General Materials For Investment Casting

Refractories
The refractories used in investment casting are mainly quartz and corundum, as well as aluminum silicate refractories, such as refractory clay, bauxite and coke gemstones. Sometimes zircon stone, magnesia (MgO) and so on are also used.
Binders
The most common binder used in investment casting is silicate colloidal solution (referred to as silicate sol), such as ethyl silicate hydrolysate, water glass and silica sol. The substances that make them up are mainly silicic acid (H2SiO3) and solvents, and sometimes stabilizers such as NaOH in silica sols.
Ethyl silicate hydrolysate is the earliest and most common binder used in silicate sol mold casting obtained by hydrolysis of ethyl silicate; The water glass shell type is easy to deform and crack, and the dimensional accuracy and surface finish of the castings poured with it are poor. However, in China, when the production of carbon steel castings and non-ferrous alloy castings with lower melting point requirements for precision requirements, water glass is still widely used in production; Silica sol has good stability, can be stored for a long time, and does not need a special hardener when making a shell, but silica sol is slightly worse at the wetting of the investment mold, and the shell hardening process is a drying process that takes a long time.