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 about 5 to about 15 wt-% chromium, at a temperature of from about 200 DEG C (473 K) to about 1400 DEG C (1673 K), more preferably 300 DEG C (573 K) to 600 DEG C (873 K) wherein the partial pressure of oxygen in said oxygen containing atmosphere is above or equal to the dissociation pressure of Fe3O4 and FeO below or equal to the dissociation pressure of Fe2O3 within the specified temperature range, and for a time sufficient to effect the formation of a film comprising iron-chromium oxide (FeCr2O4) spinel on the surface of said alloy. In a further 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.