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Cov hlau tsis xeb uas siv dav dav thiab nws cov qauv ua los ntawm cov hlau tsis xeb yog cov uas tiv taus xeb hauv cov huab cua ib puag ncig vim yog cov txheej passivation uas muaj chromium oxide. Kev xeb thiab kev yaig ntawm cov hlau feem ntau yog txuam nrog kev puas tsuaj ntawm cov txheej no, tab sis tsis tshua muaj nyob rau ntawm qib microscopic, nyob ntawm qhov keeb kwm ntawm qhov tsis sib xws ntawm qhov chaw. Hauv txoj haujlwm no, qhov sib txawv ntawm cov tshuaj lom neeg ntawm qhov chaw nanoscale uas pom los ntawm kev siv tshuab spectroscopic thiab kev tshuaj xyuas chemometric tsis tau xav txog qhov kev puas tsuaj thiab kev xeb ntawm cov hlau txias dov cerium hloov kho super duplex stainless hlau 2507 (SDSS) thaum nws tus cwj pwm kub deformation. lwm sab. Txawm hais tias X-ray photoelectron microscopy qhia txog kev npog sib npaug ntawm cov txheej Cr2O3 ntuj, cov txheej SDSS dov txias qhia txog cov txiaj ntsig passivation tsis zoo vim yog qhov kev faib tawm hauv zos ntawm Fe3 + nplua nuj nanoislands ntawm Fe / Cr oxide txheej. Kev paub no ntawm qib atomic muab kev nkag siab tob txog kev xeb ntawm cov hlau tsis xeb thiab xav tias yuav pab tiv thaiv kev xeb ntawm cov hlau zoo sib xws.
Txij li thaum muaj kev tsim cov hlau tsis xeb, qhov kev tiv thaiv corrosion ntawm ferrochromium alloys tau raug suav hais tias yog chromium, uas tsim cov oxide / oxyhydroxide muaj zog uas qhia txog tus cwj pwm passivating hauv feem ntau ib puag ncig. Piv rau cov hlau tsis xeb ib txwm muaj (austenitic thiab ferritic), super duplex stainless steels (SDSS) nrog kev tiv thaiv corrosion zoo dua muaj cov khoom siv kho tshuab zoo dua1,2,3. Kev muaj zog kho tshuab ntxiv ua rau muaj kev tsim qauv sib dua thiab me dua. Hauv kev sib piv, SDSS pheej yig muaj kev tiv thaiv siab rau pitting thiab crevice corrosion, ua rau lub neej ua haujlwm ntev dua thiab kev siv dav dua hauv kev tswj hwm kev ua qias tuaj, cov thawv tshuaj, thiab kev lag luam roj thiab roj av hauv hiav txwv4. Txawm li cas los xij, qhov ntau thiab tsawg ntawm qhov kub thiab txias kho cua sov thiab kev ua haujlwm tsis zoo cuam tshuam nws daim ntawv thov dav dav. Yog li ntawd, SDSS tau hloov kho kom txhim kho cov khoom saum toj no. Piv txwv li, Ce hloov kho thiab ntxiv ntau ntawm N 6, 7, 8 tau qhia hauv 2507 SDSS (Ce-2507). Ib qho kev sib xyaw ua ke ntawm 0.08 wt.% cov khoom siv av tsis tshua muaj (Ce) muaj txiaj ntsig zoo rau cov khoom siv kho tshuab ntawm DSS, vim nws txhim kho kev ua kom zoo ntawm cov noob thiab lub zog ciam teb ntawm cov noob. Kev hnav thiab kev tiv thaiv corrosion, lub zog tensile thiab lub zog tso zis, thiab kev ua haujlwm kub kuj tau txhim kho9. Cov nitrogen ntau tuaj yeem hloov cov ntsiab lus nickel kim, ua rau SDSS pheej yig dua10.
Tsis ntev los no, SDSS tau raug hloov pauv plastically ntawm ntau qhov kub thiab txias (kub qis, txias thiab kub) kom ua tiav cov khoom siv kho tshuab zoo heev6,7,8. Txawm li cas los xij, qhov kev tiv thaiv corrosion zoo heev ntawm SDSS yog vim muaj cov zaj duab xis oxide nyias nyias ntawm qhov chaw, uas cuam tshuam los ntawm ntau yam, xws li muaj ntau theem nrog cov ciam teb sib txawv, cov av tsis xav tau thiab cov tshuaj tiv thaiv sib txawv. cov qauv microstructure sab hauv ntawm ntau theem austenitic thiab ferritic yog deformed 7. Yog li ntawd, kev kawm txog cov khoom microdomain ntawm cov yeeb yaj kiab zoo li no ntawm qib ntawm cov qauv hluav taws xob yog qhov tseem ceeb rau kev nkag siab txog kev xeb SDSS thiab xav tau cov txheej txheem sim nyuaj. Txog tam sim no, cov txheej txheem rhiab heev ntawm qhov chaw xws li Auger electron spectroscopy11 thiab X-ray photoelectron spectroscopy12,13,14,15 nrog rau lub zog X-ray photoelectron photoelectron system sib txawv, tab sis feem ntau tsis ua tiav los sib cais, cov xwm txheej tshuaj lom neeg ntawm tib lub ntsiab lus hauv cov ntsiab lus sib txawv hauv qhov chaw ntawm nanoscale. Ob peb txoj kev tshawb fawb tsis ntev los no tau txuas qhov oxidation hauv zos ntawm chromium rau qhov kev coj cwj pwm xeb ntawm 17 austenitic stainless hlau, 18 martensitic stainless hlau, thiab SDSS 19, 20. Txawm li cas los xij, cov kev tshawb fawb no tau tsom mus rau qhov cuam tshuam ntawm Cr heterogeneity (piv txwv li, Cr3 + oxidation xeev) ntawm kev tiv thaiv corrosion. Lateral heterogeneity hauv cov xeev oxidation ntawm cov ntsiab lus tuaj yeem tshwm sim los ntawm cov sib xyaw sib txawv nrog cov khoom sib xws, xws li hlau oxides. Cov sib xyaw no tau txais ib qho me me thermomechanically processed ze rau ib leeg, tab sis sib txawv hauv cov khoom sib xyaw thiab oxidation xeev 16,21. Yog li ntawd, kev qhia txog kev puas tsuaj ntawm cov yeeb yaj kiab oxide thiab tom qab ntawd pitting yuav tsum nkag siab txog qhov tsis sib xws ntawm qhov chaw ntawm qib microscopic. Txawm hais tias muaj cov kev xav tau no, kev ntsuas ntau yam xws li lateral oxidation heterogeneity, tshwj xeeb tshaj yog ntawm hlau ntawm nano / atomic scale, tseem tsis muaj thiab lawv qhov tseem ceeb rau kev tiv thaiv corrosion tseem tsis tau tshawb nrhiav. Txog thaum tsis ntev los no, lub xeev tshuaj lom neeg ntawm ntau yam ntsiab lus, xws li Fe thiab Ca, tau piav qhia ntau yam ntawm cov qauv hlau siv cov tshuab xoo hluav taws xob X-ray photoelectron microscopy (X-PEEM) hauv cov chaw siv hluav taws xob nanoscale synchrotron. Ua ke nrog cov txheej txheem X-ray absorption spectroscopy (XAS) uas muaj zog, X-PEEM ua rau kev ntsuas XAS nrog qhov kev daws teeb meem siab thiab spectral, muab cov ntaub ntawv tshuaj lom neeg txog cov khoom sib xyaw thiab nws lub xeev tshuaj lom neeg nrog qhov kev daws teeb meem qis mus rau qhov ntsuas nanometer 23. Qhov kev soj ntsuam spectroscopic ntawm qhov chaw pib hauv qab lub tshuab microscope no pab txhawb kev sim tshuaj lom neeg hauv zos thiab tuaj yeem qhia txog qhov chaw uas tsis tau tshawb nrhiav yav dhau los hauv Fe txheej.
