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Insimbi engagqwali esetshenziswa kakhulu kanye nezinguqulo zayo ezikhandiwe zimelana nokugqwala ezimeni ezizungezile ngenxa yongqimba lwe-passivation oluhlanganisa i-chromium oxide.Ukugqwala nokuguguleka kwensimbi ngokwesiko kuhlotshaniswa nokucekelwa phansi kwalezi zingqimba, kodwa kuyaqabukela ezingeni le-microscopic, kuye ngokuthi imvelaphi ye-surface inhomogeneity.Kulo msebenzi, i-nanoscale surface chemical heterogeneity etholwe yi-spectroscopic microscopy kanye nokuhlaziywa kwekhemimethrikhi kubusa ngokungalindelekile ukubola nokugqwala kwe-cerium egoqiwe ebandayo eguqulelwe i-super duplex stainless steel 2507 (SDSS) ngesikhathi sokuziphatha kwayo kokuguga okushisayo.olunye uhlangothi.Nakuba i-X-ray photoelectron microscopy ibonise ukumbozwa ngokulinganayo kongqimba lwemvelo lwe-Cr2O3, i-SDSS egoqiwe ebandayo ibonise imiphumela engemihle yokunyakaziswa ngenxa yokusatshalaliswa kwendawo kwama-nanoislands acebile i-Fe3+ kungqimba lwe-Fe/Cr oxide.Lolu lwazi ezingeni le-athomu lunikeza ukuqonda okujulile kokugqwala kwensimbi engagqwali futhi kulindeleke ukuthi lusize ukulwa nokugqwala kwezinsimbi ezifanayo ezinengxubevange ephezulu.
Selokhu kwasungulwa insimbi engagqwali, ukumelana nokugqwala kwama-alloys e-ferrochromium kuye kwathiwa kudalwe yi-chromium, eyakha i-oxide/oxyhydroxide eqinile ekhombisa ukuziphatha okungahambi kahle ezindaweni eziningi.Uma kuqhathaniswa nezinsimbi ezivamile (i-austenitic ne-ferritic) ezingenasici, izinsimbi ezingenasici ze-super duplex (SDSS) ezinokumelana nokugqwala okungcono zinezakhiwo eziphakeme zemishini1,2,3.Ukwenyuka kwamandla okusebenza kuvumela imiklamo elula futhi ehlangene.Ngokuphambene, i-SDSS yokonga inokumelana okuphezulu nokugqwala kwemigodi nokugqwala, okuholela empilweni ende yesevisi kanye nokusetshenziswa okubanzi ekulawuleni ukungcola, iziqukathi zamakhemikhali, kanye nemboni kawoyela negesi yasogwini4.Kodwa-ke, ububanzi obuncane bamazinga okushisa okushisa nokwakheka okungekuhle kuphazamisa ukusetshenziswa kwawo okubanzi okusebenzayo.Ngakho-ke, i-SDSS ishintshiwe ukuze kuthuthukiswe izakhiwo ezingenhla.Isibonelo, ukuguqulwa kwe-Ce nokwengezwa okuphezulu kwe-N 6, 7, 8 kwethulwa ku-2507 SDSS (Ce-2507).Ukugxiliswa okufanelekile okungu-0.08 wt.% kwento yomhlaba eyivelakancane (Ce) kunomthelela onenzuzo ezimpahleni zomshini ze-DSS, njengoba kuthuthukisa ukuhluzwa okusanhlamvu namandla omngcele wokusanhlamvu.Ukumelana nokugqwala nokugqwala, amandla aqinile namandla okukhiqiza, nokusebenza okushisayo nakho kuye kwathuthukiswa9.Inani elikhulu le-nitrogen lingathatha indawo yokuqukethwe kwe-nickel ebizayo, okwenza i-SDSS ingabizi kakhulu10.
Muva nje, i-SDSS ikhubazekile ngokwepulasitiki emazingeni okushisa ahlukahlukene (izinga lokushisa eliphansi, elibandayo nelishisayo) ukuze kuzuzwe izakhiwo ezinhle kakhulu zemishini6,7,8.Kodwa-ke, ukumelana okuhle kakhulu kokugqwala kwe-SDSS kungenxa yokuba khona kwefilimu encane ye-oxide ebusweni, ethintwa izici eziningi, njengokuba khona kwezigaba eziningi ezinemingcele ehlukene yokusanhlamvu, ukuqubuka okungafuneki nokusabela okuhlukile.i-microstructure yangaphakathi ye-inhomogeneous yezigaba ezihlukahlukene ze-austenitic ne-ferritic ikhubazekile 7.Ngakho-ke, ukufundwa kwezakhiwo ze-microdomain zamafilimu anjalo ezingeni lesakhiwo se-elekthronikhi kubaluleke kakhulu ekuqondeni ukugqwala kwe-SDSS futhi kudinga amasu okuhlola ayinkimbinkimbi.Kuze kube manje, izindlela ezizwela phezulu njenge-Auger electron spectroscopy11 kanye ne-X-ray photoelectron spectroscopy12,13,14,15 kanye nohlelo oluqinile lwe-X-ray photoelectron photoelectron ziyahlukanisa, kodwa ngokuvamile ziyehluleka ukuhlukana, izimo zamakhemikhali zesici esifanayo emaphuzwini ahlukene emkhathini ku-nanoscale.Ucwaningo oluthile lwakamuva luxhumanise i-oxidation yendawo ye-chromium nokuziphatha kokugqwala okuphawuliwe kwama-austenitic stainless steels angu-17, ama-martensitic stainless steels angu-18, kanye ne-SDSS 19, 20. Nokho, lezi zifundo zigxile kakhulu kumthelela we-Cr heterogeneity (isb, isimo se-Cr3+ se-oxidation).I-Lateral heterogeneity ezimeni ze-oxidation zezakhi zingabangelwa izinhlanganisela ezihlukene ezinezakhi ezifanayo, njengama-iron oxides.Lezi zinhlanganisela zizuza njengefa usayizi omncane ocutshungulwe nge-thermomechanically eduze komunye nomunye, kodwa uhlukile ekubunjweni kanye nesimo se-oxidation16,21.Ngakho-ke, ukudalula ukucekelwa phansi kwamafilimu e-oxide bese ugoba kudinga ukuqonda kwe-surface inhomogeneity ezingeni le-microscopic.Naphezu kwalezi zidingo, ukuhlolwa komthamo okufana ne-lateral oxidation heterogeneity, ikakhulukazi yensimbi esikalini se-nano/atomic, kusantuleka futhi nokubaluleka kwako kokumelana nokugqwala akukahlolwa.Kuze kube muva nje, isimo samakhemikhali sezakhi ezihlukahlukene, njenge-Fe ne-Ca, sachazwa ngokomthamo kumasampuli ensimbi kusetshenziswa i-X-ray photoelectron microscopy (X-PEEM) ethambile ezindaweni zemisebe ye-nanoscale synchrotron.Ihlanganiswe namasu amakhemikhali e-X-ray absorption spectroscopy (XAS), i-X-PEEM yenza ukulinganisa kwe-XAS kube nokulungiswa okuphezulu kwendawo nokubukeka, ihlinzeka ngolwazi lwamakhemikhali mayelana nokubunjwa kwe-elemental kanye nesimo sayo samakhemikhali ngokulungiswa kwendawo kuze kufike esikalini se-nanometer esingu-23.Lokhu kubuka kwe-spectroscopic yesayithi lokuqaliswa ngaphansi kwesibonakhulu kusiza ukuhlolwa kwamakhemikhali endawo futhi kungabonisa ngendawo izinguquko zamakhemikhali ezazingahloliwe ngaphambili kungqimba lwe-Fe.
