OXIDATION OF LOW CHROMIUM STEELS

摘要

The present invention is a process for forming protective films on an alloy substrate by: oxidizing an alloy comprising iron and chromium in an oxygen containing atmosphere, said alloy containing from abou t 5 to about 15 wt-% chromium, at a temperature of from about 200 .degree.C (473 K) to about 1400 .degree.C (1673 K), more preferabl y 300 .degree.C (573 K) to 600 .degree.C (873 K) wherein the partial pressure of oxygen in said oxygen containing atmosphere is above or equal to the dissociation pressure of Fe304 and Fe0 below or equal to the dissociation pressure of Fe2Os within the specified temperature range, and f or a time sufficient to effect the formation of a film comprising iron-chromium oxide (FeCr2O4) spiel on the surface of said alloy. In a farth er embodiment, the film may additionally contain silicon. The figure shows the oxygen partial pressures which must be used over the specified temperature ranges to obtain mixed iron-chromium spinels.