Txoj kev tshawb fawb no nthuav dav cov txiaj ntsig ntawm PEEM hauv kev ntes cov tshuaj sib txawv ntawm nanoscale thiab nthuav tawm txoj kev tshuaj xyuas qhov chaw atomic-level kom nkag siab txog tus cwj pwm corrosion ntawm Ce-2507. Nws siv K-txhais tau tias cov ntaub ntawv chemometric cluster24 los kos duab cov tshuaj lom neeg thoob ntiaj teb (heterogeneity) ntawm cov ntsiab lus koom nrog, nrog rau lawv cov xwm txheej tshuaj lom neeg tau nthuav tawm hauv kev sawv cev suav lej. Tsis zoo li cov ntaub ntawv ib txwm muaj ntawm corrosion los ntawm chromium oxide zaj duab xis tawg, qhov tam sim no tsis zoo passivation thiab tsis zoo corrosion tsis kam yog vim muaj Fe3 + nplua nuj nanoislands nyob ze ntawm Fe / Cr oxide txheej, uas tej zaum yuav yog qhov tshwm sim ntawm cov oxides tiv thaiv. Hauv qhov chaw ntawm kev tawg, ib zaj duab xis yog tsim uas ua rau corrosion.
Tus cwj pwm corrosive ntawm deformed SDSS 2507 tau raug soj ntsuam thawj zaug siv kev ntsuas electrochemical. Hauv daim duab 1 qhia txog Nyquist thiab Bode curves rau cov qauv xaiv hauv acidic (pH = 1) aqueous solutions ntawm FeCl3 ntawm chav tsev kub. Cov electrolyte xaiv ua haujlwm ua tus neeg sawv cev oxidizing muaj zog, piav qhia txog qhov nyiam ntawm zaj duab xis passivation kom tawg. Txawm hais tias cov khoom siv tsis tau dhau los ntawm chav tsev kub pitting ruaj khov, cov kev tshuaj xyuas no tau muab kev nkag siab rau cov xwm txheej tsis ua haujlwm thiab cov txheej txheem tom qab corrosion. Lub voj voog sib npaug (Daim duab 1d) tau siv los haum electrochemical impedance spectroscopy (EIS) spectra, thiab cov txiaj ntsig sib xws tau pom hauv Rooj 1. Ib nrab voj voog tsis tiav tau tshwm sim thaum sim cov tshuaj kho thiab cov qauv kub ua haujlwm, thaum lub voj voog compressed sib xws tau dov txias (Daim duab 1b). Hauv EIS spectrum, lub voj voog semicircle radius tuaj yeem suav hais tias yog polarization resistance (Rp) 25,26. Rp ntawm cov tshuaj kho SDSS hauv Rooj 1 yog li 135 kΩ cm-2, txawm li cas los xij rau cov kub ua haujlwm thiab txias dov SDSS peb tuaj yeem pom cov nqi qis dua ntawm 34.7 thiab 2.1 kΩ cm-2 feem. Qhov kev txo qis tseem ceeb hauv Rp qhia txog qhov cuam tshuam tsis zoo ntawm cov yas deformation ntawm passivation thiab corrosion tsis kam, raws li tau pom hauv cov ntawv ceeb toom dhau los 27, 28, 29, 30.
a Nyquist, b, c Bode impedance thiab theem daim duab, thiab ib qho qauv sib npaug rau d, qhov twg RS yog qhov tsis kam ntawm electrolyte, Rp yog qhov tsis kam polarization, thiab QCPE yog qhov tsis tu ncua theem oxide siv los ua qauv rau qhov tsis zoo tagnrho capacitance (n). Cov kev ntsuas EIS tau ua tiav ntawm qhov tsis muaj peev xwm thauj khoom.
Cov kev txiav txim thawj zaug tau pom hauv daim duab Bode thiab lub tiaj tiaj siab sawv cev rau qhov tsis kam electrolyte RS26. Thaum qhov zaus txo qis, qhov impedance nce thiab lub kaum sab xis tsis zoo pom, qhia txog kev tswj hwm capacitance. Lub kaum sab xis theem nce, khaws nws tus nqi siab tshaj plaws hauv qhov ntau zaus dav, thiab tom qab ntawd txo qis (Daim Duab 1c). Txawm li cas los xij, hauv tag nrho peb qhov xwm txheej no tus nqi siab tshaj plaws tseem tsawg dua 90 °, qhia txog tus cwj pwm tsis zoo tagnrho vim yog kev sib cais capacitive. Yog li, QCPE tas li theem element (CPE) yog siv los sawv cev rau qhov kev faib tawm capacitance interfacial los ntawm qhov roughness ntawm qhov chaw lossis inhomogeneity, tshwj xeeb tshaj yog nyob rau hauv cov nqe lus ntawm atomic scale, fractal geometry, electrode porosity, tsis sib xws muaj peev xwm, thiab qhov chaw nyob ntawm qhov chaw faib tawm. Electrode geometry31,32. CPE impedance:
qhov twg j yog tus lej xav thiab ω yog lub zaus angular. QCPE yog qhov zaus tsis hloov pauv tas li proportional rau thaj chaw qhib ntawm electrolyte. n yog tus lej zog dimensionless uas piav qhia txog qhov sib txawv ntawm tus cwj pwm capacitive zoo tagnrho ntawm lub capacitor, piv txwv li qhov ze dua n yog rau 1, qhov ze dua CPE yog rau lub peev xwm ntshiab, thiab yog tias n ze rau xoom, nws yog qhov tsis kam. Qhov sib txawv me me ntawm n, ze rau 1, qhia txog tus cwj pwm tsis zoo tagnrho ntawm qhov chaw tom qab kev sim polarization. QCPE ntawm SDSS dov txias yog siab dua li cov khoom zoo sib xws, uas txhais tau tias qhov zoo ntawm qhov chaw tsis sib xws.
Zoo ib yam li feem ntau cov khoom tiv thaiv corrosion ntawm cov hlau tsis xeb, cov ntsiab lus Cr siab ntawm SDSS feem ntau ua rau muaj kev tiv thaiv corrosion zoo dua ntawm SDSS vim muaj cov zaj duab xis tiv thaiv oxide passive ntawm qhov chaw 17. Cov zaj duab xis passivating no feem ntau nplua nuj hauv Cr3 + oxides thiab / lossis hydroxides, feem ntau yog kev koom ua ke Fe2 +, Fe3 + oxides thiab / lossis (oxy) hydroxides 33. Txawm hais tias qhov sib npaug ntawm qhov chaw, txheej oxide passivating, thiab tsis muaj qhov tawg pom ntawm qhov chaw, raws li txiav txim siab los ntawm cov duab microscopic,6,7 tus cwj pwm corrosion ntawm kub-ua haujlwm thiab txias-dov SDSS yog txawv thiab yog li ntawd xav tau kev kawm tob txog qhov deformation microstructure thiab cov yam ntxwv ntawm cov hlau.
Cov qauv me me ntawm cov hlau tsis xeb uas tsis zoo li qub tau raug tshawb nrhiav ntau yam siv cov duab X-ray sab hauv thiab synchrotron siab zog (Cov Duab Ntxiv 1, 2). Kev tshuaj xyuas ntxaws ntxaws tau muab rau hauv Cov Ntaub Ntawv Ntxiv. Txawm hais tias qhov no feem ntau sib xws rau hom theem tseem ceeb, qhov sib txawv tau pom nyob rau hauv cov feem ntim ntawm cov theem, uas tau teev nyob rau hauv Cov Lus Qhia Ntxiv 1. Qhov sib txawv yuav yog vim muaj cov feem heterogeneous ntawm qhov chaw thiab cov feem ntim (XRD) uas raug rau qhov tob sib txawv ntawm kev tshawb pom nrog kev siv X-ray diffraction nrog ntau qhov chaw zog ntawm cov duab photons tshwm sim. Qhov sib piv ntau dua ntawm austenite hauv cov qauv dov txias, txiav txim siab los ntawm XRD los ntawm qhov chaw kuaj mob, qhia txog kev passivation zoo dua thiab tom qab ntawd zoo dua corrosion resistance35, thaum cov txiaj ntsig tseeb dua thiab cov ntaub ntawv qhia txog kev suav lej qhia txog cov qauv sib txawv hauv cov feem theem. Tsis tas li ntawd, qhov corrosion resistance ntawm hlau kuj nyob ntawm qib ntawm kev ua kom zoo ntawm cov noob, txo qhov loj ntawm cov noob, nce hauv microdeformations thiab dislocation density uas tshwm sim thaum lub sijhawm kho thermomechanical36,37,38. Cov qauv ua haujlwm kub ua rau pom tias muaj cov noob ntau dua, qhia txog cov noob me me, thaum cov nplhaib du uas pom hauv cov qauv dov txias (Daim Duab Ntxiv 3) qhia txog kev ua kom zoo dua qub rau nanoscale hauv kev ua haujlwm dhau los6, uas yuav tsum pab txhawb rau zaj duab xis passivation. Kev tsim thiab kev nce ntawm kev tiv thaiv corrosion. Qhov ceev ntawm dislocation siab dua feem ntau cuam tshuam nrog kev tiv thaiv qis dua rau pitting, uas pom zoo zoo nrog kev ntsuas electrochemical.
