arcoxidationofmagnesiumalloywheelhubinterceptionbyMef3largemetallurgicalmicroscopeobservationofthesample,themicro-arcoxidefilmsurfacemorphologyasshowninfigure4.Canbeseenfromthefigureinthewheelhubsurfacelayerismadeupofmanytiny"
smallvolcaniccone"
(figureprotuberantpartaroundtheholes)indendriticcombination,constitutethemeshstructure."
Smallvolcaniccone"
centerhasasmallhole,thisistheelectrolytereactionwithmatrixmicro-arcdischargechannel,namelywhenthemicro-arcspewedmoltenoxidechannel.Inaddition,becausethecurrentmicroarealocalplasmachannelisdifferentthatdifferbythesizeofthehole,bigholearealsodistributedaroundalargenumberofmicrocracks,thegenerationofmicrocracksoftenrelatedtothestressthatex