Refractory Alloys

Refractory Alloys

 

(also called scale-resistant alloys), metallic alloys that are resistant to intensive corrosion in air or other gaseous mediums at high temperatures. They are used as the construction material for moderately stressed parts of heating devices and energy installations, as well as for resistance heating elements. Refractory alloys have a nickel, iron, or nickel-iron base and contain up to 30 percent chromium; some are also alloyed with aluminum or silicon. Upon heating, a dense protective film forms on the surface of these alloys. The film consists of the products of the reaction between the components of the alloy and of the gaseous medium. As a rule, the oxide films, which contain predominantly oxides of the alloying elements (chromium, aluminum, and so on), are thermodynamically more stable than the oxides of the base elements. The protective action of the film depends on its density and adhesion to the base metal.

REFERENCES

Ignatov, D. V., and R. D. Shamgunova. O mekhanisme okisleniia splavov na osnove nikelia i khroma. Moscow, 1960.
Evans, U. R. Korroziia i okislenie metallov. Moscow, 1962. (Translated from English.)