Silicon carbide bricks are refractory products made primarily from silicon carbide. Their main characteristic is that SiC is covalently bonded and lacks typical sintering properties. Sintering is achieved through chemical reactions to form new phases, a process known as reaction sintering. SiC possesses high thermal conductivity, high high-temperature strength, excellent wear resistance, thermal shock resistance, and corrosion resistance, making it an important high-quality refractory material used in the iron and steel and non-ferrous metallurgical industries. Depending on the application environment, it can be combined with corundum bricks, lightweight corundum bricks, refractory precast components, and wear-resistant refractory castables to form a complete furnace lining system.
Silicon carbide bricks can be classified into clay-bonded silicon carbide bricks, β-silicon carbide-bonded silicon carbide bricks, silicon oxynitride-bonded silicon carbide bricks, silicon nitride-bonded silicon carbide bricks, and Sialon-bonded silicon carbide bricks according to their bonding methods.
Table 1
|
Project |
Index |
|
SiC % |
65-75 |
|
Al2O3 % |
13-15 |
|
SiO2 % |
18-20 |
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Fe2O3 % |
1-1.5 |
|
K2O Na2O CaO MgO % |
0.5-1 |
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Fire resistance ℃ |
1800 |
|
Room temperature compressive strength MPa kg/cm³ |
＞39.2 |
|
Reheated wire shrinkage % |
0.5 |
|
Apparent porosity % |
18.2-24 |
|
2kg/cLoad softening temperature ℃ |
1600 |
Table 2
|
Project |
70 silicon carbide bricks |
80 silicon carbide bricks |
85 silicon carbide bricks |
|
SiC % |
70 |
80 |
85 |
|
Apparent porosity % |
22 |
19 |
18 |
|
Bulk density g/cm3 |
2.45 |
2.5 |
2.6 |
|
Room temperature compressive strength MPa |
80 |
100 |
110 |
|
0.2MPa Load softening start temperature |
1600 |
1650 |
1650 |
Table 3
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Project |
Unit |
Export Indicators |
|
Bulk density |
kg/m3 |
2670 |
|
Apparent porosity |
% |
15 |
|
Compressive strength |
MPa |
115 |
|
Thermal shock stability (1000℃ water cooling) |
次 |
55 |
|
Load softening temperature |
℃ |
1700 |
|
Thermal conductivity(700℃) |
w/(m.k) |
15 |
|
Maximum operating temperature |
℃ |
1650 |
|
Chemical composition |
A12O3：0.6% SiO2：9% SiC：85% |
|
Table 4
|
Project |
Oxide-bonded silicon carbide bricks |
Corundum and silicon carbide bricks |
Mullite-bonded silicon carbide bricks |
High-alumina silicon carbide bricks |
|
SiC(%) |
≥85 |
≥70 |
≥65 |
≥20 |
|
Al2O3% |
- |
≥20 |
≥20 |
≥55 |
|
Bulk density (g/cm³) |
≥2.5 |
≥2.6 |
≥2.3 |
≥2.5 |
|
Apparent porosity (%) |
≤18 |
≤20 |
≤20 |
≤22 |
|
Room temperature compressive strength (Mpa) |
≥100 |
≥100 |
≥80 |
≥80 |
|
Load softening temperature (℃) |
≥1700 |
≥1700 |
≥1650 |
≥1550 |
|
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1. High thermal conductivity and stable high-temperature strength Silicon carbide has excellent thermal conductivity, and the bricks maintain high strength without deformation even at temperatures of 1400–1650 °C, with extremely low creep. This reduces maintenance frequency, extends furnace service life, and improves operational stability. |
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2. Excellent wear and erosion resistance With a Mohs hardness of 9 and a dense crystal structure, SiC can withstand impacts from high-concentration materials and severe mechanical wear. It is particularly suitable for areas subject to strong erosion and abrasion, reducing the risk of furnace shutdowns caused by material chipping or pulverization. |
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3. Excellent oxidation and corrosion resistance In oxidizing environments, SiC forms a dense SiO₂ protective layer, which further enhances its corrosion resistance. It is suitable for applications involving acidic slag, alkaline flue gas, and high-temperature combustion media, making the furnace lining more resistant to slag erosion and penetration. |
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4. Excellent thermal shock stability SiC has a low coefficient of thermal expansion (approximately 4.0–4.5 × 10⁻⁶/°C) and remains stable under conditions of frequent start-up and shutdown or large temperature fluctuations. |
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5. Customizable sizes and irregular shapes Complex and irregular shapes can be customized according to the furnace design, including furnace mouth bricks, wedge-shaped bricks, arch bricks, tubular bricks, and other special-shaped refractory products. |
SiC, silicon powder, and carbon powder are mixed in a specific proportion, shaped, and then fired in a reducing atmosphere at 1400 °C. In most cases, embedded carbon firing is used. During firing, a SiC brick is formed with an α-SiC framework and a fine-grained β-SiC matrix. The β-SiC is generated through the reaction between fine silicon powder and fine carbon powder, and the final product also contains small amounts of residual silicon and carbon.
