Application of Silica Sol in Corundum Castables

July 18, 2022

     High-purity corundum castables have excellent slag resistance, penetration resistance and spalling resistance, and are widely used in ladle, electric furnace roof, cement kiln and other parts with very harsh use environments. Corundum refractory castables often use high-purity calcium aluminate cement as a binder, and sometimes composite aluminum powder or SiO₂ powder as a composite binder. Under the condition of the coexistence of SiO₂ and CaO, low-melting substances such as calcite will be formed inside the refractory material at 1400-1500 ℃, which will affect the high-temperature performance of the material.

 

 

 

     The research shows that when silica sol is used as the binding agent of corundum castable, with the increase of silica sol content, the flow value of the castable increases, and when the silica sol is added 7% (w), the castable has good flow performance; The hot flexural strength of corundum castables with silica sol as binder at 1400℃ is higher than that with cement as binder. This is mainly because the cement-bonded sample reacts with impurities such as SiO₂ in the system to form a low melting point phase at high temperature due to the introduction of CaO; while the silica sol-bonded castable sample does not contain CaO in the system, not only does it not produce low melting point at high temperature The melting point phase material, but also a small amount of high melting point mullite phase is formed, which improves its thermal strength.

 

 

 

     At present, corundum refractory castables combined with silica sol have been used in water-cooled pipes, edge bricks, burner bricks, furnace mouths of soaking furnaces, refining furnace covers, power frequency induction furnaces, and large and medium-sized ultra-high-power electric furnace covers. Area and LF refining ladle cover and other parts, as well as around the ladle base brick, working layer and other parts are widely used.

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