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Zero Expansion Silica Brick: Premium Fused Silica Refractory for Industrial Hot Repair
1. Product Overview
Zero Expansion Silica Brick, also known as fused quartz brick or zero thermal expansion silica brick, is a high-purity amorphous silica refractory specially developed to solve thermal cracking, lining peeling and kiln shutdown losses caused by temperature fluctuations in high-temperature furnaces.
Different from conventional crystalline silica bricks with obvious thermal expansion, this product takes high-purity fused silica as the core raw material. Its unique disordered amorphous silicon-oxygen network structure delivers a near-zero thermal expansion coefficient, realizing stable dimensional performance under frequent heating and cooling cycles.
It has become the universal preferred lining and hot repair material for glass melting furnaces, coke ovens, ring baking furnaces, hot blast stoves and other thermal equipment, widely recognized by refractory buyers across glass, carbon, coking and metallurgy industries.
2. Raw Material & Complete Manufacturing Process
2.1 Core Raw Material Formula
- High-purity quartz sand (SiO₂ ≥99.5%): Smelted above 1800℃ in electric arc furnace to form fused silica aggregate, the base for zero-expansion performance.
- Ultra-low impurity control: Fe₂O₃ ≤0.1%, total flux index (Al₂O₃+alkali metal oxides) ≤0.3%, minimizing contamination to molten glass and resisting high-temperature slag erosion.
- Minor sintering aid: Trace mineralizer to optimize compactness without damaging low-expansion characteristics.
2.2 Standard Production Flow
- Quartz melting & purification: Natural high-grade quartz is fused at ultra-high temperature, pickled and screened to remove crystalline quartz and harmful impurities.
- Aggregate grading: Fused silica particles are matched in multi-size grading to improve bulk density and reduce internal pores.
- Semi-dry mixing & molding: Homogenize raw materials with binders, then press into standard or custom-shaped blanks via high-pressure vibration forming.
- Low-temperature controlled firing: Segmented temperature rise firing to retain complete amorphous silica phase, avoid crystal phase transformation and extra expansion.
- Precision finishing & full inspection: Trim dimensional tolerances, sample test all physical and chemical indicators before warehousing.
3. Core Superior Performance Advantages
3.1 Near-Zero Thermal Expansion, No Need for Expansion Joints
Thermal expansion coefficient ≤0.5×10⁻⁶/℃ from room temperature to 1000℃, almost no dimensional change during heating. When repairing kiln linings, workers do not need to reserve expansion gaps, greatly improving masonry tightness and eliminating hot air leakage that leads to energy waste and local overheating. Conventional silica bricks will produce large expansion stress after heating, easily causing brick extrusion, cracking and lining collapse.
3.2 Outstanding Thermal Shock Resistance for Online Hot Repair
Amorphous structure effectively inhibits microcrack propagation under rapid temperature change, reaching ≥30 water cooling thermal shock cycles (1100℃ to room temperature). The biggest industry value is supporting non-stop furnace hot repair: construct new lining blocks directly on 800–1100℃ hot furnace walls without shutdown, cutting huge production loss from furnace downtime (glass furnace shutdown costs can reach tens of thousands of US dollars per hour). No burst, peeling or shedding occurs after hot repair construction, extending lining service cycle.
3.3 Ultra-High Purity & Strong Acid Corrosion Resistance
SiO₂ content exceeds 99%, stable against erosion of acid flue gas, silicate slag, asphalt volatile fume and alkali vapor inside kilns. Low iron impurity avoids yellowing, bubble and stain defects on glass products, ideal for producing high-purity borosilicate glass, optical glass and food-grade glass liquid. It also resists sulfur-containing flue gas corrosion in carbon anode ring baking furnace flue corridors.
3.4 Excellent High-Temperature Mechanical Stability
- Cold crushing strength ≥35MPa; high-temperature compressive strength remains stable above 40MPa at 1000℃.
- Refractoriness under load (0.2MPa, T0.6) ≥1650℃, no softening or deformation under long-term service at 1500℃ high temperature.
- Apparent porosity controlled below 18%, reducing slag penetration and prolonging service life of furnace lining.
