Andalusite bricks are alumina-silica refractories based on andalusite, one of the three Al2SiO5 minerals, with 57-65% Al2O3. Andalusite does not fully convert to mullite below about 1400°C, so the fired brick keeps a core of low-expansion andalusite crystals inside a dense mullite shell - a...
Andalusite bricks are alumina-silica refractories based on andalusite, one of the three Al2SiO5 minerals, with 57–65% Al2O3. Andalusite does not fully convert to mullite below about 1400°C, so the fired brick keeps a core of low-expansion andalusite crystals inside a dense mullite shell — a structure that produces the material's signature resistance to thermal spalling.
XZK Group produces andalusite bricks in pressed grades XZK-AN57-P, XZK-AN60-P and XZK-AN65-P and in a cast grade XZK-AN60-C. They are used in the same structural and thermal-shock positions as sillimanite, and XZK frequently supplies both so that a rider arch or a regenerator can be zoned grade by grade.
Andalusite and sillimanite share a chemistry but not a crystal habit. Raw andalusite has a low coefficient of thermal expansion along one crystal axis, and in the kiln it mullitises only at the surface of each grain, forming a dense mullite shell around an unreacted andalusite core. Because the two phases expand differently, the fired body contains a fine, controlled network of microcracks.
Those microcracks are the reason an andalusite brick survives thermal shock so well: they blunt and deflect a propagating crack instead of letting it run through the brick. The mechanical result is a material with 15–25 water-cooling cycles of thermal shock resistance, high refractoriness under load, and very good volume stability, because the expansion that accompanies mullitisation is taken up inside the brick during firing rather than in service.
Production follows the same route as our sillimanite grades — graded andalusite aggregate, automatic batching, pressing or casting, drying and high-temperature firing. The firing schedule is set so that mullitisation is complete at the grain surface without over-firing the core, which is what preserves the crack-toughened microstructure.
| Technical Properties | XZK-AN57-P (Pressed) | XZK-AN60-P (Pressed) | XZK-AN65-P (Pressed) | XZK-AN60-C (Cast) |
| Al₂O₃ (%) | ≥ 57.0 | ≥ 60.0 | ≥ 65.0 | ≥ 60.0 |
| Fe₂O₃ (%) | ≤ 1.2 | ≤ 1.0 | ≤ 1.0 | ≤ 1.0 |
| Bulk Density (g/cm³) | ≥ 2.40 | ≥ 2.45 | ≥ 2.50 | ≥ 2.45 |
| Apparent Porosity (%) | ≤ 18 | ≤ 18 | ≤ 17 | ≤ 18 |
| Cold Crushing Strength (MPa) | ≥ 70 | ≥ 70 | ≥ 70 | ≥ 60 |
| Refractoriness Under Load (0.2MPa, ℃) | ≥ 1560 | ≥ 1580 | ≥ 1650 | ≥ 1550 |
| Thermal Shock Resistance (1100℃ water-cooled, cycles) | ≥ 25 | ≥ 20 | ≥ 15 | ≥ 25 |
Test methods follow GB/T and ISO practice; ASTM equivalents and full certificates of analysis are issued with every shipment.
Andalusite bricks are selected on the same principle as sillimanite: take the grade with the properties the position demands, and do not over-specify beyond that.
XZK-AN57-P and XZK-AN60-P give the highest thermal shock resistance at 25 and 20 cycles respectively and are the grades used for the port crown, the rider arch and other cycled structures. XZK-AN65-P trades some of that cycle count for a load softening temperature of 1650°C and is used where the brick carries a heavier structural load. XZK-AN60-C is the cast equivalent of the 60% grade for large or irregular shapes.
Andalusite and sillimanite are close enough in performance that the choice often comes down to the required cycle count and the delivered cost at that grade. Where one supplier is expected to zone a whole regenerator, XZK can quote both families on a single technical proposal.
Andalusite bricks are specified where thermal cycling is the main threat, most commonly in these positions:
Manufacturing is controlled from raw material through to finished brick. Four automatic batching lines feed 20 CNC presses ranging from 630 to 2000 tonnes, so density is set by press force rather than operator judgement, and firing runs through four 108-metre fully automatic tunnel kilns and five ultra-high-temperature shuttle kilns for a uniform soak.
Every batch is tested for bulk density, apparent porosity, cold crushing strength and refractoriness under load, and ships with a certificate of analysis. XZK Group holds ISO 9001, ISO 14001, ISO 45001 and ISO 50001 certification and operates the Henan Provincial Engineering Technology Research Center for Sintered Refractories for Glass Furnaces.
Andalusite bricks are normally supplied with sillimanite bricks, mullite bricks, silicon mullite andalusite bricks, chrome corundum bricks and low porosity fire clay bricks. See the alumina-silicon bricks range or browse all refractory products.
Acid Resistance, %:＞99.8;
Bulk Density, g/cm3:2.3-2.4;
Water Absorption, %:≤0.5;
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