Kev hloov pauv hauv cov tshuaj lom neeg ntawm cov microdomains ntawm cov ntsiab lus tseem ceeb tau raug kawm tsis tu ncua siv X-PEEM. Txawm hais tias muaj ntau yam khoom sib xyaw, Cr, Fe, Ni, thiab Ce39 tau raug xaiv ntawm no vim Cr yog lub ntsiab lus tseem ceeb rau kev tsim cov zaj duab xis passivation, Fe yog lub ntsiab lus tseem ceeb hauv hlau, thiab Ni txhim kho passivation thiab sib npaug ntawm cov qauv theem ferrite-austenitic thiab lub hom phiaj ntawm kev hloov kho Ce. Los ntawm kev kho lub zog ntawm cov hluav taws xob synchrotron, RAS tau coated los ntawm qhov chaw nrog cov yam ntxwv tseem ceeb ntawm Cr (ntug L2.3), Fe (ntug L2.3), Ni (ntug L2.3) thiab Ce (ntug M4.5). kub tsim thiab txias dov Ce-2507 SDSS. Kev tshuaj xyuas cov ntaub ntawv tsim nyog tau ua los ntawm kev koom ua ke lub zog calibration nrog cov ntaub ntawv luam tawm (piv txwv li XAS 40, 41 ntawm Fe L2, 3 ntug).
Hauv daim duab 2 qhia txog cov duab X-PEEM ntawm cov hlau ua haujlwm kub (Daim duab 2a) thiab cov hlau dov txias (Daim duab 2d) Ce-2507 SDSS thiab cov npoo XAS sib xws ntawm Cr thiab Fe L2,3 ntawm cov chaw cim ib leeg. Ntug L2,3 ntawm XAS soj ntsuam cov xwm txheej 3d tsis muaj neeg nyob tom qab electron photoexcitation ntawm qib spin-orbit splitting 2p3/2 (L3 ntug) thiab 2p1/2 (L2 ntug). Cov ntaub ntawv hais txog lub xeev valence ntawm Cr tau txais los ntawm XAS ntawm ntug L2,3 hauv daim duab 2b, e. Kev sib piv nrog cov kws txiav txim plaub. 42,43 qhia tau hais tias plaub lub ncov tau pom ze ntawm ntug L3, hu ua A (578.3 eV), B (579.5 eV), C (580.4 eV) thiab D (582.2 eV), uas cuam tshuam octahedral Cr3+, sib xws rau Cr2O3 ion. Cov spectra sim pom zoo nrog cov kev xam lej theoretical uas tau qhia hauv cov vaj huam sib luag b thiab e, tau los ntawm ntau qhov kev xam lej ntawm lub teb siv lead ua ke ntawm Cr L2.3 interface siv lub teb siv lead ua ke ntawm 2.0 eV44. Ob qho chaw ntawm cov SDSS kub-ua haujlwm thiab txias-dov yog coated nrog ib txheej sib xws ntawm Cr2O3.
ib daim duab X-PEEM thermal ntawm SDSS uas raug hloov pauv los ntawm cua sov sib raug rau b Cr L2.3 ntug thiab c Fe L2.3 ntug, d daim duab X-PEEM thermal ntawm SDSS uas dov txias sib raug rau e Cr L2.3 ntug thiab f Fe L2.3 ntug sab (f). Cov XAS spectra raug plotted ntawm ntau qhov chaw sib txawv cim rau ntawm cov duab thermal (a, d), cov kab dotted txiv kab ntxwv hauv (b) thiab (e) sawv cev rau cov XAS spectra simulated ntawm Cr3+ nrog tus nqi crystal field ntawm 2.0 eV. Rau cov duab X-PEEM, siv lub thermal palette los txhim kho kev nyeem duab, qhov twg cov xim los ntawm xiav mus rau liab yog proportional rau qhov muaj zog ntawm X-ray absorption (los ntawm qis mus rau siab).
Txawm hais tias qhov chaw ib puag ncig tshuaj lom neeg ntawm cov khoom siv hlau no li cas los xij, lub xeev tshuaj lom neeg ntawm kev ntxiv Ni thiab Ce alloying elements rau ob qho qauv tseem tsis tau hloov pauv. Daim duab ntxiv. Cov duab 5-9 qhia X-PEEM cov duab thiab XAS spectra sib xws rau Ni thiab Ce ntawm ntau qhov chaw ntawm qhov chaw ntawm cov qauv kub-ua haujlwm thiab txias-dov. Ni XAS qhia cov xeev oxidation ntawm Ni2+ hla tag nrho qhov chaw ntsuas ntawm cov qauv kub-ua haujlwm thiab txias-dov (Kev Sib Tham Ntxiv). Nws yuav tsum tau sau tseg tias, nyob rau hauv cov qauv kub-ua haujlwm, lub teeb liab XAS ntawm Ce tsis tau pom, thaum nyob rau hauv cov qauv txias-dov, lub spectrum ntawm Ce3+ tau pom. Kev soj ntsuam ntawm Ce cov chaw hauv cov qauv txias-dov qhia tau hais tias Ce feem ntau tshwm sim hauv daim ntawv ntawm precipitates.
Hauv SDSS uas tau hloov pauv los ntawm cua sov, tsis muaj kev hloov pauv hauv zos hauv XAS ntawm ntug Fe L2,3 tau pom (Daim Duab 2c). Txawm li cas los xij, Fe matrix micro-regionally hloov nws lub xeev tshuaj lom neeg ntawm xya qhov chaw xaiv tsis raug ntawm SDSS txias-dov, raws li pom hauv Daim Duab 2f. Tsis tas li ntawd, txhawm rau kom tau txais lub tswv yim tseeb ntawm kev hloov pauv hauv lub xeev Fe ntawm qhov chaw xaiv hauv Daim Duab 2f, kev tshawb fawb hauv zos tau ua tiav (Daim Duab 3 thiab Daim Duab Ntxiv 10) uas cov cheeb tsam me me tau xaiv. Cov XAS spectra ntawm ntug Fe L2,3 ntawm α-Fe2O3 systems thiab Fe2+ octahedral oxides tau ua qauv los ntawm ntau qhov kev suav teb siv siv cov teb siv lead ua ntawm 1.0 (Fe2+) thiab 1.0 (Fe3+)44. Peb pom tias α-Fe2O3 thiab γ-Fe2O3 muaj cov symmetries sib txawv hauv zos45,46, Fe3O4 muaj kev sib xyaw ua ke ntawm Fe2+ & Fe3+,47, thiab FeO45 ua ib qho divalent Fe2+ oxide (3d6). Peb pom tias α-Fe2O3 thiab γ-Fe2O3 muaj cov symmetries sib txawv hauv zos45,46, Fe3O4 muaj kev sib xyaw ua ke ntawm Fe2+ & Fe3+,47, thiab FeO45 ua ib qho divalent Fe2+ oxide (3d6).Nco ntsoov tias α-Fe2O3 thiab γ-Fe2O3 muaj cov symmetries hauv zos sib txawv45,46, Fe3O4 sib xyaw ob qho tib si Fe2+ thiab Fe3+,47 thiab FeO45 ua ke hauv daim ntawv ntawm cov oxide divalent Fe2+ (3d6).Nco ntsoov tias α-Fe2O3 thiab γ-Fe2O3 muaj cov symmetries sib txawv hauv zos45,46, Fe3O4 muaj kev sib xyaw ua ke ntawm Fe2+ thiab Fe3+,47 thiab FeO45 ua haujlwm ua ib qho kev sib xyaw ua ke Fe2+ oxide (3d6). Tag nrho cov Fe3+ ions hauv α-Fe2O3 tsuas muaj Oh txoj haujlwm xwb, thaum γ-Fe2O3 feem ntau yog sawv cev los ntawm Fe3+ t2g [Fe3+5/3V1/3]eg O4 spinel nrog cov chaw seem hauv eg txoj haujlwm. Yog li ntawd, Fe3+ ions hauv γ-Fe2O3 muaj ob qho tib si Td thiab Oh txoj haujlwm. Raws li tau hais hauv daim ntawv dhau los,45 txawm hais tias qhov sib piv ntawm ob qho sib txawv, lawv qhov sib piv eg/t2g yog ≈1, thaum nyob rau hauv rooj plaub no qhov sib piv pom eg/t2g yog li 1. Qhov no txiav txim siab qhov ua tau tias nyob rau hauv qhov xwm txheej tam sim no tsuas yog Fe3+ muaj. Xav txog qhov xwm txheej ntawm Fe3O4 nrog ob qho tib si Fe2+ thiab Fe3+, thawj qhov tshwj xeeb, uas paub tias muaj qhov tsis muaj zog (muaj zog dua) L3 ntug rau Fe, qhia txog tus lej me dua (loj dua) ntawm cov xeev t2g tsis muaj neeg nyob. Qhov no siv rau Fe2+ (Fe3+), uas qhia tau hais tias thawj qhov tshwj xeeb ntawm kev nce qhia txog kev nce hauv cov ntsiab lus ntawm Fe2+47. Cov txiaj ntsig no qhia tau hais tias kev sib koom ua ke ntawm Fe2+ thiab γ-Fe2O3, α-Fe2O3 thiab/lossis Fe3O4 dominates ntawm qhov chaw txias-kuav ntawm cov composites.