Lolu cwaningo lunweba izinzuzo ze-PEEM ekutholeni umehluko wamakhemikhali ku-nanoscale futhi luveza indlela yokuhlaziya indawo ye-athomu yezinga le-athomu yokuqonda ukuziphatha kokugqwala kwe-Ce-2507.Isebenzisa idatha yekhemimethri yeqoqo le-K-means24 ukwenza imephu yokwakheka kwamakhemikhali womhlaba (i-heterogeneity) yezinto ezihilelekile, nezimo zazo zamakhemikhali ezethulwa ekumeleleni kwezibalo.Ngokungafani necala elivamile lokugqwala okubangelwa ukuwohloka kwefilimu ye-chromium oxide, ukunganyakazi kahle kwamanje kanye nokumelana nokugqwala okungekuhle kubangelwa ama-nanoislands acebile e-Fe3+ eduze nongqimba lwe-Fe/Cr oxide, okungenzeka kube umphumela wama-oxide avikelayo.Esikhundleni sokuqhekeka, kwakhiwa ifilimu ebangela ukugqwala.
Ukuziphatha okulimazayo kwe-SDSS 2507 ekhubazekile kwaqale kwahlolwa kusetshenziswa izilinganiso ze-electrochemical.Emkhiwaneni.Umfanekiso 1 ubonisa amajika e-Nyquist kanye ne-Bode kumasampuli akhethiwe ane-acidic (pH = 1) yezixazululo ezinamanzi ze-FeCl3 ekamelweni lokushisa.I-electrolyte ekhethiwe isebenza njenge-ejenti ene-oxidizing eqinile, ebonisa ukuthambekela kwefilimu ye-passivation ukuphuka.Nakuba okokusebenza kungazange kungene ezingeni lokushisa elizinzile legumbi, lokhu kuhlaziya kunikeze ukuqonda ezehlakalweni ezingase zibe khona zokuhluleka kanye nezinqubo zangemuva kokugqwala.Isifunda esilinganayo (Fig. 1d) sasisetshenziselwa ukulingana ne-electrochemical impedance spectroscopy (EIS) spectra, futhi imiphumela ehambisanayo ehambisanayo iboniswa kuThebula 1. Imibuthano engaphelele yesigamu ibonakala lapho kuhlolwa isisombululo esiphathwayo kanye namasampula asebenzayo ashisayo, kuyilapho imibuthano ehambisanayo ecindezelweyo ehambisanayo yayigoqwe ngamakhaza (Fig. 1b).Ku-spectrum ye-EIS, i-semicircle radius ingabhekwa njengokumelana ne-polarization (Rp)25,26.I-Rp yesisombululo esiphathwe nge-SDSS kuThebula 1 icishe ibe ngu-135 kΩ cm-2, nokho ku-SDSS esetshenzwayo ebandayo negoqekayo singabona amanani aphansi kakhulu angu-34.7 kanye no-2.1 kΩ cm–2 ngokulandelanayo.Lokhu kwehla okuphawulekayo kwe-Rp kukhombisa umthelela olimazayo wokuguqulwa kwepulasitiki ku-passivation kanye nokumelana nokugqwala, njengoba kuboniswe emibikweni yangaphambilini 27, 28, 29, 30.
i-Nyquist, b, c I-Bode impedance kanye nemidwebo yesigaba, kanye nemodeli yesekethe efanayo ye-d, lapho i-RS iwukumelana ne-electrolyte, i-Rp ukumelana ne-polarization, futhi i-QCPE iyisici se-oxide yesigaba esingaguquki esisetshenziselwa ukumodela amandla angafanelekile (n) .Izilinganiso ze-EIS zenziwa ngaphandle komthwalo.
I-oda lokuqala elingaguquki liboniswa kumdwebo we-Bode futhi i-high frequency plateau imele ukumelana ne-electrolyte RS26.Njengoba imvamisa iyancipha, i-impedance iyanda futhi i-angle yesigaba esingalungile itholakala, ekhombisa ukubusa kwe-capacitance.I-engeli yesigaba iyanda, igcina inani layo eliphezulu kububanzi obuyindilinga bemvamisa, bese yehla (Fig. 1c).Kodwa-ke, kuzo zontathu lezi zimo leli nani eliphezulu lisengaphansi kuka-90°, okubonisa ukuziphatha okunamandla okungahambi kahle ngenxa yokuhlakazeka kwe-capacitive.Ngakho-ke, isici sesigaba esiqhubekayo se-QCPE (i-CPE) sisetshenziselwa ukumela ukusatshalaliswa kwe-interfacial capacitance etholakala ebukhulu obuphezulu noma ukungahambi kahle, ikakhulukazi ngokwesilinganiso se-athomu, ijometri ye-fractal, i-electrode porosity, amandla angewona afanayo, kanye nokusabalalisa kwamanje okuncike ebusweni.Electrode geometry31,32.I-CPE impedance:
lapho u-j eyinombolo engokomfanekiso futhi u-ω kuyi-angular frequency.I-QCPE imvamisa ezimele njalo ngokulingana nendawo evulekile esebenzayo ye-electrolyte.n iyinombolo yamandla angenasici echaza ukuchezuka ekuziphatheni okuhle kwe-capacitive kwe-capacitor, okungukuthi u-n oseduze no-1, i-CPE eseduze iwukuba namandla ahlanzekile, futhi uma u-n eseduze noziro, ukumelana.Ukuchezuka okuncane kwe-n, eduze noku-1, kubonisa ukuziphatha okungalungile kwe-capacitive ebusweni ngemva kokuhlolwa kwe-polarization.I-QCPE ye-SDSS egoqiwe ebandayo iphakeme kakhulu kunemikhiqizo efanayo, okusho ukuthi ikhwalithi yangaphezulu ayifani kangako.
Ngokuhambisana nezindawo eziningi zokungagqwali kwezinsimbi, okuqukethwe okuphezulu kwe-Cr kwe-SDSS ngokuvamile kuholela ekumelaneni nokugqwala okuphakeme kwe-SDSS ngenxa yokuba khona kwefilimu ye-oxide evikelayo endaweni17.Le filimu edlulayo ngokuvamile inothile ngama-Cr3+ oxides kanye/noma ama-hydroxides, ikakhulukazi ahlanganisa i-Fe2+, Fe3+ oxides kanye/noma (oxy)hydroxides 33.Naphezu kokufana kwendawo efanayo, ungqimba lwe-oxide odlulayo, futhi akukho ukuphuka okubonakalayo endaweni, njengoba kunqunywa izithombe ezincane kakhulu,6,7 ukuziphatha kokugqwala kwe-SDSS esebenza ngokushisayo negoqwe ngokubanda kwehlukile ngakho kudinga ukucwaninga okujulile kwe-deformation microstructure kanye nesakhiwo sensimbi.
I-microstructure yensimbi engagqwali ekhubazekile yaphenywa ngobuningi kusetshenziswa ama-X-ray anamandla angaphakathi kanye ne-synchrotron (Izibalo Ezingeziwe 1, 2).Ukuhlaziya okuningiliziwe kunikezwa Olwazini Olwengeziwe.Nakuba lokhu kufanelana kakhulu nohlobo lwesigaba esiyinhloko, umehluko utholwe kuzingxenye zevolumu zezigaba, ezifakwe kuhlu Lokwengeza Ithebula 1. Umehluko ungahle ubangelwe ingxenyana yesigaba esihlukile endaweni engaphezulu kanye nengxenye yevolumu (XRD) engaphansi kokujula okuhlukile kokutholwa ngokusebenzisa i-X-ray diffraction enemithombo ehlukahlukene yamandla yamafotoni esigameko.Ingxenye ephakeme uma kuqhathaniswa ye-austenite kuma-specimens agoqekile abandayo, enqunywa i-XRD evela emthonjeni waselabhorethri, ikhombisa ukudlula okungcono kanye nokumelana nokugqwala okungcono35, kuyilapho imiphumela enembe kakhudlwana nezibalo ibonisa izitayela eziphambene ngezilinganiso zesigaba.Ukwengeza, ukumelana nokugqwala kwensimbi nakho kuncike ezingeni lokulungiswa okusanhlamvu, ukunciphisa usayizi wokusanhlamvu, ukwanda kwe-microdeformations kanye nomthamo we-dislocation okwenzeka ngesikhathi sokwelashwa kwe-thermomechanical36,37,38.Ama-specimens ashisiwe abonisa imvelo yezinhlamvu eziningi, ekhombisa okusanhlamvu okungama-micron, kuyilapho izindandatho ezibushelelezi ezibonwa kuma-specimens abandayo (I-Supplementary Fig. 3) zibonisa ukuthuthukiswa okuphawulekayo okusanhlamvu ku-nanoscale emsebenzini wangaphambilini6, okufanele kusize ekudlulisweni kwefilimu.ukwakheka kanye nokwanda kokumelana nokugqwala.Ukuminyana okuphezulu kokugudluka kuvame ukuhlotshaniswa nokumelana okuphansi nokugoba, okuvumelana kahle nezilinganiso ze-electrochemical.
