Application of Silica Sol in Lightweight Thermal Insulation Castables

July 18, 2022

     The light-weight thermal insulation castable reduces the heat loss during the operation of the thermal kiln, improves the efficiency of the thermal kiln, and contributes to energy saving and consumption reduction. Alumina hollow ball castable has the advantages of high temperature resistance, good thermal insulation performance, high strength, good thermal shock resistance, good high temperature volume stability, etc., and can be directly used for the working lining of high temperature furnaces. However, because the aggregate particles of the alumina hollow spheres are spherical, and the particles are point-bonded, it cannot form a high-strength structure with interlaced networks and mutual inlays. The bonding force between the particles is extremely poor and the spalling resistance is poor. limited its use.

 

     The alumina hollow sphere castable using silica sol as a binder uses the nano-SiO₂ in the silica sol and the Al₂O₃ in the castable to react at high temperature to form mullite crystals with a network structure in the matrix, which overcomes the cement bond. The disadvantage of poor bonding ability between alumina hollow ball castables makes the castables not only have good high temperature resistance, but also have good normal temperature and high temperature strength, good thermal shock resistance and volume stability, so they have excellent performance. Use performance.

 

     In order to improve the thermal insulation performance and service life of the ladle cover, a steel plant in Shandong used cement combined with corundum hollow ball castables, but large pieces peeled off during use, which seriously affected the use effect of the ladle cover. When cement bonding is replaced by silica sol bonding, the use results show that the castable has good construction performance, and there is no obvious peeling off during use. According to the statistics of the use results, the service life of the silica sol combined corundum hollow ball castable on the ladle cover is more than twice that of the cement combined castable.

 

     The unshaped refractories combined with silica sol have good construction performance, realize rapid maintenance and demoulding, save construction time and improve construction efficiency; the castable combined with silica sol has good anti-burst performance, volume stability and thermal shock resistance Good performance, can realize rapid drying of castables, save time and energy required for baking; silica sol-bonded refractories have good bonding strength and excellent resistance to slag erosion, so they have good use. performance.

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