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Application of Silicon Carbide in Refractory Materials

Release time:

2026-03-05 09:44

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Silicon carbide (SiC) is one of the most important high‑performance non‑oxide materials in the field of high‑temperature refractories, and due to its unique physicochemical properties, it is widely used in modern industry.

The main outstanding properties of silicon carbide
• Higher melting/decomposition temperature: approximately 2700–2830°C (the actual operating temperature is often between 1600–1800°C, or even higher).
• Higher thermal conductivity (3–10 times that of conventional oxide refractories)
• A lower coefficient of thermal expansion (approximately 4.0–4.5 × 10⁻⁶/°C)
• Excellent thermal shock resistance (capable of withstanding rapid heating and cooling)
• High hardness (second only to diamond) and strong wear resistance
• Good slag resistance and resistance to erosion by molten metals (especially alkaline slags and non-ferrous metal melts)
• A dense SiO₂ protective film can form at high temperatures.
• Good chemical stability (resistant to corrosion by most acidic and alkaline melts)

The performance of silicon carbide refractories depends largely on their bonding phase; the main product forms include:

Silicon Nitride‑Bonded Silicon Carbide Bricks: Using Si₃N₄ as the bonding phase, these bricks form a needle‑like or fibrous crystalline network, offering high strength and excellent erosion resistance. They are primarily used in the belly and lower part of blast furnace shells, as well as in the lining of aluminum electrolytic cells.
β-SiC‑bonded silicon carbide bricks: The bonding phase is formed through an in-situ reaction between Si + C → β-SiC, enabling the production of large‑size components. These bricks are used in large blast furnace tuyere assembly blocks.
Clay-bonded silicon carbide bricks: Using clay as the binder, this type of brick boasts mature production processes and relatively low costs. It is primarily used in ceramic kiln furniture, zinc distillation tanks, and lining for aluminum refining furnaces.
Semi‑silicon carbide materials: With a SiC content of less than 50%, these materials are added as modifiers to conventional materials such as clay, high‑alumina, and corundum, significantly enhancing thermal shock resistance and achieving breakthrough performance. They are used in sliding rail bricks for steel rolling heating furnaces and in composite linings with stringent thermal shock requirements.
Silicon carbide castables: Unshaped materials that are convenient to install on-site. They include high‑thermal‑conductivity types and anti‑scaling types, among others. These materials are used in cement kiln preheaters, blast furnace hot stoves, cyclone separators, and similar applications.
Recrystallized silicon carbide products: Featuring no secondary bonding phase, they are directly bonded by SiC, offering high operating temperatures and excellent high‑temperature strength. They are commonly used for kiln furniture, burners, and radiant heating tubes.

Major Industrial Application Areas
1. Steel and Iron Metallurgy (a field with large-scale applications)
Blast furnace ceramic cups, tuyere assembly bricks, iron runners, slag runners, and the iron tapping area.
Lining for torpedo cars and hot metal pretreatment ladles
Converter and electric furnace—certain areas (tapping spout, bottom tapping)
2. Nonferrous Metal Smelting
Silicon carbide bricks for the sidewalls and bottom of aluminum electrolytic cells
Lining of copper, zinc, and lead smelting furnaces and rising flues
Precious metal and rare metal melting crucibles/linings
3. Ceramics and Kiln Industry (a rapidly growing sector)
Roller kiln rollers, kiln car plates, shed boards, and crucibles (especially for new energy lithium batteries, cathode materials, and sintering of photovoltaic silicon wafers)
Lining for the High-Temperature Zone of Tunnel Kilns and Shuttle Kilns
Supporting Plates for Sintering Precision Ceramics and Electronic Ceramics
4. Cement and Glass Industries
Wear‑resistant parts of the cement rotary kiln decomposition furnace, cooler, slope, and tertiary air duct
Glass melting furnace pool bottom, chest wall, and burner surroundings (alkali‑resistant)
5. Waste incineration, hazardous waste treatment, chemicals
Incinerator grate and side walls
High-temperature reactors, corrosion‑resistant pipe linings
6. New Energy and Semiconductors
Single‑crystal silicon/polycrystalline silicon melting furnace components
Thermal components for silicon carbide powder synthesis furnaces and crystal growth furnaces
Sintering Kiln Tools for Lithium Battery Ternary/Lithium Iron Phosphate Cathode Materials
Silicon carbide refractories have become a critical solution for many “bottleneck” stages in high‑temperature processes. Particularly under the “dual carbon” goals, their importance in energy‑efficient kilns, the firing of new energy materials, and metallurgical operations continues to grow.