filedhighfrequency

ResearchonHigh-frequencyinductionbrazingofPCDCutToolBeiSuna,1,*MiaoYangb,2,ZhiyiZhangc,21CollegeofMechanicalandEngineering,BeihuaUniversity,Jilin,132021,China2EngineeringTrainingCenter,BeihuaUniversity,Jilin,132021,Chinaaemail:1512974922@qq.
com,*correspondingwriterbemail:yangmiao1021@163.
com,cemail:zyzhang6@163.
comKeywords:highfrequencyinductionbrazing;Brazingfilleralloy;PCDcompact;microstructureAbstract.
ThemorphologiesofthebrazingfillarestudiedbySEMandEDS.
ThebindingforceanduselifeofPCDcuttoolarestudiedtoo.
Theresultsshowsthatthequalityofweldfillisthebestwhentimeis13and15s.
Meanwhile,theweldfillshowsmetallurgicalbond.
TheInterdiffusionofmatrixalloyandweldfillhelpstoimprovethemechanicalpropertiesofthebrazedfill.
TheoverheatfromlongtimeofhighfrequencywillcausethePCDcarbonization,whichshortentheuselifeofthetool.
IntroductionAsapropermaterialforcuttinggraphiteelectrodes,thePCDcuttingtooliswidelyusedduetoitshighhardness,highwear-resistanceandhighintensionofhardalloy[1].
ThePCDcuttingtooliscomposedofPCDcompactandbasematerial.
Usually,itcanbeobtainedbymeansofbrazingwithproperbrazingfilleralloy,solderingflux,acertainPCDcompactandbasematerial,thengrindedwithseveralmethods.
Thehigh-frequencyinductionbrazingiscommonlyusedinthebrazingofPCDcompactrecently[2-5].
Asitiswellknown,highfrequencyinductionheatingisefficiencyandhighspeed.
So,brazingtimehasasignificantimpactonthePCDtoollife.
ExperimentalproceduresTheexperimentisactuallythebrazingbetween45#steelandcarbidealloy,whichisthebottomsheetofthePCDcompact.
ThecomponentsofexperimentalbrazingfillerweredetectedbyICP-AESandlistinTable1.
ThecarbidealloyismainlycompositeofWC.
Thehigh-frequencyequipmentisWH-WI-26.
ThechemicalcompositionsofsolderingfluxwerelistinTable2.
Beforewelding,thetwomaterialwerefiledwiththeraspinordertoimprovetheweldingstrength.
Thenthesampleswerewashedwithethanolinultrasoniccleaningmachine.
Theweldingtimeis7,9,11,13,15,17,19s.
Theshearforcemeasurementwasusedforcharacterizeofweldstrength.
Theuse-lifeofthePCD-knifewasmeasuredbymachiningcarbonelectrode.
Andeverydaymachiningtimeis7hours.
ThemicrostructureoftheweldswererecordedandanalyzedbyJSM-5600SEMequipment.
Table1compositionsofexperimentalbrazingfillerTable2chemicalcompositionsofsolderingfluxKFKBF4B2O3Compositions(wt.
%)422335ResultsanddiscussionA.
WeldFigure1showstheSEMmorphologiesoftheweldfillswhichthebrazingtimeis13,15,17sseparately.
FromFigure1(a),theweldfilliswellcombinedwiththestealside,thoughithassomeAgCuZnNiCoCdMelting-pointComposition(wt.
%)48.
715.
615.
51.
21.
819.
2750℃pores.
InFigure2(b)and2(c),boththeweldfillsaresmoothandwithoutcracks,poresorinclusions.
FromFigure1,thebasematerialandthemeldfillsaremetallurgicalbondingandthecombinationsurfacearecloselytight.
Theintragranulardiffusionappearsbetweenweldandbasematerial.
TheAg,Cu,Zn,Cointhemeldbecometosolidsolution.
Figure2showstheEDSresultsofbrazingtime13s.
Frombottomtotop,therearecarbide(WC),weldfill(Ag,Cu)and45#steel(Iron).
Themicrostructureoftheweldfillappearsboundarydiffusion.
Thatmeansatthebrazingtimeof13s,theheatingofthehigh-frequencymagneticfieldmakethebothsidesoftheweldmeltedandcombined.
Whenmaterialisheatedbyhigh-frequencymagneticfield,theeddycurrentasfollow[6]:eIIxxδ10=(1)Ix--thecurrentatthedistancex;I0--thecurrentatthetop;δ--themodulusoffrequencyandthephysicalpropertiesofmaterials.
Atthedistanceof1/e(=0.
368),theδcalledskindepth.
fρδ41003.
5*=(mm)(2)ρ---theelectricalresistivity;---themagneticpermeability;f---thefrequencyoftheelectricity.
