What Is Silica Sol Precision Casting? Why Can Silica Sol Be Used For Precision Casting?

Silica sol (colloidal silica), also known as silicic acid solution, is a colloidal dispersion of amorphous silica aggregate particles in water. Silica sol has a wide range of water loss temperature, which not only destroys its bonding strength, but also makes its three-dimensional structure more stable, resulting in higher bonding strength. It is a good inorganic binder for precision casting.

In the 1960s, silica sol began to be used as a binder for precision casting. Since the 1990s, due to the increasing pressure of environmental protection, silica sol has gradually replaced the widely used polluting and expensive ethyl silicate hydrolyzate. At present, polymer-enhanced quick-drying silica sol casting material is widely used as a binder in the world's investment casting industry.

Precision casting is a general term for the process of obtaining castings with precise dimensions. Precision casting is also called lost wax casting. Its products are precise and complex, close to the final shape of the parts, and can be used directly without processing or with little processing. This is an advanced near-net shaping process. The process includes: selecting suitable molten mold materials (such as paraffin) to make molten molds; repeating the steps of impregnating refractory coatings (mainly silica sol) and spraying refractory sand on the molten mold, hardening the shell and drying; melting the inner molten mold to obtain a mold cavity; baking the shell to obtain sufficient strength and burning off the residual molten mold materials; pouring the required metal materials; solidification cooling, shelling, and sand cleaning to obtain high-precision finished products.

Silica sol is used for precision casting. Due to its good bonding ability and filling performance, the shells made have high strength, high gloss, and are easy to demold, and are widely used in this field. According to the specific use requirements, it is divided into surface silica sol and back silica sol, which consumes a lot.