Cov hlau tsis xeb thiab cov hlau carbon tsis tuaj yeem siv sib cuag ncaj qha, uas yog lub hauv paus ntsiab lus tseem ceeb hauv kev tshawb fawb txog cov ntaub ntawv thiab kev xyaum ua vaj tse. Feem ntau yog vim muaj "galvanic corrosion", feem ntau hu ua "galvanic corrosion" lossis "heterogeneous metal corrosion". Qhov no zoo li ib daim hlau carbon txi nws tus kheej los tiv thaiv cov hlau tsis xeb, ua rau cov hlau carbon xeb sai sai.
Cov hlau tsis xeb tsis tuaj yeem phim nrog cov hlau carbon vim yog: galvanic corrosion
1. Qhov sib txawv ntawm lub zog yog qhov kev tsav tsheb
Cov hlau sib txawv muaj cov haujlwm electrochemical sib txawv hauv electrolytes (xws li dej, cua noo, kua qaub, cov hauv paus, ntsev, thiab lwm yam), uas tuaj yeem nkag siab tias yog lawv cov qib sib txawv ntawm kev poob electron. Qhov sib txawv ntawm kev ua haujlwm no yog ntsuas los ntawm electrode potential.
Cov hlau uas muaj zog ua haujlwm, xws li cov hlau carbon, muaj cov electrode potentials qis dua thiab yooj yim poob electrons, ua rau lawv tsis tshua tiv taus corrosion.
Cov hlau inert (xws li cov hlau tsis xeb) muaj cov electrode potentials siab dua thiab tsis tshua muaj feem poob electrons. Qhov laj thawj uas cov hlau tsis xeb yog "stainless" yog tias cov chromium ntawm nws qhov chaw tsim cov zaj duab xis chromium oxide passivation ntom ntom, uas tiv thaiv kev xeb ntxiv.
Thaum ob lub hlau no sib cuag ncaj qha rau hauv cov electrolyte, lub voj voog roj teeb thawj zaug tau tsim.
2. Cov txheej txheem xeb
Anode (qhov kawg xeb): Cov hlau carbon, ua ib yam hlau nquag, dhau los ua anode ntawm lub roj teeb. Nws yuav yaj (xeb) thiab tso cov electrons. Qhov tshuaj tiv thaiv yog: Fe → Fe ² ⁺+2e ⁻
Cathode (qhov kawg tiv thaiv): Hlau tsis xeb, ua ib yam hlau inert, dhau los ua cathode ntawm lub roj teeb. Nws tsis xeb, tab sis tsuas yog txais cov electrons ntws los ntawm lub anode thiab siv cov electrons no los ua ke nrog electrolytes (xws li oxygen hauv dej). Qhov ua ke yog: O₂+2H₂ O+4e⁻ → 4OH⁻
Qhov Tshwm Sim: Hauv lub roj teeb no, tam sim no ntws los ntawm cov hlau carbon (anode) mus rau cov hlau tsis xeb (cathode), ua rau muaj kev nce ntxiv ntawm qhov xeb ntawm cov hlau carbon, thaum cov hlau tsis xeb raug tiv thaiv los ntawm "cathodic protection" thiab yuav luag tsis xeb.
Ib qho piv txwv tseeb:
Zoo li muaj ib tug "neeg ncaj ncees" (cov hlau carbon) thiab ib tug "neeg ntse" (cov hlau tsis xeb) koom tes ua lag luam. Thaum ntsib teeb meem (ib puag ncig uas lwj), cov neeg ncaj ncees yuav tso tseg lawv tus kheej cov txiaj ntsig (raug xeb) kom ntseeg tau tias cov neeg ntse tsis raug mob.
Cov hlau tsis xeb tsis tuaj yeem phim nrog cov hlau carbon tseem ceeb uas cuam tshuam rau cov yam ntxwv tseem ceeb
Qhov hnyav ntawm galvanic corrosion nyob ntawm cov hauv qab no:
Ib puag ncig (electrolyte):Qhov no yog qhov tseem ceeb tshaj plaws. Hauv huab cua qhuav, galvanic corrosion tsis tshwm sim vim tias tsis muaj electrolyte tsim ib lub voj voog. Tab sis nyob rau hauv cov chaw noo noo, dej hiav txwv, thaj chaw lag luam, thiab cov chaw tsuag ntsev, corrosion tuaj yeem ua tau sai thiab hnyav heev.