Izinguquko ezimweni zamakhemikhali zama-microdomain wezinto eziyisisekelo ziye zafundwa ngokuhlelekile kusetshenziswa i-X-PEEM.Naphezu kobuningi bezakhi ze-alloying, i-Cr, i-Fe, i-Ni, ne-Ce39 ikhethwe lapha ngoba i-Cr iyisici esibalulekile sokwakhiwa kwefilimu ye-passivation, i-Fe iyingxenye eyinhloko yensimbi, futhi i-Ni ithuthukisa ukunyakaza nokulinganisa isakhiwo sesigaba se-ferrite-austenitic kanye nenjongo yokuguqula i-Ce.Ngokulungisa amandla emisebe ye-synchrotron, i-RAS yahlanganiswa kusukela phezulu ngezici eziyinhloko ze-Cr (onqenqemeni L2.3), Fe (onqenqemeni L2.3), Ni (onqenqemeni L2.3) kanye no-Ce (onqenqemeni M4.5).ukwakheka okushisayo nokubandayo kwe-Ce-2507 SDSS.Ukuhlaziywa kwedatha okufanele kwenziwe ngokuhlanganisa ukulinganisa amandla nedatha eshicilelwe (isb. XAS 40, 41 ku-Fe L2, 3 imiphetho).
Emkhiwaneni.Umfanekiso we-2 ubonisa izithombe ze-X-PEEM ze-hot-worked (Fig. 2a) kanye ne-cold-rolled (Fig. 2d) Ce-2507 SDSS kanye nemiphetho ye-XAS ehambisanayo ye-Cr ne-Fe L2,3 ezindaweni ezimakwe ngazinye.Unqenqema lwe-L2,3 lwe-XAS luphenya izifunda ezingu-3d ezingenalutho ngemva kwe-electron photoexcitation kumazinga ahlukanisayo we-spin-orbit 2p3/2 (L3 edge) kanye no-2p1/2 (L2 onqenqemeni).Ulwazi mayelana nesimo se-valence se-Cr lutholwe ku-XAS emaphethelweni e-L2,3 ku-Fig. 2b, isib.Ukuqhathanisa namajaji.42,43 ibonise ukuthi iziqongo ezine zibonwe eduze konqenqema lwe-L3, okuthiwa A (578.3 eV), B (579.5 eV), C (580.4 eV) kanye no-D (582.2 eV), okubonisa i-octahedral Cr3+, ehambisana ne-Cr2O3 ion.I-spectra yokuhlola ivumelana nezibalo zethiyori eziboniswe kumaphaneli b no-e, atholwe ekubalweni okuningi kwe-crystal field kusixhumi esibonakalayo se-Cr L2.3 kusetshenziswa inkambu yekristalu engu-2.0 eV44.Zombili izindawo ze-SDSS esebenza ngokushisayo negoqwe ngokubanda zimbozwe ngongqimba olufana nolunye lwe-Cr2O3.
isithombe esishisayo se-X-PEEM se-SDSS ekhubazekile ngokushisa okuhambisana ne-b Cr L2.3 onqenqemeni kanye no-c Fe L2.3 onqenqemeni, d isithombe esishisayo se-X-PEEM se-SDSS egoqekile ebandayo esihambisana ne-e Cr L2.3 edge kanye no-f Fe L2 .3 uhlangothi lonqenqema ( f).I-spectra ye-XAS ibekwe ezindaweni ezihlukene ezimakwe ezithombeni ezishisayo (a, d), imigqa enamachashazi awolintshi ku-(b) kanye (e) imele isibukeli esilingisiwe se-XAS se-Cr3+ enenani lenkundla yekristalu elingu-2.0 eV.Ezithombeni ze-X-PEEM, sebenzisa iphalethi eshisayo ukuze uthuthukise ukufundeka kwesithombe, lapho imibala esuka kokuluhlaza okwesibhakabhaka iye kokubomvu ilingana nokuqina kokumuncwa kwe-X-ray (kusuka phansi kuye phezulu).
Kungakhathaliseki ukuthi imvelo yamakhemikhali yalezi zici zensimbi, isimo samakhemikhali sokungezwa kwezakhi ze-alloying ye-Ni ne-Ce yawo womabili amasampuli sahlala singashintshile.Umdwebo owengeziwe.Amanani 5-9 abonisa izithombe ze-X-PEEM kanye nesibukeli se-XAS esihambelanayo se-Ni ne-Ce ezindaweni ezihlukahlukene endaweni yezibonelo ezishisiwe nezigoqelwe ngokubanda.I-Ni XAS ibonisa izimo ze-oxidation ze-Ni2+ phezu kwayo yonke indawo elinganiselwe yezibonelo ezishisiwe nezigoqeke kubanda (Ingxoxo Eyengeziwe).Kufanele kuqashelwe ukuthi, endabeni yamasampula asetshenziswe ngokushisayo, isignali ye-XAS ye-Ce ayizange ibonwe, kuyilapho endabeni yamasampuli agoqelwe ngokubanda, i-spectrum ye-Ce3+ yabonwa.Ukubhekwa kwamachashazi e-Ce kumasampula agoqelwe ngokubanda kubonise ukuthi u-Ce uvela kakhulu ngendlela yemvula.
Ku-SDSS ekhubazekile ngokushisa, alukho ushintsho lwesakhiwo sendawo ku-XAS emaphethelweni e-Fe L2,3 olubonwe (Umfanekiso 2c).Kodwa-ke, i-Fe matrix micro-regionally ishintsha isimo sayo samakhemikhali ezindaweni eziyisikhombisa ezikhethwe ngokungahleliwe ze-SDSS egoqelwe ngokubanda, njengoba kuboniswe ku-Fig. 2f.Ukwengeza, ukuze uthole umqondo onembile wezinguquko esimweni se-Fe ezindaweni ezikhethiwe ku-Fig. 2f, izifundo zendawo zendawo zenziwa (Fig. 3 kanye ne-Supplementary Fig. 10) lapho izifunda ezincane eziyindilinga zikhethiwe.I-spectra ye-XAS yomkhawulo we-Fe L2,3 wezinhlelo ze-α-Fe2O3 kanye ne-Fe2+ octahedral oxides amodelwe ngokubala kwenkundla yekristalu eminingi kusetshenziswa izinkambu zekristalu ze-1.0 (Fe2+) kanye ne-1.0 (Fe3+)44. Siyaqaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 inenhlanganisela yakho kokubili i-Fe2+ & Fe3+,47, kanye ne-FeO45 njenge-divalent ngokusemthethweni i-Fe2+ oxide (3d6). Siyaqaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 inenhlanganisela yakho kokubili i-Fe2+ & Fe3+,47, kanye ne-FeO45 njenge-divalent ngokusemthethweni i-Fe2+ oxide (3d6).Qaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 ihlanganisa kokubili i-Fe2+ ne-Fe3+, 47 kanye ne-FeO45 ngendlela ye-divalent oxide Fe2+ (3d6).Qaphela ukuthi i-α-Fe2O3 ne-γ-Fe2O3 zinama-symmetries ahlukene wendawo45,46, i-Fe3O4 inenhlanganisela ye-Fe2+ ne-Fe3+,47 kanye ne-FeO45 isebenza njenge-divalent esemthethweni i-Fe2+ oxide (3d6).Wonke ama-Fe3+ ion ku-α-Fe2O3 anezikhundla ze-Oh kuphela, kuyilapho i-γ-Fe2O3 ivame ukumelwa yi-Fe3+ t2g [Fe3+5/3V1/3]isb i-O4 spinel enezikhala eg izikhundla.Ngakho-ke, ama-Fe3+ ion ku-γ-Fe2O3 anezindawo zombili ze-Td ne-Oh.Njengoba kushiwo ephepheni langaphambilini, i-45 nakuba isilinganiso sokuqina salokhu okubili sihlukile, isilinganiso sazo sokuqina isb/t2g singu-≈1, kuyilapho kulesi simo isilinganiso sokuqina esibhekwayo isb/t2g simayelana no-1. Lokhu kukhipha ukuthi kungenzeka ukuthi esimweni samanje kuphela i-Fe3+ ikhona.Uma kucatshangelwa icala le-Fe3O4 ngakho kokubili i-Fe2+ ne-Fe3+, isici sokuqala, esaziwa ngokuba nonqenqema lwe-L3 olubuthaka (olunamandla) lwe-Fe, sibonisa inombolo encane (enkulu) yezifunda ze-t2g ezingahlali muntu.Lokhu kusebenza ku-Fe2+ (Fe3+), okubonisa ukuthi isici sokuqala sokwenyuka sibonisa ukwanda kokuqukethwe kwe-Fe2+47.Le miphumela ibonisa ukuthi ukuphilisana kwe-Fe2+ ne-γ-Fe2O3, α-Fe2O3 kanye/noma i-Fe3O4 kubusa endaweni egoqekile ebandayo yezinhlanganisela.
