Hauv kev lag luam fluorochemical thiab fluorine -muaj cov xwm txheej kho dej khib nyiab, electrode tsis ua haujlwm hauvelectromagnetic flowmeterssuav rau ntau dua 60% ntawm cov khoom siv tsis ua haujlwm. Kab lus no, raws li cov txheej txheem electrochemical corrosion thiab engineering tsis ua hauj lwm cov ntaub ntawv kawm, systematically distinguishes lub corrosion sib txawv ntawm F⁻ thiab HF systems, soj ntsuam cov tsis ua hauj lwm hom ntawm 6 hom electrode cov ntaub ntawv, thiab muab ntau yam kev xaiv xws li kub coefficients thiab concentration thresholds.
Tus cwj pwm nruab nrab: Qhov Tseem Ceeb Qhov Sib Txawv Ntawm F⁻ thiab HF
Qhov yuam kev loj hauv kev xaiv engineering tsuas yog faib cov hydrofluoric acid (HF) ua "siab-concentration fluorine- muaj dej."
Cov txheej txheem corrosion ntawm ob yog qhov sib txawv:
| Yam ntxwv Dimension | Fluoride Ion System (F⁻) | Hydrofluoric Acid System (HF) |
| Tshuaj Ntuj | Muaj zog complexing tsis muaj zog acid radical | Tsis muaj zog ionizing acid (pKa≈3.2), tab sis muaj zog complexing muaj peev xwm thiab nkag mus |
| Corrosion Mechanism | Kev puas tsuaj nyuaj: Kuv + 6F⁻ → [MeF₆]⁴⁻ | Dual nres: H⁺ rhuav tshem oxide zaj duab xis, F⁻ complexes hlau ions |
| Kinetic yam ntxwv | Linear corrosion, nce tsis ua hauj lwm | Tsis yog -linear acceleration, tseem ceeb qhov pib |
| Kub rhiab heev | Corrosion tus nqi × 1.3-1.5 rau 10℃nce | Corrosion tus nqi × 1.5-2.0 rau 10℃nce |
Kev ntsuas pH:Hauv kev tsim kho vaj tsev, kev txiav txim siab yuav tsum ua ke nrog pH. Nyob rau hauv qis pH tej yam kev mob, F⁻ thiab HF hloov dua siab tshiab. Thaum pH <3, ntau qhov F⁻ hloov mus rau HF, thiab qhov kev pheej hmoo corrosion nce siab heev.
Engineering ceeb toom:Hauv HF systems, thaum concentration nce ntawm 1% mus rau 5% (ntawm chav tsev kub), tus nqi corrosion tuaj yeem nce 5-10 zaug (nyob ntawm cov khoom siv hlau), tsis yog kev sib raug zoo linear. Qhov no txhais tau hais tias thaum lub concentration pib hla, cov khoom siv lub neej expectancy poob precipitously.
