| Property | Unit | Hexagonal Boron Nitride (h-BN) | Cubic Boron Nitride (c-BN) |
|---|---|---|---|
| Crystal Structure | — | Hexagonal layered structure | Cubic (zinc blende type) |
| Density | g/cm³ | 2.27 | 3.48 |
| Mohs Hardness | — | 2 (lubricating) | Second only to diamond |
| Flexural Strength (h-BN ceramic) | MPa | 50–100 | — |
| Melting / Decomposition Point | °C | >3000 (decomposes in N₂) | >3000 |
| Maximum Service Temperature (Air) | °C | 900–1000 (oxidation limit) | ~1200 |
| Thermal Conductivity (20°C) | W/(m·K) | 15–30 (⊥c), up to 60 (∥c) | 13–20 |
| Thermal Expansion Coefficient | K⁻¹ | 0.4×10⁻⁶ – 7.5×10⁻⁶ (anisotropic) | 2.1×10⁻⁶ – 4.9×10⁻⁶ |
| Volume Resistivity (20°C) | Ω·cm | >10¹⁴ | >10¹⁴ |
| Dielectric Strength | kV/mm | 30–40 | — |
| Dielectric Constant (1 MHz) | — | 3.5–5.3 (anisotropic) | 4.5–7.1 |
