Sodium Silicate (Water Glass)
Sodium Silicate (Na₂O·nSiO₂), commonly known as Water Glass, is an alkaline solution created by dissolving amorphous silica (SiO₂) in molten sodium carbonate (Na₂CO₃) at high temperatures, or by dissolving silica in sodium hydroxide (NaOH) under pressure. It is typically supplied as a clear, viscous liquid.
Its properties as a binder are determined by its modulus, which is the ratio of silica to sodium oxide (SiO₂ / Na₂O):
- High Modulus (~3.0 to 3.8): Less alkaline, more viscous, provides higher strength and better heat resistance.
- Low Modulus (~2.0 to 2.5): More alkaline and more reactive.
Water Glass is essential as a low-temperature chemical binder in monolithic refractories and as the primary binder in the CO₂ gassing process for foundry molds.
Main Function and Characteristics
Water Glass acts as a powerful, non-hydraulic chemical binder that sets rapidly when treated with a chemical accelerator or heat.
| CHARACTERISTIC | VALUE RANGE | PRIMARY FUNCTION |
|---|---|---|
| Modulus (SiO₂ / Na₂O) | 2.0 to 3.8 | Determines reactivity, alkalinity, and final strength. |
| Purity | COMMERCIAL | Contains minor impurities; highly alkaline. |
| Set Mechanism | CHEMICAL/DRYING | Sets via dehydration, acidification, or reaction with metal oxides. |
CLASSIFICATION
- Binding Focus: Alkaline Chemical Binder – Forms a colloidal silica gel and final sodium silicate glass
- Primary Application Focus: Foundry Binders (CO₂ Gassing), Refractory Mortars, and Acid-Resistant Cements
Key Performance Metrics
| PROPERTY | TYPICAL PERFORMANCE | MECHANISM OF ADVANTAGE |
|---|---|---|
| Setting Speed | FAST (when activated) | Allows for quick turnaround in molding or patching. |
| Cold Strength | HIGH | Provides excellent mechanical strength at room temperature/drying. |
| Refractoriness | MODERATE | Na₂O is a strong flux, limiting ultimate service temperature (~1200°C). |
- The CO₂ Gassing Mechanism (Foundry Use)
The most common industrial use for Water Glass is in the foundry for sand core and mold making:
- Process: Foundry sand is mixed with low-modulus Sodium Silicate solution. The mold is formed, and then pressurized carbon dioxide (CO₂) gas is passed through the sand.
- Reaction: The CO₂ reacts with the alkaline Sodium Silicate, causing a chemical set by precipitation of a rigid silica gel (SiO₂):
Na₂O·nSiO₂ + CO₂ → Na₂CO₃ + nSiO₂ (Gel) - Benefit: This creates a rigid, high-strength mold in a matter of seconds, making the process highly efficient.
- Role in Refractory Mortars
In refractory applications (under Refractory Mortars & Mixes), Water Glass is used to bind materials like fireclay or chrome-magnesite, particularly in air-setting or intermediate-temperature joints:
- Drying Set: It forms a hard bond simply upon drying and dehydration.
- Service Limit: The presence of Na₂O acts as a strong flux, meaning the refractory material will begin to soften and melt at lower temperatures (below 1400°C) than chemically pure refractories. Therefore, Water Glass-bonded materials are restricted to intermediate or back-up zones.
- Technical Guidance
- Knock-Out: In the foundry, the Na₂CO₃ byproduct of the CO₂ gassing process raises the melting point of the binder, making the sand difficult to “knock out” (break away) from the finished casting. For this reason, organic additives are often included to help the bond break down under the heat of the molten metal.
✨ Customization Services
We offer product customization services, allowing you to tailor the appearance, dimensions, or specific markings of items like refractory shapes or bricks. This includes options for incorporating specific geometric requirements to ensure seamless integration into your process systems.
🔬 Sampling for Testing & Validation
Free product samples are available for thorough testing and validation. This allows you to confirm the quality, compatibility, and performance of our materials—such as specific bricks, castables, or raw materials—before committing to a full order.
💡 Expertise in Refractory Solutions
Leverage our deep expertise to receive detailed, application-specific refractory solutions. We move beyond just selling products by providing comprehensive plans that encompass material selection, installation guidance, and performance optimization to maximize the lifespan and efficiency of your high-temperature processes.
Rabatec products are exclusively manufactured in facilities that have achieved rigorous ISO certifications across Quality (ISO 9001), Environmental Management, and Occupational Health & Safety. This commitment ensures every product, from refractory bricks to specialized equipment, meets the highest global benchmarks for performance, sustainability, and workplace safety.