Kev soj ntsuam ntawm Electrode Material Failure Mechanisms
1. 316L Stainless Hlau: Nruam Dissolution ntawm Passive Film
316L cia siab rau Cr₂O₃ zaj duab xis passive rau kev tiv thaiv, tab sis nyob rau hauv fluorine - muaj ib puag ncig:
- Reaction Mechanism:Cr₂O₃ + 12HF → 2CrF₃ + 6H₂O los yog Cr³⁺ + 6F⁻ → [CrF₆]³⁻ (kev ua kom tsis sib haum xeeb)
- Failure Manifestation:Passive zaj duab xis tsis tuaj yeem nyob ruaj khov; lub substrate undergoes nruam uniform thinning
- Cov ntaub ntawv tseem ceeb:Ntawm 50 ppm F⁻, 60 degree, corrosion tus nqi ≈ 0.08 mm / a; Thaum F⁻> 2000 ppm, tus nqi corrosion> 2 mm / a
Tsis haum raws li cov khoom siv electrode
2. Hastelloy C-276: Cov kev txwv hauv Oxidizing ib puag ncig
- Composition Advantage:Ni-Cr-Mo ternary system - Cr muab oxidation tsis kam, Mo muab kev txo qis
- Daim ntawv thov ciam teb:Haum rau F⁻ systems thiab acidic ib puag ncig uas muaj oxidants
- HF txwv Zone: Under conditions of HF > 1% or elevated temperature (>60-80 degree), kev pheej hmoo corrosion nce ntau
Tsis pom zoo rau kev siv sijhawm ntev -
3. Titanium (Gr.2): Kev tiv thaiv Passive nyob ntawm Oxidizing Conditions
Titanium's corrosion kuj yog raws li TiO₂ passive zaj duab xis (thickness approx . 2-5 nm):
- Cov xwm txheej tsim:Qhov nruab nrab yuav tsum muaj oxidants (NO₃⁻, O₂, Fe³⁺, thiab lwm yam), lub peev xwm yuav tsum yog> -0.5V (SCE)
- HF tsis ua haujlwm:Hauv kev txo qis HF ib puag ncig, tus nqi corrosion nce ntau, tejzaum nws nce los yog dhau ntawm cov hlau tsis muaj steel; tsis muaj oxidants, TiO₂ yaj: TiO₂ + 6HF → H₂TiF₆ + 2H₂O
- Engineering Misjudgement:Qhov tshwm sim ntawm -qhov kev nkag siab tsis zoo uas "titanium resists acids" ua rau cov khoom tsis ua haujlwm hauv HF cov xwm txheej
Kev ua tsis tiav siab yuav tshwm sim
4. Tungsten Carbide (WC): Xaiv Qhov Kev Txiav Txim Siab ntawm Binder Phase
WC electrodes feem ntau siv Co los yog Ni raws li qib binder (cov ntsiab lus 6-12%):
- Failure Mechanism:F⁻ nyiam tawm tsam lub binder theem; WC nplej poob kev sib txuas thiab tshem tawm, lossis electrode porosity nce tag nrho
- Electrochemical Drift:Tom qab cov txheej txheem sib cais, cov electrode muaj peev xwm dhau los ua qhov sib txawv - ntsuas hauv kaum mus rau pua pua ntawm mV - ua rau qhov ntsuas qhov ntsuas ntws mus rau qhov sib txawv ntawm qhov muaj tseeb.
- Subtlety:Cov electrode zoo li qub (tsis muaj perforation), tab sis kev ntsuas qhov tseeb tau ploj lawm
Nkaum tsis ua hauj lwm muaj kev pheej hmoo siab dua pom corrosion
5. Tantalum (Ta): Kev txiav txim siab loj hauv HF ib puag ncig
Tantalum lub koob npe nrov rau "tiv thaiv cov kua qaub" los ntawm nws cov yeeb yaj kiab Ta₂O₅ ruaj khov, tab sis hauv HF:
- Tshuaj Reaction: Ta₂O₅ + 10HF → 2H₂[TaF₇] + 5H₂O (soluble)
- Kev ntsuas cov ntaub ntawv: Cov corrosion tseem ceeb muaj nyob rau hauv nruab nrab - mus rau - siab concentration HF (ntawm qhov kev txiav txim ntawm 0.01–0.1 mm / a, nce nrog kub)
- Engineering Conclusion: Tantalum tsis haum rau HF systems - tsuas yog siv tau rau oxidizing acids (xws li, HNO₃, H₂SO₄) thiab F⁻ systems
Muaj feem cuam tshuam
6. Pt-Ir Alloy (90:10): Kev daws qhov kawg rau cov xwm txheej hnyav
- Kev ruaj ntseg:Tseem muaj chemically inert nyob rau hauv uas tsis yog -oxidizing acid ib puag ncig (feem ntau txo tej yam kev mob); corrosion tus nqi hauv HF <0.001 mm/a
- Kev txwv:Tsawg hardness (HV≈200), raug rau yaig los ntawm cov khoom siv; raug nqi kwv yees li 15-20 npaug ntawm WC
- Siv tau Scenarios: HF>5% or temperatures>120℃nyob rau hauv heev corrosive tej yam kev mob
Conditionally siv tau
