Alman, D. E.

Jablonski, P. D.

UNT Digital Library

National Energy Technology LaboratoryOffice of Fossil EnergyInfluence of a Cerium Surface Treatment on the Oxidation Behavior of Commercial Fe- and Ni- Base AlloysDavid E. Alman and Paul D. Jablonski1450 Queen Ave., S.W.Albany, OR 97321www.netl.doe.govHigh Temperature Degradation of Fe-, Ni- and Co- Based Alloys: Alloying Element and Corrosive EnvironmentsMS&T06, Cincinnati, Ohio,  October 17, 2006D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Acknowledgements• Gordon Holcomb, Omer Doğan, Karol Schrems (assistance and discussions)• Mike Hayes (assistance in surface treatment)• Dan Davis, Ed Argetsinger (experimental setup)• Al Hunt, Shain Thompson, Richard Gregory (sample preparation)• Paul Danielson (metallography)• Keith Collins and Steve Matthes (SEM)• Marisa Arnold (ESCA, XRF, oxidation experiments)• Richard Chinn and Dave Smith (XRD)D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006• Increasing efficiency of power generation requires system to operate at higher temperatures, pressures and in hostile environments (IGCC, SOFC, USC).• COST EFFECTIVE METALLIC ALLOYS THAT CAN MEET PERFORMACE REQUIREMENTS (I.E., CREEP & CORROSION RESISTANCE ARE A KEY TO THE DEVELOPMENT OF ADVANCED POWER SYSTEMS.• Strength and creep resistance is often obtained at the expense of corrosion resistance.• NEED TO DEVELOP METHODOLOGIES TO IMPROVE HIGH TEMPERATURE COROSION RESISTANCE.¾ Alloying additions¾ Coatings¾ SURFACE TREATMENTSMotivation for ResearchD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Improving Oxidation Resistance with Reactive (Rare Earth) Elements• Well established small amounts rare earth additions improve oxidation resistance of a variety of metallic alloys¾ Ce, La, Y, etc.• Characteristics¾ Slow scale growth¾ Stabilize Cr2O3 scales at lower Cr levels• Lower Cr levels Æ lower alloy cost (especially for ferrous alloys)¾ Prevent oxide scale spallingD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Improving Oxidation Resistance with Rare Earths• Melt addition+ Elements added during ingot production (single manufacturing step)− Difficulty in melting (react with crucibles)− Surface concentration limited by solubility and diffusivity• Surface treatments+ Rare Earth concentrated where needed (at surface and have most benefit)− “Extra” manufacturing step.? Long term effectiveness (as with any coating or surface treatment)D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Research Goal• Investigate rare earth surface treatment for improving oxidation resistance of alloys for FE applications.• Two different surface treatments investigated−Developed at NETL• Similar to pack cementation: coated with a powder mixture containing CeO2 or CeN and halide activator followed by heating in a controlled atmosphere (900oC-12 hrs), after which residual “pack” coating is washed off the surface. • Patent application filed with USPTO in September, 2005.• Applied to over 50 alloys.