Thaum lub tshuab rhaub Titanium yuav tsum ua haujlwm tsis tu ncua hauv Boiling Acetic Acid, Vim li cas Cov Zaj Duab Xis Repassivation Rate dhau los ua qhov tseem ceeb ntawm kev ntseeg siab?

Acetic acid boils ntawm 118℃C. ntawm atmospheric siab, ib qho txawv electrochemical ib puag ncig rau titanium immersion rhaub. acetic acid, tsis zoo li cov oxidizing acids uas muaj zog oxidizing zaj duab xis, los yog txo cov kua qaub uas tsim cov active corrosion tsis tu ncua, zaum nyob rau hauv ib tug nruab nrab tsoom fwv qhov twg cov zaj duab xis passive yog nruab nrab. Rov qab thermal thiab electrochemical transients vim tsis sib xws ntawm lub tshuab cua sov rau thiab tawm thaum immersed hauv boiling acid ua rau cyclic zaj duab xis tawg thiab sim repassivation ntawm titanium nto. Ntawm qhov kev pabcuam no, tus nqi rov ua dua ntawm cov yeeb yaj kiab passive ua qhov tseem ceeb dua rau cov cua sov kev cia siab ntau dua li thawj zaj duab xis zoo, phab ntsa thickness lossis qib hlau puag. Tus nqi qeeb ntawm kev rov ua dua tso cai rau cov kua qaub hauv cheeb tsam kom permeate cov hlau nto thaum lub sij hawm tawm - voj voog, ua rau muaj kev puas tsuaj loj thiab ua tsis tiav ntxov.

Passive film breakdown thiab repassivation nyob rau hauv Acetic Acid

Cov cua kub ntws ua rau lub titanium raj nto yog 5-15 degrees Celsius kub dua li qhov kub ntawm cov acetic acid kub thaum lub sij hawm ntawm - voj voog. Qhov kub siab dua yog pab tau rau hauv kev sib cais titanium ions hauv cov kua qaub. Thaum lub rhaub tau muab tso tawm, lub raj saum npoo txias rau qhov kub kub (118 degree). Raws li cov khoom txias, titanium hom nyob rau hauv kev daws tej zaum yuav muaj ib tug sib txawv solubility thiab cov kua qaub chemistry ntawm lub interface tej zaum yuav tam sim no depleted nyob rau hauv ib co Chemistry. Qhov tseem ceeb tshaj, qhov muaj peev xwm ntawm electrochemical ntawm titanium nto nws txawv thaum siv cov cua sov tam sim no nres. Nyob rau hauv boiling acetic acid, cov zaj duab xis passive yog thermodynamically tsis ruaj tsis khov ntawm cov peev xwm hauv qab no ca. +0.2 V vs. SCE. Thaum lub sij hawm tawm ntawm lub voj voog, qhov voltage tuaj yeem poob qis dua qhov pib no, ua rau thaj chaw tawg ntawm zaj duab xis. Tus nqi ntawm lub hauv paus hlau dissolution txhua lub voj voog yog muab los ntawm tus nqi ntawm repassivation qhia nyob rau hauv cov nqe lus ntawm lub sij hawm tsim nyog rau cov zaj duab xis passive mus txog 95% ntawm nws ruaj khov lub xeev thickness thiab tiv thaiv cim. Electrochemical tests ntawm Qib 2 titanium hauv boiling deaerated acetic acid tau pom lub sij hawm repassivation sib txawv ntawm 30 vib nas this (zoo saum npoo av) mus rau ntau tshaj 300 vib nas this ( paug los yog thermally deteriorated nto).

Quantitative Relationship nruab nrab ntawm qhov kev puas tsuaj loj thiab tus nqi rov qab

Cov kev sib raug zoo hauv qab no rau Qib 2 titanium tau tsim los ntawm kev ntsuas kev ntsuas kev ntsuas (15 feeb ntawm, 15 feeb tawm) hauv cov dej kub npau npau glacial acetic acid (99.8%) ntawm 118 degree:

Repassivation lub sij hawm < 60 vib nas this: Hlau poob txhua lub voj voog kwv yees li . 0.02 micrometers. Nws yuav siv li 50,000 lub voj voog kom nkag mus rau phab ntsa 1.0 hli (txog 2.5 xyoo ntawm 15 feeb caij tsheb kauj vab). Kev them nyiaj rau zaj duab xis yog ua tiav ua ntej qhov pib ntawm cov kua qaub loj.

