Crucible – Graphite
Alumina Crucibles are high-purity refractory containers made from sintered aluminum oxide (Al2O3), typically ranging from 95% to 99.8% Al2O3. They are considered the standard for high-purity, high-temperature processing and analysis, valued for their extreme refractoriness, low reactivity, high mechanical strength at heat, and excellent electrical resistance.
Main Chemical Compositions & Categories
Alumina Crucibles are classified by their purity, which directly dictates their maximum service temperature (MST), chemical inertness, and price.
| PURITY GRADE | Al2O3 Content | TYPICAL MST | PRIMARY ADVANTAGE |
| Standard Purity | 95% to 96% | ~1700°C | Good mechanical strength, most cost-effective. |
| High Purity | 99.5% to 99.8% | ~1750°C to 1850°C | Maximum refractoriness and chemical inertness, minimal contamination. |
Key Properties and Performance
| PROPERTY | HIGH PURITY ALUMINA | MECHANISM OF ADVANTAGE |
| Melting Point | ~2050°C | Allows for service temperatures up to ~1850°C. |
| Chemical Inertness | EXCELLENT | Resists attack from many acidic and neutral chemicals, making it ideal for high-purity melts. |
| Hot Strength | HIGH | Maintains structural integrity and load-bearing capacity even at near-peak operating T. |
| Gas Tightness | EXCELLENT | Can be manufactured to be non-porous and vacuum-tight. |
Advantages and Key Characteristics
Alumina crucibles are the preferred choice for processes that demand chemical stability, minimal contamination, and thermal endurance beyond the limits of glass, quartz, or lower-grade ceramics.
- Purity and Contamination Control: The high Al2O3 content ensures that the crucible will not introduce impurities into the sample or melt. This is crucial for electronic materials, specialty glasses, and catalyst research where trace elements can ruin the product.
- High Thermal Endurance: Alumina maintains its crystalline structure and mechanical strength at extremely high temperatures, far exceeding those of most metal alloys, making it suitable for high-temperature sintering, melting, and calcination.
- Dimensional Stability: The high-density sintered structure ensures minimal shrinkage or deformation even after multiple heating cycles, which is important for quantitative analysis and maintaining process control.
- Electrical Insulation: Al2O3 is an excellent electrical insulator, allowing these crucibles to be used safely in electrically heated furnaces, particularly induction and resistance furnaces.
Typical Industries and Applications
This type of crucible is fundamental in both scientific research and industrial high-temperature manufacturing:
- Laboratories & Research: Differential Thermal Analysis (DTA), Thermogravimetric Analysis (TGA), high-temperature material synthesis, and sintering of ceramics/metal powders.
- Metallurgy: Melting and holding noble metals (gold, platinum), high-purity super-alloys, and reactive metals.
- Electronics & Photonics: Growing single crystals, sintering electronic ceramics, and preparing glass preforms for fiber optics.
- Chemical Industry: Calcination and high-temperature chemical reactions involving corrosive media.
Selection and Maintenance
Selection should prioritize the required purity and gas-tightness for the application:
- High Purity (99.8%): Mandatory when working with platinum group metals, electronic materials, or any substance where parts-per-million (ppm) contamination is unacceptable.
- Standard Purity (95%): Suitable for general-purpose ashing, calcining, and melting of non-sensitive materials.
- Porosity: Non-porous, high-density crucibles are required for high-vacuum and liquid-holding applications, while slightly porous crucibles are acceptable for gas-permeable reactions.
Technical Guidance: Alumina crucibles are chemically resistant to acidic and neutral melts. They are, however, attacked by highly basic materials (e.g., CaO, MgO, or basic fluxes) at high temperatures and will also react with pure silicon and iron melts under reducing conditions. They should be handled carefully, as they are brittle and susceptible to cracking from severe thermal shock or physical impact.
✨ 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. |