Izithombe ezinwetshiwe zesithombe se-photoelectron ezishisayo ze-XAS spectra (a, c) kanye (b, d) ziwela unqenqema lwe-Fe L2,3 ezindaweni ezihlukahlukene zendawo ngaphakathi kwezifunda ezikhethiwe 2 kanye no-E kumakhiwane.2d.
Idatha yokuhlola etholiwe (I-Fig. 4a kanye ne-Supplementary Fig. 11) ihlelwe futhi iqhathaniswa nedatha yamakhompiyutha ahlanzekile 40, 41, 48. Izinhlobo ezintathu ezihlukene zokubonwa kokuhlolwa kwe-Fe L-edge XAS spectra (XAS- 1, XAS-2 ne-XAS-3: Fig. 4a).Ikakhulukazi, i-spectrum 2-a (echazwa ngokuthi i-XAS-1) ku-Fig. 3b elandelwa yi-spectrum 2-b (ekulebulwe ngokuthi XAS-2) ibonwe kuyo yonke indawo yokuthola, kuyilapho i-spectra efana ne-E-3 ibonwe kumfanekiso 3d (obhalwe ukuthi XAS-3) yabonwa ezindaweni ezithile.Njengomthetho, amapharamitha amane asetshenziswe ukukhomba izifunda ezikhona ze-valence kusampula esifundweni: (1) izici ze-spectral L3 ne-L2, (2) izindawo zamandla zezici L3 kanye ne-L2, (3) umehluko wamandla L3-L2., ( 4) L2/L3 isilinganiso sokuqina.Ngokokubuka okubukwayo (Umfanekiso 4a), zontathu izingxenye ze-Fe, okungukuthi, i-Fe0, i-Fe2+, ne-Fe3+, zikhona endaweni ye-SDSS ngaphansi kocwaningo.Isilinganiso sokuqina esibaliwe esingu-L2/L3 siphinde sabonisa ukuba khona kwazo zonke izingxenye ezintathu.
i-spectra ye-XAS Efanisiwe ye-Fe enedatha yokuhlola emithathu ehlukene (imigqa eqinile i-XAS-1, i-XAS-2 ne-XAS-3 ihambisana no-2-a, 2-b no-E-3 ku-Fig. 2 kanye no-3) Ukuqhathaniswa , Octahedron Fe2+, Fe3+ ngamavelu enkundla yekristalu engu-1.0 eV, i-VD ne-XAS-5 ngokulandelanayo. 2, XAS-3) kanye nedatha ye-LCF elungiselelwe ehambisanayo (umugqa omnyama oqinile), futhi nangefomu i-XAS-3 spectra ene-Fe3O4 (isimo esixubile se-Fe) kanye ne-Fe2O3 (pure Fe3+) amazinga.
I-linear combination fit (LCF) yamazinga amathathu 40, 41, 48 yasetshenziselwa ukulinganisa ukwakheka kwe-iron oxide.I-LCF yasetshenziswa ku-spectra ye-Fe L-edge XAS ekhethiwe ebonisa ukugqama okuphezulu kakhulu, okuyi-XAS-1, XAS-2 ne-XAS-3, njengoba kuboniswe ku-Fig. 4b–d.Ngokufakwa kwe-LCF, i-10% Fe0 yacatshangelwa kuzo zonke izimo ngenxa yokuthi siqaphele i-ledge encane kuyo yonke idatha, futhi nangenxa yokuthi insimbi yensimbi iyingxenye eyinhloko yensimbi. Ngempela, ukujula kokuhlolwa kwe-X-PEEM kwe-Fe (~6 nm) 49 kukhulu kunogqinsi olulinganiselwe lwengqimba ye-oxidation (kancane> 4 nm), okuvumela ukutholwa kwesignali ku-matrix yensimbi (Fe0) ngaphansi kwesendlalelo sokudlula. Ngempela, ukujula kokuhlolwa kwe-X-PEEM kwe-Fe (~6 nm) 49 kukhulu kunogqinsi olulinganiselwe lwengqimba ye-oxidation (kancane> 4 nm), okuvumela ukutholwa kwesignali ku-matrix yensimbi (Fe0) ngaphansi kwesendlalelo sokudlula. Действительно, пробная глубина X-PEEM для Fe (~ 6 нм)49 больше, чем предполагаемая толщина слоя окисления (немного > 4 нзолья на песни), железной матрицы (Fe0) под пассивирующим слоем. Ngempela, ukujula kwe-probe X-PEEM kwe-Fe (~ 6 nm) 49 kukhulu kunokuqina okucatshangwayo kwesendlalelo se-oxidation (kancane> 4 nm), okwenza kube nokwenzeka ukuthola isignali ku-matrix yensimbi (Fe0) ngaphansi kongqimba lwe-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），允许检测的允许检测(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） 允测 允杀铁基体 （fe0） 的。 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 толщина оксидного слоя (немного > 4 нал от железной матрицы (Fe0) ниже пассивирующего слоя. Eqinisweni, ukujula kokutholwa kwe-Fe (~6 nm) 49 nge-X-PEEM kukhulu kunokuqina okulindelekile kongqimba lwe-oxide (kancane> 4 nm), okuvumela ukutholwa kwesignali ku-matrix yensimbi (Fe0) ngaphansi kwesendlalelo sokudlula. .Izinhlanganisela ezihlukahlukene ze-Fe2+ ne-Fe3+ zenziwe ukuze kutholwe isisombululo esingcono kakhulu sedatha yokuhlola ebhekiwe.Emkhiwaneni.I-4b ibonisa i-spectrum ye-XAS-1 yenhlanganisela ye-Fe2+ ne-Fe3+, lapho izingxenye ze-Fe2+ ne-Fe3+ zazifana cishe ngo-45%, okubonisa izimo ze-oxidation ezixubile ze-Fe.Ngenkathi ku-spectrum ye-XAS-2, iphesenti le-Fe2+ ne-Fe3+ iba ngu-~30% no-60%, ngokulandelanayo.I-Fe2+ ingaphansi kuka-Fe3+.Isilinganiso se-Fe2+ kuya ku-Fe3, esilingana no-1:2, sisho ukuthi i-Fe3O4 ingakhiwa ngesilinganiso esifanayo phakathi kwama-ion e-Fe.Ngaphezu kwalokho, ku-spectrum ye-XAS-3, iphesenti le-Fe2+ ne-Fe3+ liba ngu-~10% no-80%, okubonisa ukuguqulwa okuphezulu kwe-Fe2+ kuya ku-Fe3+.Njengoba kushiwo ngenhla, i-Fe3+ ingavela ku-α-Fe2O3, γ-Fe2O3 noma ku-Fe3O4.Ukuze uqonde umthombo okungenzeka kakhulu we-Fe3+, i-spectrum ye-XAS-3 yakhiwe ngamazinga ahlukene e-Fe3+ ku-Figure 4e, okubonisa ukufana kwawo womabili amazinga lapho kucutshungulwa inani eliphakeme elingu-B.Nokho, ukushuba kweziqongo zamahlombe (A: kusuka ku-Fe2+) kanye nesilinganiso sokuqina kwe-B/A kubonisa ukuthi i-spectrum ye-XAS-3 iseduze, kodwa ayihambelani ne-spectrum ye-γ-Fe2O3.Uma kuqhathaniswa nenqwaba ye-γ-Fe2O3, isiqongo se-Fe 2p XAS se-A SDSS sinokushuba okuphezulu kancane (I-Fig. 4e), okubonisa ukushuba okuphezulu kwe-Fe2+.Nakuba i-spectrum ye-XAS-3 ifana ne-γ-Fe2O3, lapho i-Fe3+ ikhona ezindaweni ze-Oh ne-Td, ukuhlonzwa kwezifunda ezihlukene ze-valence kanye nokuxhumana kuphela eduze konqenqema lwe-L2,3 noma isilinganiso sokuqina se-L2/L3 kuseyinkinga.isihloko sengxoxo eqhubekayo ngenxa yobunzima bezinto ezihlukahlukene ezithinta i-spectrum yokugcina41.