Cov duab thaij duab thermal photoelectron loj dua ntawm XAS spectra (a, c) thiab (b, d) hla ntug Fe L2,3 ntawm ntau qhov chaw hauv thaj chaw xaiv 2 thiab E hauv daim duab 2d.
Cov ntaub ntawv sim tau txais (Daim Duab 4a thiab Daim Duab Ntxiv 11) tau plotted thiab piv nrog cov ntaub ntawv rau cov tshuaj sib xyaw ntshiab 40, 41, 48. Peb hom sib txawv ntawm Fe L-edge XAS spectra (XAS- 1, XAS-2 thiab XAS-3: Daim Duab 4a). Tshwj xeeb, spectrum 2-a (qhia ua XAS-1) hauv Daim Duab 3b ua raws li spectrum 2-b (labeled XAS-2) tau pom thoob plaws thaj chaw kuaj pom, thaum spectra zoo li E-3 tau pom hauv daim duab 3d (labeled XAS-3) tau pom ntawm qhov chaw tshwj xeeb. Raws li txoj cai, plaub qhov kev ntsuas tau siv los txheeb xyuas cov xeev valence uas twb muaj lawm hauv cov qauv uas tab tom kawm: (1) cov yam ntxwv spectral L3 thiab L2, (2) qhov chaw zog ntawm cov yam ntxwv L3 thiab L2, (3) qhov sib txawv zog L3-L2. , (4) L2/L3 qhov sib piv zog. Raws li kev soj ntsuam pom (Daim Duab 4a), tag nrho peb yam khoom Fe, uas yog, Fe0, Fe2+, thiab Fe3+, muaj nyob rau ntawm qhov chaw SDSS uas tab tom kawm. Qhov piv ntawm qhov muaj zog L2/L3 kuj qhia txog qhov muaj tag nrho peb yam khoom.
Ib qho XAS spectra Simulated ntawm Fe nrog peb cov ntaub ntawv sim sib txawv uas tau pom (cov kab khov kho XAS-1, XAS-2 thiab XAS-3 sib raug rau 2-a, 2-b thiab E-3 hauv daim duab 2 thiab 3) Kev sib piv, Octahedrons Fe2+, Fe3+ nrog cov nqi crystal field ntawm 1.0 eV thiab 1.5 eV, raws li, cov ntaub ntawv sim ntsuas nrog bd (XAS-1, XAS-2, XAS-3) thiab cov ntaub ntawv LCF zoo sib xws (kab dub khov kho), thiab tseem nyob rau hauv daim ntawv XAS-3 spectra nrog Fe3O4 (lub xeev sib xyaw ntawm Fe) thiab Fe2O3 (Fe3+ ntshiab) cov qauv.
Ib qho kev sib xyaw ua ke linear (LCF) ntawm peb tus qauv 40, 41, 48 tau siv los ntsuas cov hlau oxide sib xyaw. LCF tau siv rau peb qhov xaiv Fe L-edge XAS spectra uas qhia qhov sib piv siab tshaj plaws, uas yog XAS-1, XAS-2 thiab XAS-3, raws li pom hauv daim duab 4b-d. Rau LCF fittings, 10% Fe0 tau coj mus rau hauv tus account hauv txhua kis vim qhov tseeb tias peb tau pom ib qho me me hauv txhua cov ntaub ntawv, thiab kuj vim qhov tseeb tias hlau yog cov khoom tseem ceeb ntawm hlau. Tseeb tiag, qhov tob ntawm X-PEEM rau Fe (~ 6 nm) 49 loj dua qhov kwv yees ntawm cov txheej oxidation tuab (me ntsis > 4 nm), uas tso cai rau kev kuaj pom cov teeb liab los ntawm cov hlau matrix (Fe0) hauv qab cov txheej passivation. Tseeb tiag, qhov tob ntawm X-PEEM rau Fe (~ 6 nm) 49 loj dua qhov kwv yees ntawm cov txheej oxidation tuab (me ntsis > 4 nm), uas tso cai rau kev kuaj pom cov teeb liab los ntawm cov hlau matrix (Fe0) hauv qab cov txheej passivation. Действительно, пробная глубина X-PEEM для Fe (~ 6 нм)49 больше, чем предполагаемая толщмна слоя 4 яки ( что позволяет обнаружить сигнал от железной матрицы (Fe0) под пассивирующим слоем. Tseeb tiag, qhov tob ntawm qhov probe X-PEEM rau Fe (~ 6 nm) 49 yog ntau dua li qhov tuab ntawm cov txheej oxidation (me ntsis > 4 nm), uas ua rau nws muaj peev xwm ntes tau lub teeb liab los ntawm cov hlau matrix (Fe0) nyob rau hauv cov txheej passivation.事实上，X-PEEM 对Fe (~6 nm) 49 的检测深度大于估计的氧化层厚度（略> 4 nm), 允许检测来自钝化层下方的铁基体 (Fe0)的信号.事实上 ， X-PEEM 对 Fe (~ 6 nm) 49 的 检测 深度 大于的 氧化层 厚度 略 略> 4 nm) 允薋化棵下方 铁基体 (fe0) 的。 信号 信号 信号 信号 信号 信号 信号 信号 信号Фактически, глубина обнаружения Fe (~ 6 нм) 49 с помощью X-PEEM больше, чем предполагаемая тонолщина окс 4 нм), что позволяет обнаруживать сигнал от железной матрицы (Fe0) ниже пассивирующего слоя. Qhov tseeb, qhov tob ntawm kev tshawb pom ntawm Fe (~ 6 nm) 49 los ntawm X-PEEM yog ntau dua li qhov tuab ntawm cov txheej oxide (me ntsis > 4 nm), uas tso cai rau kev tshawb pom ntawm lub teeb liab los ntawm cov hlau matrix (Fe0) hauv qab cov txheej passivation. .Ntau yam kev sib xyaw ua ke ntawm Fe2+ thiab Fe3+ tau ua tiav los nrhiav qhov kev daws teeb meem zoo tshaj plaws rau cov ntaub ntawv sim uas tau pom. Hauv daim duab 4b qhia txog XAS-1 spectrum rau kev sib xyaw ua ke ntawm Fe2+ thiab Fe3+, qhov twg cov feem pua ​​ntawm Fe2+ thiab Fe3+ zoo sib xws li ntawm 45%, qhia txog cov xeev oxidation sib xyaw ntawm Fe. Thaum rau XAS-2 spectrum, feem pua ​​ntawm Fe2+ thiab Fe3+ dhau los ua ~ 30% thiab 60%, raws li. Fe2+ ​​tsawg dua Fe3+. Qhov piv ntawm Fe2+ rau Fe3, sib npaug rau 1: 2, txhais tau tias Fe3O4 tuaj yeem tsim tau ntawm tib qho piv ntawm Fe ions. Ntxiv rau, rau XAS-3 spectrum, feem pua ​​ntawm Fe2+ thiab Fe3+ dhau los ua ~ 10% thiab 80%, uas qhia txog kev hloov pauv siab dua ntawm Fe2+ rau Fe3+. Raws li tau hais los saum toj no, Fe3+ tuaj yeem los ntawm α-Fe2O3, γ-Fe2O3 lossis Fe3O4. Yuav kom nkag siab txog qhov chaw uas Fe3+ yuav muaj feem ntau, XAS-3 spectrum tau plotted nrog cov qauv Fe3+ sib txawv hauv Daim Duab 4e, qhia txog kev zoo sib xws rau ob qho qauv thaum xav txog B peak. Txawm li cas los xij, qhov muaj zog ntawm lub xub pwg peaks (A: los ntawm Fe2+) thiab B/A intensity ratio qhia tias qhov spectrum ntawm XAS-3 yog ze, tab sis tsis sib xws nrog spectrum ntawm γ-Fe2O3. Piv rau bulk γ-Fe2O3, Fe 2p XAS peak ntawm A SDSS muaj qhov muaj zog siab dua me ntsis (Daim Duab 4e), uas qhia txog qhov muaj zog siab dua ntawm Fe2+. Txawm hais tias qhov spectrum ntawm XAS-3 zoo ib yam li γ-Fe2O3, qhov twg Fe3+ muaj nyob rau hauv Oh thiab Td txoj haujlwm, kev txheeb xyuas cov xeev valence sib txawv thiab kev sib koom tes tsuas yog raws ntug L2,3 lossis L2/L3 intensity ratio tseem yog teeb meem. ib lub ncauj lus ntawm kev sib tham txuas ntxiv vim qhov nyuaj ntawm ntau yam uas cuam tshuam rau qhov kawg spectrum41.
