Rau Titanium Immersion rhaub nyob rau hauv 5% Sodium Persulfate tov ntawm 50 degree, Vim li cas Persulfate Ion tsis Passivate titanium txawm tias muaj zog Oxidizer, Thiab Es tsis txhob ua Transpassive Dissolution?
Tso lus
Sodium persulfate (Na₂S₂O₈) yog lub zog oxidizer nrog tus qauv txo qhov peev xwm ntawm 2.01 V rau S₂O₈²⁻ / SO₄²⁻, muaj zog dua nitric acid. Ntawm titanium, persulfate ua rau transpassive dissolution es tsis ruaj khov passivation. Ntawm 50 degree, lub siab oxidation muaj peev xwm hloov cov titanium nto rau hauv cheeb tsam transpassive saum toj no 1.8 V piv rau tus qauv hydrogen electrode, qhov twg cov zaj duab xis passive lov thiab titanium yaj li Ti⁴⁺ ntawm tus nqi ntawm 0.2-0.5 hli ib xyoo. Lub transpassive dissolution yog uniform es pitting, tab sis tus nqi corrosion yog siab dhau rau feem ntau daim ntaub ntawv.
Lub Mechanism ntawm Persulfate-Induced Transpassive Dissolution
Lub cheeb tsam ruaj khov rau titanium yog nyob nruab nrab ntawm kwv yees li 0 V thiab 1.8 V. Ntawm qhov muaj peev xwm siab dua 1.8 V, TiO₂ zaj duab xis oxidizes ntxiv rau cov kua dej Ti⁴⁺ hom: TiO₂ + 2H₂O → Ti⁴⁺ + 4OH⁻ {{6.}e Persulfate, ua cov oxidizer muaj zog heev, teeb tsa lub peev xwm sib xyaw ntawm titanium mus rau 1.7-2.0 V. Hauv qhov ntau, qhov kev hloov pauv hloov tam sim no tseem ceeb. Lub corrosion yog uniform vim hais tias tag nrho cov nto yog nyob rau hauv lub transpassive cheeb tsam. Tsis muaj kev sib cais hauv zos; xwb, zaj duab xis dissolves tsis tu ncua.
Quantitative Corrosion Rate raws li Kev Ua Haujlwm ntawm Persulfate Concentration
Kev tswj xyuas hauv sodium persulfate ntawm 50℃tshaj 500 teev tau tsim cov hauv qab no rau Qib 2 titanium. Ntawm 0% persulfate (baseline), tus nqi corrosion yog 0.005-0.010 hli hauv ib xyoos, lub peev xwm saum npoo yog 0.2-0.5 V, thiab cov txheej txheem yog passive. Ntawm 1% persulfate, tus nqi yog 0.05-0.12 hli ib xyoo, lub peev xwm yog 1.2-1.5 V, thiab cov txheej txheem sib xyaw. Ntawm 3% persulfate, tus nqi yog 0.12-0.25 hli ib xyoos twg, lub peev xwm yog 1.5-1.7 V, thiab cov txheej txheem yog transpassive pib. Ntawm 5% persulfate, tus nqi yog 0.20-0.40 hli ib xyoo, lub peev xwm yog 1.7-1.9 V, thiab lub tshuab yog transpassive. Ntawm 10% persulfate, tus nqi yog 0.35-0.60 mm ib xyoos twg, lub peev xwm yog 1.8-2.0 V, thiab cov txheej txheem yog transpassive heev.
Influence ntawm Temperature ntawm Transpassive Transition
Lub cheeb tsam transpassive hloov mus rau qhov muaj peev xwm qis dua ntawm qhov kub siab dua. Ntawm 25℃thiab 5% persulfate, tus nqi corrosion yog 0.10-0.20 hli ib xyoo, thiab cov txheej txheem yog transpassive. Ntawm 40 degree, tus nqi yog 0.15-0.30 hli ib xyoos. Ntawm 50 degree, tus nqi yog 0.20-0.40 hli ib xyoos. Ntawm 60 degree, tus nqi yog 0.30-0.60 hli ib xyoos. Ntawm 70 degree, tus nqi siab tshaj 0.50 hli ib xyoo. Qhov kub siab dua ua rau qhov kev sib cais ntawm cov transpassive hnyav dua.
** Phau Ntawv Qhia Kev Xaiv Khoom rau Persulfate Service
Cov lus hauv qab no muab cov lus pom zoo rau cov cua sov hauv cov tshuaj sodium persulfate raws li qhov xav tau thiab qhov kub thiab txias.
| Persulfate Concentration (%) | Kub (degree) | Qib 2 Corrosion Rate (mm/xyoo) | Qib 7 Corrosion Rate (mm/xyoo) | Khoom siv pom zoo |
|---|---|---|---|---|
| <1 | 50 | 0.05–0.10 | 0.03–0.06 | Qib 7 nrog phab ntsa tuab |
| 1–3 | 40 | 0.08–0.15 | 0.05–0.10 | PTFE -coated titanium |
| 1–3 | 50 | 0.12–0.25 | 0.08–0.15 | Tsis pom zoo rau titanium |
| 3–5 | 30 | 0.10–0.20 | 0.06–0.12 | Tantalum los yog PTFE |
| >5 | Ib qho | >0.20 | >0.12 | Tantalum los yog PTFE |
Engineering Beyond Titanium Xaiv
Qib 7 muaj tsawg dua transpassive dissolution tus nqi tshaj Qib 2 (30-50% txo) vim palladium enrichment, tab sis qhov kev txhim kho tsis txaus los ua titanium haum rau persulfate kev pab. Phab ntsa thickness muab kev tiv thaiv corrosion; ib lub 2.0 hli phab ntsa nrog 0.20 hli ib xyoo corrosion kav 10 xyoo, tab sis qhov no yog marginal. PTFE-coated titanium heaters cais cov hlau los ntawm cov tshuaj persulfate, muab kev tiv thaiv zoo heev. Tantalum muaj qhov dav dav dua thiab muaj zog tiv taus persulfate. Zirconium kuj ua tau zoo tab sis kim.
Ua ib qho kev qhia tshwj xeeb
Rau lub titanium immersion rhaub nyob rau hauv 5% sodium persulfate ntawm 50 degree, qhov xav tau corrosion tus nqi yog 0.20-0.40 hli ib xyoo, uas yog siab dhau rau ntev - kev pab cuam lub sij hawm. Qhia rau PTFE-coated titanium rhaub (0.5 hli PTFE txheej) los yog tantalum rhaub hloov. Yog tias titanium yuav tsum tau siv, txwv cov persulfate concentration rau 2% thiab kub rau 40 degree, thiab siv 2.5 hli phab ntsa thickness. Thaum lub sijhawm ua haujlwm, saib xyuas lub ntsuas cua sov txhua xyoo; Thaum cov phab ntsa thickness nce mus txog 1.0 hli, hloov lub rhaub. Los ntawm kev nkag siab tias persulfate ua rau transpassive dissolution es tsis yog passivation, tus engineer xaiv cov ntaub ntawv tsim nyog rau qhov hnyav oxidizing ib puag ncig.
