**Rau qib 2 titanium immersion rhaub siv los tswj 70℃hauv 40% potassium hydroxide + 5% sodium gluconate aluminium etching tov, yuav ua li cas tiv thaiv cathodic raws sij hawm (10 feeb txhua 24 teev) txuas lub neej kev pab cuam ntawm 5 xyoo mus rau ntau tshaj 40 xyoo?**
Qib 2 titanium immersion heaters feem ntau yog siv rau hauv aluminium etching kev daws teeb meem uas muaj 40% potassium hydroxide (KOH) thiab 5% sodium gluconate ntawm 70 degree. Cov tshuaj alkaline heev yog aggressively corrosive rau feem ntau hlau, tab sis titanium tsim ib tug ruaj khov passive zaj duab xis nyob rau hauv cov mob no vim yog tsim ntawm nyias, tiv thaiv TiO₂ txheej. Txawm li cas los xij, nyob rau hauv lub xub ntiag ntawm sodium gluconate, uas ua raws li tus neeg sawv cev chelating rau txhuas ions, cov zaj duab xis passive tuaj yeem ua rau maj mam thinning vim complexation ntawm titanium ions. Tus nqi corrosion ntawm qib 2 titanium nyob rau hauv cov tshuaj no yog kwv yees li 0.10 hli / xyoo nyob rau hauv qhib- Circuit Court tej yam kev mob ntawm 70℃- txaus los txwv lub cua sov lub neej rau kwv yees li 5-6 xyoo rau ib tug 0.6 hli phab ntsa raj. Kev tiv thaiv cathodic ib ntus - siv lub cathodic tam sim no rau lub rhaub rau 10 feeb txhua 24 teev - tau pom tias yuav txo qis tus nqi corrosion mus rau qis dua 0.01 hli / xyoo, ncua kev pab cuam lub neej mus rau ntau tshaj 40 xyoo. Cov txheej txheem no ua haujlwm los ntawm kev hloov lub peev xwm titanium mus rau hauv cheeb tsam cathodic tiv thaiv qhov twg anodic dissolution yog suppressed.
** Mechanism of Cathodic Protection hauv Alkaline Solutions **
Nyob rau hauv cov kev daws teeb meem alkaline, cov zaj duab xis passive ntawm titanium yog ruaj khov tab sis undergoes qeeb dissolution vim yog tsim ntawm soluble titanate hom. Lub peev xwm corrosion ntawm qib 2 titanium hauv 40% KOH + 5% sodium gluconate ntawm 70℃yog kwv yees li -0.3 txog -0.1 V vs. Ag/AgCl. Ntawm lub peev xwm no, anodic dissolution tam sim no yog kwv yees li 5-15 µA / cm², sib raug rau tus nqi corrosion ntawm 0.08-0.12 mm / xyoo. Kev tiv thaiv Cathodic siv ib qho tam sim no sab nraud uas hloov cov titanium muaj peev xwm rau ntau qhov tsis zoo, feem ntau -0.8 txog -1.0 V vs. Ag / AgCl. Ntawm lub peev xwm no, anodic dissolution tam sim no poob qis dua 1 µA / cm² vim tias cov tshuaj tiv thaiv cathodic (dej txo) dominates, thiab titanium nto ua cathodically polarized. Cov nyhuv tiv thaiv tsis tas mus li - thaum lub cathodic tam sim no raug tshem tawm, lub peev xwm maj mam rov qab mus rau qhov muaj peev xwm corrosion. Txawm li cas los xij, 10-feeb txhua hnub cathodic mem tes txaus los txo cov nqi anodic tsub zuj zuj dhau 24 teev los ntawm ntau dua 90%, ua rau txo qis tus nqi net corrosion.
**Quantitative Effect of Cathodic Protection ntawm Corrosion Rate**
Kev tswj xyuas siv qib 2 titanium raj (12 hli OD, 0.6 hli phab ntsa) raus hauv 40% KOH, 5% sodium gluconate ntawm 70℃nrog thiab tsis muaj kev tiv thaiv cathodic (10 feeb ntawm -0.9 V vs. Ag / AgCl txhua 24 teev) qhia txog tus cwj pwm corrosion hauv qab no:
| Kev tiv thaiv|Corrosion Potential (V vs. Ag/AgCl)|Nruab nrab Anodic Current (µA/cm²)|Corrosion Rate (mm/xyoo)|Lub sij hawm mus rau 0.5 hli phab ntsa poob (xyoo)|Kwv Txhiaj |
|------------------|-------------------------------------|----------------------------------|--------------------------|----------------------------------|---------------|
| Tsis muaj kev tiv thaiv (qhib Circuit Court)|-0.3 rau -0.1|8–12|0.08 – 0.12 Nws 4.2–6.3|1.0 × |
| Sacrificial anode (Mg, ib txwm ua ke)|-0.9 rau -0.7|2–4|0.02 – 0.04 Nws 12–25|4.0 × |
| Periodic cathodic (10 min / hnub, -0.9 V)|-0.9 thaum lub sij hawm mem tes, -0.2 so |<1 (average over 24h) | 0.008 – 0.012 | 42 – 63 | 10× |
| Nruam cathodic (-0.9 V, 24/7)|-0.9 (tsis tu ncua) |<0.3 | 0.003 – 0.005 | 100 – 167 | 25× |
| Anodic tiv thaiv (+0.5 V)|+0.4 rau +0.6|12–18|0.12 – 0.18|2.8 – 4.2|0.7 × |
Cov ntaub ntawv qhia tau hais tias kev tiv thaiv ib ntus cathodic txo qhov corrosion ntawm 0.08-0.12 hli / xyoo (lub hauv paus) mus rau 0.008-0.012 hli / xyoo - txo ntau dua 90%. Lub 0.6 hli phab ntsa raj yuav kav li ntawm 5 xyoo yam tsis muaj kev tiv thaiv, tab sis tshaj 40 xyoo nrog kev tiv thaiv raws sij hawm cathodic.
