Passive Shield
Stays protective after stone chips, scratches and assembly damage.
Real cases get damaged
Battery cases are pressed, transported, bolted and driven over gravel for years. A coating that only protects a perfect surface is not enough. What matters is how it behaves after a stone chip, a scratch or a fastener cuts through it.
Corrosion after damage
Panels were damaged on purpose with fastener marks, stone chips, abrasion and cross-cuts, then compared with electro-coating (E-coat). E-coat developed red rust again and again. GEOMET® 730 EV stayed free of red rust in most conditions. Current mapping (SVET) around the damage showed a stable, passivated surface on GEOMET® 730 EV, while E-coat and bare GA steel showed active corrosion.
Corrosion performance
| Test | Requirement | Result |
|---|---|---|
| Salt spray (SST) | 1,000 h, no red rust | Pass |
| CCT-A | 40 cycles, no red rust | Pass |
| CCT-C | 56 cycles, loss ≤ 10% | Pass |
| CCT-F | 20 cycles, loss ≤ 10% | Pass |
| Adhesion | Cross-hatch M1.0–M2.5 | Pass |
White on the surface is the shield working
In humid conditions a light white layer can appear on the coating. XRD analysis shows it is a stable passivation layer of zinc and aluminum–silicon compounds, not a defect. We call it the Passive Shield: the coating protecting itself and the steel underneath.