The reasons for the slag formation inside graphite crucibles may include several factors:
1.Impurities: Impurities present during the preparation of graphite crucibles can undergo oxidation or react with other materials under high-temperature conditions, leading to slag formation. These impurities may originate from raw materials, manufacturing processes, or external contaminants in the usage environment.
2.Oxidation: At high temperatures, oxygen inside the graphite crucible may react with graphite or other materials, resulting in the formation of oxide slag. This oxidation reaction typically occurs when graphite surfaces are exposed to oxygen, such as during the casting of molten metals at elevated temperatures.
3.Residues: If the graphite crucible is not thoroughly cleaned after previous use, materials or coatings remaining inside the crucible may become unstable during subsequent heating, leading to slag formation.
4.Overheating: Graphite may undergo structural changes or partial melting if subjected to excessively high temperatures or thermal loads, resulting in slag formation. This situation may occur during heating processes that exceed the graphite crucible’s capacity.
5.Reaction Products: Materials inside the graphite crucible may undergo chemical reactions with added substances, producing solid products that can form slag on the surface or within the graphite.
To reduce or prevent slag formation inside graphite crucibles, measures such as using high-purity graphite materials, regular cleaning and maintenance of graphite crucibles, and controlling temperature and environmental conditions during heating processes can be implemented.