Ngokungeziwe kumehluko we-spectral esimweni samakhemikhali sezifunda ezikhethiwe ezithakaselwayo ezichazwe ngenhla, i-heterogeneity yamakhemikhali yomhlaba yezinto ezibalulekile i-Cr ne-Fe nayo yahlolwa ngokuhlukanisa yonke imibukiso ye-XAS etholwe endaweni yesampula kusetshenziswa indlela yokuhlanganisa ye-K-means..Amaphrofayili e-Edge Cr L asethelwe ukuthi akhe amaqoqo amabili afanele asatshalaliswe ngokwendawo kuma-specimens asetshenziwe ashisayo nagoqwe ngokubanda aboniswe ku-Fig.5. Kuyacaca ukuthi azikho izinguquko zesakhiwo sendawo ezithathwa njengezifana, njengoba ama-centroids amabili e-XAS Cr spectra ayaqhathaniswa.Lezi zimo ze-spectral zamaqoqo amabili zicishe zifane nalezo ezihambisana ne-Cr2O342, okusho ukuthi izendlalelo ze-Cr2O3 zihlukaniswe ngokulinganayo ku-SDSS.
I-Cr L K-isho amaqoqo esifunda sonqenqema, futhi u-b ama-XAS centroids ahambisanayo.Imiphumela ye-K-isho i-X-PEEM ukuqhathaniswa kwe-SDSS egoqelwe ngokubanda: c Cr L2.3 indawo enqenqemeni yamaqoqo e-K-means kanye no-d ama-XAS centroids ahambisanayo.
Ukubonisa amamephu onqenqema we-FeL ayinkimbinkimbi, amaqoqo athuthukisiwe amane namahlanu kanye nama-centroids ahlotshaniswa nawo (amaphrofayili e-spectral) asetshenziselwa izifanekiso ezisebenza ngokushisayo nezigoqelwe ngokubanda, ngokulandelana.Ngakho-ke, iphesenti (%) ye-Fe2+ ne-Fe3+ ingatholakala ngokufaka i-LCF eboniswe ku-Fig.4.I-pseudoelectrode engaba khona i-Epseudo njengomsebenzi we-Fe0 isetshenziselwe ukuveza i-microchemical inhomogeneity yefilimu ye-surface oxide.I-Epseudo ilinganiselwa kumthetho wokuxuba,
lapho \(\rm{E}_{\rm{Fe}/\rm{Fe}^{2 + (3 + )}}\) ilingana \(\rm{Fe} + 2e^ – \ kuya \rm { Fe}^{2 + (3 + )}\), 0.440 kanye no-0.036 V, ngokulandelanayo.Izifunda ezinamandla aphansi zinokuqukethwe okuphezulu kwenhlanganisela ye-Fe3+.Ukusatshalaliswa okungaba khona kumasampuli akhubazeke ngokushisa okushisayo kunohlamvu olugqinsi olunoshintsho olukhulu olungaba ngu-0.119 V (Fig. 6a, b).Lokhu kusatshalaliswa okungenzeka kuhlobene eduze ne-topography yendawo (Fig. 6a).Azikho ezinye izinguquko ezincike esimweni endaweni yangaphakathi ye-laminar eyabonwa (Fig. 6b).Ngokuphambene nalokho, ukuze kuxhunywe ama-oxide ahlukene anokuqukethwe okuhlukile kwe-Fe2+ ne-Fe3+ ku-SDSS egoqelwe ngokubanda, umuntu angakwazi ukubona imvelo engeyona into efanayo ye-pseudopotential (Fig. 6c, d).I-Fe3+ oxides kanye/noma (i-oxy)hydroxides yizona zakhi eziyinhloko zokugqwala kwensimbi futhi zikwazi ukungena emoyeni nasemanzini50.Kulokhu, iziqhingi ezicebile ku-Fe3+ zibhekwa njengezisatshalaliswa endaweni futhi zingathathwa njengezindawo ezigqwalile.Ngesikhathi esifanayo, i-gradient endaweni engase ibe khona, esikhundleni senani eliphelele lamandla, ingasetshenziswa njengenkomba yokwenziwa kwendawo kwamasayithi okugqwala asebenzayo.Lokhu kusatshalaliswa okungalingani kwe-Fe2+ ne-Fe3+ ebusweni be-SDSS egoqekile ebandayo kungashintsha ikhemistri yendawo futhi kunikeze indawo esebenzayo esebenza kangcono ekuqhekekeni kwefilimu ye-oxide nokusabela kokugqwala, ngaleyo ndlela kuvumele ukugqwala okuqhubekayo kwe-matrix yensimbi engaphansi, okuholela ekugqwaleni kwangaphakathi.i-heterogeneity yezakhiwo kanye nokuncipha kwezakhiwo zokuvikela zengqimba edlulayo.
I-K-isho amaqoqo nama-XAS centroids ahambisanayo endaweni esemaphethelweni e-Fe L2.3 ye-X-PEEM ac ekhubazekile eshisayo kanye ne-df ye-SDSS egoqeka ngokubanda.a, d K-isho iziqephu zeqoqo ezimbozwe ezithombeni ze-X-PEEM.Amandla okubaliwe e-pseudoelectrode (Epseudo) ashiwo kanye nesakhiwo seqoqo le-K-means.Ukukhanya kwesithombe se-X-PEEM, njengombala ku-Fig. 2 kuhambisana nokuqina kokumuncwa kwe-X-ray.
Uma kuqhathaniswa ne-Cr efanayo kodwa isimo samakhemikhali esihlukile se-Fe siholela emonakalweni ohlukile wefilimu ye-oxide namaphethini okugqwala ku-Ce-2507 esebenza ngokushisayo negoqwe ngokubanda.Le ndawo ye-Ce-2507 egoqwe ebandayo ifundwe kahle.Mayelana nokwakhiwa kwama-oxide nama-hydroxides ka-Fe emoyeni ozungezile kulo msebenzi ocishe ungathathi hlangothi, ukusabela kungokulandelayo:
Ukusabela okungenhla kwenzeka kuzimo ezilandelayo ngokusekelwe ekuhlaziyweni kwe-X-PEEM.Ihlombe elincane elihambisana ne-Fe0 lihlotshaniswa nensimbi eyinsimbi engaphansi.Ukusabela kwe-metallic Fe ngemvelo kuphumela ekwakhekeni kwesendlalelo se-Fe(OH)2 (isibalo (5)), esithuthukisa isignali ye-Fe2+ ku-Fe L-edge XAS.Ukuchayeka isikhathi eside emoyeni kungase kubangele ekwakhekeni kwe-Fe3O4 kanye/noma i-Fe2O3 oxides ngemva kwe-Fe(OH)252,53.Izinhlobo ezimbili ezizinzile ze-Fe, Fe3O4 kanye ne-Fe2O3, zingase futhi zakhe ku-Cr3+ ungqimba olunothile oluvikelayo, lapho i-Fe3O4 ikhetha ukwakheka okufanayo nokunamathelayo.Ukuba khona kwayo yomibili imiphumela kuzimo ezixubile ze-oxidation (i-XAS-1 spectrum).I-spectrum ye-XAS-2 ihambelana kakhulu ne-Fe3O4.Ngenkathi ukubhekwa kwe-spectra ye-XAS-3 ezindaweni ezimbalwa kubonise ukuguqulwa okuphelele ku-γ-Fe2O3.Njengoba ukujula kokungena kwe-X-ray engavuliwe kucishe kube ngu-50 nm, isignali evela kungqimba olungezansi iphumela ekuqineni okuphezulu kwesiqongo esingu-A.
