Views: 0 Author: Site Editor Publish Time: 2025-07-12 Origin: Site
Composite insulators, critical for power grid external insulation, face irreversible aging under coupled stresses (UV, pollution, humidity). This study deciphers multi-stress aging mechanisms and develops a nano-functional coating with integrated UV-shielding and self-cleaning properties.
Chain scission of Si-O-Si backbone under 290-400nm UV, generating Si-OH groups
- 42% tear strength loss after 2000h QUV aging (18→10.5 kN/m)
- Industrial salts (Na₂SO₄/CaSO₄) penetrate microcracks at RH>85%, triggering ion migration
- Surface resistivity drops 3 orders (10¹⁵→10¹² Ω·cm) with pollution deposition
| Aging Type | Surface Morphology | Chemical Change |
| Pure UV | Chalking & cracks (>50μm) | 63% Si-CH₃ peak reduction (FTIR) |
| Electrochemical | Crater pits (20-200μm) | New SiO₄⁻ peaks (Raman) |
| Hygrothermal | Thick water film (CA<90°) | Siloxane rearrangement (15% TGA weight loss↑) |
- UV Shield: TiO₂@SiO₂ particles (30nm) with >92% UVA reflectivity
- Self-Cleaning: Fluorinated POSS coating (surface energy 12.6 mN/m, CA 158°)
| Parameter | Conventional | Novel Coating | Improvement |
| Hydrophobicity Recovery | >72 hours | <2 hours | 36x faster |
| Pollution Flashover (ESDD 0.2mg/cm²) | 28kV/m | 46kV/m | +64% |
| Elongation after 3000h UV | 105% | 320% | +205% |
- Light-Triggered Hydrophobicity: CA increases 22° at UV>50W/m²
- Rain Cleaning: >90% pollution removal under acid rain simulation
1. Extreme Environment Tests
- Coastal area (salinity 0.35mg/cm²): Zero erosion after 3 years
- High-altitude UV zone (280W/m²): 100% HC hydrophobicity retention
2. Critical Applications
- UHVDC Transmission: Pollution withstand class upgraded from Ⅲ to Ⅳ
- Offshore Wind: Passed 25-year equivalent test (IEC 62217)
- Industrial zones: Creepage distance reduced from 31 to 25mm/kV
Molecular interface engineering resolves aging bottlenecks. Future work focuses on **stress-sensing coatings** (self-healing/conductivity tuning) for smart insulator development.