Ntxiv rau qhov sib txawv ntawm cov tshuaj lom neeg hauv cov cheeb tsam xaiv uas tau piav qhia saum toj no, qhov sib txawv ntawm cov tshuaj lom neeg thoob ntiaj teb ntawm cov ntsiab lus tseem ceeb Cr thiab Fe kuj tau soj ntsuam los ntawm kev faib tawm txhua qhov XAS spectra tau txais ntawm qhov chaw ntawm cov qauv siv K-txhais tau tias clustering txoj kev. . Cov qauv ntug Cr L tau teeb tsa los tsim ob pawg zoo tshaj plaws faib rau hauv cov qauv kub-ua haujlwm thiab txias-dov qhia hauv Figs. 5. Nws yog qhov tseeb tias tsis muaj kev hloov pauv hauv zos raug pom zoo sib xws, txij li ob lub centroids ntawm XAS Cr spectra zoo sib xws. Cov duab spectral no ntawm ob pawg yuav luag zoo ib yam li cov uas sib xws rau Cr2O342, uas txhais tau tias cov txheej Cr2O3 tau sib nrug sib npaug ntawm SDSS.
Cr L K-txhais tau tias cov cheeb tsam ntug ntawm cov pawg, thiab b yog cov XAS centroids sib xws. Cov txiaj ntsig ntawm K-txhais tau tias X-PEEM sib piv ntawm cov SDSS txias-dov: c Cr L2.3 cheeb tsam ntug ntawm K-txhais tau tias cov pawg thiab d XAS centroids sib xws.
Txhawm rau piav qhia txog cov ntawv qhia ntug FeL uas nyuaj dua, plaub thiab tsib lub pawg zoo tshaj plaws thiab lawv cov centroids (spectral profiles) tau siv rau cov qauv kub thiab txias dov, raws li. Yog li ntawd, feem pua ​​(%) ntawm Fe2 + thiab Fe3 + tuaj yeem tau txais los ntawm kev haum LCF uas pom hauv daim duab 4. Lub peev xwm pseudoelectrode Epseudo ua haujlwm ntawm Fe0 tau siv los qhia txog qhov tsis sib xws ntawm cov zaj duab xis oxide ntawm qhov chaw. Epseudo yog kwv yees li ntawm txoj cai sib xyaw,
qhov twg \(\rm{E}_{\rm{Fe}/\rm{Fe}^{2 + (3 + )}}\) sib npaug \(\rm{Fe} + 2e^ – \ rau \rm {Fe}^{2 + (3 + )}\), 0.440 thiab 0.036 V, raws li. Cov cheeb tsam uas muaj peev xwm qis dua muaj cov ntsiab lus siab dua ntawm Fe3+ compound. Qhov kev faib tawm peev xwm hauv cov qauv deformed thermally muaj tus cwj pwm layered nrog qhov kev hloov pauv siab tshaj plaws ntawm kwv yees li 0.119 V (Daim duab 6a, b). Qhov kev faib tawm peev xwm no muaj feem cuam tshuam nrog qhov chaw saum npoo (Daim duab 6a). Tsis muaj lwm qhov kev hloov pauv nyob ntawm qhov chaw hauv qab laminar sab hauv tau pom (Daim duab 6b). Ntawm qhov tsis sib xws, rau kev sib txuas ntawm cov oxides sib txawv nrog cov ntsiab lus sib txawv ntawm Fe2+ thiab Fe3+ hauv SDSS txias-dov, ib tus tuaj yeem pom qhov xwm txheej tsis sib xws ntawm pseudopotential (Daim duab 6c, d). Fe3+ oxides thiab/lossis (oxy)hydroxides yog cov khoom tseem ceeb ntawm xeb hauv hlau thiab nkag tau rau cov pa oxygen thiab dej 50. Hauv qhov no, cov kob nplua nuj hauv Fe3+ raug suav hais tias yog thaj chaw hauv zos thiab tuaj yeem suav hais tias yog thaj chaw corroded. Tib lub sijhawm, qhov gradient hauv thaj chaw muaj peev xwm, es tsis yog tus nqi ntawm lub peev xwm, tuaj yeem siv ua qhov qhia rau qhov chaw ntawm cov chaw xeb nquag. Qhov kev faib tawm tsis sib xws ntawm Fe2+ thiab Fe3+ ntawm qhov chaw ntawm SDSS txias dov tuaj yeem hloov pauv cov tshuaj lom neeg hauv zos thiab muab thaj chaw ua haujlwm ntau dua hauv oxide zaj duab xis tawg thiab cov tshuaj tiv thaiv xeb, yog li tso cai rau kev xeb tas mus li ntawm cov hlau matrix hauv qab, ua rau muaj kev xeb sab hauv. heterogeneity ntawm cov khoom thiab txo qis hauv cov khoom tiv thaiv ntawm cov txheej passivating.
K-txhais tau tias cov pawg thiab cov XAS centroids sib xws hauv thaj tsam Fe L2.3 ntug ntawm X-PEEM ac thiab df kub-deformed ntawm SDSS txias-rolled. a, d K-txhais tau tias cov phiaj xwm pawg overlaid rau ntawm cov duab X-PEEM. Lub peev xwm pseudoelectrode (Epseudo) uas tau xam tau hais nrog rau K-txhais tau tias cov phiaj xwm pawg. Qhov ci ntsa iab ntawm daim duab X-PEEM, zoo li xim hauv daim duab 2 yog proportional rau qhov muaj zog nqus X-ray.
