Non-Wetting Castables for Molten Aluminium Contact

Molten aluminium wets and penetrates ordinary refractory, and it attacks silica directly (4Al + 3SiO₂ → 2Al₂O₃ + 3Si), stripping silicon into your melt. Once it penetrates, it oxidises inside the pore structure and grows corundum, which expands and spalls the hot face away. A non-wetting castable combines a high alumina, low silica matrix with additives that stop the melt entering the pore network in the first place.

Use the high-strength grade. Al-Mg alloys are more aggressive than commercial-purity aluminium, and our High-Strength Al-Mg Resistant grade runs 79.5% Al₂O₃ with 80/110/120 N/mm² cold crushing strength at 110/816/1200°C, specified for melting furnaces and high-impact zones. The self-flow grade (77.2% Al₂O₃) suits launders, holding furnaces and congested shapes where placement matters more than impact resistance.

It largely does not, and selecting on temperature alone is the classic mistake. At 700-800°C these linings sit far below their rated service temperature. What actually kills them is penetration, corundum growth and alloy chemistry. Pick the grade on the alloy you run and the zone you are lining, not on the headline temperature figure.

It is CUMI's Thermal Ceramics (Tri-Mor) bauxite-based hydraulic-bond grade, 77% Al₂O₃ with 2900 kg/m³ density and the highest service temperature in our range at 1400°C. It is placed by vibrocasting at roughly 5.0-5.8% water by weight. We supply it alongside our self-flow and high-strength grades for aluminium melting and holding furnace duty.

No. Never patch an aluminium contact lining with a silica-bearing material, it will be reduced by the melt and become the next failure point. Patch with a matching non-wetting grade. Dry-out also matters: these are dense low cement castables, and trapped moisture causes explosive spalling, so always follow a controlled dry-out schedule after a repair.