Thaum cov xim av xeb (spots) tshwm rau saum npoo ntawm cov kav hlau stainless, tib neeg xav tsis thoob: "Stainless hlau tsis xeb, thiab yog tias nws xeb, nws tsis yog stainless hlau, thiab tej zaum yuav muaj teeb meem nrog cov hlau."Qhov tseeb, qhov no yog ib qho kev xav tsis zoo txog kev tsis nkag siab ntawm stainless hlau.Stainless hlau kuj yuav xeb nyob rau hauv tej yam kev mob.
1. Stainless hlau tsis xeb
Stainless hlau kuj tsim ib qho oxide rau ntawm qhov chaw.Cov txheej txheem xeb ntawm tag nrho cov hlau stainless tam sim no nyob rau hauv kev ua lag luam yog vim muaj cov khoom siv Cr.Lub hauv paus ua rau (mechanism) ntawm stainless hlau corrosion kuj yog passive zaj duab xis txoj kev xav.Lub npe hu ua passivation zaj duab xis yog ib zaj duab xis nyias uas yog tsim los ntawm Cr2O3 ntawm cov hlau tsis muaj steel.Vim tias muaj cov yeeb yaj kiab no, qhov corrosion ntawm stainless hlau substrate nyob rau hauv ntau yam xov xwm yog hindered, thiab qhov tshwm sim no hu ua passivation.Muaj ob qhov xwm txheej rau kev tsim cov yeeb yaj kiab passivation no.Ib qho yog tias stainless hlau nws tus kheej muaj peev xwm ntawm tus kheej-passivation, thiab nws tus kheej-passivation muaj peev xwm yog nrawm nrog cov ntsiab lus ntawm chromium, yog li nws muaj xeb kuj;Ib qho kev tsim ntau dua yog tias cov hlau tsis muaj hlau ua ib zaj duab xis passivation nyob rau hauv tus txheej txheem ntawm corroded nyob rau hauv ntau yam aqueous tov (electrolytes), uas cuam tshuam corrosion.Thaum cov zaj duab xis passivation puas lawm, ib zaj duab xis passivation tshiab tuaj yeem tsim tam sim ntawd.
Qhov laj thawj yog vim li cas cov yeeb yaj kiab tsis zoo ntawm cov hlau tsis muaj peev xwm tiv thaiv corrosion muaj peb yam ntxwv: ib qho yog tias cov tuab ntawm cov yeeb yaj kiab tsis tshua muaj nyias, feem ntau tsuas yog ob peb microns thaum cov ntsiab lus chromium yog> 10.5%;lwm qhov yog qhov tshwj xeeb lub ntiajteb txawj nqus ntawm cov zaj duab xis passive yog ntau dua qhov tshwj xeeb lub ntiajteb txawj nqus ntawm lub substrate;Ob tus yam ntxwv no qhia tau hais tias cov zaj duab xis passivation yog nyias thiab ntom, yog li nws yog ib qho nyuaj rau cov zaj duab xis passive yuav tsum tau tawg los ntawm corrosive nruab nrab kom sai corrode lub substrate;tus yam ntxwv thib peb yog tias chromium concentration ratio ntawm passive zaj duab xis Lub substrate yog ntau tshaj peb zaug ntau dua;Yog li ntawd, cov zaj duab xis passive muaj siab corrosion kuj.
2. Nyob rau hauv tej yam kev mob, stainless hlau kuj yuav corroded
Daim ntawv thov ib puag ncig ntawm stainless hlau yog qhov nyuaj heev, thiab yooj yim chromium oxide passive zaj duab xis tsis tuaj yeem ua tau raws li qhov yuav tsum tau muaj kev tiv thaiv corrosion siab.Yog li ntawd, cov ntsiab lus xws li molybdenum (Mo), tooj liab (Cu), thiab nitrogen (N) yuav tsum tau ntxiv rau cov hlau raws li kev siv sib txawv los txhim kho cov muaj pes tsawg leeg ntawm cov zaj duab xis passivation thiab txhim kho corrosion kuj ntawm stainless hlau.Qhov sib ntxiv ntawm Mo txhawb nqa kev sib koom ua ke vim tias cov khoom corroded MoO2- nyob ze rau ntawm lub substrate thiab tiv thaiv corrosion ntawm substrate;Qhov sib ntxiv ntawm Cu ua rau cov zaj duab xis passive ntawm cov hlau tsis muaj hlau muaj CuCl, uas txhim kho kev ua haujlwm ntawm cov zaj duab xis passive vim tias nws tsis cuam tshuam nrog qhov nruab nrab corrosive.Corrosion tsis kam;Ntxiv N, vim hais tias cov zaj duab xis passivation yog enriched nrog Cr2N, Cr concentration nyob rau hauv lub passivation zaj duab xis yog nce, yog li txhim kho corrosion kuj ntawm stainless hlau.
Lub corrosion kuj ntawm stainless hlau yog conditional.Ib qib ntawm stainless hlau yog corrosion resistant nyob rau hauv ib tug tej yam nruab nrab, tab sis tej zaum yuav puas nyob rau hauv lwm yam nruab nrab.Nyob rau tib lub sij hawm, corrosion kuj ntawm stainless hlau kuj yog txheeb ze.Txog tam sim no, tsis muaj cov hlau tsis muaj hlau uas tsis muaj corrosive hauv txhua qhov chaw.
Stainless hlau muaj peev xwm tiv taus atmospheric oxidation - uas yog, xeb kuj, thiab kuj muaj peev xwm corrode nyob rau hauv xov xwm uas muaj acids, alkalis, thiab ntsev - uas yog, corrosion kuj.Txawm li cas los xij, qhov loj ntawm nws lub peev xwm los tiv thaiv corrosion yog hloov nrog cov tshuaj muaj pes tsawg leeg ntawm cov hlau nws tus kheej, lub xeev kev tiv thaiv, kev siv cov xwm txheej thiab hom kev tshaj tawm ib puag ncig.Piv txwv li, 304 steel yeeb nkab muaj peev xwm tiv thaiv corrosion zoo heev nyob rau hauv qhov chaw qhuav thiab huv si, tab sis yog tias nws tau txav mus rau thaj tsam ntawm ntug dej hiav txwv, nws yuav xeb sai sai hauv hiav txwv pos uas muaj ntsev ntau;thaum lub 316 steel yeeb nkab qhia tau hais tias zoo.Yog li ntawd, nws tsis yog txhua yam ntawm stainless hlau uas tuaj yeem tiv taus corrosion thiab xeb hauv ib puag ncig.
Post lub sij hawm: Sep-23-2022