Pitting corrosion yog ib qho chaw hauv zos zais corrosion tsis ua haujlwm ntawm titanium cua sov raj. Fluoride ions, concentrated chloride ions thiab acidic tshuaj nyob rau hauv nruab nrab hauv zos tawg titanium dioxide passive zaj duab xis. Me me anode pits tsim rau ntawm cov hlau nto, thiab kaw occluded corrosive microenvironment yog tsim nyob rau hauv pits. Corrosion nkag mus rau hauv sai sai raws lub qhov kab noj hniav, uas ua rau los ntawm - phab ntsa perforation thiab tam sim ntawd nruab nrab leakage nrog NW nyuam qhuav pom tag nrho cov phab ntsa nyias nyias ntawm sab nrauv. Qhov kev puas tsuaj zoo li no muaj qhov tsis txaus ntseeg thiab zais cia, uas yog ib qho ntawm cov ntaub ntawv txaus ntshai tshaj plaws rau titanium siab-cov kav dej cua sov.
1. Occluded Electrochemical Corrosion Mechanism
A dense TiO₂ film naturally forms on titanium surface to isolate the matrix from corrosive media. Fluoride ions muaj qhov muaj zog permeability thiab tuaj yeem hloov cov pa oxygen hauv oxide zaj duab xis los tsim cov titanium fluorine complexes soluble, tsim cov ntsiab lus kev puas tsuaj hauv zos ntawm txheej tiv thaiv. Tawm titanium hlau nyob rau ntawm qhov chaw tsis xws luag ua raws li anode thiab dissolves preferentially tsim thawj pits. Cov hlau cations sib sau tsis tu ncua hauv lub qhov, nyiam ntau halogen ions kom txav mus rau hauv kab noj hniav kom sib npaug ntawm cov nqi hluav taws xob. Hydrolysis cov tshuaj tiv thaiv txo tus nqi pH nyob rau hauv pits thiab accelerates anodic dissolution ntawm lub substrate. Qhov chaw nyob ib puag ncig titanium tsis zoo ua haujlwm loj - thaj chaw cathode, tsim lub cathode loj-anode cheeb tsam piv uas ua rau muaj kev txhim kho corrosion hauv cov pits. Pits ua kom tob kom txog thaum nkag mus rau hauv cov yeeb nkab phab ntsa, thaum sab nrauv pom yuav luag tsis muaj qhov pom tseeb corrosion.
2. Cov hauj lwm zoo tshaj plaws rau Pitting Corrosion
Cov yeeb nkab phab ntsa npog los ntawm sediments, scale thiab attachments tsim occluded stagnant aav;
Cov kua dej hloov pauv cov cheeb tsam uas nruab nrab evaporates thiab fluorine/chlorine ntsev precipitate thiab enrich hauv zos;
Deg khawb, vuam discoloration thiab machining cov cim nrog puas thawj passive zaj duab xis;
Cov kav dej tuag uas tsis yog - ncig nruab nrab zoo li qub uas ua rau muaj kev sib txuas ntxiv ntawm corrosive ions;
Condensation thaj chaw uas cov kua qaub thiab cov dej ntsev sib txuas ua ke rau ntawm lub raj nplaim.
3. Qhov tseem ceeb Inducing Factors ua rau Pitting puas
Tshaj fluoride thiab chloride ion concentration nyob rau hauv cov txheej txheem nruab nrab thiab circulating system;
Kev ua haujlwm siab kub nce kev ua haujlwm ntawm corrosive ions thiab zaj duab xis tawg muaj peev xwm;
Tsis muaj kev tshaj tawm -weld pickling thiab anodic oxidation kev kho mob ua rau tsis tiav kev tiv thaiv zaj duab xis;
Ntev - lub sij hawm adhesion ntawm plua plav thiab xeb tsim cov txheej thaiv tiv thaiv cov khoom xyaw corrosive;
Cov cuab yeej kaw nrog cov kua corrosive residual kaw hauv cov kav dej tsis muaj khoob.
4. Tag nrho -Txuas Kev Tiv Thaiv thiab Tswj Kev Ntsuas Kev Ntsuas
① nruj me ntsis tswj cov fluorine thiab halogen ion cov ntsiab lus nyob rau hauv circulating nruab nrab
Txhim kho hauv online pom thiab cov khoom siv tshem tawm ion los txiav tawm cov khoom siv los ntawm cov kua dej.
② Siv cov ncej- ua anodic oxidation reinforcement
Tsim ib daim duab tuab, compact oxide zaj duab xis los txhim kho pitting tsis kam.
③ Tsim kom muaj tshuaj ntxuav tu thiab ntxuav lub tshuab tsis tu ncua
Tshem tawm cov nplai thiab cov pob zeb kom tshem tawm cov kab mob occluded corrosion microenvironment.
④ Txhim kho cov kav dej kom zoo kom tshem tawm cov qhov muag tsis pom dej
Khaws cov dej ntws thiab ntws tawm cov chaw nres nkoj kom tsis txhob ntev - lub sij hawm static enrichment ntawm corrosive Cheebtsam.
⑤ Ntxiv cov tshuaj tiv thaiv tshwj xeeb rau cov tshuaj fluorine- uas muaj cov haujlwm ua haujlwm
Complex dawb fluoride ions los suppress dissolution ntawm titanium passive zaj duab xis.
5. Kev Tiv Thaiv Cov Teeb Meem Sib piv
表格
| Medium & Kho hom | Pitting Corrosion Risk | Daim ntawv thov tswv yim |
|---|---|---|
| High fluorine nruab nrab + tsis muaj qhov chaw passivation + av nplaum | Random sai perforation nyob rau hauv luv luv kev pab cuam lub sij hawm | Purify nruab nrab thiab ua tag nrho anodic oxidation tam sim ntawd |
| Ion concentration tswj + periodic tu + standardized passivation | Ua tau zoo txwv qhov pib thiab nthuav dav | Pa titanium pipeline txheem kev saib xyuas specification |
| Txhim kho anodic oxidation + nruab nrab inhibitor koob tshuaj | Tsawg heev pitting tsis ua hauj lwm txaus ntshai | Siab -corrosion hnyav ua hauj lwm tej yam kev mob nyiam txoj kev |
Xaus
Pitting corrosion ntawm titanium cua sov raj yog pib los ntawm halogen ions rhuav tshem cov zaj duab xis passive thiab intensified los ntawm tus kheej -accelerating occluded electrochemical cov tshuaj tiv thaiv nyob rau hauv corrosion kab noj hniav. Cov tswv yim tiv thaiv tseem ceeb suav nrog kev txwv corrosive ion concentration nyob rau hauv nruab nrab, ntxiv dag zog rau qhov chaw tiv thaiv zaj duab xis los ntawm anodic oxidation, tshem tawm hauv zos stagnation thiab sediment coverage, thiab ntxiv cov tshuaj tiv thaiv kab mob. Kaw-Txoj kev tswj hwm kev kho nruab nrab, tom qab- txheej txheem kev kho saum npoo thiab kev saib xyuas txhua hnub tuaj yeem tiv thaiv kom tsis txhob muaj kev sib tsoo tshwm sim los ntawm pitting perforation ntawm titanium cua sov raj.