−Described in a paper by P.Y. Hou and J. Stringer (H/S)• J. Electrochem Soc., Vol 134, No. 7, July 1987, pp. 1836-1849• Coupons heated to 200oC were coated with a cerium-nitrate slurry (10w/o nitrate adjusted with HNO3 to pH=2), followed heating in air at 400oC to decompose to CeO2D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Oxidation Experiments• Coupons − 25.4 x12.5 x thickness − placed in Al2O3 crucible (to collect any oxide spall)− Polished through 600 grit surface finish• Oxidation testing− in dry air  − air+3%H2O (bubbling dry air through two ~ 1m water columns)• “pseudo-cyclical”− coupons placed in pre-heated furnace; after pre-determined time interval coupons removed and weight change recorded; coupons were then replaced in furnace for next cycleTypical furnace for oxidation testingD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Diffraction Angle (2 Theta)15 20 25 30 35 40 45 50 55 60 65 70Relative Intensity0500100015002000S1E RCS1S2ES1ES1S2ES1FeRCE S1S1ER S2ECS1EECroferCrofer + Ce S1=(Mn,Cr,Fe)3O4E=Cr2O3R=TiO2S2=(Mn,Cr,Fe)2O3Fe=Fe-Cr alloyC=CeO24000 hrs-800oC-Air+3%H2O800oC-Air+3%H2O-500hrsBinding Energy (eV)01002003004005006007008009001000Relative Intensity0100020003000400050006000Mn 3pCrofer 22APUCrofer 22APU+Ce Cr 3sSi  2sCe 4p3Si 2p / Ce 4dC 1sTi 2pO 1sTi 2sCr 2pMn 2pCe 3d5Ce 3d3Mn 2sCr 2SFe 2pTime at 800oC, hrs0 100 200 300 400 500ASR (mOhms-cm-2)56789Crofer 22APU: 800oC-Air+3%H2OTime (hrs)0 1000 2000 3000 4000Specific Mass Change (g/cm2)0.00000.00020.00040.00060.00080.00100.00120.0014Crofer 22APU+Ce Surface TreatmentCrofer 22APUCrofer 22APU+CeCrofer 22APUCrofer 22APU+CeLower ASR 9 for interconnectCrofer+Ce CroferCeO2 incorporated into scaleESCA surface analysisX-ray diffractionCrofer 22APU is a “commercial” Fe-22Cr-0.5Mn ferritic steel developed for SOFC interconnect application at the JuelichResearch Center and  marketed by ThyssenKrupp.ASR measurements courtesy of G.Xia and G.Yang from PNNLTreatment improved oxidation resistance by factor of  ~ 2-3D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006• IN100, MAR-M 247 • Haynes 230, IN625• Haynes 242 • IN718, IN600• 316, 321, 347• AL-20-25+Nb• MA965• 446, EBrite• Crofer22APU• 441,430• 409• P91 • SAVE 12Ni-base alloysCommercial Alloys Cerium Surface Treatedaustenitic steelsferritic/martensitic steelsferritic steelsD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Alloy CompositionsAlloy Nominal Composition Alloy ClassIN625Al-20-25+NbNi-22Cr-10Mo-0.5Mn-4(Nb+Ta)Fe-20Cr-25Ni-1.5Mn-1.5Mo-0.3NbNickelAusteniticNickelAusteniticAusteniticFerriticIN600347321441Ni-18Cr-8Fe-1MnFe-18Cr-10Ni-2Mn-(Nb+Ta)10x(C)Fe-18Cr-10Ni-2Mn-(Ti)5x(C+N)Fe-18Cr-1Mn-0.5Ti-(0.3+9xC)NbD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Chemical Composition (wt%, by XRF)Ta W Co V Nb Ti CType321 Type347 IN600   IN625   0.044 <0.010 0.030 0.020 0.001 0.69 0.080.034 <0.010 0.049 0.091 0.77 0.010 0.080.40 0.037 <0.010 0.011 0.18 0.26 0.010.34 0.032 <0.010 0.026 3.37 0.25 0.01Fe Ni Mo Cu Mn Cr Si AlType321 68.92 10.18 0.13 0.16 1.63 17.49 0.55 0.075Type347 70.57 8.99 0.20 0.16 1.17 17.49 0.40 <0.010IN600   9.48 71.94 0.15 0.19 0.92 15.99 0.21 0.24IN625   4.15 61.75 8.76 0.055 0.056 20.92 0.17 0.13D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Type 347/321800oC-Air+3%H2OTime (hrs)0 500 1000 1500 2000 2500Specifiic Mass Change (mg/cm2)-60.0-50.0-40.0-30.0-20.0-10.00.010.0347321347+Ce321+CeFe-18Cr-10Ni: AusteniticD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006-4-3-2-1010 500 1000 1500 2000 2500Time, HoursTP347HFG3% H2O-Air  X+800C760C700C650COxidation of Type 347 HFG-20-15-10-5050 500 1000 1500 2000Number of Cycles (Hours)TP347HFG50% H2O-50% Air760CCourtesy ofGordon R. Holcomb, NETL, 2006 D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006 600 hours at 800oCSpecific Mass Change (g/cm2) -0.0200.0000.005 