In the foundry industry, when graphite is coated on the surface of a solid, a smooth film with firm adhesion can be formed, which is the good coating performance of graphite and a good mold release agent for casting. The commonly used graphite powder for casting includes crystalline graphite powder (flake graphite powder) or cryptocrystalline graphite powder (earth graphite powder, also known as microcrystalline graphite powder and black lead powder).
Although sometimes graphite powder does not form bright carbon when pouring molten iron, the wetting angle of graphite to molten iron is far greater than 90 °, that is, the sand mold is not wetted by molten iron. Moreover, the pores on the surface are blocked by earth and stone toner, and the molten iron is not easy to penetrate and drill into the sand grains, which can prevent the casting from sticking sand and improve the surface smoothness of the casting. Graphite powder has a good lubricating effect, which improves the compactness and fluidity of molding sand, reduces the air permeability, reduces the ejection resistance of samples, and improves the molding performance of molding sand.