FAQ
Q
What are the key performance indicators of refractory ball? How to judge the quality?
A
The core performance indicators of fire-resistant balls include:
Fire resistance (usually ≥1750℃)
Compressive strength (ability to resist compression at high temperatures)
Thermal shock stability (ability to resist sudden changes in temperature)
Chemical stability (ability to resist corrosion by acids and alkalis)
Bulk density (affects the efficiency of heat storage)
When choosing and purchasing, you need to check third-party test reports and pay attention to the purity of the raw materials (e.g., alumina content of ≥92%) and the production process (isostatic molding is used or not). The following is a list of the most popular products in the market.
Q
What is the maximum service temperature of refractory castables?
A
Different types of refractory castables have different temperature ranges:
Low Cement Castables (LCC): 1400°C~1600°C
High Alumina Castables: 1600°C~1800°C
Corundum Castables: 1800°C~1900°C
Silicon Carbide Castables: 1600°C~1800°C (for reducing atmosphere)
Q
What is the maximum operating temperature of lightweight heat-insulating bricks?
A
The temperature range of lightweight insulation bricks varies with different materials, and the common types are as follows:
Diatomaceous earth bricks: 900°C~1100°C
High-alumina lightweight bricks: 1200°C~1400°C
Mullite lightweight bricks: 1400°C~1600°C
Alumina hollow sphere bricks: 1600°C~1800°C
Q
What are the main advantages of electrofused zirconia corundum bricks?
A
Fused zirconia corundum bricks have superb corrosion resistance: the addition of zirconia (33%-41%) significantly improves the resistance to glass liquid and chemical slag erosion, especially suitable for melting pools and flow holes in glass kilns.
High refractoriness: the use temperature can reach over 1750℃, and the structure is stable under long-term high temperature environment.
Low porosity: the electrofusion process makes the bricks dense with low porosity (<1%), reducing the risk of melt penetration.
Thermal shock resistance: not easy to crack under rapid temperature change, adapt to the frequent start and stop of industrial kilns.
Q
What is the core difference between corundum bricks and other refractory bricks (such as LZ-75 high alumina bricks)?
A
Corundum brick takes alumina (Al₂O₃≥90%) as the core component, and its performance is significantly better than that of ordinary high alumina bricks:
Ultra-high-temperature resistance: the long-term use temperature is up to 1700-1800 ℃, which is far more than that of the LZ-75 high alumina bricks (1600-1650 ℃);
Extremely dense: bulk density ≥3.2g/cm³, apparent porosity <15%, and the resistance to slag penetration is improved by more than 50%;
Mechanical strength: Normal temperature compressive strength ≥80MPa, abrasion resistance is 3-5 times of high alumina bricks.
Q
What is the core difference between silica bricks and other refractory bricks (e.g. high alumina bricks, magnesium bricks)?
A
Silica brick is mainly composed of silicon dioxide (SiO₂≥93%), with the following unique properties:
High load softening temperature: up to 1650-1680 ℃, excellent volumetric stability at high temperatures;
Acid environment suitability: resistance to acidic slag (such as glass liquid, coke oven gas) is far more than that of the alkaline refractory bricks;
Low thermal expansion: the coefficient of thermal expansion of 600 ℃ or more is close to zero, suitable for high temperature constant temperature kilns.
Q
What is the core difference between clay bricks and other refractory bricks (e.g. high alumina bricks, silica bricks)?
A
Clay bricks are characterized by a core Al₂O₃ content of 30%-48%, with the following differentiating advantages:
Cost-effectiveness: low raw material cost, suitable for budget-sensitive projects;
Thermal shock resistance: low coefficient of thermal expansion (4.5×10-⁶/°C), better resistance to rapid cold and heat than most refractory bricks;
General-purpose: widely used in low and medium-temperature kiln furnaces (<1300°C) such as boilers, chimneys, heat treatment furnaces.
Q
What is the core difference between high alumina bricks and other refractory bricks (such as clay bricks and silica bricks)?
A
High-alumina bricks are distinguished by their alumina (Al₂O₃) content, and have the following unique advantages:
High-alumina content: Al₂O₃ content of 50%-90%, with a significantly higher high-temperature resistance than that of clay bricks (Al₂O₃<50%);
Resistance to chemical erosion: better than that of silica bricks (SiO₂ dominated) in terms of acid/alkaline slag tolerance;
Mechanical strength: room-temperature compression strength of ≥ 30MPa, 2-3 times that of clay bricks; suitable for high-load kiln environments. 2-3 times, suitable for high load kiln environment.
Q
How to choose the type of refractory bricks according to the temperature and chemical environment?
A
Refractory bricks need to be selected to match the working conditions:
Temperature rating:
1200-1400℃: clay bricks (low cost, general purpose);
1400-1600℃: high alumina bricks (Al₂O₃ content of 50-80%);
>1600℃: corundum bricks (Al₂O₃ ≥ 90%) or magnesia bricks (MgO ≥ 85%).
Resistance to chemical attack:
Acidic environment (e.g. glass kiln): silicon brick (SiO₂≥93%);
Alkaline slag (e.g. cement kiln): magnesium-chromium brick or dolomite brick;
Reductive atmosphere: silicon carbide brick (made of SiC).
Q
What are the core advantages of refractory castables over traditional refractory bricks?
A
Refractory castables are a kind of high-performance unshaped refractory materials molded by on-site casting, and its core advantages include:
Construction flexibility: complex shapes can be cast, seamlessly fitting the equipment lining, reducing heat loss in the joints;
Strong resistance to thermal shock: through the optimization of micropowder technology and bonding agent, the resistance to sudden changes in temperature is better than most of the stereotyped bricks;
Repairing convenience: local damages can be quickly repaired without dismantling the whole structure, reducing the cost of machine downtime; Energy saving benefits: low thermal conductivity formula (e.g. lightweight castables) can reduce heat dissipation of kilns by 10-25%. Energy-saving benefits: low thermal conductivity formulations (e.g. lightweight castables) reduce heat dissipation from the kiln, resulting in energy savings of 10-25%.