When A Titanium Immersion Heater Is Installed In A 10% Sodium Metasilicate Solution At 80°C, Why Does The Silicate Ion Form A Protective, Non-Porous Film Only At PH >11, Va PH 9 da nima bo'ladi?
Xabar QOLDIRISH
In sodium metasilicate (Na₂SiO₃) solutions at 80°C, silicate ions polymerize on titanium surfaces. At pH >11, silikat uzluksiz, g'ovak bo'lmagan{1}}himoya plyonka hosil qiladi (qalinligi 0,5–2 mkm). pH 9 da plyonka g'ovakli, yorilib ketgan va himoya qilmaydi{6}}, bu xlorid yoki boshqa tajovuzkor turlarning kirib kelishiga va chuqurchalar paydo bo'lishiga imkon beradi.
Filmning miqdoriy sifati va pH
10% Na₂SiO₃ da 80 darajada 500 soat davomida:
| pH | Film qalinligi (µm) | Filmning porozligi | Korroziya darajasi (mm/yil) | Pitting Presentmi? |
|---|---|---|---|---|
| 8 | 0.1–0.3 | Yuqori | 0.15–0.30 | Ha |
| 9 | 0.2–0.5 | Yuqori | 0.08–0.20 | Vaqti-vaqti bilan |
| 10 | 0.5–1.0 | O'rtacha | 0.04–0.10 | Kamdan-kam |
| 11 | 1.0–1.5 | Past | 0.02–0.05 | Yo'q |
| 12 | 1.5–2.5 | Juda past | 0.01–0.03 | Yo'q |
| 13 | 2.0–3.0 | Juda past | 0.005–0.015 | Yo'q |
Haroratning pH talabiga ta'siri
| Harorat (daraja) | Himoya plyonkasi uchun minimal pH | Tavsiya etilgan pH |
|---|---|---|
| 60 | 10.5 | 11.0 |
| 80 | 11.0 | 11.5 |
| 100 | 11.5 | 12.0 |
Silikat xizmati uchun pH nazorati bo'yicha qo'llanma
| Ishlaydigan pH | Film sifati | Tavsiya etilgan harakat |
|---|---|---|
| >11 | Himoya | Yo'q |
| 10–11 | Marginal | NaOH bilan pH ni oshiring |
| 9–10 | Kambag'al, g'ovakli | Add NaOH to raise to >11 |
| <9 | Himoyasiz- | Qayta loyihalash yechimi |
Muhandislik bo'yicha tavsiya
Natriy metasilikat xizmati uchun 80 daraja, natriy gidroksid qo'shilishi yordamida pH ni 11 dan yuqori saqlang. PH ni nazorat qilish orqali muhandis titanda himoya-g'ovak bo'lmagan silikat plyonka hosil bo'lishini ta'minlaydi.