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Steel industry Blast furnace tuyeres, iron troughs, and chutes.
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Building materials industry Tunnel kilns, roller kilns, and lime kilns.
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Energy and environmental protection industry Incinerators and circulating fluidized bed boilers. |
Non-ferrous metals industry Aluminum electrolytic cells and copper melting furnaces.
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Chemical industry High-temperature reactors and desulfurization tower linings.
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Packaging methods:
Standard trays with moisture-proof film and protective paper corners.
Fumigated wooden crates or non-fumigated plywood crates are used for irregularly shaped bricks.
Custom packaging is also available to meet export requirements and specific working conditions, ensuring that products remain undamaged and dry during transportation.
Q1: What are the advantages of SiC bricks compared to corundum bricks?
A: Silicon carbide bricks offer superior wear resistance, higher thermal conductivity, and better resistance to rapid heating and cooling. They are particularly suitable for applications with severe erosion and large temperature fluctuations.
Q2: Can SiC bricks be used in oxidizing atmospheres?
A: Yes. A protective SiO₂ layer forms on the surface of SiC, enhancing oxidation resistance. This makes them suitable for oxidizing and mildly reducing atmospheres.
Q3: Can you customize irregularly shaped bricks?
A: Yes. We can customize bricks based on provided drawings or samples. Please provide the following details:
a) Brick dimensions (length × width × height, in mm)
b) Required quantity
c) Application scenario (e.g., furnace location, temperature range, corrosive medium)
d) Special performance requirements (e.g., enhanced thermal shock resistance, erosion resistance)
We will evaluate production feasibility and provide a tailored solution and quotation.
Q4: Are SiC bricks suitable as insulation bricks?
A: Silicon carbide has high thermal conductivity and is not suitable as an insulating material. However, it can be used together with lightweight corundum bricks, lightweight mullite bricks, or other insulating materials to form a composite lining.
Q5: What is the typical service life of SiC bricks?
A: Service life depends on operating temperature, erosion intensity, and lining structure. Generally, in stable conditions such as tunnel kilns or incinerators, SiC bricks last 18–36 months. In high-wear areas, such as blast furnace tuyeres or troughs, they typically last 6–18 months-about 30–80% longer than ordinary high-alumina bricks.
Q6: Is a special masonry method required?
A: No complex process is required. However, it is recommended to use high-strength binders or SiC-bonded mortar, maintain brick joints of 1.5–2.5 mm, and stagger joints in high-temperature areas to enhance overall lining strength.
Q7: Can SiC bricks be used in strongly reducing or highly alkaline environments?
A: Standard SiC bricks are suitable for weakly reducing or neutral atmospheres. They are easily corroded in strongly alkaline vapors or highly reducing environments. For harsh conditions, consider silicon nitride-bonded SiC bricks or special SiC variants with higher alkali resistance.
Q8: Does the high thermal conductivity of SiC bricks increase heat loss?
A: No. SiC bricks are mainly used in high-temperature working layers, where high thermal conductivity reduces thermal stress and improves lining stability. Heat insulation is provided by backing materials, such as lightweight mullite bricks or ceramic fiber modules. Combined use can significantly reduce heat loss and improve overall energy efficiency.
Q9: Can SiC bricks be used with castables or plastics?
A: Yes. SiC bricks are often combined with wear-resistant refractory castables, silicon carbide plastics, corundum-mullite castables, and other materials to form a more erosion-resistant and stable composite lining. Proper combination can extend the overall lining life by 20–50%.
Q10: Do you support OEM/ODM cooperation?
A: Yes. We fully support OEM and ODM services and can provide flexible solutions from product customization to full-chain services according to customer requirements.
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