GEOMET® 730 EV
← Overview Saving Lives

Ceramic Armor

Above 1,500 °C the coating turns into ceramic and holds the fire inside the case.

The risk

A lithium-ion cell that overheats can start a chain reaction. Heat passes from cell to cell and flames can break through the battery case within minutes. The case is the last barrier between that fire and the cabin. Its job in that moment is simple: hold long enough for everyone to get out.

The requirement

Battery upper cases are tested with a torch and abrasive grit at the same time. The case must show no ignition for five minutes. Seven alternative solutions were tested against this requirement. Each failed for a different reason: sensitivity to moisture, adhesives that ignited, surfaces that did not suit the process, cost, or material supply. GEOMET® 730 EV met the fire requirement, the corrosion specification and series-production needs at the same time.

How Ceramic Armor works

Normal operation Steel battery case Zn · Al · nano-Si flakes in an inorganic binder >1,500 °C Thermal runaway Steel stays shielded Ceramic Armor Gahnite · Mullite · Willemite Verified by XRD and SEM analysis
Ceramic phaseFormulaMelting point
GahniteZnAl₂O₄≈ 1,900 °C
MulliteAl–Si–O≈ 1,850 °C
WillemiteZn₂SiO₄≈ 1,500 °C

The coating does not melt away. It changes into ceramic phases that withstand the heat of a battery fire. That chemistry, not a slogan, is what we mean by Ceramic Armor.