Reasons for Using Green Silicon Carbide (GC) in SiC/Al Composites
Green silicon carbide features high purity, low impurity content, excellent thermal conductivity and structural stability, along with well-controlled interfacial reactions. It enables the production of SiC/Al composites with high thermal conductivity, low thermal expansion and superior mechanical strength.
1. Purity & Impurity Content: Governing Interfacial Stability
Green silicon carbide: SiC content ≥ 98.5%–99.2% (up to 99.9% for premium grades); total iron and aluminum impurities ≤ 0.17%, metallic impurities < 5 ppm, with nearly no free silicon or free carbon.
Key impact: Molten aluminum tends to react with silicon carbide at high temperatures and form aluminum carbide (Al₄C₃), a brittle phase prone to pulverization when exposed to water. With fewer impurities and lower oxygen content, green silicon carbide restrains interfacial reactions, minimizes brittle byproducts and ensures stable interfacial bonding.
2. Thermal Conductivity & Thermal Expansion: Compatibility with Aluminum Matrix
Green silicon carbide: Thermal conductivity ranges from 120–350 W/(m·K); coefficient of thermal expansion (CTE) is 4.5–5.5 ppm/℃, which matches well with aluminum (23 ppm/℃).
Key impact: SiC/Al composites are widely applied in electronic heat dissipation, aerospace structures and automotive brake components, where high thermal conductivity and low thermal expansion are essential. Using green silicon carbide can control the CTE of finished composites within 6–12 ppm/℃ and achieve thermal conductivity of 200–250 W/(m·K), delivering outstanding dimensional stability and heat dissipation performance.
3. Hardness, Strength & Wear Resistance: Core Reinforcement Performance
Green silicon carbide has a Mohs hardness of 9.5, with complete crystal structures and minimal internal defects. It retains high mechanical strength even at temperatures up to 1000 ℃.
Key impact: As a reinforcing phase, green silicon carbide greatly improves the hardness, wear resistance, tensile strength and flexural strength of the aluminum matrix. When added at a volume fraction of 20%–30%, it boosts wear resistance by 3 to 5 times and mechanical strength by 50% to 100%.
4. Chemical Stability & Processability: Adaptability to Composite Manufacturing
Green silicon carbide boasts high chemical inertness, good acid and alkali resistance, and excellent oxidation resistance. It barely reacts with aluminum, magnesium and other metals at temperatures below 1400 ℃. Its regular grain shape and clean surface ensure good wettability with molten aluminum, enabling stable production via stirring infiltration, pressure infiltration and powder metallurgy, and raising the overall yield rate.
5. Comparison Between Green Silicon Carbide for SiC/Al Composites
| Comparison Item | Green Silicon Carbide (GC) | Impact on SiC/Al Composites |
|---|---|---|
| SiC Purity | 98.5%–99.2% | Higher purity ensures more stable interface |
| Impurities (Fe+Al) | ≤ 0.17% | Lower impurities reduce the formation of Al₄C₃ |
| Thermal Conductivity | 120–350 W/(m·K) | Higher thermal conductivity delivers better heat dissipation |
| CTE | 4.5–5.5 ppm/℃ | Lower CTE provides better dimensional stability |
| Interfacial Reaction | Mild and controllable | Directly determines service life and operational reliability |
| Application Scenarios | High-end heat dissipation, aerospace, electronics | Ideal for high-performance composite materials |
6. Conclusion & Application Recommendations
Green silicon carbide is the preferred material for components requiring high thermal conductivity, low thermal expansion and high reliability, including heat sinks for 5G base stations, IGBT substrates, aerospace structural parts and high-performance brake discs.
Green Silicon Carbide Particle Sizes
| Grit Size | D0 (μm) | D3 (μm) | D50 (μm) | D94 (μm) |
|---|---|---|---|---|
| #240 | ≤127 | ≤103 | 57.0±3.0 | ≥40 |
| #280 | ≤112 | ≤87 | 48.0±3.0 | ≥33 |
| #320 | ≤98 | ≤74 | 40.0±2.5 | ≥27 |
| #360 | ≤86 | ≤66 | 35.0±2.0 | ≥23 |
| #400 | ≤75 | ≤58 | 30.0±2.0 | ≥20 |
| #500 | ≤63 | ≤50 | 25.0±2.0 | ≥16 |
| #600 | ≤53 | ≤41 | 20.0±1.5 | ≥13 |
| #700 | ≤45 | ≤37 | 17.0±1.5 | ≥11 |
| #800 | ≤38 | ≤31 | 14.0±1.0 | ≥9.0 |
| #1000 | ≤32 | ≤27 | 11.5±1.0 | ≥7.0 |
| #1200 | ≤27 | ≤23 | 9.5±0.8 | ≥5.5 |
| #1500 | ≤23 | ≤20 | 8.0±0.6 | ≥4.5 |
| #2000 | ≤19 | ≤17 | 6.7±0.6 | ≥4.0 |
| #2500 | ≤16 | ≤14 | 5.5±0.5 | ≥3.0 |
| #3000 | ≤13 | ≤11 | 4.0±0.5 | ≥2.0 |
| #4000 | ≤11 | ≤8.0 | 3.0±0.4 | ≥1.8 |
| #6000 | ≤8.0 | ≤5.0 | 2.0±0.4 | ≥0.8 |
| #8000 | ≤6.0 | ≤3.5 | 1.2±0.3 | ≥0.6 |
Contact Information
Reasons for Using Green Silicon Carbide in SiC/Al Composites-Zhengzhou Haixu Abrasives Co., Ltd.
Whatsapp/Mobile:+86 18039336686
Email: cassiel@zzhaixu.cn
Web:https://whitefusedalumina.cn/
Whatsapp/Mobile:+86 18039336686
Email: cassiel@zzhaixu.cn
Web:https://whitefusedalumina.cn/