3.5 Low Heat Conductivity & Energy Saving
Uniform micro-pore structure lowers thermal conductivity, effectively locking heat inside the kiln, reducing surface heat loss of furnace walls and cutting fuel consumption for smelting and baking production lines.
4. Main Industrial Application Scenarios
4.1 Glass Melting Furnace (Largest Application Field)
- Kiln crown, upper side wall, breast wall, doghouse and flow channel lining;
- Emergency hot repair of damaged crown and wall bricks during production;
- Special lining for low-alkali, high-purity glass melting tanks.
4.2 Carbon Anode Ring Baking Furnace
Repair of flue corridor, crossover flue and fire group partition walls. It adapts to alternating high and low temperature cycles of flue gas, resists corrosion of asphalt volatile tar and sulfur flue gas, prevents flue brick cracking and air leakage, stabilizing temperature uniformity inside anode pits to guarantee carbon anode block quality.
4.3 Coke Oven & Hot Blast Stove
Hot patching of oven chamber walls, regenerator checker brick areas and flue passages. Resists erosion of coke oven gas, carbon deposition and high-temperature airflow scouring, extending overhaul intervals of coking equipment.
4.4 Other High-Temperature Thermal Equipment
- Non-ferrous metal smelting furnaces, lime kilns, ceramic firing kilns;
- Heat preservation lining of electric arc furnace upper sections;
- Custom special-shaped bricks for laboratory high-temperature kilns.
5. Standard Technical Index Reference
- SiO₂: ≥99%
- Fe₂O₃: ≤0.1%
- Flux index (Al₂O₃+2R₂O): ≤0.3%
- Bulk density: ≥1.86 g/cm³
- Cold crushing strength: ≥35 MPa
- Apparent porosity: ≤18%
- Refractoriness under load (0.2MPa): ≥1650℃
- Thermal expansion rate (20–1000℃): ≤0.2%
- Thermal shock resistance (1100℃ water cooling): ≥30 cycles
6. Construction, Storage & Transportation Guidance
6.1 Masonry & Hot Repair Tips
- For cold construction: Use matching silica mortar; no expansion gaps required between adjacent zero expansion silica bricks.
- For online hot repair: Clean residual slag and loose refractory on the hot wall surface before installation; tightly fit bricks with the original lining to avoid gaps.
- Avoid violent impact during hoisting to prevent edge and corner chipping affecting tight masonry.
6.2 Storage Requirements
Store in dry, covered warehouses to prevent long-term damp erosion. Stack on wooden pallets with separating mats between layers to avoid surface scratch and crack. Keep away from acidic chemical raw materials.
6.3 Transport Protection
Wrap each pallet with waterproof plastic film; add foam buffer strips around brick edges during sea and land transportation. Fix pallets tightly to eliminate collision damage in transit.
7. Customization & Supply Service
We provide full-range customized zero expansion silica brick solutions for global thermal equipment manufacturers and smelters:
- Purity customization: Standard 99% SiO₂ grade for general repair, ultra-high purity 99.9% grade for optical glass kilns.
- Shape customization: Standard rectangular bricks, arch bricks, wedge bricks, curved special-shaped bricks matched to flue corridor, kiln crown and flow channel dimensions.
- Performance tuning: Adjust porosity and density according to client working temperature and corrosion environment.
- Flexible supply: Mass bulk shipment for large kiln overhaul projects, small batch sample support for laboratory and trial production; mixed loading with silica mortar, ramming paste and other refractory accessories.
8. Conclusion
Zero Expansion Silica Brick fills the performance gap of traditional silica refractories under frequent temperature fluctuation conditions. Its core near-zero expansion property solves long-standing pain points including lining cracking, frequent overhaul and costly furnace shutdown in high-temperature industrial furnaces.
Whether for new kiln lining construction or online hot repair of glass furnaces, carbon anode baking furnaces and coke ovens, this fused silica brick reduces overall equipment maintenance cost, improves furnace thermal efficiency and stabilizes finished product quality, becoming an irreplaceable high-value refractory material in modern high-temperature manufacturing industries.
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