Black Silicon Carbide (Black SiC) for Refractory Use

Black silicon carbide  (also called segment sand/ refractory sand) refers to coarse, sized SiC particles (typically 0–10mm) mainly used in refractories & metallurgy. It’s not the fine grit for grinding wheels, but larger crushed grains for high-temperature linings.

Key Specifications

• Standard sizes: 0–1mm, 1–3mm, 3–5mm, 5–10mm
• Purity grades (SiC min): 90%, 95%, 97%, 98%
• Typical impurities: Fe₂O₃ ≤ 1.5–2.0%, Free C ≤ 1.0–2.0%

1. Advantages as Refractory Raw Material

• High temperature resistance: Melting point ~2600°C, excellent thermal stability in high-temperature furnaces
• High thermal conductivity & low thermal expansion: Resists thermal shock, not easy to crack under rapid heating/cooling
• Corrosion resistance: Resists erosion by molten iron, slag, alkali, and non-ferrous metal melts
• High hardness & wear resistance: Great anti-abrasion for furnace linings and structural parts
• Oxidation resistance (with reasonable formulation): Stable in reducing & neutral atmospheres

2. Main Refractory Applications

1. Furnace lining & refractory bricks
   • Precast SiC refractory bricks, fired bricks for industrial kilns
   • Used in steelmaking, iron smelting, non-ferrous smelting furnaces
2. Kiln furniture / furnace structural parts
   • Kiln shelves, saggers, beams, supports for ceramic firing, powder metallurgy
   • Long service life under continuous high temperature
3. Iron & steel industry
   • Tundish linings, blast furnace inner lining, runner castables
   • Resists molten iron/slag erosion
4. Aluminum & non-ferrous metallurgy
   • Lining materials for aluminum electrolytic cells
   • Anti-corrosion blocks for molten aluminum tanks
5. Monolithic refractories (castables / ramming mixes)
   • Black SiC grit/powder added to high-temperature castables
   • Improves wear resistance, thermal shock resistance and service life

3. Grade & Particle Requirements for Refractory

• Use low-iron, high-purity metallurgical/refractory grade black SiC
• Coarse grit + fine powder compound gradation for dense refractory casting/bricks
• Strict control of free silicon, carbon and oxide impurities

4. Difference: Black SiC vs Green SiC for Refractory

• Black SiC: Lower cost, dominant for general refractory, metallurgical furnace linings, heavy anti-slag scenarios
• Green SiC: Higher purity, more for high-end ceramics, precision grinding, advanced refractory in ultra-high temp oxidizing environments