347 moist air w/ spall: 0.00590 347 moist air w/o spall: -0.02250 347+Ce moist air: 0.00008347 dry air: 0.00027347+Ce dry air: 0.00007Influence of Moisture on the Oxidation behavior of TYPE 347TYPE 347Environment did not affect behavior of alloy in treated condition. Environment significantly influenced the behavior of alloy in untreated condition.D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Scale Formation During Oxidation of Type 347800oCDry Air600 hrs800oCMoist Air600 hrs800oCMoist Air2000 hrs347Cr1.3Fe0.7O3Mn1.5Cr1.5O4FeFe2O4(magnetite)Cr1.3Fe0.7O3Fe2O3*NiCr2O4*FeCr2O4Cr2O3Fe2O3*NiCr2O4*347+CeCr2O3Mn1.5Cr1.5O4CeO2Cr2O3Mn1.5Cr1.5O4CeO2Cr2O3MnCr2O4CeO2* found in spallD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Scale Morphology321321+Ce15Ni5Fe5Cr0.5Mn75Ox 10Ni5Fe8Cr0.5Mn75Ox 13Ni4Fe9Cr1Mn71Ox 11Cr2Fe7Ni1Mn77Ox 18Cr2Fe1Ni2Mn77OCompositions in at% determined by WDX analysisD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Scale Morphology321321+Ce12Cr12Fe7Mn8Ce59Ox10Cr14Fe4Mn10Ce59Ox23Cr13Fe3Mn60O25Cr1Fe1Mn2Ti9Si59O15Ni5Fe5Cr0.5Mn75Ox 10Ni5Fe8Cr0.5Mn75Ox 13Ni4Fe9Cr1Mn71Ox 11Cr2Fe7Ni1Mn77Ox 18Cr2Fe1Ni2Mn77OCompositions in at% determined by WDX analysisD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 200618Cr Alloys800oC-Air+3%H2OTime (hrs)0 500 1000 1500 2000 2500Specific Mass Change (mg/cm2)0.000.200.400.600.801.00IN600441 347+CeIN600+Ce441+CeIN600: Nickel AlloyNi-18Cr-8Fe-1Mn441: FerriticFe-18Cr-1Mn-0.5Ti-(0.3+9xC)Nb347: AusteniticFe-18Cr-10Ni-2Mn -(Nb+Ta)10x(C)D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006800oC-Air+3%H2O-2000hrsIN600 441+Ce 44125Cr14Mn59O37Cr62O20Fe18Ti9Cr50O35Fe2Nb21Cr34O28Cr20Mn10Ce42O34Cr18Mn45O37Cr62OLess internal oxidation25Cr12Mn3Ni56O30Cr23Ni5Fe40O27Cr15Al2Si6Mn48OCompositions in at% determined by WDX analysisD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006High Temperature Alloys800oC-Air+3%H2OTime (hrs)0 200 400 600 800 1000 1200Specific Mass Change (mg/cm2)0.000.100.200.300.40AL-20-25-NbAL-20-25-Nb+CeIN625IN625+CeIN600IN600+CeD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006IN625:800oC-Air+3%H2O-2000hrsD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006IN625:800oC-Air+3%H2O-2000hrs58Ni13Cr3Nb10Mo2OCompositions in at% determined by WDX54Ni13Cr7Nb10Mo5Ti2O76Ti3Cr10Nb1Ni8O38Cr60O36Ni13Cr5Nb7Mo6Al32O31Ce17Cr45O38Cr2Ti56O61Ni8Cr16Nb9Mo3OIN625 IN625+CeD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Base Alloy Behavior• 347/321 (18Cr-10Ni) austenitic alloys Æ oxide scale spalledÆFe2O3 formation• AL-20Cr-25Nb+Nb austenitic alloy Æ did not spall• Ferritic alloy (441) and Ni alloy (IN600) Æ did not spallÆ Cr2O3 formation? WHY?• Chemical Potentials and DiffusivitiesD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Comparison of Chemical PotentialTemperature (C)400 500 600 700 800 900 1000 1100 1200Chemical Potential-1.2e+5-1.0e+5-8.0e+4-6.0e+4-4.0e+4-2.0e+4μ (Fe,347) μ (Fe,IN600) μ (Cr,347) μ (Cr,IN600) Note that the chemical potential for Fe and Cr are about the same in 347ss while in IN600 Cr has a much higher chemical potential.D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Comparison of Chemical PotentialNote that the chemical potential for Fe and Cr are about the same in 347ss while in AL2025 Cr has a much higher chemical potential.Temperature (C)400 500 600 700 800 900 1000 1100 1200Chemical Potential-90000-80000-70000-60000-50000-40000-30000-20000μ (Fe,347) μ (Fe,2025) μ (Cr,347) μ (Cr,2025) D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Comparison of Chemical PotentialHere we see  that the chemical potential for Fe and Cr are about the same in 347ss and in 441ss.  