5% natriy persulfat eritmasida 50 graduslik titaniumli suv isitgichi uchun, nega persulfat ioni kuchli oksidlovchi bo'lishiga qaramay, titanni passivlashtirmaydi va uning o'rniga transpassiv erishni keltirib chiqaradi?
Xabar QOLDIRISH
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 va SCE), bu erda passiv plyonka parchalanadi va titan yiliga 0,2-0,5 mm tezlikda Ti⁴⁺ sifatida eriydi.
Korroziyaning miqdoriy darajasi Persulfat konsentratsiyasiga nisbatan
Na₂S₂O₈ da 50 gradusda 500 soat davomida:
| Persulfat konsentratsiyasi (%) | Korroziya darajasi (mm/yil) | Yuzaki potentsial (V va SCE) | Mexanizm |
|---|---|---|---|
| 0 | 0.005–0.010 | 0.2–0.5 | Passiv |
| 1 | 0.05–0.12 | 1.2–1.5 | Aralash |
| 3 | 0.12–0.25 | 1.5–1.7 | Transpassiv boshlanishi |
| 5 | 0.20–0.40 | 1.7–1.9 | Transpassiv |
| 10 | 0.35–0.60 | 1.8–2.0 | Qattiq transpasiv |
Haroratning transpassiv o'tishga ta'siri
| Harorat (daraja) | 5% persulfat - korroziya darajasi (mm/yil) | Mexanizm |
|---|---|---|
| 25 | 0.10–0.20 | Transpassiv |
| 40 | 0.15–0.30 | Transpassiv |
| 50 | 0.20–0.40 | Transpassiv |
| 60 | 0.30–0.60 | Og'ir |
Muhandislik bo'yicha tavsiya
Persulfat eritmalari uchun transpassiv eritma tufayli titan tavsiya etilmaydi. PTFE{1}}qoplamali isitgichlar yoki tantaldan foydalaning. Agar titandan foydalanish kerak bo'lsa, 30 darajadan past haroratda ishlang va persulfat miqdorini cheklang<2%. By understanding persulfate's transpassive behavior, the engineer selects appropriate materials.