I-XPA spectrum ibonisa ukuthi ingxenye ye-Fe kufilimu ye-oxide inesakhiwo esinengqimba esihlanganiswe nongqimba lwe-Cr oxide.Ngokuphambene nezimpawu zokudlula ngenxa ye-inhomogeneity yendawo ye-Cr2O3 ngesikhathi sokugqwala, naphezu kongqimba olufanayo lwe-Cr2O3 kulo msebenzi, ukumelana nokugqwala okuphansi kubonakala kuleli cala, ikakhulukazi kuma-specimens abandayo.Ukuziphatha okuphawuliwe kungaqondwa njengokungafani kwesimo se-chemical oxidation kungqimba olungaphezulu (Fe), oluthinta ukusebenza kokugqwala.Ngenxa ye-stoichiometry efanayo yongqimba olungaphezulu (i-iron oxide) kanye nesendlalelo esingaphansi (i-chromium oxide) ukusebenzisana okungcono kwe-52,53 (ukunamathela) phakathi kwabo kuholela ekuthuthweni kancane kwe-iron noma i-oxygen ions ku-lattice, okuholela ekwandeni kokumelana nokugqwala.Ngakho-ke, isilinganiso esiqhubekayo se-stoichiometric, okungukuthi isimo esisodwa se-oxidation se-Fe, singcono kunezinguquko ezisheshayo ze-stoichiometric.I-SDSS ekhubazekile ngenxa yokushisa inendawo efanayo, isendlalelo sokuvikela esiminyene, kanye nokumelana nokugqwala okungcono.Nakuba i-SDSS egoqekile ebandayo, ukuba khona kweziqhingi ezicebile ze-Fe3+ ngaphansi kwesendlalelo sokuvikela kwephula ubuqotho bobuso futhi kubangela ukugqwala kwe-galvanic ne-substrate eseduze, okuholela ekwehleni okubukhali kwe-Rp (Ithebula 1).I-spectrum ye-EIS kanye nokumelana nokugqwala kwayo kuncishisiwe.Kungabonakala ukuthi ukusatshalaliswa kwendawo kweziqhingi ezicebile ze-Fe3+ ngenxa yokuguqulwa kwepulasitiki kuthinta kakhulu ukumelana nokugqwala, okuwumphumela kulo msebenzi.Ngakho-ke, lolu cwaningo luveza izithombe ze-spectroscopic microscopic zokunciphisa ukumelana nokugqwala kwamasampula e-SDSS afundwe ngendlela yokuguqulwa kwepulasitiki.
Ngaphezu kwalokho, nakuba ingxubevange enezici zomhlaba ezingavamile ezinsimbi zezigaba ezimbili zibonisa ukusebenza okungcono, ukusebenzisana kwalesi sakhi esingeziwe ne-matrix yensimbi ngayinye ngokuya ngokuziphatha kokugqwala ngokuya ngedatha ye-spectroscopic microscopy kuhlala kungaqondakali.Ukubonakala kwamasiginali e-Ce (nge-XAS M-edges) kubonakala kuphela ezindaweni ezimbalwa ngesikhathi sokugoqeka okubandayo, kodwa ayanyamalala ngesikhathi sokushintshashintsha okushisayo kwe-SDSS, okubonisa imvula yendawo ye-Ce ku-matrix yensimbi, kunengxubevange ye-homogeneous.Nakuba kungathuthuki kakhulu izakhiwo zemishini ye-SDSS6,7, ukuba khona kwezakhi zomhlaba ezingavamile kunciphisa usayizi wezinto ezifakiwe futhi kucatshangwa ukuthi kuvimbela umgodi endaweni yokuqala54.
Sengiphetha, lo msebenzi udalula umphumela we-surface heterogeneity ekugqwaleni kwe-2507 SDSS elungiswe nge-cerium ngokulinganisa okuqukethwe kwamakhemikhali ezingxenyeni ze-nanoscale.Siphendula umbuzo wokuthi kungani insimbi engagqwali igqwala ngisho nangaphansi kwesendlalelo se-oxide esivikelayo ngokulinganisa i-microstructure yayo, i-surface chemistry, nokucutshungulwa kwesignali kusetshenziswa i-K-means clustering.Kuye kwatholakala ukuthi iziqhingi ezicebile nge-Fe3+, okuhlanganisa nokuhlanganisa kwazo i-octahedral kanye ne-tetrahedral kuso sonke isici se-Fe2+/Fe3+ exubile, ziwumthombo womonakalo nokugqwala kwefilimu ye-oxide egoqelwe ngokubanda i-SDSS.I-Nanoislands ebuswa yi-Fe3+ iholela ekumelaneni nokugqwala okubi ngisho nalapho kukhona ungqimba olwanele lwe-stoichiometric Cr2O3 passivating.Ngaphezu kwenqubekelaphambili ye-methodological ekunqumeni umthelela we-nanoscale chemical heterogeneity on corrosion, umsebenzi oqhubekayo kulindeleke ukuthi ugqugquzele izinqubo zobunjiniyela ukuze kuthuthukiswe ukumelana nokugqwala kwezinsimbi ezingenasici ngesikhathi sokwenziwa kwensimbi.
Ukuze kulungiswe ingot ye-Ce-2507 SDSS esetshenziswe kulolu cwaningo, ukwakheka okuxubile okuhlanganisa i-Fe-Ce master alloy evalwe ngeshubhu yensimbi emsulwa yancibilika esithandweni sokungenisa imvamisa esimaphakathi esingu-150 kg ukuze kukhiqizwe insimbi encibilikisiwe futhi ithululwe esikhunjeni.Ukwakheka kwamakhemikhali kukalwa (wt%) kufakwe kuhlu Lokwengeza 2 Ithebula 2. Ama-ingots aqala ukushisa abe amabhlogo.Khona-ke i-annealed ku-1050 ° C ngamaminithi angu-60 ukuthola insimbi esimweni sesisombululo esiqinile, bese icinywa emanzini ekamelweni lokushisa.Amasampula ahlolisisiwe acutshungulwa ngokuningiliziwe kusetshenziswa i-TEM ne-DOE ukuze kufundwe izigaba, usayizi wokusanhlamvu kanye ne-morphology.Ulwazi oluthe xaxa mayelana namasampula kanye nenqubo yokukhiqiza lungatholakala kweminye imithombo6,7.
Amasampula e-Cylindrical (φ10 mm × 15 mm) okucindezela okushisayo acutshungulwa ukuze i-axis ye-cylinder ihambisane nesiqondiso sokuguqulwa kwebhulokhi.Ukucindezelwa kwezinga lokushisa eliphezulu kwenziwa emazingeni okushisa ahlukahlukene ebangeni lika-1000-1150°C kusetshenziswa isifanisi esishisayo se-Gleeble-3800 ngesilinganiso sobunzima obuqhubekayo ebangeni lika-0.01-10 s-1.Ngaphambi kokuguqulwa, amasampula ashiswa ngesilinganiso esingu-10 °C s-1 imizuzu emi-2 endaweni yokushisa ekhethiwe ukuze kuqedwe ukuthamba kwezinga lokushisa.Ngemuva kokuthola ukufana kwezinga lokushisa, isampula yakhubazeka yaba inani langempela le-0.7.Ngemuva kokuguqulwa, amasampula acinywa ngokushesha ngamanzi ukuze alondoloze isakhiwo esikhubazekile.I-specimen eqinile ibe isisikwa ngokuhambisana nesiqondiso sokucindezela.Kulolu cwaningo oluthile, sikhethe isifanekiso esinesimo sokuqina esishisayo esingu-1050°C, 10 s-1 ngoba ubulukhuni obuncane obuphawuliwe babuphezulu kunezinye izifanekiso7.
