Silica Brick – Silica Mullite
Main Chemical Compositions & Categories
Silica Mullite bricks are intermediate refractories containing high SILICA (SiO2) and a significant proportion of MULLITE (Al2O3-SiO2). The Mullite phase is introduced either through raw materials or formed in-situ during high-temperature firing.
| CATEGORY | SiO2 CONTENT | Al2O3 CONTENT | KEY FEATURE |
| SILICA MULLITE | 70% to 85% | 15% to 28% | Balanced TUL and thermal stability |
| SEMI-SILICA | 85% to 92% | $\text{< 10\%}$ | Max TUL, less thermal shock resistance |
Key Properties and Performance
| PROPERTY | TYPICAL PERFORMANCE | VARIATION WITH MULLITE CONTENT |
| Temperature Under Load (TUL) | VERY HIGH (Excellent) | SLIGHTLY DECREASES compared to pure Silica, but the high TUL is maintained by the SiO2 matrix. |
| Thermal Shock | GOOD | SIGNIFICANTLY IMPROVES over standard Silica or Semi-Silica due to the presence of the Mullite phase, which has a lower thermal expansion coefficient. |
| Corrosion | EXCELLENT RESISTANCE to ACIDIC slag and glass | IMPROVES structural integrity against corrosion compared to Silica, but is still rapidly attacked by BASIC fluxes (CaO, MgO). |
| Erosion Resistance | GOOD | IMPROVES over true Silica due to the dense, interlocking nature of the Mullite network. |
Advantages and Key Characteristics
Silica Mullite bricks are a choice for processes that require the high-temperature TUL of Silica but also experience higher levels of thermal cycling or abrasion than pure Silica can tolerate.
- Improved Thermal Cycling: The Mullite phase acts as a buffer against thermal stress, reducing the likelihood of cracking and spalling, which are common failure modes for true Silica bricks.
- High Load Bearing (TUL): The dominant SiO2 matrix ensures the structural load-bearing capability is maintained almost up to the fusion point, essential for large, self-supporting crowns.
- Erosion Resistance: The introduction of the rigid, hard Mullite phase provides better resistance to physical wear from high-velocity gases or abrasive dust compared to the glassier matrix of pure Silica.
Typical Industries and Applications
Silica Mullite is used in high-temperature zones that need both structural stability and resilience:
- Glass Industry: Crowns, regenerator settings, and flues in glass melting furnaces that undergo frequent or aggressive thermal changes.
- Coke Ovens: Walls and roofs, where a balance of high TUL and resistance to thermal variation is needed.
- Furnace Crowns: Used where the crown may need to be repaired or cooled down periodically, which would risk catastrophic failure with true Silica.
Furnace Areas and Service Zones
They are used in zones demanding structural integrity under varying heat:
- FURNACE CROWNS AND ARCHES: Where structural strength must be maintained, but where temperature gradients or cooling cycles are expected.
- TRANSITION ZONES: Areas where refractories meet other material types or where temperature fluctuations are greatest.
Key Data Sheet Properties to Consider
Selection criteria focus on the successful marriage of the two key phases:
- Al2O3-SiO2 Content: Verify the composition is in the range that maximizes Mullite formation while retaining high SiO2 content for TUL.
- Thermal Shock Resistance: Look for supplier data demonstrating superior thermal cycling resistance compared to standard Silica grades.
- Refractoriness Under Load (TUL): Must meet the required structural stability temperature, often only slightly lower than pure Silica.
- Permanent Linear Change (PLC): Critical to ensure volume stability is maintained after the initial thermal cycle.
Technical Guidance: Silica Mullite should be specified when thermal stability (resistance to shock) is the limiting factor for a true Silica crown. It provides a safety factor against cracking during unexpected cooling events or rapid furnace heat-up, while retaining the essential high-temperature load-bearing performance.
✨ 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. |
