SiALON-Bonded SiC Brick (XZK-SASiC) for Blast Furnace Bosh & Belly

XZK-SASiC is the SiALON-bonded member of our nitride-bonded silicon carbide range. It exists for one reason: some furnaces are limited by penetration rather than abrasion, and when that is the case, lower porosity is worth paying for.

Porosity Is the Penetration Highway

Alkali vapour, zinc and slag do not attack a lining uniformly — they travel in through the pore network. Open porosity is the road they take. At 15.0% apparent porosity, XZK-SASiC is the densest grade in our nitride-bonded range, which means there is simply less cross-section for ingress and the penetration front advances more slowly.

On furnaces with a heavy alkali or zinc load, this is often the difference between a lining that holds its hot face and one that degrades from the inside while the surface still looks intact.

Reading the Si₃N₄ Number Correctly

XZK-SASiC is specified at Si₃N₄ ≥5%, while XZK-NSiC grades are specified at ≥20%. This is frequently misread as a weaker bond. It is not — the bonding phase is different. SASiC develops its bond through a SiALON phase, so the measured silicon nitride content is lower by design. What matters is the outcome, and on every performance indicator that counts in the bosh, SASiC matches or exceeds the Si₃N₄-bonded grades: density 2.69 vs 2.67 g/cm³, porosity 15.0% vs 16.0%, crushing strength equal at 160 MPa, hot modulus of rupture equal at 45 MPa.

Full Property Profile

Thermal conductivity runs 29 W/(m·K) at 300 °C, 21 at 700 °C, 16.5 at 1000 °C and 15 at 1200 °C — sufficient to keep the hot face in a manageable band on a properly cooled furnace. Thermal expansion is 5.0 ×10⁻⁶ K⁻¹, RUL is above 1700 °C, and thermal shock is rated at 30 cycles at 1100 °C water quench.

Selection Guidance

• Choose SASiC when alkali or zinc load is high, penetration depth is the controlling failure mode, or you want the lowest-porosity nitride-bonded option available.
• Choose NSiC72 when abrasion and gas velocity dominate and penetration is not the limiting mechanism — it is usually the more economical call.

We will recommend per zone from your furnace drawing, cooling configuration and alkali load rather than defaulting to the most expensive grade.

Quality and Supply

Minimum order 20 metric tons with 20–35 day lead time. Thermal conductivity is verified per batch, along with density, porosity, cold and hot strength, RUL and chemistry. Large blocks are produced to drawing with machined faces, dry trial-fitted, and numbered to your installation sequence.

Where This Grade Sits in the Lining System

Silicon carbide and carbon grades are selected for what they do with heat rather than for what they resist. Thermal conductivity decides whether the cooling system ever sees the load, and the bonding system decides how long the material survives alkali attack and oxidation once it does.

XZK supplies sialon bonded sic brick as one zone of a zoned package rather than as a standalone item: the grades normally zoned alongside it — among them si₃n₄ bonded sic brick — are documented on the silicon carbide and carbon refractories page, and the vessel-level architecture — where each zone starts and ends, and which mechanism actually limits the campaign — is set out on the blast furnace page.

For a complete vessel programme built on this class of material, including the wear survey that set the zoning, see the MMK Magnitogorsk No.10 BF and 375 t ladle programme project reference.