Calcium-Silicon (CaSi) is an alloy composed of calcium, silicon, and sometimes other elements such as aluminum, iron, and manganese. It is commonly used as a deoxidizer, desulfurizer, and inoculant in the steel and casting industry.

As a deoxidizer, CaSi is added to molten steel to remove dissolved oxygen and other impurities that can affect the quality of the final product. As a desulfurizer, CaSi reacts with sulfur in the steel to form calcium sulfide, which can be removed from the molten steel more easily. As an inoculant, CaSi promotes the formation of graphite nodules in gray iron casting, which improves the ductility and strength of the cast iron.

One advantage of using CaSi is its high density, which allows it to sink quickly into the molten metal and distribute evenly throughout the melt. Additionally, CaSi is relatively low in cost compared to other alloying elements, making it an economical choice for many applications.

One disadvantage of using CaSi is that it can sometimes form slag, which can reduce the effectiveness of the deoxidation process. Additionally, excessive use of CaSi can lead to increased levels of calcium in the steel, which can have negative effects on its mechanical properties. Therefore, it is important to use CaSi in moderation and carefully control the amount added to the molten metal.