Al₂O₃-SiO₂ Ceramic Crucible

Core Features

1. Synergistic Complementary Mechanical and Thermal Properties

   In the composite system, Al₂O₃ provides high hardness (HV≥1200), high flexural strength (≥150 MPa) and excellent wear resistance, while SiO₂ contributes ultra-low thermal expansion coefficient (0.8~2.5×10⁻⁶/℃, 20~800℃) and outstanding thermal shock stability. It can withstand rapid cooling from 800℃ to room temperature without cracking, with thermal shock resistance cycles ≥50 times. Both mechanical strength and thermal stability are superior to single alumina or quartz crucibles.
2. Ultra-High Purity and Low Impurity Contamination

   Using 4N (99.99%) high-purity alumina powder and 6N (99.9999%) fused silica powder as raw materials, the total content of metallic impurities (Fe, Cu, Ni, Na, etc.) is ≤50 ppb, hydroxyl content (OH⁻) ≤20 ppm, and no volatile impurities. No impurities are precipitated during high-temperature use, avoiding contamination of high-purity materials such as molten silicon and optical glass, and meeting the high-cleanliness requirements of the semiconductor and photovoltaic industries.
3. Excellent High-Temperature and Chemical Stability

   The long-term service temperature can reach 1200~1400℃, and the maximum short-term service temperature is 1600℃ (in inert gas atmosphere). Except for strong alkaline melts (such as NaOH, KOH), it has excellent corrosion resistance to acidic, neutral melts and most high-temperature gases. It can stably hold molten silicon, aluminum, glass liquid and high-temperature chemical reagents, with a service life 2~3 times longer than that of single quartz crucibles.
4. Customizable Structure and Dimensional Compatibility

   Various structural designs are supported: straight cylinder type, special-shaped type, covered type, and type with diversion port. Customizable inner diameter φ20~φ500 mm, height 50~800 mm, wall thickness 3~20 mm, with dimensional tolerance ≤±0.05 mm. For semiconductor applications, high-precision slots or bearing platforms can be designed; for photovoltaic applications, the crucible volume and diversion structure can be optimized to meet the needs of different equipment and processes.

Technical Parameters (Typical Values)

Application Fields

1. Semiconductor Manufacturing

   Used for material bearing in key processes such as wafer high-temperature annealing, post-implantation annealing and epitaxial growth. The low thermal expansion characteristic of high-silica composite crucibles can match the thermal expansion coefficient of wafers, reducing wafer warpage caused by thermal stress; high cleanliness can avoid heavy metal impurity contamination, compatible with advanced processes of 28 nm and above.
2. Photovoltaic Silicon Processing

   Served as auxiliary crucibles for polycrystalline silicon ingot casting and monocrystalline silicon pulling, or used in silicon purification and doping processes. The high strength and wear resistance of high-alumina composite crucibles can withstand the scouring of molten silicon, and the thermal shock stability of high-silica type is suitable for frequent heating and cooling processes, improving silicon purity and yield.
3. Optical Glass and Crystal Growth

   Used for melting and growth of high-refractive-index optical glass, laser crystals and fluorescent crystals. The low impurity content of composite ceramics can ensure the optical uniformity of glass and crystals, and the excellent chemical stability can avoid reactions between the crucible and the melt, suitable for the preparation of high-end optical components.
4. High-Temperature Chemical Synthesis and Laboratories

   As a reaction container for high-temperature solid-state reactions and molten salt synthesis, it can hold acidic, neutral high-temperature melts and chemical reagents, suitable for small-scale laboratory synthesis and industrial batch production, with the advantages of high-temperature resistance, corrosion resistance and high cleanliness.

Preparation Process

1. Raw Material Preparation and Mixing: Select 4N high-purity alumina powder and 6N fused silica powder, weigh them accurately according to the designed ratio, add dispersant and wet-mill in a planetary ball mill for 24~48 hours to ensure uniform mixing of raw materials with particle size distribution D50≤1 μm.
2. Forming Process: According to the crucible structure and size, choose slip casting, dry pressing or isostatic pressing. Isostatic pressing can obtain green bodies with higher density, better uniformity and more controllable dimensional tolerance.
3. Binder Removal and Sintering: Debind the green body at 200~400℃ to remove the forming agent; then sinter in a high-temperature sintering furnace at 1400~1600℃ in air or inert gas atmosphere for 4~8 hours to achieve densification and crystal bonding of raw materials.
4. Precision Machining and Polishing: Perform diamond cutting and grinding on the sintered crucible to control dimensional tolerances such as inner diameter, height and wall thickness; polish the inner wall to a surface roughness Ra≤0.1 μm to reduce friction resistance between the melt and the crucible.
5. Cleaning and Quality Inspection: Remove surface impurities by ultra-pure water ultrasonic cleaning and plasma cleaning, detect impurity content by ICP-MS, mechanical properties by universal testing machine, and dimensional accuracy by laser thickness gauge. Qualified products are vacuum-sealed and packaged.

Usage and Storage Recommendations

1. Usage Notes
   • Preheat at 200~300℃ for 2~4 hours before first use to remove surface-adsorbed moisture; during high-temperature use, heat and cool slowly (heating rate ≤5℃/min, cooling rate ≤3℃/min) to avoid thermal shock cracking.
   • Avoid contact with strong alkaline melts and hydrofluoric acid to prevent crucible corrosion; avoid severe collision during handling and use to prevent mechanical damage.
   • High-silica crucibles are suitable for scenarios requiring high thermal shock stability, while high-alumina crucibles are suitable for scenarios requiring high mechanical strength.
2. Storage Conditions

   Seal and store in a dry and clean environment, with storage temperature 5~30℃ and relative humidity ≤40%, avoiding moisture, dust contamination and severe collision. The shelf life is 12 months under vacuum packaging.