Tech Team · Kintek Solution

Alumina crucibles are widely used in high-temperature applications due to their excellent thermal and mechanical properties. The temperature range of alumina crucibles varies depending on the alumina content and the specific application. Generally, 99% alumina crucibles can withstand temperatures up to 1700°C for long-term use and up to 1800°C for short-term use. Lower alumina content crucibles, such as 85% alumina, have a lower temperature range, typically up to 1350°C for long-term use and 1400°C for short-term use. These crucibles exhibit high thermal conductivity, low thermal expansion, and excellent mechanical strength, making them suitable for various high-temperature processes.

Key Points Explained:

1. Temperature Range Based on Alumina Content:

   • 99% Alumina Crucibles:
     • Long-term use: Up to 1700°C.
     • Short-term use: Up to 1800°C.
     • These crucibles are ideal for very high-temperature applications and exhibit excellent high-temperature insulation properties and mechanical strength.
   • 85% Alumina Crucibles:
     • Long-term use: Up to 1350°C.
     • Short-term use: Up to 1400°C.
     • Suitable for stable environments where temperature changes are not too rapid.

2. Thermal and Mechanical Properties:

   • High Thermal Conductivity: Alumina crucibles have a thermal conductivity of about 3000 W/m·K, which allows for efficient heat transfer.
   • Low Thermal Expansion: This property ensures that the crucibles maintain their structural integrity even at high temperatures.
   • Mechanical Strength: Alumina crucibles are harder than iron or graphite, providing high resistance to mechanical stress and internal pressure.

3. Chemical Stability:

   • Resistance to Chemical Reactions: Alumina crucibles do not react with air, water vapor, hydrogen, or CO, even at temperatures as high as 1700°C. This makes them suitable for use in various chemical environments.
   • Contamination-Free: The chemical stability ensures that there is no risk of contamination, which is crucial for processes requiring high purity.

4. Applications:

   • High-Temperature Processes: Alumina crucibles are used in processes that require extreme heat, such as melting metals, sintering, and high-temperature chemical reactions.
   • Stable Environments: Lower alumina content crucibles are suitable for long-term use in stable environments where temperature fluctuations are minimal.

5. Comparison with Other Materials:

   • Graphite Crucibles: While graphite crucibles can withstand higher temperatures (up to 3000°C), they are more prone to contamination and heat stress damage compared to alumina crucibles.
   • Iron Crucibles: Alumina crucibles are harder and have a higher thermal expansion coefficient, making them more suitable for high-pressure applications.

In summary, the temperature range of alumina crucibles is highly dependent on their alumina content, with 99% alumina crucibles being suitable for the most extreme high-temperature applications. Their excellent thermal and mechanical properties, along with chemical stability, make them a preferred choice for various industrial processes.

Summary Table:

Alumina Content	Long-Term Use	Short-Term Use	Key Features
99% Alumina	Up to 1700°C	Up to 1800°C	High thermal conductivity, low thermal expansion, excellent mechanical strength
85% Alumina	Up to 1350°C	Up to 1400°C	Suitable for stable environments, good thermal properties

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