EFFECT OF MAGNETRON-SPUTTERED Al FILM ON LOW-TEMPERATURE PACK-ALUMINIZING COATING FOR OIL CASING STEEL N80

Low-temperature aluminizing coating was prepared onto the surface of oil casing steel N80 with a magnetron-sputtered Al film to improve its corrosion resistance. Results show that magnetron-sputtered Al film is able to form gradient aluminide coating, composed of iron aluminide FeAl3, Fe2Al5 and Fe3Al with different contents of aluminum. Both the density and continuity of iron aluminide layer for oil casing steel N80 with magnetron-sputtered Al film can be improved. Under the same corrosion condition, aluminized oil casing steel N80 with a magnetron-sputtered Al film shows an outstanding corrosion resistance than those of original and aluminized ones without magnetron-sputtered Al film. The positive effect of Al film is considered as the concentration change of active Al atom for diffusion to form the aluminizing coating during the pack processing.