Ceramic crucibles can withstand different levels of heat depending on their composition and the specific conditions under which they are used.
How much heat can a ceramic crucible take? (7 Crucial Factors to Consider)
1. Composition of the Crucible
For a 99.70% pure alumina crucible, it can withstand temperatures up to 1800°C in a redox atmosphere of 1650°C–1700°C.
An 85% alumina ceramic crucible can withstand temperatures up to 1400°C in a reduction-oxidation atmosphere of 1290℃~1350℃.
A 99% alumina ceramic crucible, under a reduction-oxidation atmosphere of 1650℃~1700℃, can withstand temperatures up to 1800°C.
2. Atmosphere Conditions
It is important to note that alumina ceramic crucibles are suitable for melting samples with acidic substances such as K2S2O7 but not applicable for melting samples with alkaline substances such as NaOH, Na2O2, Na2CO3, as these can cause corrosion to the crucible.
Alumina ceramic crucibles should also be kept away from hydrofluoric acid (HFA).
3. Thermal Conductivity and Expansion
Both 85% and 99% alumina ceramic crucibles have excellent high-temperature insulation and mechanical strength, with large thermal conductivity and low thermal expansion.
4. Chemical Reactivity
A 99% alumina ceramic crucible does not react with air, water vapor, hydrogen, or CO even at 1700℃.
5. Application in Metal Melting
Carbon-bonded and ceramic-bonded clay graphite and silicon carbide crucibles are widely used for melting and holding various metals and alloys.
The temperature range for these crucibles varies from 400°C/750°F to 1600°C/2912°F, depending on the specific metal being melted.
6. Specific Examples
A specific example is given for a >99.6% Alumina (Al2O3) High Form Crucible with a 1000 ml capacity, which can be used at operating temperatures up to 1750°C in both oxidizing and reducing atmospheres.
7. Proper Heating and Cooling Procedures
When using alumina crucibles, it is important to follow proper heating and cooling instructions to minimize the risk of thermal shock.
Gradual warming up and cooling down are recommended, with heating rates of 150-300°C per hour and cooling rates often half of the heating rate (75-150°C per hour).
Continue exploring, consult our experts
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