Introduction
Refractory silica fume is an ultrafine powder material with high-purity amorphous silicon dioxide (SiO₂) as its main component. It is a key raw material in the field of refractory materials due to its excellent high-temperature resistance and chemical stability.
It is mainly produced through the recovery of flue gas from electric furnaces in the metallurgical industry-such as during the production of ferrosilicon and industrial silicon. After dust removal and collection, ultrafine particles are formed, typically ranging in size from 0.1 to 1 μm, with a specific surface area of up to 15–25 m²/g. It exhibits strong pozzolanic activity.
Advantage
1. Outstanding High-Temperature Resistance
With a melting point of up to 1713 ℃, silica fume performs exceptionally in high-temperature environments (e.g., 1000–1600 ℃). It can undergo a secondary reaction with cement hydration products (Ca(OH)₂) to form C-S-H gel with a low calcium-to-silicon ratio. This results in a denser structure with improved high-temperature resistance, significantly enhancing the refractory material's thermal shock resistance and load softening temperature.
It also helps reduce the sintering temperature of refractory materials, promotes low-temperature sintering, and minimizes shrinkage and cracking at high temperatures.
2. Microstructure and Filling Effect
Ultrafine silica fume particles can fill the gaps between refractory aggregates (e.g., corundum, mullite) and cement particles, increasing the matrix density by 10%–20% and reducing overall material porosity. This improves resistance to slag erosion (e.g., from steel or furnace slag).
It also enhances the fluidity of castables, reduces water demand, prevents pore formation caused by water evaporation, and increases structural compactness.
3. Chemical Stability and Reactivity
Due to its high purity (SiO₂ content typically ≥92%, with low levels of impurities such as Fe₂O₃ and Al₂O₃), silica fume exhibits excellent resistance to chemical erosion in both acidic and alkaline slag environments.
Its strong pozzolanic activity accelerates the hardening process and improves early strength-especially useful in low cement (LCC), ultra-low cement (ULCC), and no cement (NCC) castables. It helps reduce cement content, thereby lowering CaO content at high temperatures and improving slag resistance.
4. Balance Between Workability and Performance
Silica fume offers an adjustable setting time and is compatible with various additives (e.g., accelerators, retarders), making it suitable for different construction techniques such as casting, spraying, and ramming.
It enhances both flexural and compressive strength, thereby extending the service life of refractory materials. It performs well in high-temperature zones such as blast furnace iron troughs, ladle linings, and cement kiln linings.
Application
|
Application Scenarios |
Functions and Typical Products |
|
Metallurgical Industry |
Ladle castables, intermediate ladle working layers, blast furnace tundish pummels, iron pre-treatment equipment linings, utilizing their slag and thermal shock resistance. |
|
Building Materials and Kilns |
Refractory bricks for cement kiln firing zones, lattice bricks for glass kiln heat storage chambers, linings for ceramic kilns, resistant to high-temperature melt and gas erosion. |
|
Refractory Castables |
Low- or no-cement castables (with aggregates such as corundum, spinel, etc.) for quick repair or monolithic casting in high-temperature areas, such as furnace walls. |
|
Special Refractory Products |
Refractory compacts, coroplasts, refractory coatings for joints and repair layers in high-temperature equipment to improve sealing and resistance to scouring. |
|
Other High-Temperature Areas |
Refractory linings for waste incinerators, refractory layers for chemical reactors, resistant to high-temperature corrosion and erosion by complex media. |
Comparison of differences with ordinary silica fume
|
Indicator Category |
Refractory Silica Fume |
Ordinary Silica Fume (for Concrete) |
|
Purity (SiO₂) |
SiO₂≥92% (high-quality products can reach ≥95%), impurities (Fe₂O₃, CaO, etc.) ≤1% |
SiO₂≥85%, relatively higher content of impurities (such as Fe₂O₃, Al₂O₃) |
|
Particle Size & Specific Surface Area |
Particle size concentrated at 0.1~1μm, specific surface area 20~25 m²/g |
Particle size 0.5~2μm, specific surface area 15~20 m²/g |
|
High-temperature Resistance |
Melting point at 1713℃, stable structure under high temperature, strong slag corrosion resistance |
Temperature resistance ≤300℃, prone to cracking due to crystal transformation at high temperatures |
|
Pozzolanic Activity |
1000~1600℃ (metallurgical furnaces, high-temperature equipment) |
Ambient temperature ~300℃ (construction concrete, marine structures) |
|
Slag Resistance |
High-temperature activity index ≥110% (significant secondary reaction above 1000℃) |
Ambient-temperature activity index ≥85% (mainly contributes to early strength) |
|
Typical Applications |
Volcanic ash activity index ≥110% (high temperature activity is more critical) |
Focus on early activity (reaction at room temperature) |
Selection and Use Key Points
Purity and Impurity Control:
Select the appropriate SiO₂ content based on the operating temperature and slag erosion conditions (e.g., SiO₂ ≥ 95% is recommended for temperatures above 1400 ℃). Avoid impurities such as Fe₂O₃ and CaO, which can reduce refractoriness.
Form Selection:
Powdered silica fume has good dispersion properties and is suitable for dry construction applications.
Mixing Ratio Design:
The typical dosage in refractory castables is 5%–10%. It should be properly matched with aggregates (e.g., corundum, mullite) and binders (e.g., calcium aluminate cement, sol-gel) to achieve a balance between fluidity and strength.
Construction and Curing:
Maintain a construction temperature of 15–25 ℃ and relative humidity of 60%–70%. Avoid rapid temperature increases after initial setting. Keep the surface moist during the curing period to prevent cracking (refer to the curing standards for refractory cement).
7*24 hours online response
Provide professional after-sales protection
Our address
Qinghua Management Dist., Dashiqiao City, Yingkou City, Liaoning, China
Phone Number
+8613700131695
+8618540210631
info@zinfon-refractory.com
Hot Tags: refractory silica fume, China refractory silica fume manufacturers, suppliers, factory, high temperature refractory cement, refractory cement suppliers, high temperature cement, secar cement, heatproof cement, cement china