Material Overview
Silicon Carbide (SiC) is a high-performance advanced ceramic material renowned for its exceptional hardness (second only to diamond), thermal stability (up to 1,700°C), and resistance to wear, corrosion, and oxidation. Composed of silicon and carbon atoms in a covalent lattice, SiC ceramics are widely used in aerospace, semiconductor manufacturing, energy systems, and industrial machinery due to their unique combination of mechanical and thermal properties.
Technical Data Table
| Property | Reaction-Bonded SiC | Hot-Pressed SiC | Sintered SiC |
|---|---|---|---|
| Density | 3.02 g/cm³ | 3.21 g/cm³ | 3.10 g/cm³ |
| Flexural Strength | 350–450 MPa | 500–600 MPa | 400–500 MPa |
| Thermal Conductivity | 120 W/mK | 270 W/mK | 180 W/mK |
| Max. Operating Temp. | 1,400°C | 1,700°C | 1,600°C |
Key Features
- Ultra-High Hardness: Mohs hardness of 9.5, ideal for abrasive environments like mining and cutting tools.
- Thermal Conductivity: Ranges from 120–270 W/mK, enabling efficient heat dissipation in high-power electronics.
- Chemical Inertness: Resists acids (e.g., HCl, H₂SO₄), alkalis, and molten metals, ensuring longevity in corrosive settings.
- Oxidation Resistance: Maintains structural integrity at 1,600°C in air due to a protective SiO₂ surface layer.
Applications
- Semiconductor: Wafer handling arms, plasma etching components, and susceptors for CVD reactors.
- Energy: Heat exchangers, burner nozzles, and turbine blades in gas turbines.
- Industrial: Wear-resistant liners for pumps, seals, and valves in chemical processing.
- Automotive: Brake discs and bearings for electric vehicles (EVs) due to lightweight and thermal stability.
Manufacturing Techniques
- Reaction Bonding: Infiltrates silicon into carbon preforms, achieving near-net-shape components with 95% density.
- Hot Pressing: Produces ultra-dense ceramics (>99% density) for high-stress applications.
- Additive Manufacturing: Enables complex geometries (e.g., lattice structures) via 3D printing with SiC-polymer composites.
Silicon carbide outperforms metals due to its ultra-high thermal stability (1,700°C vs. 500°C for stainless steel) and oxidation resistance. For example, SiC burner nozzles in gas turbines reduce maintenance costs by 70% compared to nickel alloys, while its low thermal expansion (4.0×10⁻⁶/°C) prevents cracking under thermal cycling.
Fracture toughness is enhanced via grain refinement (e.g., two-step sintering) and second-phase additions like VB₂ or Si₃N₄. These methods suppress abnormal grain growth and create weak interfaces that deflect cracks. For instance, SiC-VB₂ composites achieve fracture toughness of 5.2 MPa√m, 30% higher than pure SiC.
- Chemical Processing: SiC-lined pipes transport corrosive media (e.g., sulfuric acid) with a service life exceeding 5 years, reducing replacement frequency by 80%.
- Semiconductor: SiC components resist plasma erosion in etching chambers, extending tool lifespan by 50%.
- Energy: Molten salt reactors use SiC seals to prevent leakage in high-temperature, corrosive environments.
RBSC offers cost efficiency and complex shape fabrication without machining. By infiltrating molten silicon into porous carbon preforms, RBSC achieves flexural strengths up to 450 MPa and densities >95%. It is widely used in large-scale components like kiln furniture and rocket nozzles.