Crevice corrosion yog lub zos corrosion nyob rau hauv ib tug qauv sib txawv, thiab nws tuaj yeem ntsuas nrog nws cov khoom siv hauv qab. Thaum ntxov uas titanium nyob rau hauv seawater, olicizer corrosion, thiab lwm yam xov xwm ntub acid thiab lwm yam xov xwm, tau tshaj tawm ib qho ntxiv. Crevice corrosion kev puas tsuaj ntawm cov khoom siv.
Titanium crevice corrosion thiab allient kub, chloride hom thiab siab, pens thiab geometry ntawm crevice thiab ntau lwm yam. Tsis tas li ntawd, Titanium thiab PTFE, titanium thiab asbestos thiab lwm yam castallic muaj pes tsawg leeg ntawm cov crevice, dua li titanium muaj pes tsawg leeg ntawm cov crevice corrosion ntau dua.
Kev tshawb nrhiav hauv kev tshawb fawb thiab txawv teb chaws thiab kev lag luam, titanium crevice corrosion muaj cov yam ntxwv hauv qab no thiab txoj cai.
① Qhov tshwm sim ntawm Crevice corrosion muaj lub sijhawm sib ntsib, thiab cov khoom siv ntawm cov tshuaj lom neeg, thiab qhov loj me thiab ntsuas hluav taws xob ntawm cov crevice. Titanium nyob rau hauv cov tshuaj hauv sodium tshuaj, qhov siab dua qhov ntsuas kub, tom qab ntawd tus nqi qis dua, yog qhov muaj zog dua cov rhiab heev ntawm cov pob corrosion.
② Qhov muaj pes tsawg leeg thiab ph yeej ntawm kev daws teeb meem hauv kev ua txhaum yog txawv ntawm lub cev daws. Feem ntau hais lus, qhov sib txawv hauv qhov qis dua cov pa, chloride ions hauv cov kev daws teeb meem hauv lub cev), tus nqi sam thiaj poob rau<1, the gap in the electrode potential becomes more negative, thus making the gap in the titanium in the active state. Laboratory electrochemical measurements show that the crevice corrosion potentials of various halide ions are in the order of CI- ＜ Br- ＜ I-, i.e., titanium in chloride has the greatest crevice corrosion sensitivity, which is the opposite of titanium's pitting corrosion sensitivity.
(iii) Lub crevice corrosion ntawm titanium feem ntau yog ib cheeb tsam ntawm cov npoo crevice, thiab feem ntau tsis tshwm sim nkag siab txog tag nrho cov kev sib cav sib ceg. Crevice corrosion tom qab xaus rau lub sijhawm tsim kom loj hlob, uas yog, ib zaug ntawm kev txhim kho kev txhim kho ntawm kev txhim kho kev ua kom ncaj ncees, qhov kev puas tsuaj hauv zos thiab kev puas tsuaj.
Cov txheej txheem ntawm titanium crevice corrosion feem ntau nrog hydrogen nqus, thiab txawm tias muaj rab koob hauv titanium tuaj yeem pom siv cov tsom iav me me. Nrog kev nce ntawm hydrogen nqus, cov hydride ntawm cov npoo txuas ntxiv ntxiv, ua rau cov xeb kom nrawm dua thoob plaws lub rooj tsavxwm. Nyob rau tib lub sijhawm, hydrogen tsis tu ncua txuas ntxiv mus rau hauv cov hlau, cov nag los ua hydrosion, ua rau muaj kev ntxhov siab sab nraud.
⑤ Tom qab xyoo kev tshawb fawb, cov duab lub cev ntawm cov txheej txheem corrosion ntawm titanium tau ua kom meej dua. Luv luv, nws tau muab faib ua ob theem: lub sijhawm tsim kom loj hlob thiab lub sijhawm ua haujlwm.
Thaum pib ntawm lub sijhawm tshaj tawm, tib cov tshuaj tiv thaiv yog nqa tawm sab hauv thiab sab nraud ntawm crevice. Nws cov tshuaj coob ntawm cov pa hluav taws xob noj pa oxygen, thiab thaum cov tshuaj tiv thaiv kab mob, thiab cov tshuaj tiv thaiv kab mob no tsuas yog ua rau titanium - tsuas yog nqa tawm sab hauv crevice. Raws li lub titanium ions hauv kev cigice txuas ntxiv ntxiv, cigrate rau hauv kev sib tw kom tswj tau tus nqi sib npaug thiab tsis zoo rau evice. Nyob rau tib lub sijhawm, titanium i muab cov khoom lag luam corrosion thiab your, titanium hydroxide, titanium hydroxide lub cev qhuav dej tau txheeb xyuas li ti2. Lub hydrolysis cov tshuaj tiv thaiv ua rau tus nqi py hauv lub crevice txo qis, txuas ntxiv rhuav tshem cov passive ntawm titanium. Yog li ntawd, ib zaug tsim kom loj hlob lub sijhawm ntawm kev txhim kho corrosion yog lawm, nws txoj kev loj hlob sai heev, uas yog hu ua "Autocatalytic nyhuv".
(6) ntawm cov "geometric yam" ntawm crevice corrosion ntawm titanium, muaj qee yam xws li crevice ntev, crevice dav thiab cov sib piv ntawm cov crevice. Cov txiaj ntsig no feem ntau yuav tsum tau txiav txim siab sim rau cov ncauj lus tshwj xeeb thiab tsis yog theoretically yeej. Kev ntsuam xyuas qhia rau peb tias qhov nyiam ntawm crevice corrosion ntawm nqaim ntawm nqaim tshaj qhov uas dav ntawm cov leeg ntawm 0. 5 hli.
(7) Txhawm rau txhim kho cov xeb ntawd ntawm titanium hauv kev txo cov inorganic corrosion, ti-pd alloys feem ntau yog cov kev ua haujlwm zoo nkauj rau cov titanium, tshwj xeeb yog TI-PD alloys. Titanium Deg Callice Instating Palladium plating lossis anodic oxidation thiab lwm yam kev kho mob anodic tuaj yeem txhim kho kev ua tau zoo ntawm titanium crevice corrosion tsis kam.
