High Alumina Castables are formulated using 75–88% high-alumina aggregates from downdraft kilns and 88% high-alumina fine powder as the fine component. Additional raw materials include α-Al₂O₃ micro powder, silica micro powder, and other fine powders, combined with a controlled amount of water-reducing agent. By optimizing the type and dosage of expansion additives, the castable's matrix composition is tailored to achieve excellent high-temperature creep resistance, thermal shock stability, and high load softening temperature.
Compared with traditional formulations, high alumina castables place higher demands on creep performance, thermal shock resistance, and load softening temperature. Adjustments in particle size distribution, incorporation of specialized admixtures, and reduction of cement content enhance performance by increasing intermediate-temperature strength and load softening temperature, while reducing thermal conductivity, resulting in superior thermal efficiency. These castables exhibit impermeability, erosion resistance, wear resistance, and good mechanical properties, contributing to strong overall furnace structure, improved airtightness compared to brick-built furnaces, extended service life, reduced maintenance costs, and economic benefits.
During high-temperature operation, density differences can cause expansion when andalusite transforms into mullite. Therefore, andalusite can be introduced as an additive. Additionally, metallic silicon may be incorporated to optimize the matrix composition, which reduces shrinkage, enhances high-temperature resistance, and further improves creep resistance, thermal shock stability, and load softening temperatur
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NAME/INDEX /ITEM |
UNIT |
High alumina refractory castable |
High alumina, high strength, low cement Refractory castable |
High alumina, high strength, low cement Refractory castable |
High alumina, high strength, low cement Refractory castable |
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|
G-14 |
G-15 |
G-16 |
G-16K |
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Chemical compsition |
Al2O3 ≥ |
% |
60 |
65 |
70 |
75 |
|
SiO2 ≥ |
25 |
20 |
20 |
20 |
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Cold modulus of rupture ≥ |
110℃×24h |
MPa |
8.0 |
10 |
10 |
10 |
|
1100℃×3h |
8.0 |
12 |
12 |
10 |
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|
Cold crushing strength ≥ |
110℃×24h |
MPa |
80 |
80 |
80 |
100 |
|
1100℃×3h |
80 |
100 |
100 |
100 |
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Bulk density 110℃×24h ≥ |
g/cm³ |
2.45 |
2.55 |
2.65 |
2.75 |
|
|
Linear change after heating(1100℃×3h) |
% |
-0.1～-0.3 |
-0.1～-0.3 |
-0.1～-0.3 |
-0.1～-0.3 |
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|
Maximum operating temperature |
℃ |
1450 |
1500 |
1600 |
1650 |
|
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Construction reference water addition amount |
% |
6～7.5 |
6～7 |
5.5～6.5 |
4.5～5.5 |
|
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Construction method |
Vibration |
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Characteristic |
Add heat-resistant steel fiber according to user requirements |
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High alumina castables commonly use metallic silicon, kyanite, or andalusite as expansion agents. Each of these materials contributes to controlled expansion and enhances the high-temperature properties of the castable:
Metallic Silicon:
At high temperatures, metallic silicon undergoes oxidation, nitriding, and mullitization reactions, which significantly improve the creep resistance of high alumina castables.
Kyanite:
During heating, kyanite transforms into a mixture of mullite and SiO₂, accompanied by volume expansion of 16%–18%. This transformation forms a well-developed acicular mullite network, and the resulting volume change is minimal upon cooling, exhibiting irreversible expansion that enhances the castable's structural stability.
Andalusite:
As a member of the kyanite group, andalusite transforms into mullite during heating, producing a controlled volume expansion of approximately 4%. This irreversible crystal transformation results in superior refractory properties, including:
●Refractoriness exceeding 1800 °C
●Resistance to rapid heating and cooling
●High mechanical strength and thermal shock resistance
●Excellent slag resistance
●High load-bearing transformation point
●Good chemical stability
●High Refractoriness:
Based on a high-alumina system, suitable for medium- and high-temperature furnace applications.
●Stable Mechanical Strength:
Maintains good mechanical strength at both ambient and elevated temperatures, ensuring reliable structural performance.
●Excellent Dimensional Stability:
Exhibits low high-temperature shrinkage and strong resistance to cracking during long-term service.
●Strong Construction Adaptability:
Suitable for monolithic casting construction, allowing efficient installation and seamless lining structures.
●Outstanding Cost Performance:
Combines reliable performance with wide applicability, providing a cost-effective refractory solution.
High alumina castables are widely used in:
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Heating furnaces, soaking furnaces, and hot blast stoves in the metallurgical industry |
Boiler furnaces, flues, and air chambers in the power industry
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Preheaters, decomposition furnaces, and tertiary air ducts in the cement industry |
Cracking furnaces and heating furnaces in the petrochemical industry
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Working and structural linings of various industrial furnaces and kiln
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Packaging: 50 kg moisture-proof composite woven bags, palletized for safe transportation.
Storage: Store in a dry and well-ventilated place, protected from moisture and rain.
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