Ingots

An ingot is a piece of relatively pure material, usually metal, that is cast into a shape suitable for further processing. In steelmaking, it is the first step among semi-finished casting products. Ingots usually require a second procedure of shaping, such as cold/hot working, cutting, or milling to produce a useful final product. Non-metallic and semiconductor materials prepared in bulk form may also be referred to as ingots, particularly when cast by mold based methods.Precious metal ingots can be used as currency (with or without being processed into other shapes), or as a currency reserve, as with gold bars.

Metal, either pure or alloy, heated past its melting point and cast into a bar or block using a mold chill method.

A special case are polycrystalline or single crystal ingots made by pulling from a molten melt.

Single crystal ingots (called boules) of materials are grown (crystal growth) using methods such as the Czochralski process or Bridgeman technique.

The boules may be either semiconductors (e.g. electronic chip wafers, photovoltaic cells) or non-conducting inorganic compounds for industrial and jewelry use (e.g., synthetic ruby, sapphire).

Single crystal ingots of metal are produced in similar fashion to that used to produce high purity semiconductor ingots, i.e. by vacuum induction refining. Single crystal ingots of engineering metals are of interest due to their very high strength due to lack of grain boundaries. The method of production is via single crystal dendrite and not via simple casting. Possible uses include turbine blades.

In the United States, the brass and bronze ingot making industry started in the early 19th century. The US brass industry grew to be the number one producer by the 1850s. During colonial times the brass and bronze industries were almost non-existent because the British demanded all copper ore be sent to Britain for processing. Copper based alloy ingots weighed approximately 20 pounds (9.1 kg).

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