Silicon Nitride vs. Alumina
Silicon nitride belongs to the non-oxide engineering ceramics classification, while alumina belongs to the oxide-based engineering ceramics. There are 17 material properties with values for both materials. Properties with values for just one material (9, in this case) are not shown.
For each property being compared, the top bar is silicon nitride and the bottom bar is alumina.
Metric UnitsUS Customary Units
Mechanical Properties
| Compressive (Crushing) Strength, MPa | 600 to 2950 | |
| 1920 to 2750 |
| Elastic (Young's, Tensile) Modulus, GPa | 140 to 310 | |
| 220 to 370 |
| Flexural Strength, MPa | 130 to 810 | |
| 260 to 430 |
| Fracture Toughness, MPa-m1/2 | 3.1 to 6.2 | |
| 3.7 to 7.2 |
| Poisson's Ratio | 0.24 to 0.27 | |
| 0.22 to 0.24 |
Thermal Properties
| Maximum Temperature: Mechanical, °C | 1000 to 1330 | |
| 650 to 1730 |
| Maximum Thermal Shock, °C | 290 to 750 | |
| 200 to 300 |
| Specific Heat Capacity, J/kg-K | 720 to 800 | |
| 870 to 940 |
| Thermal Conductivity, W/m-K | 12 to 31 | |
| 14 to 30 |
| Thermal Expansion, µm/m-K | 2.5 to 3.2 | |
| 6.7 to 8.2 |
Electrical Properties
| Dielectric Constant (Relative Permittivity) At 1 MHz | 8.0 to 10 | |
| 7.8 to 11 |
| Dielectric Strength (Breakdown Potential), kV/mm | 18 | |
| 8.9 to 12 |
| Electrical Resistivity Order of Magnitude, 10x Ω-m | 11 to 12 | |
| 6.2 to 14 |
Otherwise Unclassified Properties
| Density, g/cm3 | 2.2 to 3.4 | |
| 3.4 to 4.1 |
Common Calculations
| Stiffness to Weight: Axial, points | 34 to 53 | |
| 35 to 53 |
| Stiffness to Weight: Bending, points | 65 to 78 | |
| 57 to 62 |
| Thermal Diffusivity, mm2/s | 7.5 to 13 | |
| 3.7 to 10 |