High Temperature Alumina Plates

High purity alumina crucible for metal casting or sample preparation. Recommended to be used with our high temperature furnaces.

Features

• Purity: Al2O3 > 99.5%;  Fe2O3 < 0.01%
• 100% impervious
• Maximum working temperature: 1750°C
• Constant working temperature: 1600°C
• Density: > 3.8 g/cm3

Important Guidelines for Using 99% Alumina Crucibles

To ensure optimum performance and extend the service life of 99% high-purity alumina (Al₂O₃) crucibles, please follow these recommended operating guidelines:

1. Avoid Direct Flame Heating
   Do not heat the crucible directly with a gasoline torch, acetylene flame or alcohol burner. Uneven and localized heating can create excessive thermal stress and may cause the crucible to crack.

2. Control Heating and Cooling Rates

   Avoid rapid temperature changes during both heating and cooling.

   • Below 1200°C: temperature change should be <5°C/min
   • Above 1200°C: temperature change should be <4°C/min

   During cooling, controlled furnace cooling is recommended. Switching off the furnace at high temperature may result in excessively rapid cooling during the initial stage and increase the risk of cracking.

3. Maintain Clearance from Heating Elements
   Keep the crucible at least 5 cm away from heating elements, such as carbon tubes, silicon-molybdenum rods (MoSi₂) or heating wires. Alumina crucibles should not be used for applications involving the combustion of carbon- and iron-related materials.
4. Support Large Crucibles Properly
   For larger crucibles, avoid placing the bottom directly against the furnace chamber floor. Use suitable high-temperature-resistant alumina supports/spacers to raise the crucible and allow air circulation underneath. This helps promote more uniform heating and can extend crucible service life.
5. Avoid Materials Containing Metal Powders
   Do not use the crucible to fire materials containing carbon powder, iron powder, aluminium powder or other metallic components. Differences in cooling rates between the exterior and internally retained heat may create excessive thermal gradients, potentially causing surface spalling, cracking or other damage.
6. Load and Unload at Room Temperature
   The crucible should preferably be placed into and removed from the furnace at room temperature. Avoid exposing a hot crucible to a large temperature difference between the furnace and the surrounding environment, as thermal shock may cause cracking or damage.