Repassivation lub sij hawm 60-120 sec. Hlau poob txhua lub voj voog 0.05-0.10 micrometers. Tag nrho cov kev nkag mus tau nce mus rau 10,000-20,000 cycles (6-12 lub hlis). Localized nres manifests nws tus kheej raws li ib tug ntiav pits thiab tsis li niaj hnub thinning.

Repassivation lub sij hawm: 120-300 vib nas this. Hlau poob txhua lub voj voog: 0.15-0.40 µm. Tag nrho kev nkag mus 3,000-7,000 cycles (2-4 lub hlis). Cov pits dhau los ua qhov sib sib zog nqus thiab sib sib zog nqus, tsim ib qho chaw ntxhib. Qhov no slows repassivation ntxiv nyob rau hauv ib tug zoo tswv yim voj.

Repassivation lub sij hawm> 300 s: Active corrosion tseem nyob rau feem ntau ntawm lub voj voog tawm. Cov ntaub ntawv poob tseem tshwm sim txog thaum cov khoom raug perforated tom qab 1000-2000 cycles (2-4 lub lis piam). Qhov saum npoo tuaj yeem dhau los ua qhov ua haujlwm tas mus li.

Cov yam ntxwv cuam tshuam rau Repassivation Rate ntawm Titanium hauv Boiling Acetic Acid

Tus nqi repassivation tsis yog cov khoom vaj khoom tsev tab sis nyob ntawm ntau yam tswj thiab tswj tsis tau:

Deg oxide mob: Lub Hoobkas khaws thiab cua- hnub nyoog rau 72 teev, raj repassivates hauv 40-50 vib nas this. Qhov tsis muaj qhov ruaj khov precursor zaj duab xis ua rau lub sijhawm rov ua dua ntawm 80-120 vib nas this rau qhov tshiab abraded lossis raws li kos nto.

Dissolved oxygen cov ntsiab lus: Feem ntau, boiling acetic acid yuav muaj tsawg dua 1 ppm yaj oxygen. Bubbling cua los ntawm cov kua qaub (tsis siv tau los yog muaj kev nyab xeeb nrog cov vapors volatile) txo lub sij hawm rau repassivation rau 20-30 vib nas this. Oxygen-dawb nitrogen daim pam ncua lub sij hawm repassivation mus rau 150-200 s.

Cuam tshuam cov tshuaj chloride: 50 ppm chloride hauv acetic acid nce lub sij hawm repassivation los ntawm ib qho ntawm 2-3 vim yog kev sib tw nrog acetate ions rau qhov chaw adsorption ntawm qhov chaw.

Titanium Qib 7 (0.12% rau 0.25% Pd) Kev suav nrog palladium txo lub sijhawm rov qab los ntawm kwv yees li 60% piv rau Qib 2 nyob rau hauv tib lub sijhawm. Qhov no yog vim lub catalytic cuam tshuam ntawm cov hlau noble ntawm cathodic txo cov tshuaj tiv thaiv.

Phau Ntawv Qhia Txog Kev Tswj Xyuas Repassivation rau Daim Ntawv Thov

Cov lus hauv qab no muab cov txheej txheem kev txiav txim siab rau kev ua haujlwm tsis tu ncua ntawm titanium rhaub hauv boiling acetic acid nyob rau hauv cov nqe lus ntawm lub voj voog zaus thiab purity ntawm cov kua qaub.

