CO₂ Process Sodium Silicate Casting Binder: For Rapid-Curing Foundry Sand

Silicate sodium used for casting, commonly known as “water glass”, is an important inorganic adhesive. Its key parameter, “modulus”, usually ranges from 2.2 to 3.4. By reacting with CO₂ or adding hardening agents such as organic esters, the sand mold can be rapidly hardened and achieve the required strength. It is widely used in the manufacturing of sand molds and sand cores for steel casting and iron casting due to its wide source, low cost, and non-toxic and environmentally friendly properties.

Appearance and Packaging

This is a colorless, light yellow or bluish-gray transparent viscous liquid that can be easily dissolved in water.

The core advantages and features of  sodium silicate casting binder

1.The sodium silicate used for casting possesses excellent bonding strength and process adaptability.
It can ensure that the sand mold has sufficient high-temperature strength and surface stability, effectively preventing casting defects such as sand extrusion and sand inclusion, and is suitable for the production of complex castings.

2. Significantly improved collapsibility
By adjusting the modulus of sodium silicate or adding special modified components, the residual strength can be reduced. After the casting is poured and cooled, the sand mold is easily collapsed, significantly reducing the difficulty of sand removal and labor intensity. It is particularly suitable for cast iron and cast steel parts.

3. Environmental and Safety Advantages
Silicic acid sodium is an inorganic substance, free of harmful elements such as nitrogen, sulfur, and phosphorus. It does not produce irritating smoke, thus safeguarding the health of workers.

4. Low moisture absorption, good storage stability
High-quality sodium silicate has a low moisture absorption rate. The sand molds produced can be stored for a longer period of time, reducing the problem of mold failure due to moisture re-entry and making production scheduling more flexible.

Application scenarios of sodium silicate Sand Binder for Steel & Iron Casting

1.Applicable process:
CO₂ cold crucible method
Ester hardening self-setting sand method
Vacuum Replacement Hardening (VRH) method

2.Type of castings produced:
Cast steel parts: Large cast steel components, carbon steel and alloy steel castings.
Cast iron parts: Gray cast iron, ductile iron, large cast iron components.
Non-ferrous metal castings: Copper alloys, aluminum alloys castings, etc.

Guide for the Use of Sodium Silicate in Casting

1. Mixing ratio suggestion: Based on the characteristics of the raw sand, the casting requirements, and the hardening process, it is recommended to determine the optimal value through experiments.

2. Mixing sand process: It is suggested to add sodium silicate first, mix evenly, and then add other additives to ensure uniform distribution.

3. Hardening control:
CO₂ method: Control the concentration, pressure, and action time of CO₂.
Ester hardening method: Select the appropriate type and ratio of ester curing agent according to the environmental temperature and the size of the sand mold, and control the usable time and demolding time.

4. Storage conditions: Store in a sealed manner in a cool and ventilated place to prevent exposure to sunlight and freezing. The shelf life is usually 6-12 months.

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