1. Core Functions (Adapted to NEV Working Conditions)
- Efficient Thermal Conduction & Heat Dissipation
With a thermal conductivity of about 3.3~6.3 W/(m·K), far higher than pure resin matrix. It forms continuous thermal conduction channels in potting adhesive, quickly dissipating heat generated by battery cells and motor controllers, and preventing thermal runaway and material aging.
- Adjust Coefficient of Thermal Expansion (CTE)
White fused alumina features an extremely low linear expansion coefficient (~3.3×10⁻⁶/℃). It reduces the CTE of adhesive layer, matches the thermal expansion properties of silicon chips, aluminum shells and PCB boards, and relieves internal stress, cracking and delamination under cold and thermal cycling conditions.
- High Insulation & Voltage Resistance
High purity with Al₂O₃ ≥ 99.5%, low sodium and low iron content, and high volume resistivity. It meets the automotive electronic insulation standard of AC 2000V/DC 3000V, effectively avoiding short circuit and electric leakage risks.
- Structural Reinforcement & Wear Resistance
Mohs hardness up to 9.0, improving the hardness, permanent compression deformation, puncture resistance and oil/wear resistance of gaskets, adapting to the vibration and oil pollution environment of chassis and battery packs.
- Low Oil Absorption & Easy Processing
Oil absorption value ≤ 8%, no obvious viscosity increase. It ensures good fluidity and high filling rate of potting adhesive, suitable for automatic dispensing and pouring processes.
2. NEV-Grade Technical Specifications (Key Selection Standards)
2.1 Chemical Composition (High Purity & Low Impurity Required)
- Al₂O₃: ≥ 99.5% (99.7% low-sodium type is preferred)
- Na₂O: ≤ 0.1% (prevent alkali precipitation at high temperature, electrode corrosion and insulation degradation)
- Fe₂O₃: ≤ 0.05% (low conductivity, anti-rust)
- SiO₂: ≤ 0.1%
- Magnetic substance: ≤ 0.002%
2.2 Common Particle Size for Gaskets
- Recommended particle size: 60# 4000#~8000#
- Requirements: Concentrated particle size distribution, regular spherical particle shape, no oversized particles to avoid scratching, stress concentration and pinholes.
2.3 Physical Properties
- True density: 3.95~4.0 g/cm³
- Mohs hardness: 9.0
- Melting point: 2250℃, heat resistance >1800℃
- Surface treatment: Acid & water washed, inert treated for better bonding with resin matrix and no agglomeration.
3. Application Scenarios
- Battery System: Potting of battery cells/modules, water cooling plate sealing gaskets, PACK & BDU sealing gaskets
- Electric Drive System: Potting and sealing gaskets for motor controllers, OBC and DC/DC converters
- High-voltage Harness & Connectors: Thermal conductive, insulating and sealing potting adhesive
4. Selection & Procurement Key Points
- Choose low-sodium white fused alumina (Na₂O ≤ 0.1%) to avoid high-temperature aging and insulation failure.
- Match particle size with adhesive thickness: thinner gaskets require finer particle size (D50 ＜ 5μm).
- Silane coupling agent surface modification is recommended to enhance interface bonding, reduce water absorption and improve toughness.
- Compliance: Meet RoHS and REACH standards, heavy metal free.
5. Filler Comparison for Potting Adhesive & Gaskets
| Filler Material | Thermal Conduction | Insulation Performance | CTE Matching | Cost Level | Application Scope |
|---|---|---|---|---|---|
| White Fused Alumina | Medium-High | Excellent | Excellent | Medium | Universal for New Energy Vehicles |
| Aluminum Nitride (AlN) | Ultra-High | Excellent | Excellent | High | Ultra-high heat dissipation scenarios |
| Quartz Powder | Low | Good | Good | Low | Ordinary insulation use |
| Aluminum Hydroxide | Low | Good | General | Medium | Mainly for flame retardancy |