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LUDOX® Collodial Silica in Precision Investment Casting

Enhance strength and precision in investment casting with LUDOX® colloidal silica–the binder of choice for experts.

Precision Investment Casting (PIC) is often used to make metal parts as diverse as intricate components for airplane engines to large steel valves for chemical plants. Grace’s LUDOX® colloidal silica serves two functions in the PIC process: as the binder and as the fluid to suspend other slurry ingredients.

Why LUDOX® colloidal silica?

With LUDOX® colloidal silica, both particle size and particle size distribution are tailored by carefully controlling the manufacturing process. This allows the particle size distributions of LUDOX® colloidal silicas to be very narrow when compared to most competitive grades with the same average particle size. The uniformity of particle size and distribution provides our customers with enhanced consistency and control of their processes.

How is LUDOX® colloidal silica used in the PIC process?

When the PIC process is undertaken using colloidal silica, the silica material serves the crucial function of being the ceramic binder that bonds to the refractory grain and forms a strong, cohesive casting. 

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What are the benefits of using LUDOX® colloidal silica in PIC?

Excellent adhesion and stability of the ceramic shell:

This ensures that the mold maintains its shape and integrity during the casting process. This results in high-dimensional accuracy and smooth surface finishes of the final cast product.

Enhanced thermal shock resistance of the mold:

Reduces the risk of cracking and improves the overall durability and quality of the casting.

No volatile organic compounds (VOC):

Unlike ethyl-silicate used in some PIC processes, LUDOX® colloidal silica contains no VOCs.

High compatibility with refractory gains:

LUDOX® colloidal silica is highly compatible with a variety of refractory grains such as fused silica, zircon, alumina, etc., allowing it to be used effectively in a wide range of investment casting applications.

What types of LUDOX® colloidal silica binders are used for PIC?

Grace offers two types of LUDOX® colloidal silica for investment castings: standard alkaline binders and ultra-stable binders:

  • Standard Alkaline Binders (LUDOX® HS and SM colloidal silicas) are particularly suitable in the initial stages of creating a ceramic shell (known as primary coat) because it provides excellent adhesion to wax patterns and has good wetting properties. These grades are also preferred for their faster drying rates and strong green (unfired) strength compared to acidic grades. Alkaline grades are highly compatible with a wide range of refractory grains including fused silica and zircon.
  • Ultra-Stable Binders (LUDOX® SK colloidal silica) are more suitable when lower drying temperatures are needed to achieve slower drying time, beneficial to build thicker shells and highly compatible with alumina and zircon grains.

We offer a wide range of grades suitable to match the demand of specific casting applications and processes, such as desired mold strength, drying time, surface finish, and compatibility with different refractory grains. Fill out the form to download the brochure to learn more about LUDOX® colloidal silica for PIC and request to speak to an expert.