热浸镀锌助镀工艺的研究与应用(4)

53(Ch).Alloyingprocessbasedonpowersherardizingtechnolo2gywasconductedforST12steeltoimprovethecorrosionre2sistanceofthesteel.ThemicrostructureandcorrosionbehavioroftheZn2Fealloyingcoatingwasinvestigatedusinganopticalmi2croscope,anX2raydiffractometer,andanM352corrosionmeas2urementsystem.TheresultsshowedthattheZn2Fealloyingcoat2ingwascomposedofГphaseandδ1phase,withtheδ1phasetobedominant.TheZn2Fealloyingcoatinghadachemicalcompo2sitionofFeZn7andfarbetterstaticcorrosionresistancethantheST12steelandhotgalvanizingaswell.Moreover,theZn2Feal2loyingcoatinghadapotentialabout-920mVandcouldbeusedasapositivecoatingforthesteel.

Keywords:corrosion;Zn2Fealloying;powersherardizing;δ1phase

MeasurestoKeepSuitableHumidityinWetSpraying2Bak2ingBooth

WANGJi2fang(DepartmentofMechanicalEngineering,BeijingInstituteofMachinery,Beijing100085,China)CailiaoBaohu2005,38(8),54～55(Ch).Themeasurestokeepsuitablehu2midityinwetspraying2bakingboothwereanalyzedintermsoftheoreticalanalysis,structuredesign,andequipmentoperation.Itwaspointedoutthatasakindofnewcoatingequipmentsuit2ablefortheproductionoflargebatchparts,wetspraying2bakingboothwasapplicabletooverflowpainting.Basedonthecompari2sonofthedifferencesandcharacteristicsofdry2typeandwet2typespraying2bakingbooths,itwassuggestedthatthekeytode2velopnovelwetspraying2bakingboothwastoproperlycontrolthehumidity.Itwasfeasibletogetridofthestandard2exceedinghu2midityinwetspraying2bakingboothmakinguseofproperhumid2ity2controllingmeasures.

Keywords:spray2bakingbooth;spraypainting;bakingpaintingResearchandPracticeonFluxingTechnologyforHotDipGalvanizing

KONGGang,LUJin2tang,XUQiao2yu(SchoolenceandEngineering,SouthChinaGuangzhou510640,China)Cailiao),(Ch).Thequalityofhotdipgalvanizingarecltoogy.Thustherecentresearchonthefluxingtechnolo2gyweresummarized,andthefluxingmechanismwassumma2rized.Theoptimizedcompositionandtreatmentparametersofflu2xingforbatchhotdipgalvanizingwererecommendedasconcen2trationofammoniumzincchloride200～400g/L,ratiobetweenammoniumchlorideandzincchloride1.2～1.6,concentrationofironsaltsbelow1wt%,pHvalue4～5,andtemperature60～80℃.Theeffectsofconcentration,theratiobetweenammoniumchlorideandzincchloride,theconcentrationofironsalts,pHvalue,andtemperatureofthefluxweresummedup.Itwassup2posedthatitcouldbefeasibletopreparethehotdipgalvanizingcoatingofgoodqualityatalowzincconsumptionbystrictlycon2trollingthecompositionandtreatmentparametersofthefluxing.Keywords:hotdipgalvanizing;fluxing;composition

ComparisonofTwoFusionWeldingTechniquesforValveSurfaceSealing

aab

ZHANGFu2bang,HUChun2lian,HOUShang2ling,CHEN

a

Sheng2sheng(a.AlloyPowderFactory;b.SchoolofSciences,LanzhouUniversityofTechnology,Lanzhou730050,China)

CailiaoBaohu2005,38(8),59～60(Ch).Vacuumhigh2fre2

quencyfusionweldingandplasmaoverlayweldingtechniqueswereusedtoprepareCo2Cr2Wcoatingsforvalvesurfacesealinginanautomobileengine.Thestructuresandwear2andcorrosion2resistanceoftheCo2Cr2Wcoatingspreparedusingthetwotech2niqueswerecomparativelyinvestigated.Itwasfoundthatexcel2lentjointswereformedbetweenthematrixandthecoatingspre2pared.Thecoatingmadebyplasmaoverlayweldingtechniquehadslimtreedendritemicrostructuremorecompactthantheequiaxialcrystalmicrostructureofthecoatingmadebyvacuumhigh2frequencyfusionweldingtechnique.Moreover,theplasmaoverlayweldingtechniqueismoresuitabletothevalvesurfacesealingoftheautomobileenginethanthevacuumhigh2frequencyfusionweldingtechnique.Thiswasbecausethecoatingmadebytheplasmaoverlayweldinghadmuchbetterwear2andcorrosion2resistancethanthatmadebyvacuumhigh2frequencyfusionweld2ing,astestedonRFThightemperaturefrictionandweartesterat550℃andin10%HNO3solutionfor20h.

Keywords:fusionweldingtechnology;microstructure;wearre2sistance;corrosionresistance

ElectroplatingandOxidizingBlackeningforPowerMetal2lurgicalIron2BasedWares(Ⅱ)

(CHURong2bangResearchInstituteofShipRadar,Nanjing

210003,China)CailiaoBaohu2005,38(8),61～63(Ch).Thepretreatmenttechnologiessuchasdegreasingatelevatedtempera2ture,sealingofmicro2poresandpofintermediatecoatingwerehighlightedwithrespecttooplatingandoxidizedwder2basedwares.Thecurrentwofthetechnologiesforofthepowdermetallur2wereintroducedaswellfromaviewpointofproduction.Itwaspointedoutthepretreatmentin2cludingdegreasingatelevatedtemperature,sealingofmicro2poresandplatingofintermediatecoatingallhadprominenteffectonensuringthequalityoftheelectroplatedandoxidizedblack2enedmodifiedlayeronthepowdermetallurgicaliron2basedwares.

Keywords:electroplating;oxidizingblackening;ironbasepowdermetallurgicalwares;pretreatmentFailureAnalysisofGCr15SteelDie

ZHANGBo,YANGYi2chun(ShanghaiMint,Shanghai200061,China)CailiaoBaohu2005,38(8),64～66(Ch).SomeminutecracksoccuronthesurfaceofGCr15diesusedfortheprepara2tionofcommemorativecoinsinashort2termoperation,whichcauseslotsof“flashspots”onthecommemorativecoinsandaf2fectsthesurfacequalityoftheproduct.Thusfailureanalysiswasconductedforthesteeldiesusingmacroandmicrotestmethods.Theresultshowedthatthefailureofthesteeldiewasmainlyat2tributedtothegenerationofalargeamountofmeshycracksonchromiumplatingsurface.

Keywords:failureanalysis;die;GCr15steel

SeaoverEditorialCommittee:K.V.Frolov,V.T.Troshchenko,L.A.Sosnovskiy,

Yu.N.Drozdov,T.Bell,HanshanDong,HongKeeLee

JournalofMaterialsProtectionVol.38.No.8,Aug.2005PublishedbyMaterialsProtectionPublishingHouseEditedbyMaterialsProtectionEditorialDepartmentAdd:126BaofengErlu,Wuhan430030,P.R.ChinaTel:+0086-27-83641679　Fax:+0086-27-83638752

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