Castable Refractory Material for Aluminium Thimbles

The patent applies composite materials by combining fused silica aggregate with a colloidal silica binder system instead of traditional cement bonding. This creates a refractory composite that maintains erosion resistance while significantly extending operational life from 500 to over 800 casts. The composite structure integrates refractory aggregate particles within a silica-based matrix that provides both mechanical strength and chemical stability against molten aluminium.

The patent changes the chemical and physical parameters of the bonding system by replacing cement with colloidal silica. This parameter change transforms the binder from a calcium-based cement to a silicon-based colloidal system that cures to form a more durable, erosion-resistant matrix. The colloidal silica provides different bonding characteristics and thermal stability that directly address the limited operational life of conventional cement-bonded refractories.

The patent applies preliminary action by incorporating a dispersing agent into the castable refractory mixture before casting. This dispersing agent pre-prevents particle agglomeration and ensures uniform distribution of refractory aggregates throughout the matrix. By addressing particle distribution in advance, the material achieves both ease of casting and high machining precision, as the uniform structure allows for consistent dimensional control during subsequent machining operations.

The patent substitutes mechanical mixing and compaction methods with a chemical dispersion system. Instead of relying on mechanical forces to achieve uniform particle distribution, the dispersing agent chemically stabilizes the slurry to prevent settling and agglomeration. This substitution enables the material to be easily cast while maintaining the particle uniformity necessary for precise machining and consistent dimensions.

The patent converts the harmful aspect of soluble ceramic fibre into a benefit by utilizing the solubility characteristic. The soluble ceramic fibre is intentionally included to provide excellent thermal shock resistance, and its solubility is leveraged during the curing process where water extraction creates a controlled porous structure that enhances thermal performance. The fibre's solubility, which could be harmful, is transformed into a useful feature for achieving the desired thermal properties and microstructure.

The patent utilizes porous materials by incorporating soluble ceramic fibre that creates a controlled porous microstructure during curing. As the soluble fibre dissolves or is extracted, it leaves behind a porous network that improves thermal shock resistance by reducing thermal gradients and stress. This intentional porosity, created through the soluble fibre's decomposition, provides thermal benefits while the fibre itself is selected to minimize health risks.