Silica sol, also commonly known as silica solution in the industry, with a gas molecular structure formula of SiO2 · nH2O, is a colloidal dispersion of amorphous SiO2 aggregated particles in water. The dehydration temperature range of silica sol is very wide. Water loss not only damages its bonding strength, but also makes its three-dimensional structure more stable and produces higher bonding strength. It is a good inorganic adhesive for precision casting.

In the 1960s, silica sol began to be used as a binder in the field of precision casting. After the 1990s, due to the increasing environmental pressure, the unparalleled environmental advantages of silica sol gradually replaced the widely used silica sol. Silica sol has a high cost hydrolysis product of contaminated ethyl silicate. At present, the investment casting industry worldwide widely uses polymer reinforced quick drying silica sol as a binder.

Precision casting refers to the process of obtaining precision dimensional castings. Precision casting, also known as wax loss casting. Its products are precise, complex, and close to the final shape of the parts. It can be used directly without processing or with minimal processing. Develop advanced technology. This process includes: selecting suitable investment materials (such as paraffin) for investment; The process of repeatedly immersing refractory coatings (mainly silica sol) and refractory sand into castings, hardening the outer shell, and drying; Then reuse internal investment to dissolve and obtain cavities; Bake the shell to obtain sufficient strength and burn off the remaining investment materials; Metal materials required for casting; Solidify and cool, and clean the sand after shelling to obtain high-precision finished products.

Silica sol is used for precision casting. Due to its excellent adhesion and filling performance, the shell produced has high strength, casting glossiness, and is easy to peel off. Widely used in this field. Among them, according to specific usage requirements, it is further divided into surface silica sol and back silica sol, with a huge amount of usage.