Cast Iron Enamel Technology and Production Process (3)
Release time:
2026-03-12 09:46
Source:
China Enamel Industry Association
(Continued from previous article)
I. The Influence of Various Chemical Components in Cast Iron
Manganese in cast iron: Manganese generally does not have a significant impact on cast iron enamel quality. However, it greatly affects the quality of castings. It can combine with sulfides in molten iron to form relatively stable manganese sulfide, which exists in the slag, thus reducing the sulfur content in the casting and increasing its strength. Simultaneously, manganese sulfide easily accumulates on the surface of castings, and when exposed to air and water, it can form sulfates, resulting in rust spots. If these rust spots are not thoroughly sandblasted, the enamel layer can easily peel off. If the sandblasting is thorough, it will not have a harmful effect on the cast iron enamel.

Phosphorus in cast iron: Phosphorus improves the fluidity of molten iron, allowing for the casting of thinner parts. Therefore, the phosphorus content in cast iron is important. However, the phosphorus content should not be too high. If the phosphorus content in the casting exceeds 1%, the casting is brittle and prone to thermal cracking of the enamel layer during firing. Therefore, increasing the temperature of the molten iron is preferable to improving the fluidity of the molten iron.
Sulfur in cast iron: Sulfur in castings is harmful to enamel. Because sulfur dissolves in cementite, it hinders the graphitization process of carbon. Sulfur also easily precipitates sulfides on the surface of castings, causing cracks or pinholes, and easily forms white cast iron, resulting in pinholes and bubbles during enamel firing, which is particularly harmful to enamel. Therefore, the sulfur content in cast iron must be controlled to be less than 0.1%.
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