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​​Investment Casting Binders


 

Precision investment casting simplifies the manufacturing process for complex metal parts requiring high dimensional accuracy. Such parts may be cast with an almost unlimited selection of metals and alloys, and large parts of the casting process can be automated.

​​The process consists of encasing an expendable wax or plastic pattern of the piece to be produced in a ceramic shell by repetitively dipping the pattern in a slurry containing refractory grain and LUDOX® colloidal silica, stuccoing with coarser refractory grain, and drying.

The expendable pattern is melted out, the ceramic shell is fired, and metal is poured into the hollow shell. After solidification of the metal, the shell is broken away and discarded.

LUDOX® colloidal silica has high bonding power with a variety of refractory grains such as

  • Zircon
  • Fused silica
  • Alumina
  • ​Aluminosilicates 
The resulting shells are strong, with low coefficients of thermal expansion and excellent surface reproduction. Unlike ethyl silicate systems, LUDOX® colloidal silica contains no volatile organic compounds (VOC).

Refractory grains readily disperse in LUDOX® colloidal silica to form slurries that have consistent properties and long pot life. LUDOX® HS and SM are the most frequently used alkaline grades. The acidic LUDOX® SK binders result in superior pot life and shell properties in many systems, especially for zircon slurries. 

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