Silicon carbide castables combine SiC grain with a refractory bond to produce a lining that resists abrasion, thermal shock and alkali attack far better than an alumina castable of the same temperature class. The high thermal conductivity of SiC spreads heat quickly and limits hot-spot stress,...
Silicon carbide castables combine SiC grain with a refractory bond to produce a lining that resists abrasion, thermal shock and alkali attack far better than an alumina castable of the same temperature class. The high thermal conductivity of SiC spreads heat quickly and limits hot-spot stress, which is why the material is specified around burners and in charging areas where mechanical wear is the dominant failure mechanism.
XZK Group supplies SiC castables with SiC content from roughly 40% to 75%. They are non-melt-contact materials: SiC reacts with glass and its carbon content can cause colour and seed defects, so it is used where the lining is attacked mechanically rather than brought into contact with the melt.
The body is built from graded SiC grain, usually up to about 5 mm, mixed with fines and bonded with calcium aluminate cement or, in higher-duty grades, a silica or silica-fume bond that reduces the lime content. Small additions of silicon metal or aluminium act as antioxidants. SiC is extremely hard and has a thermal conductivity several times that of dense alumina, so the castable conducts heat away from the hot spot instead of letting it build up.
In an oxidising atmosphere above roughly 1300°C, SiC oxidises and forms a thin silica skin that protects the grain beneath it; antioxidants support the formation of that protective layer and slow carbon loss. In contact with molten glass, however, SiC is chemically attacked and can release carbon into the melt, so it is never placed in the melt path. Its real strength is resistance to abrasion and to alkali vapour, both of which are mechanical or chemical problems rather than melt-contact problems.
Placement is similar to other castables, but because SiC conducts heat so readily the body heats through quickly and needs a measured dry-out rather than a long soak. The material is dense and hard, so formwork and mixing equipment wear faster than with an alumina mix, and the water addition must be held constant to keep porosity predictable.
| Project | TGJ - 85 | TGJ - 80 | TGJ - 78 | TGJ - 76 | |
| SiC, % | ≥ 85 | 80 | 78 | 76 | |
| Bulk Density, g/cm³ | ≥ 2.5 | 2.36 | 2.34 | 2.24 | |
| Compressive Strength, MPa | 110 °C × 24h | ≥ 45 | 22 | 36 | 6 |
| 1400 °C × 3h | ≥ 70 | 52 | 68 | 22 | |
| Flexural Strength, MPa | 110 °C × 24h | ≥ 5.5 | 3.5 | 6.8 | 2.5 |
| 1400 °C × 3h | ≥ 11 | 6 | 28 | 3.5 | |
| Linear Change after Firing, % | 1400 °C | 0.12 | 0.3 | 0.13 | 0.2 |
| Thermal Conductivity, W/(m·K) | 850 °C | ≥ 8.6 | 3.8 | 3.4 | 3.14 |
Grades separate first by SiC content. A moderate-SiC castable around 45–55% is the economical choice for general abrasion service and for backing behind a harder face. A high-SiC castable of 70% and above is specified for the most severe wear, such as burner surrounds and charging zones, where the extra cost is recovered by a longer life.
The second choice is the bond. A cement-bonded SiC castable is easy to place and suits most positions; a low-cement or silica-bonded grade raises refractoriness and oxidation resistance where the service temperature is high. Antioxidant additions should be specified wherever the atmosphere is oxidising and the temperature exceeds about 1300°C. Because SiC is unsuitable for melt contact, the material is always paired with a melt-contact refractory such as high alumina castable or a brick working face, with insulating castable behind it.
Silicon carbide castable is used where wear and thermal shock, rather than melt corrosion, decide lining life:
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.
Silicon carbide castables sit alongside high alumina castable, insulating castable, lightweight mullite castable and high alumina silicon carbide bricks in the monolithic refractory range. Browse all refractory products.
Al₂O₃:46%-60%;
Fe₂O₃: 0.7%-1.0%;
Operating Temp:1300-1500℃;
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