What is Silica Sol Investment Casting?

Silicon (colloidal colloid), also known as silicic acid solution or colloidal dispersion of silica aggregates in water. Colloidal sol increases the temperature loss of water while also making the three-dimensional junction structure more stable and producing higher bonding strength. It is a high-quality non-adhesive bond made of precision cast iron.

Silica sol was first used as a binder for precision casting in the 1960s. Due to increasing environmental pressures since the 1990s, silica sol has gradually replaced the widely used ethyl silicate hydrolyzate, which is highly polluted and expensive. At present, polymer-reinforced quick-drying silica sol is widely used as a binder in the investment casting industry around the world.

Precision casting is a broad term for the process of producing castings with precise dimensions. Lost wax casting is another name for investment casting. Its products are sophisticated, close to the final shape of the part, and can be used directly or with minimal machining. This is a sophisticated near net shape process. The procedure consists of the following steps: selecting a suitable investment material (such as paraffin) to make an investment pattern; repeating the steps of dipping refractory coating (the main component is silica sol) and spraying refractory sand on the investment pattern, hardening the shell, and drying; melting the inner investment pattern, obtaining the mold cavity; baking the shell to obtain sufficient strength; and burning off the residual investment material.

Precision casting makes use of silica sol. It is widely used in this field due to its good bonding ability and filling performance, which results in a shell with high strength, high gloss, and ease of demoulding. It is divided into surface silica sol and back silica sol, depending on the specific use requirements.