One of the most popular high performance tribomaterials is silicon carbide (SiC), which has been marketed for more than 25 years. It has excellent corrosion resistance, excellent abrasion and wear resistance, low coefficients of friction and thermal expansion, high thermal conductivity, and hardness greater than tungsten carbide, among other qualities.
The following silicon carbide grades are available:
- Reaction Bonded Silicon Carbide (RB SiC) is a very cost-effective material that has good chemical resistance and excellent wear properties.
- Sintered Silicon Carbide (SSiC) is the most resistant to chemically hostile fluids and is best for high temperature applications because it contains no free silicon.
- A mixture of silicon carbide and free graphite is known as graphite-loaded silicon carbide. To enhance the tribological performance and lubricity of RB SiC (RB SiC + C) or SSiC (SSiC + C), graphite is added to create a composite.
| Parameter | Unit | RB SiC | SSiC |
| Density | g/cm3 | 3.0-3.05 | 3.10 |
| Free Silicon Content | % | 12% | – |
| Crystal Size | μm | 8-20 | 5-7 |
| Hardness | Rockwell | HRA 90 | >HRA 93 |
| Compressive Strength | Mpa | 2700 | 3000 |
| psi | 391,500 | 435,000 | |
| Flexural Strength | Mpa | 400 | 400 |
| psi | 58,000 | 58,000 | |
| Fracture Toughness | Mpa.m1/2 | 4.3 | 4.5 |
| Elastic Modulous | Gpa | 390 | 410 |
| psi | 57×106 | 59×106 | |
| Poisson’s Ratio | / | 0.15 | 0.15 |
| Thermal Expansion Coefficient | 1×10-6/K | 4.3 | 4.3 |
| Parameter | Unit | RB SiC + C | SSiC + C |
| Density | g/cm3 | 2.70 | 2.85 |
| Free Silicon Content | % | – | – |
| Crystal Size | μm | – | – |
| Hardness | Rockwell | HRA 82 | HRA 85 |
| Compressive Strength | Mpa | 1500 | 2000 |
| psi | 217,500 | 290,000 | |
| Flexural Strength | Mpa | 200 | 300 |
| psi | 29,000 | 435,000 | |
| Fracture Toughness | Mpa.m1/2 | – | – |
| Elastic Modulous | Gpa | 250 | 320 |
| psi | 36.3×106 | 46.4×106 | |
| Poisson’s Ratio | / | – | – |
| Thermal Expansion Coefficient | 1×10-6/K | – | – |