Cr sib npaug zos tab sis cov tshuaj lom neeg sib txawv ntawm Fe ua rau muaj kev puas tsuaj ntawm cov zaj duab xis oxide sib txawv thiab cov qauv xeb hauv Ce-2507 kub-ua haujlwm thiab txias-dov. Cov khoom no ntawm Ce-2507 txias-dov tau raug kawm zoo. Hais txog kev tsim cov oxides thiab hydroxides ntawm Fe hauv huab cua ib puag ncig hauv qhov kev ua haujlwm yuav luag tsis muaj zog no, cov tshuaj tiv thaiv yog raws li nram no:
Cov kev tshuaj xyuas saum toj no tshwm sim hauv cov xwm txheej hauv qab no raws li X-PEEM kev tshuaj xyuas. Lub xub pwg me me uas sib raug rau Fe0 yog txuam nrog cov hlau hlau hauv qab. Cov tshuaj tiv thaiv ntawm cov hlau Fe nrog ib puag ncig ua rau muaj Fe (OH) 2 txheej (equation (5)), uas ua rau Fe2 + teeb liab hauv Fe L-edge XAS zoo dua. Kev raug huab cua ntev ntev yuav ua rau muaj Fe3O4 thiab / lossis Fe2O3 oxides tom qab Fe (OH) 252,53. Ob hom Fe ruaj khov, Fe3O4 thiab Fe2O3, kuj tuaj yeem tsim nyob rau hauv Cr3 + nplua nuj tiv thaiv txheej, uas Fe3O4 nyiam cov qauv sib xws thiab nplaum. Qhov muaj ob qho tib si ua rau muaj cov xeev oxidation sib xyaw (XAS-1 spectrum). XAS-2 spectrum feem ntau sib raug rau Fe3O4. Thaum kev soj ntsuam ntawm XAS-3 spectra hauv ntau qhov chaw qhia txog kev hloov pauv tag nrho rau γ-Fe2O3. Vim tias qhov tob ntawm cov duab X-rays uas tsis tau nthuav tawm yog li 50 nm, lub teeb liab los ntawm txheej qis dua ua rau muaj zog dua ntawm lub ncov A.
Lub spectrum XPA qhia tau hais tias Fe Cheebtsam hauv zaj duab xis oxide muaj cov qauv txheej ua ke nrog Cr oxide txheej. Hauv kev sib piv rau cov cim ntawm passivation vim yog qhov tsis sib xws hauv zos ntawm Cr2O3 thaum lub sijhawm xeb, txawm hais tias muaj txheej sib xws ntawm Cr2O3 hauv txoj haujlwm no, kev tiv thaiv corrosion qis tau pom hauv qhov no, tshwj xeeb tshaj yog rau cov qauv dov txias. Tus cwj pwm pom tau tuaj yeem nkag siab tias yog qhov sib txawv ntawm lub xeev oxidation tshuaj hauv txheej sab saud (Fe), uas cuam tshuam rau kev ua haujlwm corrosion. Vim yog tib lub stoichiometry ntawm txheej sab saud (hlau oxide) thiab txheej qis (chromium oxide) 52,53 kev sib cuam tshuam zoo dua (adhesion) ntawm lawv ua rau qeeb thauj cov hlau lossis cov pa oxygen hauv lub lattice, uas, ua rau muaj kev nce hauv kev tiv thaiv corrosion. Yog li ntawd, qhov sib piv stoichiometric tas mus li, piv txwv li ib lub xeev oxidation ntawm Fe, zoo dua rau kev hloov pauv stoichiometric sai sai. SDSS kub-deformed muaj qhov chaw sib xws ntau dua, txheej tiv thaiv denser, thiab kev tiv thaiv corrosion zoo dua. Thaum rau SDSS uas dov txias, qhov muaj Fe3 +-nplua nuj kob nyob rau hauv cov txheej tiv thaiv ua txhaum kev ncaj ncees ntawm qhov chaw thiab ua rau galvanic xeb nrog cov substrate ze, uas ua rau muaj kev poob qis hauv Rp (Rooj 1). Lub EIS spectrum thiab nws qhov kev tiv thaiv corrosion raug txo qis. Nws tuaj yeem pom tias qhov kev faib tawm hauv zos ntawm Fe3 + nplua nuj kob vim yog cov yas deformation feem ntau cuam tshuam rau qhov kev tiv thaiv corrosion, uas yog qhov kev tawg hauv txoj haujlwm no. Yog li, txoj kev tshawb fawb no nthuav tawm cov duab spectroscopic microscopic ntawm kev txo qis hauv kev tiv thaiv corrosion ntawm SDSS cov qauv kawm los ntawm txoj kev yas deformation.
Ntxiv mus, txawm hais tias kev sib xyaw nrog cov khoom siv av tsis tshua muaj nyob rau hauv cov hlau ob-theem qhia tau tias muaj kev ua tau zoo dua, kev sib cuam tshuam ntawm cov khoom ntxiv no nrog ib tus neeg hlau matrix hauv cov nqe lus ntawm kev coj tus cwj pwm corrosion raws li cov ntaub ntawv spectroscopic microscopy tseem tsis meej. Qhov tshwm sim ntawm Ce teeb liab (ntawm XAS M-edges) tsuas yog tshwm sim hauv ob peb qhov chaw thaum lub sijhawm txias dov, tab sis ploj mus thaum lub sijhawm kub deformation ntawm SDSS, qhia txog cov dej nag hauv zos ntawm Ce hauv cov hlau matrix, es tsis yog homogeneous alloying. Txawm hais tias tsis txhim kho cov khoom siv kho tshuab ntawm SDSS6,7, qhov muaj cov khoom siv av tsis tshua muaj txo qhov loj ntawm cov khoom suav nrog thiab xav tias yuav tiv thaiv pitting hauv thaj chaw pib 54.
Xaus lus, txoj haujlwm no qhia txog qhov cuam tshuam ntawm qhov sib txawv ntawm qhov chaw ntawm qhov xeb ntawm 2507 SDSS hloov kho nrog cerium los ntawm kev ntsuas cov tshuaj lom neeg ntawm cov khoom nanoscale. Peb teb cov lus nug vim li cas cov hlau tsis xeb txawm tias nyob hauv qab txheej oxide tiv thaiv los ntawm kev ntsuas nws cov microstructure, chemistry ntawm qhov chaw, thiab kev ua cov teeb liab siv K-txhais tau tias clustering. Nws tau tsim tsa tias cov kob nplua nuj hauv Fe3 +, suav nrog lawv cov octahedral thiab tetrahedral sib koom ua ke raws li tag nrho cov yam ntxwv ntawm kev sib xyaw Fe2 + / Fe3 +, yog qhov ua rau puas tsuaj thiab xeb ntawm cov yeeb yaj kiab oxide txias-rolled SDSS. Nanoislands dominated los ntawm Fe3 + ua rau tsis kam corrosion txawm tias nyob rau hauv qhov muaj txaus stoichiometric Cr2O3 passivating txheej. Ntxiv nrog rau kev nce qib hauv kev txiav txim siab txog qhov cuam tshuam ntawm nanoscale tshuaj lom neeg heterogeneity ntawm corrosion, kev ua haujlwm txuas ntxiv mus yuav txhawb cov txheej txheem engineering los txhim kho qhov tsis kam corrosion ntawm cov hlau tsis xeb thaum lub sijhawm steelmaking.
Txhawm rau npaj cov khoom siv Ce-2507 SDSS ingot siv rau hauv txoj kev tshawb no, cov khoom sib xyaw ua ke suav nrog Fe-Ce master alloy kaw nrog lub raj hlau ntshiab tau yaj hauv 150 kg nruab nrab zaus induction cub kom tsim cov hlau molten thiab nchuav rau hauv pwm. Cov tshuaj sib xyaw ntsuas (wt%) tau teev nyob rau hauv Supplementary Table 2. Ingots thawj zaug kub forged rau hauv blocks. Tom qab ntawd nws tau annealed ntawm 1050 ° C rau 60 feeb kom tau txais hlau hauv lub xeev ntawm cov khoom khov, thiab tom qab ntawd quenched hauv dej mus rau chav tsev kub. Cov qauv kawm tau kawm tiav hauv kev nthuav dav siv TEM thiab DOE los kawm cov theem, qhov loj me ntawm cov noob thiab morphology. Cov ntaub ntawv ntxaws ntxiv txog cov qauv thiab cov txheej txheem ntau lawm tuaj yeem pom hauv lwm qhov chaw 6,7.
