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Price Comparison
Material Type | Price Level | Cost Drivers |
Si₃N₄-bonded SiC (Silicon Nitride Bonded SiC) | Higher | High-purity silicon powder required; high nitriding temperature (1400–1500°C); long production cycle (7–10 days) |
Reaction-Bonded SiC (RB-SiC) | Lower | Simpler process (liquid silicon infiltration); lower sintering temperature (1450–1600°C); shorter production cycle (3–5 days) |
Reason for Price Difference:
The silicon nitride bonding process requires precise control and high-purity silicon powder (≥99.9%, industrial grade, ~20,000–30,000 RMB/ton), while RB-SiC can use metallurgical grade silicon (lower cost, ~10,000–15,000 RMB/ton).
Performance Comparison
1. Mechanical Properties
Property | Si₃N₄-bonded SiC | Reaction-Bonded SiC |
Flexural Strength (RT) | 80–120 MPa | 150–250 MPa |
Flexural Strength (1400°C) | 70–90 MPa | 50–80 MPa |
Fracture Toughness | 6.5–7.5 MPa·m¹/² | 4.0–4.5 MPa·m¹/² |
Hardness | Mohs 9.2 | Mohs 9.5 |
Key Difference:
Si₃N₄-bonded SiC maintains better mechanical stability at high temperatures, while RB-SiC has higher hardness at room temperature but loses strength more rapidly at elevated temperatures.
2. Thermal Properties
Property | Si₃N₄-bonded SiC | Reaction-Bonded SiC |
Thermal Conductivity | 25–35 W/(m·K) | 120–200 W/(m·K) |
Thermal Expansion Coefficient | 4.2×10⁻⁶/°C | 4.5×10⁻⁶/°C |
Maximum Service Temperature | 1750°C (oxidizing atmosphere) | 1600°C (limited by free silicon) |
Key Difference:
RB-SiC offers much higher thermal conductivity (ideal for heat dissipation), but Si₃N₄-bonded SiC withstands higher temperatures.
3. Chemical Stability
Property | Si₃N₄-bonded SiC | Reaction-Bonded SiC |
Oxidation Resistance | ≤0.5% weight gain at 1400°C | Accelerated oxidation above 1300°C due to free silicon |
Molten Metal Resistance | >2000 hours (Al/Zn) | ~1500 hours (Al) |
Acid/Alkali Resistance | <0.1g/m² loss in 98% H₂SO₄ | 0.3g/m² loss in concentrated HCl |
Key Difference:
Si₃N₄-bonded SiC performs better in highly corrosive environments, while RB-SiC is more susceptible to acid attack due to free silicon content.
Application Recommendations
- Si₃N₄-bonded SiC:
Best for electrolytic cell linings, high-temperature kiln rollers, desulfurization nozzles, and other applications requiring long-term stability above 1400°C and resistance to chemical corrosion.
- Reaction-Bonded SiC:
Ideal for semiconductor heat treatment fixtures, mechanical seal parts, and components requiring high thermal conductivity and hardness at room temperature.
Summary
Si₃N₄-bonded SiC is about 30–50% more expensive but offers superior high-temperature stability and corrosion resistance. Reaction-bonded SiC is more cost-effective and excels in applications demanding high thermal conductivity and hardness at lower temperatures. The optimal choice depends on the specific requirements for operating temperature, chemical environment, and budget.
- Author:QDSIC
- URL:https://blog.qdsic.com/article/Silicon-Carbide-Bonded-with-Silicon-Nitride-vs-Reaction-Bonded-Silicon-Carbide
- Copyright:All articles in this blog, except for special statements, adopt BY-NC-SA agreement. Please indicate the source!
