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PLASMAPASTEBORONIDINGTREATMENTOFTHESTAINLESSSTEELAISI3041INTRODUCTIONAA3003ALLOYSINRECENTYEARS,THEDEVELOPMENTOFSURFACETREATMENTPROCESSHASBEENEXTENSIVERESEARCHTOIMPROVETHEAPPLICATIONOFSTAINLESSSTEELUNDERHIGHTEMPERATUREANDPRESSUREWEARANDOXIDATIONRESISTANCESTAINLESSSTEELSURFACETREATMENTMETHODSAVAILABLE,INCLUDINGNITROGEN2,CARBURIZING,PLASMACOATING,BORONPENETRATIONINPARTICULAR,THEBORIDEISBORONPENETRATIONANDDIFFUSIONINTOTHESURFACEOFTHEBORIDELAYERHARDNESSHVBETWEENIN13002100OFTHESURFACETREATMENTBORIDELAYERHASEXCELLENTHEATRESISTANCEANDCORROSIONRESISTANCE,ANDBORIDEHAVEBEENAPPLIEDTOIMPROVETHEVALVE,BURNERS,NOZZLESANDOTHERSURFACEPROPERTIES,WHENTHEYAREEXPOSEDTOHIGHTEMPERATUREANDPRESSUREWHENINTHEWATERANDOILRECENTLY,HOWEVER,IMPROVEDTECHNOLOGYSUCHASPLASMABORONIZINGINFILTRATIONPROCESSHASBEENEXTENSIVELYSTUDIED,BECAUSETHETRADITIONALBORONIZINGPROCESS,SUCHASTHEOFFICIALSALTBATHANDGASNITRIDINGBORONBORONWILLAPPEAR,SUCHASENVIRONMENTALPOLLUTION,TOXIC,EXPLOSIVENATUREOFTHEPROBLEMPLASMABORONIZINGHASMANYADVANTAGESOVERTRADITIONALBORONIZINGPROCESSFOREXAMPLE,EXPECTAHIGHENERGYEFFICIENCYASASOURCEOFHIGHENERGYPLASMATOBEUSEDINPLASMABORONIZINGPROCESS,ANDDISTORTIONCANBEMINIMIZED,BECAUSETHEPROCESSINGTEMPERATUREISRELATIVELYLOWERTHANTHETRADITIONALPROCESSHOWEVER,PLASMABORONIZINGPROCESSALSOHASITSOWNLIMITATIONSBZH6ANDBC13GASWASUSEDASABORONSOURCEGAS,BUTGASISRELATIVELYEXPENSIVEANDTOXIC,EXPLOSIVEINAVACUUMCHAMBERBYBORONCHLORIDECORROSIONISANOTHERSERIOUSPROBLEMFORTHEPLASMABORONIZINGINTHISSTUDY,ASTHEDEVELOPMENTOFASOLUTIONTOTHEPROBLEMMENTIONEDABOVEANDMOREINTHEPROCESSOFBORONPENETRATIONINONEATTEMPT,INVOLVINGTHEUSEOFAMORPHOUSBORONANDBORAXNA2B4O7CREAMISASIMPLEPROCESSOFPLASMAPASTYBORONIZINGMETHODSHAVEBEENDESIGNED,THEBESTPLASMABORONIZINGPASTEHASCONDUCTEDASURVEYOFPROCESSCONDITIONS,THUSTHEFORMATIONOFBORIDELAYERMETHODHASCERTAINCHARACTERISTICS2EXPERIMENTALTHEREALAISI304STAINLESSSTEELSPECIMENSDIAMETER15MM,THICKNESS25MMWASUSEDFORTHISTESTSANDPAPER1200,AFTERPOLISHINGTHESURFACEOFTHESAMPLESPECIMEN,CLEANOFFTHEDIRTAFTERTHESAMPLESAREBROUGHTINTOTHELABORATORY,INTHEH2ATMOSPHEREFORSPUTTERCLEANINGOFTHESPECIMENISTHEFIRSTTOBECARRIEDOUTINARH221GASENVIRONMENT,WITHDIFFERENTPROPORTIONSOFBORONANDBORAXMIXTUREOFBORONPENETRATIONAGENTSDOBORONIZINGPLASMATREATMENTBEGAN,IN1023,1073,1123,1173AND1223KSEVERALHEATEDATDIFFERENTTEMPERATURESFORUPTO7HOURSUSINGMICROSCANNINGELECTRONMICROSCOPEHITACHI52400TOSTUDYITSMICROSCOPICSTRUCTURE,ACCELERATINGVOLTAGEOF20KVELECTRONMICROPROBEANALYSISDONEVICKERSHARDNESSWASMEASUREDUSINGA01KGFORCELOAD,USINGTHEAVERAGEOFSEVENREADINGSCUKRAYDIFFRACTIONXRAYDIFFRACTIONANALYSISWASUSEDPLASMAPASTYBORIDEOFAPPARATUSANDDETAILSOFOTHERTRIALSINREFERENCE6USINGDESCRIPTION3RESULTSANDDISCUSSION31CREAMMIXTURERATIOOFBORIDELAYERFORMATIONFIG1THEEFFECTOFVARIOUSRATIOSOFAMORPHOUSBORONANDBORAXMIXTURETHICKNESSOFTHEBORIDELAYERFIG1SHOWSTHEPROPORTIONOFPASTEWITHDIFFERENTBORIDEINTHE1123KTEMPERATUREINSULATION15HOURSAFTERTHEBORIDELAYERTHICKNESSOBSERVEDWITHTHEMASSFRACTIONOF20AND70OFBORAXTOFORMATHICKBORIDELAYERANDWITHTHEMASSFRACTIONOF100OFAMORPHOUSBORONTOFORMANYMEASURABLETHICKNESSOFBORIDELAYERISNOTOBSERVED,WHICHMAYBEATTRIBUTEDTOTHEPENETRATIONOFBORONINPLASMADURINGTHEAMORPHOUSBORONASTHEMELTINGPOINTDUETOSURFACEDIFFUSIONOFTHELACKOFACTIVITYOFBORONWHENTHEMASSFRACTIONOFBORAXTO20,THEACTIVEFORMOFTHEBORIDELAYERWASOBSERVEDDURINGTHEINFILTRATIONOFBORON,BORONATOMS,B0,ISCREAMOFTHEBORONHYDRIDEBNHMOFDECOMPOSITION,ANDTHEBORONATOMSINTOTHEMOLTENBORAXORB0GLOWDISCHARGEINTHEACTIVEBORONATOMSB1FINALLY,THEBORONATOMS,B1,PROLIFERATION,ANDIRONREACTION,ANDTHENTHEFORMATIONOFBORIDELAYERWITHTHEMASSFRACTIONOF30AND70OFTHEBORONPASTEOFBORAXBORIDELAYERFORMATIONWASALSOOBSERVED,WHICHMAYBEATTRIBUTEDTOTHEEFFECTIVEMECHANISMOFLIQUIDELECTROLYTE,WHENTHEBORAXWITHTHECREAMINTHEINCREASEINTHENUMBER,THEMOBILITYOFMOLTENBORAXINCREASETHETIMEMOREOVER,THEMASSFRACTIONOF40AND55OFTHEPASTE,WHENTHESLOWRATEOFBORIDEWASOBSERVED,ASSHOWNINFIGURE1PRESUMABLY,FORINCLUDINGGAS,ELECTROLYSIS,ELECTROLYSIS,ETC,AVARIETYOFNONLIQUIDBORONIZINGMECHANISM,THEACTIVEINGREDIENTINTHISRANGEWILLBEDIFFICULTFORSOMEREASON,THENEEDFORFURTHERINVESTIGATIONFIGURE1STAINLESSSTEELBORIDELAYERTHICKNESSLESSTHANMILDCARBONSTEEL,WHICHCONFIRMSPREVIOUSLYREPORTEDRESULTS7,8NOTONLYBECAUSEOFTHESTAINLESSSTEELSURFACEHASAPROTECTIVELAYER,BUTALSOINCHROME,NICKELBORIDEONTHESURFACEBUTALSOTHEPROTECTIVELAYER,THEYFORMWITHTHEGRAINBOUNDARY,THEREBYPREVENTINGTHEDIFFUSIONOFBORON7,8ITWASALSOPOINTEDOUTTHAT,DUETOTHEINCREASEINTHENUMBEROFBORON,PASTEBECOMESEXCESSIVE,ADHESIVEONTHESURFACEWHENTHEPLASMASAMPLESPASTYBORONIZINGBEGAN,LEADINGTOTHERECOVERYOFTHISCREAMISVERYLOWCONSIDERINGTHEHIGHCOSTOFBORON,THEREFOREINFERPLASMAPASTYPASTYBORIDECOMPONENTSWITHTHEBESTMASSFRACTIONOF30AMORPHOUSBORONAND70OFBORAX32EFFECTOFTEMPERATUREANDTIMEONTHERATEOFFORMATIONOFTHEBORIDELAYERFIG2RELATIONBETWEENTHEBORONIDINGTEMPERATUREANDTIMESONTHEFIGURE2SHOWSTHETEMPERATUREANDTIMEONTHEBORIDEBORIDELAYERDEPTHACCORDINGTOTHEPARABOLICTHEORY,WITHTHEINFILTRATIONTIMEANDTEMPERATUREINCREASEDBORON,BORIDELAYERDEPTHWILLALSOINCREASETHISSHOWSTHATTHEBORIDELAYERFORMATIONRATEBECOMESSLOWASTIMEINCREASESBORONPENETRATIONTHISCANBEEXPLAINEDBYTHEFACTTHATTHEFORMATIONOFBORIDELAYERONTHESURFACEOFTHENIRICHLAYERBELOWANDCHROMIUMRICHLAYERPLAYSTHEROLEOFDIFFUSIONBARRIER,INHIBITTHEACTIVITYOFBORONDIFFUSIONFURTHEREXPLANATIONWILLBEGIVENLATERINTHEARTICLE33CHANGESINCROSSSECTIONHARDNESSDISTRIBUTIONFIG3HARDNESSCURVESOFAISI304BORONIZEDFORVARIOUSTIMESAT1173KPLASMABORIDESPECIMENSIN1023,1073,1123K,HOLDINGSEVENHOURSTOGETTHEBORIDELAYERTHICKNESSCANNOTBEMEASURED,ANDTHEIRHARDNESSMEASUREMENTISIMPOSSIBLEIN1173AND1223KTEMPERATUREPLASMABORONIZING,INANYCASE,THEFORMATIONOF30TO40MICRONSTHICKBORIDELAYER；BORIDESAMPLESOFPLASMAFOR7HOURSAT1223KCROSSSECTIONHARDNESSMEASUREMENTRESULTSARESUMMARIZEDINFIGURE3ONBORIDEINPLASMA7HOURSAFTERTHESPECIMENSFOUNDONTHEMAXIMUMDEPTHOFTHENITRIDEDLAYEROF45MICRONS,ANDTHEMAXIMUMHARDNESSOF1800TO2000OFTHENITRIDEDLAYER
