pHAZ91D1,2,2,2,1(1.5106402.510650):AZ91DSEM、EDS、pH、。pH35pH=4。。Ca(NO3)2、、。::TG146.2+2:A:1000-8356(2012)05-0565-04EffectofAdditivesandpHonPhyticAcidConversionCoatingsonAZ91DMagnesiumAlloyZHAOYa-qing1,2,QIWen-jun2,SONGDong-fu2,XIANGXing-hua1(1.MaterialScienceandEngineeringCollege,SouthChinaUniversityofTechnology,Guangzhou510640,China;2.MaterialProcessingInstitute,GuangzhouResearchInstituteofNonferrousMetals,Guangzhou510650,China)Abstract:ThediecastingmagnesiumalloyAZ91Dwastreatedinsolutionsofdifferentphyticacid.TheinfluenceofadditivesandpHvaluesonthethickness,morphologyandthecorrosionresistanceofconversioncoatingswasinvestigatedbySEM,EDS,andSoakingmethod.Theresultsshowthat,whenpHvalueincreasedfrom3to5,thethicknessandcorrosionresistanceoftheconversioncoatingsincreasesfirstly,andthendecreases.WhenpH=4,thethicknessreachesthemaximum,andthecorrosionresistanceisthebest.Thecoatingsformedinacidsolutionswithadditivearethickerthanthatinthepureacidsolutions,andalsothesizeofcracksofthefomerissmaller.TheperformanceoftheconversioncoatingformedinthephyticacidsolutioncontainedtheadditivesofCa(NO3)2,ammoniummetavanadateandsodiumtartaricisthebest.Keywords:chemicalconversiontreatment;phyticacid;diecastingMg-alloy;additives;conversioncoatings,、、、[1]。[2~5],,[6]。、Cr6+,。,[2,7,8]。,6,。,[9~13]。[11]、[12]、[13],。。pHAZ91D,SEM、EDS,。11.1AZ91D,60mm×40mm,3mm,w%:Al8.96、Zn0.68、Mn0.55、Si0.043、Cu0.02、Fe0.003、Ni0.003,Mg。50%。、、、,。180、400、600、800、1000,。→→→→。,:2012-03-22;:2012-04-15:(2010A090100033);(2011A080403005):(1985-),,,.:.E-mail:yqzhao2006@sina.comFOUNDRYTECHNOLOGYVol.33No.5May2012565··pH。1。1.2JEOLJSM-5310(SEM)(EDS),,。,GB/T9274-1988,360h,20%Cr2O3,。22.1pHpH,6。1-3#1,4-5#2。1(a)12pH,pH4,pH。,,,;,,。,。pH,,,;pH,,,,。,pH,。,,。pH4,。1(b)pH。。pH。pH=3,,,,,,,[14]。pH=5,,,,,,,,,。pH=4,,,。2.2、1,pH,。1,,,。,。1Fig.1Thevariationofthethicknessandcorrosionratioofconversioncoating1Tab.1Compositionofconvertingsolutionandprocess/minpH/℃1(50%)20mL/L2g/L1g/L2g/L1033252(50%)20mL/L2g/L1g/L2g/L104253(50%)20mL/L2g/L1g/L2g/L105254(50%)20mL/L103255(50%)20mL/L10425FOUNDRYTECHNOLOGYVol.33No.5May2012566··,,。pH,pH。2EDS,3.12μm,2,、,,1.61μm;,,。,,P,,20%,50%,Ca、V,、,V。2。1,,,,。,2,1,2,1/5。,。2.221000。1#,1μm。。3#,2μm。2#,0.3μm,。32#,、、,PP,,V2O3。4#,2,,2。AZ91D2,αβ,α(-1.73V[14])β(-1.0V[14]),αβ,,,,、(),,。4#2μm。6#2,,。5#2,,,。45#,Mg、Al、C、O、P,Mg,AlAZ91D,Zn,Zn。PC、O。1,226AZ91DFig.2SEMimagesofconversioncoatingsofAZ91Dalloyinsixkindsofphyticacidsolutions2w(%)Tab.2ChemicalcompositionofcrosssectioncharacteristicareaCOMgAlPCaV137.2933.8016.364.555.631.101.27100.00231.9415.4443.736.012.87100.0033.0787.459.48100.00:pHAZ91D《》05/2012567··,,。pH=4,2#,1000,2000,,,,,5#,,。,,。3(1)、。、、,,1/5,,,,。(2)pH、。pH,,;pH,,,,。pH4,、,。:[1],.AZ91[J].,2011,32(4):566-568.[2]ALRudd,CBBreslin,FMansfeld.Thecorrosionprotectionafford-edbyrareearthconve-rsioncoatingsappliedtomagnesium[J].Cor-rosionScience,2000,42(2):275.[3]AYfantis,IPaloumpa,DDSchmeiβer,etal.Novelcorrosion-resistantfilmsforMgalloys[J].SurfaceandCoatingTechnology,2002,151-152:400.[4]KZChong,TSShih.Conversion-coatingtreatmentformagnesiumalloysbyapermanganate-phosphatesolution[J].MaterialsChem-istryandPhysics,2003,80(1):191.[5]HUmehara,MTakaya,STerauchi.Chrome-freesurfacetreatmentsformagnesiumalloy[J].SurfaceandCoatingTechnology,2003,169-170:666.[6],,,.[J].,2004,25(11):468.[7]HuoHW,LiY,WangFH.CorrosionofAZ91Dmagnesiumalloywithachemicalconversioncoatingandelectrolessnickellayer.CorrSci,2004,46:1467.[8]YangKH,GerMD,HwuWH,SungY,LiuYC.StudyofVana-dium-BasedChemicalconversionCoatingonthecorrosionResis-tanceofMagnesiumAlloy[J].MaterialsChemistryandPHysics,2007,101:480-485.[9]ShimakuraToshiaki,IshidaYutaka,WatanableTomomi.US5348640,1994[Chem.Abstr.1993,119.276889e].Lin,CS;Lin,HC;Lin,KM;Lai,WCCorros.Sci.[10]LiuJianrui,GuoYina,HuangWeidong.StudyontheCorrosionRe-sistanceofPHyticAcidConversionCoatingforMagnesiumAlloys[J].Surface&CoatingTechnology,2006,201:1536-1541.[11],,.AZ91D[J].,2006,(1):16-19.[12],,,.AZ91D[J].,2009,(2):4-7.[13],,,.AZ91D[J].,2011,(1):3-5.[14]LiuJianrui,GuoYina,HuangWeidong.StudyontheCorrosionRe-sistanceofPhyticAcidConversionCoatingforMagnesiumAlloys.SurfaceandCoatingTechnology,2006,201:1536-1541.32#w(%)Tab.3Chemicalcompositionof2#characteristicareaCOMgAlPCaV111.4129.2644.023.617.402.361.94100.00215.4575.646.402.52100.0045#w(%)Tab.4Chemicalcompositionof5#characteristicareaOMgAlP129.9459.415.155.50100.00FOUNDRYTECHNOLOGYVol.33No.5May2012568··