325# Silicon Carbide Powder as Refractory Material

Silicon carbide (SiC) powder, particularly 325# (approximately 44 microns or 325 mesh), is widely used in refractory applications due to its exceptional thermal stability, high thermal conductivity, and resistance to thermal shock and chemical corrosion. Below are key details about its use in refractories:

Why Use 325# SiC Powder in Refractories?

1. High Thermal Conductivity (~120–270 W/m·K)

   • Ensures even heat distribution, reducing thermal stress.

2. Excellent Thermal Shock Resistance

   • Low thermal expansion coefficient prevents cracking under rapid temperature changes.

3. Superior Oxidation Resistance

   • Forms a protective SiO₂ layer at high temperatures (~1,200°C+), enhancing durability.

4. Chemical Inertness

   • Resists attack by acids, alkalis, and molten metals (e.g., aluminum, iron).

5. Mechanical Strength

   • High hardness (Mohs ~9.5) improves abrasion resistance in refractory linings.

Applications in Refractories

1. Furnace Linings & Kiln Furniture

   • Used in blast furnaces, cement kilns, and non-ferrous metal processing due to its ability to withstand temperatures up to 1,600°C (2,912°F) in oxidizing environments.

2. Steel & Foundry Industry

   • Lining for ladles, crucibles, and troughs handling molten metals.

3. Incinerators & Waste Treatment

   • Resists corrosive gases (e.g., HCl, SO₂) at high temperatures.

4. Ceramic Binders & Castables

   • Mixed with alumina or silica to enhance thermal shock resistance in monolithic refractories.

How 325# SiC Powder is Used in Refractories

• As an Additive:

  • Added to refractory mixes (e.g., alumina-SiC, silica-SiC) to improve thermal conductivity and strength.

• In Bonded Refractories:

  • Combined with nitride or oxide bonds (e.g., Si₃N₄, Al₂O₃) for high-performance shapes.

• Coating Material:

  • Applied as a protective layer on refractory bricks to reduce wear.

Key Considerations for Use

1. Oxidation at High Temperatures

   • Above 1,400°C (2,552°F), SiC oxidizes to SiO₂ + CO; this can be mitigated with antioxidants (e.g., Si, Al).

2. Particle Size Distribution

   • 325 mesh (44 µm) balances sintering behavior and packing density in refractory formulations.

3. Binder Compatibility

   • Requires compatible binders (e.g., silica sol, phosphate) to prevent cracking during curing.