Abrasive-Kev sib tw Corrosive hauv Thermoelectric Casting
Bismuth telluride (Bi₂Te₃) slurries ntawm 120℃nrog 30% khib nyiab yog siv rau thermoelectric wafer casting. Tellurium hais (Mohs 2.5) tsim ib qho abrasive-ib puag ncig corrosive qhov twg tellurium reacts nrog noo noo los tsim tellurous acid (H₂TeO₃), ua kom PFA degradation. Kev txheeb xyuas ntau los ntawm 7 cov chaw tsim khoom siv hluav taws xob qhia tau hais tias kev sib koom ua ke nce hnav tus nqi los ntawm 2.5x piv rau kev puas tsuaj ib leeg. Rau 8000-teev kev pab cuam lub neej, tus qauv PFA yuav tsum tau 3.5mm phab ntsa, thaum iav-filled PFA (Shore D 72) yuav tsum tau 2.5mm phab ntsa.
Tellurium Abrasion thiab Corrosion Mechanism
Tellurium hais (10-50 µm) abrade PFA nto, nthuav tawm cov polymer tshiab. Tellurium reacts nrog dej: Te + 2H₂O → TeO₂ + 4H⁺ + 4e⁻, forming tellurous acid (pH 3-4). Cov kua qaub tawm tsam qhov chaw abraded, softening polymer rau ntxiv abrasion. Qhov kev sib koom ua ke no ua rau nrawm hnav tsis tau kwv yees los ntawm ob qho tib si mechanism. Kev ntsuas ntawm 120℃nrog 30% Bi₂Te₃, 2 m / s shear:
| PFA Qib | Abrasion nkaus xwb (mm / 1000h) | Corrosion nkaus xwb (mm / 1000h) | Synergy tus nqi (mm / 1000h) | Synergy Factor |
|---|---|---|---|---|
| Txheem (Shore D 65) | 0.15 | 0.08 | 0.45 | 2.0x |
| Iav - puv (Shore D 70) | 0.08 | 0.06 | 0.25 | 1.8x |
| Iav - puv (Shore D 72) | 0.06 | 0.05 | 0.18 | 1.6x |
| Cov pa roj carbon - puv (Shore D 75) | 0.04 | 0.05 | 0.14 | 1.6x |
Qhov tseem ceeb ntawm phab ntsa Thickness rau 8000-teev Kev Pabcuam
Yam tsawg kawg nkaus dielectric thickness yog 1.2 hli. Yuav tsum tau pib thickness=1.2mm + (synergy rate × 8000h). Rau 8000h (1 xyoos txuas ntxiv):
| PFA Qib | Synergy tus nqi (mm / 1000h) | Hnav hauv 8000h (mm) | Yuav tsum tau Initial Wall (mm) | Tswv yim Specification |
|---|---|---|---|---|
| Txheem (Shore D 65) | 0.45 | 3.6 | 4.8 | 5.0mm (tsis siv tau) |
| Iav - puv (Shore D 70) | 0.25 | 2.0 | 3.2 | 3.5mm ib |
| Iav - puv (Shore D 72) | 0.18 | 1.44 | 2.64 | 3.0mm ib |
| Cov pa roj carbon - puv (Shore D 75) | 0.14 | 1.12 | 2.32 | 2.5 hli |
Siab -Shear Mixing Effects
Siab- shear mixing (impeller tip speed 4-}6 m/s) tsub kom ob qho tib si puas thiab corrosion. Ntawm 5 m / s, kev sib koom ua ke rau iav - puv PFA (Shore D 72) ob npaug rau 0.36 mm / 1000h, xav tau 4.0mm thawj phab ntsa. Rau siab- kev pab cuam shear, qhia cov pa roj carbon-filled PFA nrog 3.5mm phab ntsa.
Tellurium Concentration thiab Particle Loj
Higher tellurium concentration increases wear. At 40% solids, synergy rate increases 40%; at 20% solids, decreases 30%. Particle size also matters: coarse particles (>100 µm) ua rau 2x hnav cov khoom zoo (<20 µm). For Bi₂Te₃ casting with controlled particle size distribution, specify carbon-filled PFA for d90 > 50 µm.
Specification Qhia
For Bi₂Te₃ slurries at 120°C, 30% solids, 8000-hour service, specify carbon-filled PFA (Shore D 75) with 2.5mm minimum wall thickness for standard mixing (2-3 m/s). For high-shear mixing (>4 m / s), qhia 3.5mm phab ntsa. Yuav tsum tau muab daim ntawv pov thawj ntawm cov khoom siv abrasive- kuaj corrosive nrog Bi₂Te₃ slurry. Tus nqi them rau cov pa roj carbon- puv PFA (40-50% dhau tus qauv) yog qhov tsim nyog los ntawm kev ua haujlwm ntawm 8000-teev kev pabcuam hauv lub thermoelectric wafer casting, qhov twg lub rhaub tsis ua haujlwm ua rau cov khoom tsis raug nqi $ 50,000-200,000. Rau kev sim-scale ntau lawm, iav-filled PFA nrog 4.0mm phab ntsa thiab 4000-teev hloov yuav siv tau.
