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Why are antimony alloys useful for casting molds?

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A labeled periodic table entry for antimony shows its symbol Sb, atomic number 51, atomic weight 121.76, electron configuration, and name. It is a solid, weakly acidic other metal with a rhombohedral crystal structure at room temperature. — antimony Properties of antimony.

Antimony alloys are highly valued for casting molds because they possess the rare characteristic of expanding upon solidification. This expansion forces the molten alloy to fill the small, intricate crevices of a casting mold, ensuring a sharp and precise definition of the final product.1

In addition to this property, antimony is frequently added to other metals, such as lead and tin, to increase their overall strength and hardness. These qualities make antimony-based alloys, such as type metal, particularly effective for applications requiring detailed and durable castings.1