Green Silicon Carbide for SiC-Reinforced Advanced Composite Materials

1. Core Properties for Reinforcement

2. Functions in SiC-Reinforced Composites

2.1 Mechanical Reinforcement & Toughening

• Load bearing: Evenly distributed hard particles share external stress, boosting flexural and tensile strength by over 30%.
• Crack deflection: Forces cracks to propagate around particles and extends crack paths, with fracture toughness up to 8 MPa·m¹ᐟ².
• Grain refinement: Restrains grain growth of the matrix, achieving simultaneous improvement in strength and toughness.

2.2 Thermal Management Enhancement

• Establishes continuous thermal conduction pathways and reduces interfacial thermal resistance. The thermal conductivity of polymer matrix rises from 0.2 to 3.5 W/(m·K); adding 20% green SiC to alumina ceramic increases thermal conductivity from 30 to 60 W/(m·K).
• Low thermal expansion coefficient matches well with matrices, eliminating internal stress under cyclic temperature from -50 °C to 200 °C and tripling thermal shock resistance service life.

2.3 Functional Improvement

• Wear resistance: Particles bear friction load, lifting the wear resistance of composites by 3 times for brakes, bearings and other components.
• Electrical insulation: High-purity green SiC features excellent insulation for electronic packaging and high-voltage modules.
• Corrosion resistance: Resists acid, alkali and oxidation, maintaining stable performance in humid and corrosive environments.

3. Applications in Mainstream Composite Systems

3.1 Ceramic Matrix Composites (SiCₚ/SiC, Al₂O₃/SiC)

• Formula: 15–25% green SiC micropowder + SiC/Al₂O₃ matrix; sintering temperature: 1600–1800 °C.
• Performance: Heat resistance above 1600 °C, flexural strength ≥500 MPa, thermal conductivity ≥60 W/(m·K).
• Applications: Hot-end components of aero-engines, rocket nozzles, semiconductor heat dissipation substrates.

3.2 Metal Matrix Composites (Al/SiC, Mg/SiC)

• Formula: 10–20% green SiC micropowder + aluminum/magnesium alloy; manufactured via powder metallurgy or die casting.
• Performance: Specific strength 8 times that of steel, thermal conductivity ≥180 W/(m·K), coefficient of thermal expansion ≤5×10⁻⁶/°C.
• Applications: New energy vehicle battery brackets, 5G base station heat sinks, lightweight aerospace structural parts.

3.3 Polymer Matrix Composites (Epoxy/Silicone Rubber/SiC)

• Formula: 15–30% green SiC micropowder + epoxy resin/silicone rubber; cured at room or medium temperature.
• Performance: Thermal conductivity ≥2 W/(m·K), breakdown voltage ≥15 kV/mm, service life against wear doubled.
• Applications: Electronic encapsulant, LED heat dissipation substrates, thermal interface gaskets for high-power devices.

4. Key Selection & Quality Control Criteria

1. Purity: Choose grade ≥99.5% for high-end electronics and aerospace; 98.5–99.0% for general industrial wear-resistant products. Excessive Fe, Ca and other impurities will deteriorate interfacial performance.
2. Particle Size: D50 1–3 μm for ceramic matrix (high sintering density); D50 5–10 μm for metal matrix (good dispersibility); 0.5–1 μm nano-grade for polymer matrix (high thermal conductivity).
3. Surface Modification: Treated with silane or titanate coupling agents to enhance interfacial bonding and lower porosity.
4. Impurity Control: Free carbon ≤0.2%, oxygen content ≤0.5% to prevent high-temperature oxidation and adverse interfacial reactions.

5. Market & Development Trends