Intheheatingprocess,whenthetemperatureofthesteelisreachto800~900℃,cm≈410ρ,T1≈,thenf503=δ,(3)thefrequencyoftheequipmentis300~500KHz,9.
0~7.
0=δ(mm).
So,theheatingdepthinthisresearchislessthan0.
9mm.
Figure3showstheEDSresultsofthecarbideandweldfillofbrazingtime15s.
Meanwhile,Figure4showstheEDSresultsofthe45#steelandweldfillofbrazingtime15s.
FromFigure3and4,thematerialofweldandthebasealloysbothoccursmutualdissolution.
Theamountofbasealloysdissolvedislistas[4]:()VSteSVCGαρ=1(4)G--theamountofbasealloydissolvedperunitarea;ρ--thedensityofliquidbrazingfill;V--thevolumeofliquidbrazingfill;S--thecontactareaofliquidandsolid;α--thesolubilitycoefficientofthebasematerialinliquidbrazingfill;t--thetimeofcontact.
Theamountofbasealloydissolvedwouldchangedthecompositionofthebrazingfill,whichimproveditsstrengthandhardness.
Accordingtoformula2.
4,theincreasingofthevolumeofliquidbrazingfill,temperatureandthesolubilitylimitwouldleadedtoincreasingthebasealloydissolvedexcessively.
So,properprocessparametersshouldbechosentoavoidoverdissolvingofbasealloy.
Otherwise,thematerialinbrazingfillalsomovetothebasealloy.
Accordingtodiffusionlaw[7]:dtDDDSDxcm=(5)mD--Theamountofbrazingfilldiffusionintobasealloy;D—diffusioncoefficient;S—diffusionarea;xcDD--concentrationgradient;dt--diffusiontime.
Fromformula(5),inthisexperimentthetemperatureisthemostimportantfactor.
Andthetemperatureisstraightlytotheusetimeofthehighfrequency.
Inthisstudy,theweldtimewaschosedfrom11to15s,whichwouldgetproperfusionheat.
(a)Bindingregions(b)Bindingregions(c)BindingregionsFigure1TheSEMmorphologiesofbrazingtime13s(a),15s(b)and17s(c).
Figure2TheEDSresultsofthebrazingtime13s.
Figure3TheEDSresultsofthecarbideandweldfillofbrazingtime15s.
B.
WeldingStrengthThestrengthoftheweldwithbrazingtimeisshowninFigure1.
Thestrengthofweldincreaseswithbrazingtimetill15s,thendecreases.
Duetotheskineffectofthehighfrequencyinductionheatingtheweldingfluxattheweldsmeltsfirst.
Thentheinsideoftheweldsmeltsrelyonconductionheating.
Withtheincreasingofthebrazingtime,thetemperatureofthesampleincreaseswithhighspeed.
TheAg,Cu,Zn,Ni,CoandCdinthebrazingfillmeltedandbecametosolidsolution.
Themoltenstateofbrazingfilltheweldgapbycapillaryaction.
Meanwhile,thebasemetaldissolvedintothebrazingfillduringthebrazingprocess.
Thestrengthofthebrazingfillshowsthattheheatofthehigh-frequencyinductionisbenefittoimprovethebindingforceofthesteelandcarbidein15s.
Thealongwiththeheatingtime,thecompositionoftheweldfillturnedtobedestroyedbytheexcessiveheat.
C.
Use-lifeFigure6showstheuselifealongwiththebrazingtime.
Theuselifeincreasedwithbrazingtimetill15s,thendecreased.
Whentimeincreasedto19s,theuselifedroppedtojust6hours.
TheuselifewasaboutthePCDcuttinglifeforcarbonelectrode.
Thoughthestudyfocusontheweldfill,thefinalaimwastoproducePCDcuttool.
Formtheanalysisoftheweldfill,thefusionheatnotonlyinfluencethequalityoftheweldfillbutalsothePCDuselife.
CisthemainelementinPCD,theexcessivelyhightemperaturewouldleadthePCDtocarbonizedandbecomeinvalid.
Thatisseriouslyissuetoconsider.
Inthisstudy,itshouldbeasshortaspossibletodeterminetheweldingtime.
CombineFigure5and6,theproperweldingtimeis15s.
Figure4TheEDSresultof17sFigure5.
ThestrengthoftheweldfillwithbrazingtimeConclusionThebrazingfillofsteelandcarbidealloyonPCDknifeisstudied.
Theconclusionsareasfollows:1).
Thequalityofweldfillisthebestwhentimeis13and15s.
Meanwhile,theweldfillshowsmetallurgicalbond.
2)TheInterdiffusionofmatrixalloyandweldfillhelpsimprovethemechanicalpropertiesofthebrazed.
3)TheoverheatfromlongtimeofhighfrequencywillcausethePCDcarbonization,whichshortentheuselifeofthetool.
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Figure6.
Theuse-lifeoftheweldfillwithbrazingtime