Amasampula amakhulu (80 × 10 × 17 mm3) esixazululo esiqinile se-Ce-2507 asetshenziswe kumshini wokugaya we-LG-300 wezigaba ezintathu ongavumelaniyo we-asynchronous two-roll enezakhiwo ezingcono kakhulu zemishini phakathi kwawo wonke amanye amazinga okuguqulwa6.Izinga lobunzima nokwehliswa kogqinsi kumzila ngamunye ngu-0.2 m·s-1 no-5%, ngokulandelana.
Indawo yokusebenzela ye-electrochemical ye-Autolab PGSTAT128N isetshenziselwe ukulinganisa kwe-electrochemical ye-SDSS ngemva kokugoqeka okubandayo kuya ekunciphiseni ngo-90% kogqinsi (uhlobo lweqiniso olulingana no-1.0) nangemuva kokucindezela okushisayo ku-1050°C ku-10 s-1 kuya kuhlobo lwangempela luka-0.7.Indawo yokusebenza ineseli enama-electrode amathathu ane-calomel electrode egcwele njenge-reference electrode, i-graphite counter electrode, kanye nesampula ye-SDSS njenge-electrode esebenzayo.Amasampula asikwa abe amasilinda anobubanzi obungu-11.3 mm, ezinhlangothini lapho izintambo zethusi zazidayiselwe khona.Amasampula abe eselungiswa nge-epoxy, eshiya indawo evulekile yokusebenza engu-1 cm2 njenge-electrode esebenzayo (uhlangothi olungezansi lwesampula yesilinda).Qaphela ngesikhathi sokwelashwa kwe-epoxy kanye nokugcotshwa kwesihlabathi nokupholisha okulandelayo ukuze ugweme ukuqhekeka.Izindawo zokusebenza zazigaywe futhi zapholishwa ngokumiswa kokupholishwa kwedayimane ngosayizi wezinhlayiyana ezingu-1 μm, zigezwe ngamanzi acwecwe kanye ne-ethanol, futhi zomiswe emoyeni obandayo.Ngaphambi kokulinganisa kwe-electrochemical, amasampula aphucuziwe ayevezwa emoyeni izinsuku ezimbalwa ukuze akhe ifilimu yemvelo ye-oxide.Isixazululo esinamanzi se-FeCl3 (6.0 wt%), esizinzile sibe yi-pH = 1.0 ± 0.01 nge-HCl ngokwezincomo ze-ASTM, sisetshenziselwa ukusheshisa ukugqwala kwensimbi engagqwali55 ngenxa yokuthi siyagqwala uma kukhona ama-ion e-chloride anamandla okwenza i-oxidizing kanye ne-pH ephansi ye-G3 ne-PH8 Amazinga AphansiGxilisa isampula kusixazululo sokuhlola ihora elingu-1 ukuze ifinyelele eduze kwesimo esizinzile ngaphambi kokwenza noma yiziphi izilinganiso.Kumasampula anesixazululo esiqinile, esakheke ngokushisayo, nagoqeka ngokubanda, izilinganiso ze-impedance zenziwa kumandla wesekethe evulekile (OPC) ka-0.39, 0.33, no-0.25 V, ngokulandelana, ebangeni lemvamisa ukusuka ku-1 105 kuye ku-0.1 Hz enobubanzi obungu-5 mV.Zonke izivivinyo zamakhemikhali ziphindwe okungenani izikhathi ezi-3 ngaphansi kwezimo ezifanayo ukuze kuqinisekiswe ukukhiqizwa kabusha kwedatha.
Ezilinganisweni ze-HE-SXRD, amabhulokhi ensimbi ayi-rectangular duplex akala u-1 × 1 × 1.5 mm3 alinganiswe ukuze kulinganiswe ukwakheka kwesigaba se-beam se-Brockhouse high-energy wiggler e-CLS, Canada56.Ukuqoqwa kwedatha kwenziwa ngejometri ye-Debye-Scherrer noma i-geometry yokudlulisela ekamelweni lokushisa.Ubude beza beza be-X-ray abalinganiswe ngesilinganisi se-LaB6 bungu-0.212561 Å, obuhambisana no-58 keV, ephakeme kakhulu kunaleyo ye-Cu Kα (8 keV) evame ukusetshenziswa njengomthombo we-X ray elabhorethri.Isampula yayitholakala ebangeni elingu-740 mm ukusuka kumtshina.Ivolumu yokutholwa yesampula ngayinye ngu-0.2 × 0.3 × 1.5 mm3, enqunywa usayizi wohlaka nogqinsi lwesampula.Yonke idatha iqoqwe kusetshenziswa umtshina wendawo we-Perkin Elmer, umtshina we-X-ray wephaneli eyisicaba, amaphikseli angu-200 µm, 40×40 cm2 kusetshenziswa isikhathi sokuchayeka esingu-0.3 s namafreyimu angu-120.
Izilinganiso ze-X-PEEM zamamodeli amabili akhethiwe zenziwa esiteshini sokugcina se-Beamline MAXPEEM PEEM elabhorethri ye-MAX IV (Lund, Sweden).Amasampula alungiswa ngendlela efanayo neyezilinganiso ze-electrochemical.Amasampula alungisiwe agcinwa emoyeni izinsuku ezimbalwa futhi akhishwa ku-vacuum chamber ye-ultrahigh ngaphambi kokukhanyiswa ngama-synchrotron photon.Ukulungiswa kwamandla komugqa we-beam kutholwe ngokulinganisa i-spectrum ye-ion yesivuno endaweni yenjabulo ukusuka ku-N 1 s ukuya ku-1\(\pi _g^ \st\) eduze ne-hv = 401 eV ku-N2 ngokuncika kwamandla e-photon ku-E3/2 , 57. Uhlaka olulinganiselwe lokulinganisa lunikeze umugqa wokuhlola we-Vwi we-ΔE. Ngakho-ke, ukulungiswa kwamandla e-beamline kwalinganiselwa ukuthi kube ngu-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 ph/s ngokusebenzisa i-monochromator eguquliwe ye-SX-700 ene-Si 1200-line mm−1 grating ye-Fe 2p L2, L2, Cr3pdge2, Cr3pdge2 edge2 kanye ne-Ce M4,5 onqenqemeni. Ngakho-ke, ukulungiswa kwamandla e-beamline kwalinganiselwa ukuthi kube ngu-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 ph/s ngokusebenzisa i-monochromator eguquliwe ye-SX-700 ene-Si 1200-line mm−1 grating ye-Fe 2p L3 edge, L2.3 edge 2. kanye ne-Ce M4.5 onqenqemeni. Таким образом, энергетическое разрешение канала пучка было оценено как E/∆E = 700 эВ/0,3 эВ > 2000 и поток ≈1012 нохроматора SX-700 с решеткой Si 1200 штрихов/мм для Fe кромка 2p L2,3, кромка Cr 2p L2,3, кромка Ni 2p L2,3 and кромка Ce M4,5. Ngakho-ke, ukulungiswa kwamandla kwesiteshi se-beam kulinganiselwa ukuthi i-E/∆E = 700 eV/0.3 eV > 2000 kanye ne-flux ≈1012 f/s kusetshenziswa i-monochromator eguquliwe ye-SX-700 ene-Si grating yemigqa engu-1200/mm ye-Fe edge 2p L2, 3, i-Cep 2 edge, i-Cep 2, i-Cep Cr2 edge. 4.5.因此，光束线能量分辨率估计為E/ΔE = 700 eV/0.3 eV > 2000 和通量≈1012 ph/s，通过的使用带有1Si 120 -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 边缘.