BAE Systems sintered Silicon Nitride (Si3N4) is produced to be an isotropic near full density material offering excellent wear resistance. Pressureless sintering allows for near net shape forming of complex components for a wide variety of structural applications. Through control of processing and chemistry, the grain boundary or intergranular phase is engineered to be crystalline in BAE Systems PSX Si3N4 and amorphous in BAE Systems PSG Si3N4.
BAE Systems PSX Si3N4 has improved elevated temperature properties while BAE Systems PSG has excellent room temperature properties. BAE Systems RBSN (Reaction Bonded Silicon Nitride) is an excellent engineering material containing no glassy second phase for wear and high temperature applications in which 20-25% fine porosity is desired or permissible. The following chart lists typical properties:
| Grade of Sintered Si3N4 | PSG | PSX | RBSN | |
| Bulk Density | g/cm^3 |
3.24 |
3.24 | 2.2-2.5 |
| Average Grain Size |
μm |
1.2 | 1.0 | 1.0 |
| Flexural Strength, (4-Pt MOR) | Ksi | 100 | 102 | 35-42 |
| @ RT | MPa | 690 | 700 | 240-290 |
| Characteristic Strength | MPa | 720 | 740 | 250-310 |
| Weibull Modulus (m) | 15 | 14 | - | |
| Elastic Modulus (E) | GPa | 320 | 310 | 75 |
| Poisson's Ratio (n) | 0.27 | 0.24 | 0.24 | |
| Hardness (Vickers 5.0 kg) | kg/mm^2 | 1450 | 1450 | - |
| Fracture Toughness (Chevron Notch) | MPa-m^2 | 5.7 | 6.0 | - |
| Thermal Expansion (RT-1000°C) | 10-6/°C | 3.3 | 3.4 | 3.3 |
| Thermal Conductivity @RT | (W/m-k) | 30 | 30 | 12 |
| Electrical Resistivity |
Ω-cm |
>10^14 | >10^14 | >10^14 |
