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) is a strong oxidizer (E° = 2.01 V for S₂O₈²⁻/SO₄²⁻), stronger than nitric acid. However, on titanium, persulfate causes transpassive dissolution rather than stable passivation. At 50°C, the high oxidation potential shifts the titanium surface into the transpassive region (>1.8 V vs. SCE), qhov twg cov zaj duab xis passive lov thiab titanium dissolves li Ti⁴⁺ ntawm tus nqi ntawm 0.2-0.5 hli ib xyoo.
Quantitative Corrosion Rate vs. Persulfate Concentration
Hauv Na₂S₂O₈ ntawm 50℃rau 500 teev:
| Persulfate Concentration (%) | Corrosion Rate (mm / xyoo) | Surface Potential (V vs. SCE) | Mechanism |
|---|---|---|---|
| 0 | 0.005–0.010 | 0.2–0.5 | Passive |
| 1 | 0.05–0.12 | 1.2–1.5 | Mixed |
| 3 | 0.12–0.25 | 1.5–1.7 | Transpassive pib |
| 5 | 0.20–0.40 | 1.7–1.9 | Transpassive |
| 10 | 0.35–0.60 | 1.8–2.0 | Mob hnyav transpassive |
Qhov cuam tshuam ntawm Temperature ntawm Transpassive Transition
| Kub (degree) | 5% Persulfate - Corrosion Rate (mm / xyoo) | Mechanism |
|---|---|---|
| 25 | 0.10–0.20 | Transpassive |
| 40 | 0.15–0.30 | Transpassive |
| 50 | 0.20–0.40 | Transpassive |
| 60 | 0.30–0.60 | Mob hnyav |
Kev pom zoo engineering
Rau cov kev daws teeb meem persulfate, titanium tsis pom zoo vim tias muaj kev cuam tshuam kev sib hloov. Siv PTFE-coated heaters lossis tantalum. Yog tias titanium yuav tsum tau siv, ua haujlwm qis dua 30℃thiab txwv persulfate rau<2%. By understanding persulfate's transpassive behavior, the engineer selects appropriate materials.
