Application of silica sol in refractory materials

Silica sol can be used as a bonding agent for refractory materials. Suitable for alkaline, netral and acid refractory materials. Silica sol can be directly used as a binding agent for refractory materials, especially semi-dry pressed refractory materials without adding other additives. As a binder for amorphous refractory materials, especially spray materials, a hardener must be added to adjust the setting and hardening speed. Generally, the following methods can be used to adjust the gel time: (1) Add acid. The gelation time of silica sol is affected by its pH value. Generally, the pH value of silica sol solution is between 8.5 and 10.5 inches. Silica sol is stable. It is relatively stable when the pH value is lower than 3.5 points. It is not easy to produce gel. Whenthe pH value is between 4 and 8, the viscosity increases rapidly. This is caused by the agglomeration between colloidal particles, which eventually turns into a gel.

The principle of silica sol as a binder for refractory castables is based on sol-gel technology. Due to its large surface area and strong adsorption, silica sol is distributed on the surface of refractory material particles and forms a gel around the particles. During this process, the hydroxyl groups on the surface of the particles solidify and remove moisture, forming a Si-O-Si bonded spatial network structure, which generates the strength of the refractory material during construction and maintenance. After the construction body dries, the gel binds the aggregate to form a skeleton, providing strength.

The application of silica sol in aluminum silicon carbide castables can significantly improve the slag resistance of refractory materials; as a binding agent for pure aluminate cement, silica sol can significantly shorten construction time, extend service life, and improve thermal strength; silica sol can be used as a binder for pure aluminate cement. The binding agent of organic resin and tar can greatly reduce environmental pollution and improve construction performance and usability. Refractory materials using silica sol as a binder have the advantages of high strength, good high-temperature volume stability, and good thermal shock resistance. It improves the construction performance and service life of the material, and has been promoted and applied in unshaped refractory materials.