However, recall that the ferritic structure (BCC) allows for much greater diffusion rate thus providing a protective chrome rich layer.Temperature (C)400 500 600 700 800 900 1000 1100 1200Chemical Potential-80000-70000-60000-50000-40000-30000-20000μ (Fe,347) μ (Fe,441) μ (Cr,347) μ (Cr,441) Similar Cr (18 w/o) but different crystal structuresD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Cr Diffusivities In BCC vs. FCC StructuresTime (Days)0 200 400 600 800 1000 1200 1400 1600 1800Cr Diffusion Distance (microns)050100150200250300350Fe(19Cr) Ni(19Cr) 800CD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006800oC-Air+3%H2OTime (hrs)0 500 1000 1500 2000Specific Mass Change (g/cm2)0.00000.00020.00040.00060.00080.0010Crofer 22APU (Fe-22Cr)Haynes 230 (Ni-22Cr)Cr Diffusivities In BCC vs. FCC StructuresTime (Days)0 200 400 600 800 1000 1200 1400 1600 1800Cr Diffusion Distance (microns)050100150200250300350Fe(19Cr) Ni(19Cr) Ni-22CrFe-22CrD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006650oC-Air+3%H2OTime (hrs)0 200 400 600 800 1000Specific Mass Change (g/cm2)0.0000.0050.0100.0150.0200.0250.030HR 52+CeHR 52HR 52-TCInfluence of Thermal Portion of Surface TreatmentThermal portion of process does not improve oxidation resistance.  Presence of rare earth (Ce) slurry is needed to improve oxidation resistance.HR52 & HR52TCÆ Fe2O3HR52+CeÆCr2O3subjected to thermal portion of treatment w/o Ce modificationCe surface modifiedD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006RE Alloying Additions vs. Surface Treatment800oC-air+3%H2OTime (hrs)0 500 1000 1500 2000Specific Mass Change (g/cm2)0.00000.00020.00040.00060.00080.00100.00120.00140.0016F1=Fe-22Cr-0.5Mn-0.1Ti F2=F1+0.05 mischmetal (Ce,La,Pr,Nd)F3=F1+0.1 mischmetalCrofer 22APU (0.1La)F1+Ce Surface Treatment 12 to 26%reduction in mass gainw/ melt addition60%reduction in mass gain w/surface treatmentSurface treatment more effective than in melt addition for improving oxidation resistanceD.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Summary/Conclusion• Base Alloy Behavior explained in terms of chemical potentials and diffusivities.• Ce surface treatment Æ suppressed the formation of Fe2O3 formation in 347/321 Æ promoted formation of adherent Cr2O3 scales • Ce surface treatment retard Cr2O3 growth rate and internal oxidation? Why?? CeO2 surface particles that effect oxide nucleationÆ. promotes nucleation of Cr2O3 scales?????? Chemical potentials of minor constituents are increased (such as Ti)Æ slows subsequent diffusion????D.E. Alman and P.D. Jablonski, NETL, MS&T06, October 17, 2006Current and Future Work• LONG TERM EXPOSURES− ACCELERATED TESTS ON CHROMIA FORMERS• BETTER CHARACTERIZATION OF SCALES• MECHANICAL PROPERTIES AND CREEP BEHAVIORRoom TempσUTS(MPa)σYS(MPa)Elongation(%)347 662 287 52347+Ce 649 257 47Courtesy of Karol K. Schrems, NETL, 2006

Influence of a Cerium surface treatment on the oxidation behavior of commercial Fe- and Ni-base alloys

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Influence of a Cerium surface treatment on the oxidation behavior of commercial Fe- and Ni-base alloys

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