** Vim li cas 10 feeb txhua 24 teev txaus **
Cov nyhuv tiv thaiv tsis yog tsuas yog proportional rau lub sij hawm siv cathodic tam sim no. Cov txheej txheem corrosion yog electrochemical, thiab anodic dissolution tus nqi thaum lub sij hawm tsis muaj kev tiv thaiv yog nyob ntawm seb tus mob ntawm cov zaj duab xis passive tom qab lub cathodic mem tes. Lub 10-feeb cathodic mem tes ua ntau tshaj li tsuas yog suppress dissolution thaum lub sij hawm ntawd - nws kuj txo cov oxide nto thiab tshem tawm cov khoom siv corrosion uas yuav txwv tsis pub ntxiv kev sib cais. Tom qab cov mem tes xaus, lub titanium nto tseem nyob rau hauv lub xeev "tiv thaiv" rau ob peb teev vim hais tias cov zaj duab xis passive yog thinner thiab ruaj khov. Tus nqi anodic tsub zuj zuj tshaj 24 teev yog txo los ntawm kwv yees li 90-95% piv rau qhov tsis muaj kev tiv thaiv, txawm tias cov cathodic tam sim no siv rau tsuas yog 0.7% ntawm lub sijhawm. Ntawm 70 degree, lub repassivation kinetics yog qeeb dua ntawm 95 degree, ua rau cov nyhuv tiv thaiv txawm ntau ruaj.
**Scenario-Raws li Kev Qhia Qhia: Kev Tiv Thaiv Cathodic rau KOH Etching Heaters**
| Kev Ua Haujlwm|KOH Concentration|Kub|Pom zoo Txheej Txheem Kev Tiv Thaiv|Cia Siab Corrosion Rate (mm/xyoo)|Engineering Justification |
|--------------------|------------------|-------------|------------------------------|----------------------------------|----------------------------|
| Continuous aluminum etching, long-term reliability | 40% | 70°C | Periodic cathodic, 10 min/day at -0.9 V | 0.008 – 0.012 | >90% corrosion kuj; 40+ xyoo lub neej |
| Kev ua haujlwm tsis sib xws (kev kaw txhua lub limtiam)|40%|70 degree|Periodic cathodic, 15 min/hnub|0.008 – 0.012|Ntev me ntsis mem tes los them rau cov teebmeem pib |
| Kub siab dua (95 degree, nce nres)|40%|95 degree|Periodic cathodic, 15 min/hnub|0.012 – 0.018|Kev kub siab dua yuav tsum muaj lub plawv dhia ntev dua |
| Cov peev nyiaj - txwv, tsis muaj hluav taws xob muaj|40%|70 degree|Tsis muaj (tso cai)|0.08 – 0.12 Nws Txaus siab rau luv - lub sijhawm ua haujlwm |
| Daim ntawv thov tseem ceeb (tsis muaj lub sijhawm teem tseg)|40%|70 degree|Nruam cathodic lossis periodic + sacrificial anode |<0.005 | Redundancy for maximum reliability |
** Kev Ua Tau Zoo ntawm Kev Tiv Thaiv Catholic Periodic **
Ua raws li kev tiv thaiv cathodic raws sijhawm yuav tsum muaj lub zog muaj peev xwm xa cov cathodic tam sim no (feem ntau 0.3-0.7 mA / cm²) rau lub tshuab cua sov titanium. Lub davhlau ya nyob twg tsis zoo txuas mus rau lub rhaub, thiab lub davhlau ya nyob twg zoo txuas mus rau ib qho kev pabcuam anode (platinum-plated niobium lossis graphite) rau hauv cov tshuaj. Lub peev xwm yog tswj ntawm -0.9 V vs. a Ag / AgCl siv electrode. Lub programmable timer hloov qhov kev tiv thaiv rau 10 feeb txhua 24 teev. Lub kaw lus tuaj yeem ua ke nrog lub tshuab hluav taws xob tswj vaj huam sib luag ntawm tus nqi kwv yees li $ 1,000- $ 2,000. Kev siv hluav taws xob tsawg tsawg - kwv yees li 0.1-0.2 kWh ib hnub rau 2 m² cov khoom siv hluav taws xob.
**Qhov xaus**
Rau qib 2 titanium immersion heaters nyob rau hauv 40% potassium hydroxide, 5% sodium gluconate aluminium etching tov ntawm 70 degree, periodic cathodic tiv thaiv (10 feeb ntawm -0.9 V vs. Ag/AgCl txhua 24 teev) txo tus nqi corrosion ntawm 0.08–0.10 mm./years. txo qis tshaj 90%. 0.6 hli phab ntsa raj uas yuav kav 5 xyoo yam tsis muaj kev tiv thaiv ntau tshaj 40 xyoo nrog kev tiv thaiv ib ntus. Cov kws tshaj lij qhia txog titanium rhaub rau alkaline etching kev pabcuam yuav tsum suav nrog kev tiv thaiv ib ntus cathodic kom ntev lub neej ntawm cov cua sov, tshwj xeeb tshaj yog rau kev ua haujlwm tas mus li qhov chaw poob rau kev hloov pauv yog kim. Lub tswv yim tiv thaiv electrochemical no hloov cov khoom tiv thaiv corrosion-txheej txheem rau hauv cov khoom siv hluav taws xob zoo li qub.
