Types and Precautions for Graphite Crucibles

Graphite crucibles have excellent thermal conductivity and high-temperature resistance. They exhibit a very low coefficient of thermal expansion, making them highly resistant to thermal shock. They are also resistant to strong acids and bases, making them suitable for heating various liquids. Beyond their chemical applications, graphite crucibles are widely used in metallurgy, casting, machinery, and chemical industries.

Types of Graphite Crucibles

Graphite crucibles can be categorized based on their application and composition:

1. Clay Graphite Crucibles: Used primarily for melting non-ferrous metals like gold, silver, and aluminum.
2. Silicon Carbide Graphite Crucibles: Suitable for melting metals with higher melting points, such as copper, brass, and bronze.
3. High-Purity Graphite Crucibles: Used in industries requiring high-purity materials, like the semiconductor and solar industries.

Special Precautions for Graphite Crucibles

1. Avoid Mechanical Shock: Do not subject the crucible to mechanical impact. Avoid dropping or striking it from a height.
2. Keep Dry: Store the crucible in a dry place and avoid contact with water.
3. Dry Before Use: Ensure the crucible is completely dry before use. Do not expose it to water after drying.
4. Heat Distribution: Avoid directing the flame directly at the bottom of the crucible. If the flame hits the bottom, noticeable black marks may appear.
5. Remove Residual Metals: After shutting down the furnace, remove any remaining aluminum or copper from the crucible to avoid leaving any liquid inside.
6. Use of Flux: Use fluxes (deoxidizers) sparingly. Overuse can corrode the crucible, leading to cracks.