Cov qauv cylindrical (φ10 mm × 15 mm) rau kev nias kub tau ua tiav kom lub axis ntawm lub tog raj kheej sib luag rau qhov kev taw qhia deformation ntawm lub block. Kev nias kub siab tau ua tiav ntawm ntau qhov kub hauv qhov ntau ntawm 1000-1150 ° C siv Gleeble-3800 thermal simulator ntawm qhov nrawm tas li hauv qhov ntau ntawm 0.01-10 s-1. Ua ntej deformation, cov qauv tau cua sov ntawm qhov nrawm ntawm 10 ° C s-1 rau 2 feeb ntawm qhov kub xaiv kom tshem tawm qhov kub gradient. Tom qab ua tiav qhov kub sib xws, cov qauv tau deformed mus rau qhov tseeb strain nqi ntawm 0.7. Tom qab deformation, cov qauv tau tam sim ntawd quenched nrog dej kom khaws cov qauv deformed. Cov qauv hardened ces txiav sib luag rau qhov kev taw qhia compression. Rau qhov kev tshawb fawb tshwj xeeb no, peb tau xaiv cov qauv nrog qhov kub kub ntawm 1050 ° C, 10 s-1 vim tias qhov microhardness pom tau siab dua lwm cov qauv7.
Cov qauv loj heev (80 × 10 × 17 mm3) ntawm cov tshuaj khov Ce-2507 tau siv rau hauv LG-300 peb-theem asynchronous ob-yob zeb nrog cov khoom siv kho tshuab zoo tshaj plaws ntawm txhua qib kev hloov pauv 6. Tus nqi ntxhov siab thiab kev txo qhov tuab rau txhua txoj kev yog 0.2 m·s-1 thiab 5%, raws li.
Ib lub chaw ua haujlwm hluav taws xob Autolab PGSTAT128N tau siv rau kev ntsuas hluav taws xob SDSS tom qab dov txias mus rau 90% txo qis hauv qhov tuab (1.0 sib npaug qhov tseeb ntawm qhov nyuaj) thiab tom qab kub nias ntawm 1050 ° C rau 10 s-1 mus rau qhov tseeb ntawm 0.7. Lub chaw ua haujlwm muaj peb-electrode cell nrog lub electrode calomel saturated ua lub electrode siv, lub electrode counter graphite, thiab tus qauv SDSS ua lub electrode ua haujlwm. Cov qauv tau txiav rau hauv lub tog raj kheej nrog lub cheeb ntawm 11.3 hli, rau sab ntawm cov xov hlau tooj liab tau soldered. Cov qauv tau kho nrog epoxy, tawm hauv thaj chaw ua haujlwm qhib ntawm 1 cm2 ua lub electrode ua haujlwm (sab hauv qab ntawm cov qauv cylindrical). Ceev faj thaum lub sijhawm kho ntawm epoxy thiab tom qab ntawd sanding thiab polishing kom tsis txhob tawg. Cov chaw ua haujlwm tau av thiab polished nrog pob zeb diamond polishing suspension nrog qhov loj me ntawm 1 μm, ntxuav nrog dej distilled thiab ethanol, thiab ziab hauv huab cua txias. Ua ntej kev ntsuas electrochemical, cov qauv polished tau raug rau huab cua rau ob peb hnub los tsim ib zaj duab xis oxide ntuj. Ib qho kua dej ntawm FeCl3 (6.0 wt%), ruaj khov rau pH = 1.0 ± 0.01 nrog HCl raws li ASTM cov lus pom zoo, yog siv los ua kom cov hlau tsis xeb 55 sai dua vim nws yog corrosive nyob rau hauv qhov muaj cov chloride ions nrog lub peev xwm oxidizing muaj zog thiab pH qis Cov qauv ib puag ncig G48 thiab A923. Muab cov qauv rau hauv cov kua kuaj rau 1 teev kom txog thaum ruaj khov ua ntej ua qhov ntsuas. Rau cov qauv khov kho, cov qauv kub-tsim, thiab cov qauv dov txias, kev ntsuas impedance tau ua tiav ntawm qhov qhib circuit potentials (OPC) ntawm 0.39, 0.33, thiab 0.25 V, feem, hauv qhov zaus ntawm 1 105 txog 0.1 Hz nrog qhov loj ntawm 5 mV. Tag nrho cov kev sim tshuaj tau rov ua dua tsawg kawg 3 zaug nyob rau hauv tib qho xwm txheej kom ntseeg tau tias cov ntaub ntawv rov ua dua.
Rau kev ntsuas HE-SXRD, cov hlau duplex duplex uas ntsuas 1 × 1 × 1.5 mm3 tau ntsuas los ntsuas qhov sib xyaw ua ke ntawm lub zog siab Brockhouse wiggler ntawm CLS, Canada56. Kev sau cov ntaub ntawv tau ua tiav hauv Debye-Scherrer geometry lossis transmission geometry ntawm chav tsev kub. Lub wavelength X-ray calibrated nrog LaB6 calibrator yog 0.212561 Å, uas sib raug rau 58 keV, uas siab dua li ntawm Cu Kα (8 keV) feem ntau siv ua qhov chaw X-ray hauv chaw kuaj mob. Cov qauv tau nyob ntawm qhov deb ntawm 740 hli ntawm lub tshuab ntes. Lub ntim ntes ntawm txhua tus qauv yog 0.2 × 0.3 × 1.5 mm3, uas yog txiav txim siab los ntawm qhov loj ntawm lub teeb thiab qhov tuab ntawm cov qauv. Tag nrho cov ntaub ntawv tau sau los ntawm kev siv lub tshuab ntes thaj chaw Perkin Elmer, lub tshuab ntes X-ray tiaj tus, 200 µm pixels, 40 × 40 cm2 siv lub sijhawm raug ntawm 0.3 s thiab 120 thav duab.
Kev ntsuas X-PEEM ntawm ob lub qauv xaiv tau ua tiav ntawm Beamline MAXPEEM PEEM kawg chaw nres tsheb hauv MAX IV chav kuaj (Lund, Sweden). Cov qauv tau npaj tib yam li kev ntsuas electrochemical. Cov qauv npaj tau khaws cia rau hauv huab cua rau ob peb hnub thiab degassed hauv lub tshuab nqus tsev ultrahigh ua ntej raug irradiated nrog synchrotron photons. Lub zog daws teeb meem ntawm kab beam tau txais los ntawm kev ntsuas cov ion yield spectrum hauv thaj chaw excitation los ntawm N 1 s mus rau 1 \ (\ pi _g ^ \ ast \) ze hv = 401 eV hauv N2 nrog kev vam khom ntawm lub zog photon ntawm E3 / 2, 57. Cov spectra kwv yees tau muab ΔE (dav ntawm kab spectral) ntawm kwv yees li 0.3 eV hauv qhov ntsuas zog. Yog li ntawd, qhov kev daws teeb meem ntawm lub zog ntawm lub teeb tau kwv yees tias yog E/∆E = 700 eV/0.3 eV > 2000 thiab flux ≈1012 ph/s los ntawm kev siv lub tshuab SX-700 monochromator uas tau hloov kho nrog Si 1200-kab mm−1 grating rau ntug Fe 2p L2,3, ntug Cr 2p L2,3, ntug Ni 2p L2,3, thiab ntug Ce M4,5. Yog li ntawd, qhov kev daws teeb meem ntawm lub zog ntawm lub teeb tau kwv yees tias yog E/∆E = 700 eV/0.3 eV > 2000 thiab flux ≈1012 ph/s los ntawm kev siv lub tshuab SX-700 monochromator uas tau hloov kho nrog lub grating Si 1200-kab mm−1 rau ntug Fe 2p L2.3, ntug Cr 2p L2.3, ntug Ni 2p L2.3, thiab ntug Ce M4.5. Таким образом, энергетическое разрешение канала пучка было оценено как E/∆E = 700 эВ/0,3 э∉ 2000 от 2000 и 2000 при использовании модифицированного монохроматора SX-700 с решеткой Si 1200 штрихов/мм для Fe кромка, 2p, 2 кромка, 2p, L2, 2 кромка Ni 2p L2,3 и кромка Ce M4,5. Yog li, qhov kev daws teeb meem zog ntawm lub beam channel tau kwv yees li E/∆E = 700 eV/0.3 eV > 2000 thiab flux ≈1012 f/s siv lub SX-700 monochromator hloov kho nrog Si grating ntawm 1200 kab/hli rau Fe ntug 2p L2, 3, Cr ntug 2p L2.3, Ni ntug 2p L2.3, thiab Ce ntug M4.5.