DEFN = 'Containing free oxygen atoms which combine with metal to form metal oxides in the reaction called oxidation.'
An oxidising atmosphere in a furnace drives out carbon. See also Reducing. 
Firing in a kiln atmosphere where oxygen is present. Electric kiln firings are always considered to be in oxidising atmospheres.
The production of a stable oxide layer on a steel component by heating in a controlled atmosphere. Provides corrosion protection and reduced friction.