Nyob rau hauv Titanium Tube Bundle rhaub rau 20% Ammonium Nitrate tov ntawm 80 degree, PH (4.5 Vs . 6.5) Yuav Ua Li Cas Hloov Cov Passivation tam sim no ntom thiab pheej hmoo ntawm kev ntxhov siab Corrosion tawg?
Tso lus
Hauv 20% ammonium nitrate (NH₄NO₃) ntawm 80 degree, pH cuam tshuam rau tus cwj pwm passivation ntawm titanium. Ntawm pH 6.5 (ze nruab nrab), cov zaj duab xis passive ruaj khov, nrog passivation tam sim no ntom ntawm 0.05-0.1 µA / cm² thiab tsawg SCC kev pheej hmoo. Ntawm pH 4.5 (acidic los ntawm hydrolysis), passivation tam sim no ceev nce mus rau 0.5-2 µA / cm², thiab cov kev pheej hmoo ntawm kev nyuaj siab corrosion cracking (SCC) nce ho vim nitrate ion aggression ntawm qis pH.
Quantitative Passivation Current vs. pH
Rau Qib 2 titanium hauv 20% NH₄NO₃ ntawm 80 degree:
| pH | Passivation tam sim no ceev (µA / cm²) | SCC Initiation Sijhawm (teev) | SCC Risk |
|---|---|---|---|
| 6.5 | 0.05–0.10 | >5,000 | Tsawg |
| 6.0 | 0.08–0.15 | 3,000–5,000 | Tsawg- Nruab nrab |
| 5.5 | 0.15–0.30 | 1,000–3,000 | Nruab nrab |
| 5.0 | 0.30–0.70 | 500–1,500 | Siab |
| 4.5 | 0.50–1.50 | 200–800 | Mob hnyav |
| 4.0 | 1.0–3.0 | 100–400 | hnyav heev |
Cov nyhuv ntawm chloride thiab nitrate kev sib cuam tshuam
| pH | Chloride (ppm) | SCC Risk | Pom zoo Qib |
|---|---|---|---|
| 6.5 | 0 | Tsawg | Qib 2 |
| 6.5 | 100 | Nruab nrab | Qib 2 |
| 5.5 | 0 | Nruab nrab | Qib 2 |
| 5.5 | 100 | Siab | Qib 7 |
| 4.5 | 0 | Siab | Qib 7 |
| 4.5 | 100 | Mob hnyav | Qib 7 + cais |
pH Control Guide
| Ua haujlwm pH | Pom zoo ua | Cia siab SCC-Lub Neej Dawb (Qib 2) |
|---|---|---|
| >6.0 | Tsis muaj | >10 xyoo |
| 5.5–6.0 | Saib xyuas pH txhua lub lim tiam | 5-10 xyoo |
| 5.0–5.5 | Ntxiv NH₄OH kom nce pH | 3-5 xyoos |
| 4.5–5.0 | Siv qib 7 titanium | 5–8 xyoo (Qib 7) |
| <4.5 | Rov tsim txheej txheem | <2 years |
Kev pom zoo engineering
Rau kev pabcuam ammonium nitrate, tswj pH siab tshaj 5.5 rau Qib 2 lossis siab dua 5.0 rau Qib 7. Ntxiv ammonium hydroxide kom tsis txhob muaj kua qaub. Los ntawm kev tswj cov pH, tus kws ua choj txo cov passivation tam sim no ceev thiab tiv thaiv kev ntxhov siab corrosion tawg.