因此 , 光束线 能量 分辨率 為 為 為 δe = 700 EV/0.3 EV> 2000 和 ≈1012 PH/S , 使用 带有 带有 12 mm . I-SX-700 单色器 于 于 用 用 用Fe 2p L2.3 边缘、Cr 2p L2.3 边缘、Ni 2p L2.3 边缘和Ce M4.5 边缘.Ngakho-ke, uma usebenzisa i-monochromator ye-SX-700 eguquliwe enomugqa we-1200 we-Si grating.3, Cr edge 2p L2.3, Ni edge 2p L2.3 kanye ne-Ce edge M4.5.Skena amandla e-photon ngezinyathelo ezingu-0.2 eV.Kumandla ngamunye, izithombe ze-PEEM zarekhodwa kusetshenziswa isitholi se-fiber-coupled TVIPS F-216 CMOS esinamabhini angu-2 x 2, esihlinzeka ngokulungiswa kwamaphikseli angu-1024 x 1024 endaweni yokubuka engu-20 µm.Isikhathi sokuchayeka sezithombe bekungu-0.2 s, isilinganiso samafreyimu angu-16.Amandla esithombe se-photoelectron akhethwa ngendlela yokuthi anikeze isignali ephezulu ye-electron yesibili.Zonke izilinganiso zenziwa ngesenzakalo esivamile kusetshenziswa i-photon beam eqondile.Ulwazi olwengeziwe mayelana nezilinganiso lungatholakala ocwaningweni lwangaphambilini.Ngemva kokufunda imodi yokuhlonza isamba se-electron yield (TEY) kanye nokusetshenziswa kwayo ku-X-PEEM49, ukujula kwesilingo sale ndlela kulinganiselwa ukuthi kungaba ngu-4-5 nm kusignali ye-Cr futhi cishe u-6 nm we-Fe.Ukujula kwe-Cr kusondelene kakhulu nogqinsi lwefilimu ye-oxide (~4 nm)60,61 kuyilapho ukujula kwe-Fe kukhulu kunogqinsi.I-XRD eqoqwe emaphethelweni e-Fe L iyingxube ye-XRD yama-iron oxides kanye ne-Fe0 evela ku-matrix.Esimweni sokuqala, amandla ama-electron akhishiwe avela kuzo zonke izinhlobo zama-electron ezingaba negalelo ku-TEY.Kodwa-ke, isignali yensimbi ehlanzekile idinga amandla e-kinetic aphezulu ukuze ama-electron adlule ungqimba lwe-oxide aye phezulu futhi aqoqwe yi-analyzer.Kulokhu, isignali ye-Fe0 ngokuyinhloko ibangelwa ama-electron e-LVV Auger, kanye nama-electron esibili akhishwa yiwo.Ukwengeza, ukuqina kwe-TEY okunikelwe yilawa ma-electron abola phakathi nendlela yokuphunyuka kwama-electron, okuqhubeka nokunciphisa impendulo ye-Fe0 kumephu ye-iron XAS.
Ukuhlanganisa ukumbiwa kwedatha kukhyubhu yedatha (idatha ye-X-PEEM) kuyisinyathelo esibalulekile ekukhipheni ulwazi olufanele (izakhiwo zamakhemikhali noma ezibonakalayo) ngendlela ye-multidimensional.I-K-means clustering isetshenziswa kakhulu emikhakheni eminingana, okuhlanganisa ukubona komshini, ukucutshungulwa kwesithombe, ukuqashelwa kwephethini okungagadiwe, ubuhlakani bokwenziwa, nokuhlaziya ngokwezigaba.Isibonelo, i-K-means clustering isebenze kahle ekuhlanganiseni idatha yesithombe se-hyperspectral.Empeleni, kudatha yezici eziningi, i-algorithm ye-K-means ingaziqoqa kalula ngokusekelwe olwazini mayelana nezimfanelo zazo (izakhiwo zamandla e-photon).I-K-means clustering i-algorithm ephindaphindwayo yokuhlukanisa idatha ibe ngamaqembu angu-K angagqagqani (amaqoqo), lapho iphikseli ngayinye ingeyeqoqo elithile kuye ngokusatshalaliswa kwendawo kwe-chemical inhomogeneity ekubunjweni kwensimbi yesakhiwo esincane.I-algorithm ye-K-means ihlanganisa izigaba ezimbili: esigabeni sokuqala, kubalwa amasentimitha angu-K, futhi esigabeni sesibili, iphuzu ngalinye linikezwa iqoqo elinamacentroid angomakhelwane.Isikhungo se-gravity yeqoqo sichazwa njenge-arithmetic mean yamaphoyinti edatha (i-XAS spectrum) yalelo qoqo.Kunamabanga ahlukahlukene okuchaza ama-centroid angomakhelwane njengebanga le-Euclidean.Ukuze uthole isithombe esifakiwe sika-px,y (lapho u-x kanye no-y ewukulungiswa ngamaphikseli), i-CK iyisikhungo samandla adonsela phansi eqoqo;lesi sithombe singabe sesihlukaniswa (sihlanganiswe) sibe amaqoqo angu-K kusetshenziswa i-K-means63.Izinyathelo zokugcina ze-algorithm ye-K-means clustering yilezi:
Isinyathelo sesi-2. Bala ubulungu bawo wonke amaphikseli ngokuya nge-centroid yamanje.Isibonelo, ibalwa ukusuka ku-Euclidean ibanga d phakathi kwesikhungo nephikseli ngayinye:
Isinyathelo sesi-3 Yabela iphikseli ngayinye ku-centroid eseduze.Bese ubala kabusha izindawo ze-K centroid kanje:
Isinyathelo sesi-4. Phinda inqubo (izibalo (7) kanye (8)) kuze kuhlangane amasentimitha.Imiphumela yokugcina yekhwalithi yokuhlanganisa ihlotshaniswa ngokuqinile nokukhetha okungcono kakhulu kwama-centroids okuqala.Okwesakhiwo sedatha ye-PEEM yezithombe zensimbi, ngokuvamile u-X (x × y × λ) iyikhyubhu yedatha yamalungu afanayo angu-3D, kuyilapho ama-eksisi angu-x kanye no-y amelela ulwazi lwendawo (ukulungiswa kwephikiseli) kanye ne-axis ethi λ ihambisana nefothoni.isithombe se-spectral samandla.I-algorithm ye-K-means isetshenziselwa ukuhlola izifunda zentshisakalo kudatha ye-X-PEEM ngokuhlukanisa amaphikseli (amaqoqo noma amabhlogo angaphansi) ngokuya ngezici zawo ze-spectral futhi kukhishwe ama-centroid angcono kakhulu (amaphrofayili e-XAS spectral) kumhlaziyi ngamunye.iqoqo).Isetshenziselwa ukutadisha ukusatshalaliswa kwendawo, izinguquko ze-spectral zendawo, ukuziphatha kwe-oxidation, nezimo zamakhemikhali.Isibonelo, i-algorithm yokuhlanganisa ye-K-means yasetshenziswa ezifundeni ze-Fe L-edge kanye ne-Cr L-edge endaweni esebenza ngokushisayo negoqelwe ngokubanda i-X-PEEM.Izinombolo ezihlukene zamaqoqo e-K (izifunda ze-microstructure) zahlolwa ukuze kutholwe amaqoqo nama-centroids afaneleka kakhulu.Lapho lezi zinombolo ziboniswa, amaphikseli anikezwa kabusha kuma-cluster centroids ahambisanayo.Ukusabalalisa kombala ngakunye kuhambisana nendawo emaphakathi yeqoqo, okubonisa ukuhlelwa kwendawo kwezinto zamakhemikhali noma ezibonakalayo.Ama-centroids akhishiwe ayinhlanganisela yomugqa ye-spectra ehlanzekile.
Idatha esekela imiphumela yalolu cwaningo iyatholakala ngesicelo esifanele esivela kumbhali we-WC ofanele.
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