📦 Logistics Excellence: Shipping, Packaging, and Marking
Minimizing Risk: We manage all logistics to minimize handling touchpoints and transit shock. Our carriers are pre-vetted for their experience in transporting heavy, fragile, and sensitive industrial materials.
Traceability: Every shipment includes comprehensive documentation and tracking information, providing end-to-end visibility and ensuring precise delivery coordination for your site.
Protection is Paramount: Our packaging strictly follows industry standards to prevent damage, corner chipping, and moisture absorption—especially critical for materials like Basic Refractory Bricks and Refractory Mortars & Mixes.
Robust Palletization: Products are secured on fumigated, high-strength export pallets (e.g., 1100x950mm or similar sturdy dimensions) using heavy-duty strapping and durable protective wrapping (polyethylene sheeting, cardboard, etc.) to withstand long-distance travel and multiple loadings.
Moisture Control: Sensitive materials are protected with appropriate sealing and, where necessary, desiccants or moisture-vapor proof enclosures to maintain the product's integrity until installation.
Clear Identification: All outer packaging is clearly marked on multiple sides with large, legible text for immediate identification and safe handling.
Full Traceability: Markings include all essential data points: Product Name, Quality Grade, Batch Number, Quantity, Net/Gross Weight, Order Number, and the Final Destination/Construction Area. This ensures every pallet can be accounted for and correctly staged upon arrival.
Safety & Compliance: We adhere to all regulatory requirements for marking, labeling, and placarding—especially for any items classified as Dangerous Goods—to ensure full compliance with international and domestic transport regulations.
❓ Frequently Asked Questions (FAQ)
Question | Elaborated Answer |
Q: What is the Refractoriness Under Load (RUL) of your refractories? | A: Refractoriness Under Load (RUL) is a critical property that defines the maximum temperature our materials can withstand while under compressive stress before deforming (softening). Since we offer a wide range of materials—from Alumina-Silicate Bricks to high-performance Silicon Carbide Bricks—the RUL varies significantly. For specific product data, please refer to the product data sheet or submit a quote request for the material you are interested in. |
Q: Where are the Rabatec refractories and materials produced? | A: Our products are primarily sourced from specialized manufacturing plants in China. Crucially, these facilities have all undergone rigorous audits and achieved comprehensive ISO certifications (Quality, Environment, and Safety), ensuring that production adheres to the highest global standards for consistency and performance. |
Q: What refractory materials does the company offer? | A: We supply a comprehensive portfolio of advanced refractory solutions, including: Shaped Products: Alumina & Silica Bricks, Basic & Specialized Bricks (e.g., Magnesia), SiC & Structural Ceramics, and Precast Shapes. Monolithic Products: Refractory Castables, Mixes & Mortars. Insulation: Insulation Fibre and High-Performance Insulation Products. |
Q: How should I choose the appropriate refractory material for my application? | A: Selecting the correct refractory is paramount to process efficiency. The choice depends on three key factors: 1. Operating Environment: Maximum process temperature and thermal cycling (shock). 2. Chemical Attack: Type of slag, molten metal, or corrosive gas being handled (acidic, neutral, or basic). 3. Mechanical Stress: Abrasion, erosion, and static load requirements. We recommend utilizing our detailed refractory solutions service to consult with our engineers for an optimized, application-specific recommendation. |
Q: Which monolithic material should I choose when patching an existing lining? | A: For patching and minor repairs, the ideal monolithic material depends on the parent lining material, the patching depth, and the need for a rapid return to service. Common choices include: Refractory Mortars & Mixes (for minor joints/surfaces) or Plastic Refractories (for areas requiring physical compaction). Always choose a patch material chemically compatible with the existing lining to ensure proper bonding and service life. |
Q: Can I receive product samples before placing a major order? | A: Yes. We gladly provide product samples for your internal testing and validation purposes. This ensures you can confirm the quality, composition, and fit of the material—such as our Refractory Castables or Alumina-Silicate Bricks—in your specific operational environment before committing to a bulk purchase. |
Q: Do you provide certifications to verify material quality? | A: Absolutely. We provide product-related inspection certificates and quality assurance documentation upon request. This verifies that your order has passed all internal quality control checks and meets the required material specifications and industry standards. |
Q: What measures are taken for product protection during transport? | A: We ensure quick, reliable transport by using robust, industrial packaging that strictly follows industry standards. This includes high-strength palletization, heavy-duty strapping, and weather-resistant wrapping to protect fragile items like bricks and mixes from corner chipping, mechanical damage, and moisture during transit. |
