High temperature oxidation resistance of M42C stainless steel coatings deposited on the surface of cast iron through atmospheric plasma spraying

• The M42C coatings deposited by APS had much better oxidation resistance than those of cast irons at 400 °C, 530 °C and 700 °C.
• The oxidation resistance of the M42C coating was close to that of the bulk at 700 °C.
• Martensites with dot, long-strip and bulk shapes existed in as-sprayed M42C coatings.
• Chromite spinel FeCr2O4 was formed to hinder the further oxidation in the oxided M42C coatings.

M42C stainless steel coatings were deposited on the surface of cast iron through atmospheric plasma spray with different plasma arc powers of 30 kW, 35 kW and 40 kW to obtain higher oxidation resistance than that of cast iron. The high temperature oxidation tests were carried out at 400 °C, 530 °C and 700 °C. It was found that the oxidation mass gains of the M42C coatings were much lower than those of cast irons during initial oxidation. With the increase of oxidation temperature and time, the oxidation mass gains of cast irons increased much more quickly than those of the M42C coatings. At 400 °C and 530 °C, the oxidation mass gains of the M42C coatings were higher than that of the M42C bulk. When the temperature reached 700 °C, the oxidation mass gains of the M42C coatings were just a little higher than that of the M42C bulk. Chromite spinel FeCr2O4 were formed which could hinder the further oxidation in the M42C coating. During the service of the M42C coatings at 700 °C, the oxidation resistance of the M42C coating was increased to the level close to that of the bulk.