The 3L mullite brick, XZK-3L-ML50, is a densified mullite refractory with at least 50% Al2O3 that is engineered for three lows: low apparent porosity of 15% or below, low creep of 0.5% or below at 1400°C over 50 hours, and low iron content of 0.8% Fe2O3 or below. The combination targets the...
The 3L mullite brick, XZK-3L-ML50, is a densified mullite refractory with at least 50% Al2O3 that is engineered for three lows: low apparent porosity of 15% or below, low creep of 0.5% or below at 1400°C over 50 hours, and low iron content of 0.8% Fe2O3 or below. The combination targets the structural positions that must hold their shape for a full campaign.
XZK Group produces the 3L grade for the load-bearing foundation courses of the regenerator and other positions where creep and volume stability decide the life of the lining.
Creep is the quiet failure mode of a glass furnace. A brick does not have to melt to fail; it only has to deform slowly under load at temperature. In a regenerator, the rider arch carries the weight of the whole checkerwork setting above it, and if it creeps by a few millimetres a year the flues close and the chamber loses its heat-exchange capacity. The 3L grade is designed against that failure.
Three process choices deliver the result. Densification closes the porosity to 15% or below, which increases the load-bearing cross-section of the brick and slows the diffusion processes that allow deformation. A mullite matrix, developed from a controlled mix of mullite and alumina raw materials, carries the load on interlocking crystals rather than on a glassy bond. And keeping iron low avoids the low-melting phases that soften a refractory from the inside.
The result is a brick with a refractoriness under load of at least 1600°C, a creep rate of 0.5% or below at 1400°C over 50 hours, cold crushing strength of 80 MPa and bulk density of 2.45 g/cm3. Thermal shock resistance stands at 8 water-cooling cycles at 1100°C, which places the material among the load-bearing rather than the spalling-resistant grades.
| Technical Properties | XZK-3L-ML50 |
| Al₂O₃ (%) | ≥ 50 |
| Fe₂O₃ (%) | ≤ 0.8 |
| Bulk Density (g/cm³) | ≥ 2.45 |
| Apparent Porosity (%) | ≤ 15 |
| Cold Crushing Strength (MPa) | ≥ 80 |
| Refractoriness Under Load (0.2MPa, ℃) | ≥ 1600 |
| Thermal Shock Resistance (1100℃ water-cooled, cycles) | ≥ 8 |
| Creep Rate (0.2MPa, 1400℃ 50h, %) | ≤ 0.5 |
Test methods follow GB/T and ISO practice; ASTM equivalents and full certificates of analysis are issued with every shipment.
The 3L mullite range is a single densified grade, XZK-3L-ML50, so selection is a matter of confirming that the position is a creep-limited one rather than a corrosion-limited or thermal-shock-limited one.
Use it for the load-bearing foundation of the regenerator and for structural courses that must stay true for a full campaign. Where the position is also exposed to strong alkali vapour or to heavy thermal cycling, a complementary material is the better choice: a sillimanite or andalusite brick for cycled structures, and a low porosity fire clay or mullite brick for the courses around it.
Because the value of the 3L grade lies in its creep resistance, XZK reports creep rate and refractoriness under load on the certificate of analysis for every batch, so the purchaser can verify the property that actually governs the design.
3L mullite bricks are placed where load and time, rather than chemistry, govern the life of the lining:
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.
3L mullite bricks are supplied with mullite bricks, sillimanite bricks, low porosity fire clay bricks and mullite insulating 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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