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Cov yam ntxwv ntawm chloride ion corrosion yog raws li hauv qab no

1. Cov txiaj ntsig ntawm Cl-on hlau xeb tau tshwm sim hauv ob yam: ib qho yog txhawm rau txo qhov muaj peev xwm tsim cov yeeb yaj kiab passivation ntawm cov khoom siv lossis txhawm rau txhawm rau rhuav tshem zaj duab xis passivation, yog li txhawb kev txhim kho hauv zos; ntawm qhov tod tes, nws txo qhov kev daws teeb meem ntawm CO2 hauv cov kua dej. , Yog li txhawm rau txhawm rau txhawm rau txhim kho qhov xeb ntawm cov khoom.

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Cl- muaj cov yam ntxwv ntawm lub vojvoog me me ion, muaj peev xwm nkag tau zoo, thiab muaj zog nqus tau los ntawm cov hlau. Qhov siab dua qhov siab ntawm Cl-, muaj zog ua kom muaj zog ntawm cov kua dej thiab txo qis qhov kev tiv thaiv ntawm cov electrolyte. Qhov yooj yim dua nws yog Cl- kom ncav cuag cov hlau nto thiab ua kom cov txheej txheem ntawm kev xeb hauv zos; lub xub ntiag ntawm Cl- hauv ib puag ncig cov kua qaub yuav tsim cov tshuaj chlorides ntawm cov hlau nto Ntsev txheej, thiab hloov FeCO3 zaj duab xis nrog cov khoom tiv thaiv, ua rau muaj qhov xeb pitting ntau. Thaum lub sijhawm txheej txheem txhim kho, Clˉ tsis tsuas yog ua rau hauv qhov pitting qhov, tab sis kuj sib sau ua ke nyob rau thaj chaw uas tsis muaj qhov ua pitting. Qhov no tej zaum yuav yog txheej txheem thaum ntxov ntawm kev tsim lub qhov taub. Nws cuam tshuam tias cov txheej txheem hluav taws xob ob txheej txheej ntawm kev sib txuas ntawm cov hlau sib xyaw thiab cov khoom xeb cov yeeb yaj kiab tau yooj yim dua rau qhov tshwj xeeb tshaj tawm adsor Clˉ, uas ua rau kev mloog zoo ntawm Clˉ ntawm kev sib cuam tshuam nce. Hauv qee thaj chaw, Clˉ yuav sib sau ua ke thiab tsim cov nuclei, ua rau muaj kev cuam tshuam sai sai anodic hauv thaj chaw no. Txoj hauv kev no, cov hlau sib xyaw ua ke yuav raug corroded los ntawm kev khawb tob, tsim cov pitting qhov. Kev sib tawg ntawm cov hlau anode yuav ua rau kom nthuav dav ntawm Clˉ los ntawm cov khoom lag luam xeb ua zaj duab xis rau hauv qhov pitting pits, thiab txuas ntxiv ua kom muaj kev mloog zoo ntawm Clˉ hauv qhov dej pitting. Cov txheej txheem no yog Clˉ Cov txheej txheem catalytic yog tias thaum Clˉ concentration ntau dua tus nqi tseem ceeb, cov hlau anode yuav ib txwm nyob hauv lub xeev qhib thiab yuav tsis dhau mus. Yog li ntawd, nyob rau hauv catalysis ntawm Clˉ, cov pitting qhov yuav txuas ntxiv mus thiab tob zuj zus. Txawm hais tias Na cov ntsiab lus hauv kev daws teeb meem yog qhov siab, kev tsom xam lub zog ntawm cov khoom xeb zaj duab xis tsis pom muaj nyob ntawm Na keeb, qhia tias cov yeeb yaj kiab cov khoom xeb muaj lub luag haujlwm tseem ceeb hauv kev nthuav tawm ntawm cations rau cov hlau qhia; thaum lub anion yog qhov yooj yim nkag mus. Cov yeeb yaj kiab cov khoom lag luam dhau mus txog qhov cuam tshuam ntawm cov substrate thiab zaj duab xis. Qhov no qhia tau tias cov yeeb yaj kiab cov khoom xeb tau xaiv cov ion, ua rau nce ntxiv hauv cov tshuaj anion ntawm qhov interface.

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2. Kev txhuam ntawm austenitic stainless hlau los ntawm chloride ions feem ntau ua rau pitting corrosion.
Mechanism: Chloride ions tau yooj yim adsorbed ntawm zaj duab xis passivation, nyem tawm cov pa atoms, thiab tom qab ntawd ua ke nrog cov cations hauv zaj duab xis passivation los tsim cov tshuaj chlorides. Raws li qhov tshwm sim, lub qhov me me tau corroded ntawm lub cev raug hlau. Cov qhov me me no hu ua pitting nuclei. Cov tshuaj chlorides no tau yooj yim hydrolyzed, yog li ntawd tus nqi pH ntawm cov tshuaj hauv lub qhov me me yuav poob, thiab cov tshuaj yuav ua kua qaub, yaj ib feem ntawm cov yeeb yaj kiab oxide, ua rau cov hlau ions ntau dhau. Txhawm rau txhawm rau txhawm rau txhawm rau tiv thaiv qhov tsis zoo ntawm hluav taws xob hauv lub qhov, sab nrauv txuas ntxiv mus rau saum huab cua. Kev tsiv teb tsaws chaw sab hauv, cov hlau hauv qhov khoob yog ntxiv hydrolyzed. Hauv lub voj voog no, cov hlau tsis muaj hlau austenitic txuas ntxiv txhim kho kom sai dua thiab sai dua, thiab txhim kho mus rau qhov tob ntawm lub qhov kom txog thaum tsim qhov tsim.

3. Cl- muaj qhov ua rau cuam tshuam rau qhov txhav txhav. Thaum xeb pib, cov hlau poob hluav taws xob ntawm qhov anode. Nrog kev txhim kho txuas ntxiv ntawm cov tshuaj tiv thaiv, hlau tsis tu ncua poob hluav taws xob, ntau qhov Fe2 ntau nyob hauv qhov sib txawv, thiab cov pa tawm sab nraud qhov sib txawv tsis yooj yim nkag mus. Cov mobile heev Cl- nkag mus rau qhov sib txawv thiab ua rau muaj kev mloog zoo, ua tau zoo FeCl2 nrog Fe2, thiab FeCl2 yog hydrolyzed Lub cim ntawm H ua rau tus nqi pH hauv qhov crevice kom poob rau 3 txog 4, yog li ua kom muaj zog ntxiv.


Sijhawm Tshaj Tawm: Aug-12-2021