Furnace Atmosphere

Gas that surrounds the material in a furnace. Generally, an atmosphere is supplied to protect the material against damage that would result if heated in ambient air. For ferrous wire, atmospheres protect against oxidation and decarburization. Some atmospheres are “inert,” protecting the material by displacing air (e.g., nitrogen). Other atmospheres are “reactive,” protecting the material by chemically reacting with the air (e.g., hydrogen). In practice, furnace atmospheres tend to be a mixture of inert and reactive components. These gas mixtures are either delivered separately in bulk and then mixed, or are generated at the site of the furnace. See Controlled Atmosphere.