Why add foundry chromite sand during casting?
The main reasons for using foundry chromite sand in casting include its excellent physical and chemical properties. Chromite sand plays a variety of important roles in the casting process, as follows:
Preventing sand from sticking to the surface of castings: Chromite sand is often used as the surface sand of large steel castings in casting production, which can effectively prevent sand from sticking to the surface of castings and improve the quality of castings. It has a stable heated volume and high thermal conductivity. It has a good resistance to alkaline slag when in contact with molten metal, and it has the characteristics of solid phase sintering, which can well prevent the penetration of molten metal and avoid the occurrence of sand sticking defects.
As a chilling material: Foundry chromite sand is a chilling material that can replace part of the chilled iron, increase the cooling rate of the casting, and prevent casting defects such as cracks and pores. Its thermal conductivity is several times greater than that of silica sand, which can significantly increase the cooling rate of castings.
Enhancing material properties: The chromium element in chromite sand is one of the main components of stainless steel, which can increase the corrosion resistance, hardness and strength of the material, and improve the wear resistance and high temperature performance of the material. Chromium forms chromium carbide with carbon in steel, further improving the hardness and wear resistance of the material.
Refractory aggregate: After grinding, chromite sand can be used as refractory aggregate for casting coatings, enhancing the refractory properties of coatings and ensuring the stability and safety of castings in high temperature environments.
Preventing casting defects: Chromite sand has good refractory resistance, low linear expansion coefficient and does not react with metal oxides, which can effectively prevent casting defects such as veining and sand inclusions.
Applied to a variety of casting processes: Chromite sand is used in combination with sand casting, furan resin self-hardening sand, water glass self-hardening sand and other processes for large-volume and heavy cast iron and steel parts, which is conducive to cooling the castings in a predetermined order and improving the compactness and strength of the castings.