Intermittent Operation Pattern & Acetic Acid Zoo Pom Zoo Tswv Yim rau Repassivation Control Core Rationale & Reliability Modification
Acetic acid> 99.5% Tsis muaj chlorides < 10 cycles ib hnubFactory passivated, qib 2 titaniumLow cycle suav tso cai rau spontaneous repassivation ntawm cycles. Cia lub sij hawm repassivation mus txog 120 s. Standard specs rau lub rhaub yog zoo.
10–50 cycles ib hnub twg, acetic acid 95–99%, chlorides tau Qib 7 titanium (Pd-muaj) Palladium ntxiv txo cov sij hawm rov qab mus rau 30–50 vib nas this. 3 mus txog 5 lub sij hawm lub voj voog ntev dua rau cov nqi pib dua.
50–200 cycles/hnub (nquag batch ua haujlwm), sib txawv acid purity Qib 7 titanium ntxiv rau anodic polarization (sab nraud DC fais fab mov, +0.3 V vs. Ag/AgCl) Sab nraud voltage ua rau kom ceev repassivation (10-20 vib nas this) tsis hais cov kua qaub chemistry. Tus nqi khoom siv ntxiv. Haum rau cov txheej txheem tseem ceeb, tsis tu ncua.
Qib 2 tam sim no lub rhaub dej kub, zoo- paub txog cov teeb meem kev rov ua dua ntxiv Ntxiv cov kab hluav taws xob tso tawm thoob plaws lub tshuab hluav taws xob lub tshuab hluav taws xob.Small sab nraud capacitor (10,000 uF) khaws lub peev xwm ntog thaum lub sijhawm tawm - mus. Pheej yig refit. Txo lub sij hawm repassivation los ntawm 30 mus rau 50 feem pua.
Engineering Beyond Passivation Rate

Tus nqi repassivation tsis hloov lwm yam qauv tsim, tab sis overlays rau lawv. Phab ntsa thickness yog tag nrho cov khoom pub rau kev puas tsuaj ntau dhau mus. Lub raj nrog qeeb repassivation (200 sec) tab sis phab ntsa tuab heev (2.5mm) txawm li cas los xij tuaj yeem muaj lub neej ua haujlwm txaus (2-3 xyoos) yog tias daim ntawv thov tso cai rau txoj kab uas hla thiab cov khoom siv ntau dua. Ntawm qhov tod tes, lub raj nrog ceev repassivation (50 vib nas this) tab sis nyias phab ntsa (0.7 hli) tuaj yeem ua tsis tiav vim tsis muaj qhov tshwj xeeb tuab. Tus cwj pwm repassivation kuj tseem cuam tshuam los ntawm lub zog ceev ntawm lub tshuab cua sov thaum lub sij hawm ntawm lub voj voog: lub zog ntau dua (ntau dua 30 W / cm^2) ua rau lub rougher deg microtopography thaum lub sijhawm ua haujlwm, uas ua rau thaj chaw zoo thiab ua rau lub zog rov qab los ntawm 20-30% piv rau nruab nrab lub zog ceev (15^-20 cm).

Formulating Reasoned Specification

Yog hais tias tus titanium rhaub rau kev khiav hauj lwm tsis sib xws hauv boiling acetic acid, thov electrochemical repassivation cov ntaub ntawv nyob rau hauv hluavtaws acetic acid ntawm qhov kev khiav hauj lwm kub ntawm tus neeg muag khoom. Qhia rau qib 7 titanium rau txhua daim ntawv thov uas yuav pom ntau dua 20 lub voj voog ib hnub lossis uas muaj cov tshuaj chloride ntsuas tau. Kev teeb tsa uas twb muaj lawm uas siv cov tshuab cua sov qib 2 yuav tsum ua raws li cov txheej txheem ua ntej txheej txheem hauv qab no. Khiav lub rhaub tsis tu ncua rau 48 teev ntawm 80℃hauv cov kua qaub tshiab los tsim cov yeeb yaj kiab ruaj khov ua ntej lub luag haujlwm cyclic. Thaum lub sij hawm tawm - mus, saib xyuas qhov qhib - qhov hluav taws xob hluav taws xob ntawm lub rhaub nrog cov khoom siv hluav taws xob siv; qhov muaj peev xwm tsawg dua +0.1 V vs. SCE qhia tias muaj kev phom sij qeeb qeeb thiab xav tau kev cuam tshuam. Tus kws tshaj lij, siv tus nqi rov ua dua raws li tus qauv tsim thiab kev ua haujlwm zoo, hloov cov cwj pwm tsis zoo ntawm titanium hauv cov dej kub npau npau rau hauv cov txheej txheem kev txiav txim siab, tswj kev degrading.