Thaum lub Titanium Sheath rhaub yog siv los boil ib 5% Sodium Tartrate tov ntawm 103 degree, Vim li cas lub Tartrate Ion Complex Titanium Ions thiab tiv thaiv rov qab, ua rau Uniform Corrosion ntawm 0.2 hli ib xyoo?
Tso lus
Tartrate ion (C4H4O6 2-) yog ib tug muaj zog chelating tus neeg saib xyuas rau titanium nyob rau hauv 5% sodium tartrate ntawm 103℃(boiling). Tartrate tsim titanium soluble-tartrate complexes: Ti⁴⁺ + 3C₄H₄O₆²⁻ → [Ti(C₄H₄O₆)₃]⁴⁻ Tsis zoo li chloride lossis fluoride, uas ua rau pitting. Qhov complexation no tshem tawm Ti 4+ ions los ntawm qhov chaw raws li lawv tsim, thiab tseem tiv thaiv kev tsim cov txheej txheem ruaj khov. Yog tsis muaj kev tiv thaiv txheej, titanium corrodes uniformly ntawm 0.15-0.25 hli / xyoo uas tsis muaj pitting hauv zos. Tom qab thawj theem hloov pauv tus nqi corrosion yog lub sijhawm ywj pheej.
Lub Mechanism ntawm Uniform Corrosion ntawm Tartrate
Tartrate ions muaj ntau pawg hydroxyl thiab carboxyl uas tsim muaj tsib - koom nrog chelate rings nrog Ti(IV). Qhov tsim tsis tu ncua ntawm Ti-tartrate complex yog qhov tshwj xeeb siab (log K=20). Qhov no ua kom ntseeg tau tias ib qho Ti 4+ liberated los ntawm cov hlau nto yog tam sim ntawd complexed thiab tshem tawm mus rau kev daws. Tsuas yog nyob rau hauv qhov chaw siab heev ntawm Ti⁴⁺ yog cov khoom solubility ntawm TiO₂ tshaj thiab yog li cov zaj duab xis passive tsis tuaj yeem tsim. Lub corrosion ua tiav los ntawm kev sib cais ntawm cov hlau ncaj qha: Ti → Ti4+ + 4e- thiab nrawm nrawm. Cov txheej txheem zoo ib yam vim tias tsis muaj zaj duab xis passive yuav tsum tau tawg hauv zos.
Quantitative corrosion tus nqi piv rau concentration ntawm tartrate
Cov nram qab no tau tsim los rau Qib 2 titanium nyob rau hauv kev tswj xyuas rau 500 teev nyob rau hauv boiling sodium tartrate daws (103 degree). Corrosion npaum li cas 0.005-0.010 hli hauv ib xyoos Surface Bright Mechanism Passive 0% tartrate (dej huv) Ntawm 1% tartrate, tus nqi yog 0.03-0.06 hli / xyoo, qhov saum npoo yog lub teeb etched, thiab cov txheej txheem sib xyaw. Ntawm 3% tartrate, tus nqi yog 0.08-0.15 hli / xyoo, qhov saum npoo yog uniformly etched thiab complexation yog cov txheej txheem tseem ceeb. Ntawm 5% tartrate, tus nqi yog 0.15-0.25 hli / xyoo, qhov saum npoo yog homogeneous thiab matte, thiab cov txheej txheem yog complexation-dominant. Tus nqi ntawm 10% tartrate yog 0.2-0.35 hli hauv ib xyoos, qhov saum npoo yog uniformly matte, thiab cov txheej txheem yog complexion loj.
pH thiab qhov kub thiab txias nyob ntawm tus nqi ntawm Complexation
Tus nqi ntawm complexation thiab tus nqi ntawm corrosion nyob ntawm pH thiab kub. Ntawm 60 degree, pH 7 nrog 5% tartrate, tus nqi corrosion yog 0.04-0.08 mm / xyoo. Tus nqi yog 0.08-0.15 mm/xyoo ntawm 80℃thiab pH 7. Ntawm 100 degree, pH 7, tus nqi yog 0.15–0.25 mm/xyoo. 0.10-0.18 mm/xyoo ntawm 100℃thiab pH 9 (siab dua pH txo corrosion) Ntawm 100℃thiab pH 0.5 hli (qhov tsawg dua pH 0.3) pH accelerates corrosion). Kev ua kom lub zog yog ~ 50kJ / mol.
Titanium Heaters - Phau Ntawv Qhia rau Tartrate Concentration thiab pH Control
Cov lus hauv qab no muab cov lus pom zoo ntawm Qib 2 thiab Qib 7 titanium tso cua sov ua haujlwm hauv cov tshuaj sodium tartrate.
Concentration Sodium Tartrate (%) Kub (degree) Corrosion Rate (mm/xyoo) pH Qib 2 Qib 7 Corrosion Rate (mm/xyoo)<1 100 7 0.03–0.06 0.02–0.04 Acceptable Recommendation 1–3 80 7 0.05–0.10 0.03–0.06 Acceptable 1–3 3–5 80 7 0.08–0.15 0.05–0.10 Use Grade 7 Recommendation 3–5 100 7 0.15–0.25 0.10–0.18 Use Grade 7 plus thick wall Recommendation
5–10 100 9 0.10–0.18 0.06–0.12 Increase pH >10 Any Any >0.20 >0.12 Tsis pom zoo Lwm yam Engineering dua li Tartrate Concentration Control
Tus nqi ntawm complexation nyob ntawm qhov zoo ntawm titanium. Cov nqi corrosion ntawm Qib 7 (palladium stabilized) yog 30-50% qis dua cov qib 2 hauv cov kev daws teeb meem tartrate, txij li cov palladium pab tswj cov yeeb yaj kiab nyias nyias txawm tias nyob rau hauv cov xwm txheej nyuaj. Qib 12 yog theem nruab nrab ntawm kev txhim kho. Phab ntsa thickness muab kev tiv thaiv corrosion; ib lub 2.0 hli phab ntsa yuav kav 13 xyoo nrog ib tug uniform corrosion ntawm 0.15 hli ib xyoo. Cov polished nto tsis muaj kev cuam tshuam me ntsis ntawm kev sib txhuam corrosion. Tus nqi corrosion yog txo los ntawm 30-40% ntawm kev ntxiv sodium hydroxide kom nce pH mus rau 9. Thaum qhov kub thiab txias yog txo los ntawm 100℃mus rau 80℃tus nqi txo los ntawm 50%.
Muab cov ntaub ntawv qhia tshwj xeeb
Rau titanium sheath rhaub hauv 5% sodium tartrate ntawm 103 degree. Uniform corrosion yog cov txheej txheem tseem ceeb. Siv qib 7 titanium kom txo qhov corrosion ntawm 0.10 txog 0.18 hli / xyoo. Siv 2.0 hli phab ntsa thickness rau 10 mus rau 15 xyoo kev pab cuam lub neej. Yog tias ua tau, kho qhov pH mus rau 9 siv sodium hydroxide lossis txo qhov kub kom txog 80 degree. Thaum lub sijhawm ua haujlwm, lub rhaub phab ntsa thickness yuav tsum tau kuaj txhua xyoo los ntawm ultrasonic gauges; Thaum cov phab ntsa thickness nce mus txog 0.5 hli, lub rhaub yuav tsum tau hloov. Tus kws ua haujlwm nkag siab tias tartrate ions ua ke nrog titanium ions thiab inhibit repassivation uas ua rau muaj kev cuam tshuam zoo corrosion. Tus kws tshaj lij xaiv qhov raug qib thiab phab ntsa thickness ntawm cov khoom.
