High alumina silicon carbide bricks combine a high-alumina matrix with a silicon carbide fraction, and are known in the industry by their Chinese product name, guimo brick. The SiC addition raises thermal conductivity and thermal shock resistance and gives the brick a hard, wear-resistant...
High alumina silicon carbide bricks combine a high-alumina matrix with a silicon carbide fraction, and are known in the industry by their Chinese product name, guimo brick. The SiC addition raises thermal conductivity and thermal shock resistance and gives the brick a hard, wear-resistant surface, which is why the material is used in the positions that face flame scour and rapid cycling.
XZK Group presses the series in three grades — XZK-GM1650, XZK-GM1600 and XZK-GM1550 — with Al2O3 from 60% to 65%, and supplies them as part of the combustion and regenerator system.
A conventional high alumina brick is largely an insulator. Adding silicon carbide changes that: SiC has a thermal conductivity many times that of an alumina refractory, so the brick spreads heat and evens out the temperature gradient through its section. A smaller gradient means lower internal stress, and lower internal stress is what gives the material its improved thermal shock resistance.
SiC is also extremely hard and chemically stable. In the alumina-silica matrix it provides a distributed hard phase that resists abrasive batch dust and flame-borne particles, and it improves resistance to alkali vapour because the SiC grains are less readily attacked than the surrounding matrix. The trade-off is oxidation: in a strongly oxidising atmosphere SiC slowly oxidises to silica, so the brick is specified where the atmosphere and temperature profile are within its capability, with the silica layer forming a protective skin.
Manufacture requires care because SiC oxidises readily at firing temperature. The kiln atmosphere, particle sizing and binder system are all set to protect the carbide during firing, and the resulting body is press-formed and fired to a density of 2.55–2.65 g/cm3 with cold crushing strength from 85 to 90 MPa.
| Technical Properties | XZK-GM1650 | XZK-GM1600 | XZK-GM1550 |
| Al₂O₃ (%) | ≥ 65 | ≥ 63 | ≥ 60 |
| Bulk Density (g/cm³) | ≥ 2.65 | ≥ 2.60 | ≥ 2.55 |
| Apparent Porosity (%) | ≤ 17 | ≤ 17 | ≤ 19 |
| Cold Crushing Strength (MPa) | ≥ 85 | ≥ 90 | ≥ 90 |
| Refractoriness Under Load (0.2MPa, ℃) | ≥ 1650 | ≥ 1600 | ≥ 1550 |
| Thermal Shock Resistance (1100℃ water-cooled, cycles) | ≥ 10 | ≥ 10 | ≥ 12 |
Test methods follow GB/T and ISO practice; ASTM equivalents and full certificates of analysis are issued with every shipment.
The three grades are distinguished by refractoriness under load and by density, and they are selected on the basis of the working temperature of the position.
XZK-GM1650, with RUL of 1650°C and Al2O3 at 65%, is the hot-zone grade and is used for the hottest positions in the combustion and regenerator structures. XZK-GM1600, at 1600°C and 63% alumina, is the general high-temperature grade. XZK-GM1550, at 1550°C and 60% alumina with a slightly higher porosity allowance, is the economic grade for positions where the temperature is lower.
Note that thermal shock resistance of the series runs from 10 to 12 cycles at 1100°C water cooling. Where a position cycles harder than that, a sillimanite, andalusite or fused silica brick is likely to be the better answer.
High alumina silicon carbide bricks are used in the hot, scoured and thermally cycled parts of a glass furnace, including:
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.
High alumina silicon carbide bricks are supplied with silicon mullite andalusite bricks, SK series high alumina bricks, sillimanite bricks and silicon carbide castables. 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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