因此，光束线能量分辨率估计为E/ΔE = 700 eV/0.3 eV > 2000 和通量≈1012 ph/s，通过忦 1012 ph/s光栅的改进的SX-700 单色器用于Fe 2p L2,3 边缘、Cr 2p L2,3 边缘、Ni 2p L2,3 边缘和Ce M4,5 边。因此 ， 光束线 能量 分辨率 为 为 δe = 700 EV/0.3 EV> 2000 和 ≈1012 有 PH/S ， 2 帽用线 mm-1 光栅 改进的 SX-700 单色器 于 于 用用 用Fe 2p L2.3 边缘、Cr 2p L2.3 边缾輘 、 Ni M4.5 yog qhov zoo tshaj plaws.Yog li ntawd, thaum siv lub tshuab SX-700 monochromator uas tau hloov kho nrog 1200 kab Si grating. 3, Cr ntug 2p L2.3, Ni ntug 2p L2.3 thiab Ce ntug M4.5.Luam theej duab lub zog photon hauv 0.2 eV kauj ruam. Ntawm txhua lub zog, cov duab PEEM tau kaw cia siv lub tshuab fiber-coupled TVIPS F-216 CMOS detector nrog 2 x 2 bins, uas muab qhov kev daws teeb meem ntawm 1024 x 1024 pixels hauv 20 µm teb pom. Lub sijhawm raug ntawm cov duab yog 0.2 s, nruab nrab 16 thav duab. Lub zog duab photoelectron raug xaiv rau hauv txoj hauv kev kom muab lub teeb liab electron theem nrab siab tshaj plaws. Txhua qhov kev ntsuas tau ua tiav ntawm qhov tshwm sim ib txwm siv lub teeb photon linearly polarized. Xav paub ntxiv txog kev ntsuas tuaj yeem pom hauv kev tshawb fawb yav dhau los. Tom qab kawm txog hom kev kuaj pom tag nrho electron yield (TEY) thiab nws daim ntawv thov hauv X-PEEM49, qhov tob sim ntawm txoj kev no kwv yees li 4-5 nm rau lub teeb liab Cr thiab txog 6 nm rau Fe. Qhov tob Cr yog ze heev rau qhov tuab ntawm zaj duab xis oxide (~ 4 nm) 60,61 thaum qhov tob Fe loj dua qhov tuab. XRD sau ntawm ntug ntawm Fe L yog sib xyaw ntawm XRD ntawm cov hlau oxides thiab Fe0 los ntawm lub matrix. Hauv thawj qhov xwm txheej, qhov muaj zog ntawm cov electrons uas tawm los ntawm txhua hom electrons uas ua rau TEY. Txawm li cas los xij, lub teeb liab hlau ntshiab xav tau lub zog kinetic siab dua rau cov electrons kom dhau los ntawm txheej oxide mus rau saum npoo thiab raug sau los ntawm lub tshuab ntsuas. Hauv qhov no, lub teeb liab Fe0 feem ntau yog vim LVV Auger electrons, nrog rau cov electrons theem nrab uas lawv tso tawm. Tsis tas li ntawd, qhov muaj zog TEY uas cov electrons no pab txhawb nqa yuav lwj thaum txoj kev khiav tawm ntawm electron, ua rau txo qis Fe0 spectral teb hauv daim ntawv qhia hlau XAS.
Kev koom ua ke cov ntaub ntawv mining rau hauv lub data cube (X-PEEM cov ntaub ntawv) yog ib kauj ruam tseem ceeb hauv kev rho tawm cov ntaub ntawv tseem ceeb (cov khoom siv tshuaj lom neeg lossis lub cev) hauv ntau txoj hauv kev. K-txhais tau tias clustering yog siv dav hauv ntau qhov chaw, suav nrog kev pom tshuab, kev ua duab, kev paub txog tus qauv tsis muaj tus saib xyuas, kev txawj ntse dag, thiab kev tshuaj xyuas kev faib tawm. Piv txwv li, K-txhais tau ua tau zoo hauv kev sib sau ua ke cov ntaub ntawv duab hyperspectral. Hauv paus ntsiab lus, rau ntau cov ntaub ntawv, K-txhais algorithm tuaj yeem yooj yim sib sau ua ke raws li cov ntaub ntawv hais txog lawv cov cwj pwm (cov khoom siv zog photon). K-txhais clustering yog ib qho algorithm iterative rau kev faib cov ntaub ntawv mus rau hauv K pawg tsis sib tshooj (clusters), qhov twg txhua pixel koom nrog ib pawg tshwj xeeb nyob ntawm qhov kev faib tawm ntawm cov tshuaj lom neeg tsis sib xws hauv cov khoom siv microstructural ntawm hlau. K-txhais algorithm suav nrog ob theem: hauv thawj theem, K centroids raug suav, thiab hauv theem thib ob, txhua qhov taw tes raug muab ib pawg nrog cov centroids nyob sib ze. Qhov chaw nruab nrab ntawm lub ntiajteb txawj nqus ntawm ib pawg yog txhais tias yog qhov nruab nrab ntawm cov ntsiab lus ntawm cov ntaub ntawv (XAS spectrum) rau pawg ntawd. Muaj ntau qhov deb los txhais cov centroids nyob sib ze ua qhov deb Euclidean. Rau daim duab nkag ntawm px,y (qhov twg x thiab y yog qhov kev daws teeb meem hauv pixels), CK yog qhov chaw nruab nrab ntawm lub ntiajteb txawj nqus ntawm pawg; daim duab no tuaj yeem raug faib ua pawg (clustered) rau hauv K pawg siv K-means63. Cov kauj ruam kawg ntawm K-means clustering algorithm yog:
Kauj Ruam 2. Xam qhov kev koom tes ntawm txhua lub pixels raws li lub centroid tam sim no. Piv txwv li, nws yog xam los ntawm Euclidean qhov deb d ntawm lub plawv thiab txhua pixel:
Kauj Ruam 3 Muab txhua lub pixel rau qhov chaw ze tshaj plaws. Tom qab ntawd rov xam cov chaw ntawm K centroid raws li hauv qab no:
Kauj Ruam 4. Rov ua cov txheej txheem (equations (7) thiab (8)) kom txog thaum cov centroids sib sau ua ke. Cov txiaj ntsig zoo kawg ntawm kev sib sau ua ke muaj feem cuam tshuam nrog qhov kev xaiv zoo tshaj plaws ntawm cov centroids pib. Rau cov qauv ntaub ntawv PEEM ntawm cov duab hlau, feem ntau X (x × y × λ) yog lub voos xwmfab ntawm cov ntaub ntawv 3D array, thaum cov x thiab y axes sawv cev rau cov ntaub ntawv spatial (pixel resolution) thiab cov λ axis sib raug rau cov duab photon. zog spectral. Lub K-txhais algorithm yog siv los tshawb nrhiav cov cheeb tsam uas txaus siab rau cov ntaub ntawv X-PEEM los ntawm kev sib cais pixels (clusters lossis sub-blocks) raws li lawv cov yam ntxwv spectral thiab rho tawm cov centroids zoo tshaj plaws (XAS spectral profiles) rau txhua analyte. cluster). Nws yog siv los kawm txog kev faib tawm spatial, kev hloov pauv spectral hauv zos, tus cwj pwm oxidation, thiab cov xwm txheej tshuaj lom neeg. Piv txwv li, K-txhais clustering algorithm tau siv rau Fe L-ntug thiab Cr L-ntug cheeb tsam hauv cov kub-ua haujlwm thiab txias-dov X-PEEM. Ntau tus lej ntawm K pawg (cheeb tsam ntawm microstructure) tau raug sim kom pom cov pawg thiab centroids zoo tshaj plaws. Thaum cov lej no tau tso tawm, cov pixels raug xa rov qab mus rau cov centroids sib xws. Txhua qhov kev faib tawm xim sib raug rau qhov chaw ntawm pawg, qhia txog qhov chaw ntawm cov khoom siv tshuaj lom neeg lossis lub cev. Cov centroids uas tau rho tawm yog cov kab sib xyaw ua ke ntawm cov spectra ntshiab.
Cov ntaub ntawv txhawb nqa cov txiaj ntsig ntawm txoj kev tshawb fawb no muaj nyob rau ntawm qhov kev thov tsim nyog los ntawm tus sau WC.
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