Combating Corrosion Degradation of Turbine Materials Using HVOF Sprayed 25% (Cr3C2-25(Ni20Cr)‎)‎ + NiCrAlY Coating

Abstract EN

High velocity oxy fuel process (HVOF) is an advanced coating process for thermal spraying of coatings on to components used in turbines.

HVOF process is a thermal spray coating method and is widely used to apply wear, erosion, and corrosion protective coatings to the components used in industrial turbines.

25% (Cr3C2-25(Ni20Cr)) + NiCrAlY based coatings have been sprayed on to three turbine materials, namely, Ti-31, Superco-605, and MDN-121.

Coated and uncoated substrates were subjected to hot corrosion study under cyclic conditions.

Each cycle consisted of 1 hour heating at 800°C followed by 20 minutes air cooling.

Gravimetric measurements were done after each cycle and a plot of weight gain as a function of number of cycles is drawn.

Parabolic rate constants were estimated for the understanding of corrosion behaviour.

It was observed that coated Ti-31 and MDN-121 were more resistant compared to the uncoated ones.

Uncoated superco-605 was undergoing sputtering during corrosion study and hence comparison between coated and uncoated superco-605 was difficult.

The cross-sectional analysis of the corroded, coated samples indicated the presence of a thin layer of chromium oxide scale on the top of the coating and it imparted better corrosion resistance.

Parabolic rate constants also indicated that coating is more beneficial to Ti-31 than to MDN-121.