Qhov txawv ntawm qhov muaj peev xwm:Qhov sib txawv ntawm ob hom hlau loj npaum li cas, qhov muaj zog ntawm kev xeb. Qhov sib txawv ntawm cov hlau carbon thiab cov hlau tsis xeb loj txaus ua rau muaj kev xeb loj.
Qhov piv ntawm thaj chaw anode rau cathode:Qhov no yog ib qho ntawm cov xwm txheej txaus ntshai tshaj plaws. Yog tias thaj chaw ntawm cathode (cov hlau tsis xeb) loj thiab thaj chaw ntawm anode (cov hlau carbon) me me, qhov hluav taws xob xeb yuav muaj ntau heev rau ntawm cov hlau carbon me me, ua rau nws xeb tag nrho thiab tawg hauv lub sijhawm luv luv. Piv txwv li, yog tias lub tank hlau tsis xeb raug kho nrog cov hlau carbon bolt, cov hlau carbon bolt yuav xeb thiab tawg sai sai.
Yuav ua li cas tiv thaiv thiab daws cov hlau tsis xeb txuas nrog cov hlau carbon?
Hauv kev siv ua haujlwm, peb feem ntau yuav tsum txuas cov hlau tsis xeb thiab cov hlau carbon ua ke, thiab yuav tsum tau ua cov kev ntsuas cais tawm:
1. Kev rwb thaiv hluav taws xob:Qhov no yog txoj kev zoo tshaj plaws thiab feem ntau siv. Ntxiv cov khoom siv rwb thaiv tsev uas tsis conductive ntawm ob lub hlau kom txiav tawm lub voj voog tam sim no.
- Siv cov gaskets/ntxhua khaub ncaws rwb thaiv tsev: Siv cov yas (xws li PVC, nylon), roj hmab, lossis cov gaskets hluavtaws ntawm cov kev sib txuas flange.
- Siv cov bushings thiab washers uas muaj rwb thaiv tsev: Hauv cov kev sib txuas bolted, siv cov yas bushings ntawm bolts thiab cov qhov carbon steel, thiab siv cov washers rwb thaiv tsev hauv qab cov txiv ntoo.
- Txheej txheej cais: Tsuag epoxy resin, pleev xim lossis siv lwm yam txheej rau ntawm qhov chaw sib cuag. Feem ntau pom zoo kom txheej ob qho tib si, lossis tsawg kawg yog txheej cathode (steel stainless hlau), vim tias yog tias tsuas yog txheej anode (carbon steel) xwb, thaum txheej puas lawm, qhov xeb ntawm qhov chaw puas yuav hnyav dua.
2. Kev tswj hwm ib puag ncig:Khaws cov khoom sib txuas kom qhuav thiab huv li sai tau kom tsis txhob muaj electrolyte sib sau ua ke.
3. Siv cov ntaub ntawv hloov pauv:ntxiv ib lub hlau uas muaj lub peev xwm electrode ntawm ob lub hlau (xws li txhuas), tab sis txoj kev no tsis tshua siv thiab xav tau kev tsim qauv zoo.
4. Kev tiv thaiv cathodic:Tag nrho cov qauv yog hloov pauv mus ua cathode los ntawm kev siv hluav taws xob sab nraud lossis txi ib qho anode (xws li zinc block), tab sis qhov no feem ntau yog siv rau cov qauv loj xws li nkoj thiab cov kav dej.
Xaus lus
Cov hlau tsis xeb thiab cov hlau carbon tsis tuaj yeem sib cuag ncaj qha vim tias lawv tuaj yeem tsim cov roj teeb tseem ceeb hauv cov chaw electrolyte noo noo, ua rau muaj kev xeb galvanic ntawm cov hlau carbon ua lub anode. Txhawm rau kom tsis txhob muaj qhov xwm txheej no, yuav tsum tau ua cov kev ntsuas cais hluav taws xob thaum lub sijhawm tsim thiab teeb tsa, xws li siv cov gaskets rwb thaiv tsev, bushings, thiab coatings, kom ntseeg tau tias muaj kev nyab xeeb thiab lub neej ntev ntawm cov khoom siv.
Lub sijhawm tshaj tawm: Lub Kaum Hli-29-2025