According to different formulas, cast iron contains very different ingredients. Among them, the content of a small amount of metal such as manganese, silicon, sulfur, and phosphorus has a great influence on the production, processing and final properties. Today I will share with you the influence of the composition of cast iron in cast iron enamel .

The cast iron components (chemical composition) suitable for the enamel industry are as follows:

Carbon (total) 3.25~3.60%

Graphite carbon 2.8~3.2%

Compound carbon 0.22~0.52%

Silicon 2.25~3.0%

Manganese 0.45~0.65%

Phosphorus 0.6~0.95%

Sulfur 0.05~0.10%

The control of the composition of cast iron is mainly suitable for cast iron and enameling projects. It must have good fluidity when it is melted. The molten slurry fills the mold without generating bubbles and a large amount of slag. The effects of various main ingredients on the properties of enamel are as follows:

1. Carbon

The carbon content in cast iron should be less than 3.7%, because the total carbon content in cast iron is high, among which graphite-type carbon and cementite are also quite high. When they are fired at high temperature, they will easily decompose a large amount of CO and CO2 gas to cause porcelain Layer defects. Cast iron with a total carbon content of more than 4.2% should not be used as a green body for enamel materials.

2. Silicon

Like manganese, it enhances the hardness and elasticity of cast iron, and at the same time promotes the separation of graphitic carbon and hinders the effect of cementite, which is beneficial to enamel materials. If the content is greater than 2.2%, the properties of the casting are likely to develop hard and brittle. However, excessive silicon will cause the graphite structure to become coarser, reduce adhesion and appear porosity.

3. Manganese

When the manganese content is less than 0.5%, the cast iron can be softened, but when the content exceeds 2%, it will harden the cast iron. At the same time, manganese can promote the dissolution of carbon in iron, and a small amount of manganese can increase the toughness of iron.

4. Phosphorus

Phosphorus below 0.7% has little effect on the properties of iron, but when added in large amounts, it weakens the mechanical properties and wrinkles on the surface of cast iron. Phosphorus can reduce the shrinkage of iron and increase the softness. In addition, phosphorus has the function of increasing the fluidity of molten iron, which is helpful for the casting of thin sheets or workpieces with complex shapes.

5. Sulfur

Sulfur contributes to the formation of compound carbon and increases the hardness, brittleness and shrinkage of cast iron. Since sulfur will reduce the mechanical properties of iron, and at the same time generate gas that forms enamel defects, its content must be kept below 0.1%.

The chemical composition of cast iron has a great influence on the coefficient of thermal expansion. Carbon and silicon have the strongest influence. When the silicon content is less than 1.7%, the expansion coefficient of cast iron is high. When the silicon content increases, the expansion coefficient of cast iron decreases. Other elements have no significant influence on the expansion coefficient of cast iron.