Microstructural Characterization and Cyclic Hot Corrosion Behaviour of Sputtered Co–Al Nanostructured Coatings on Superalloy

Abstract

Nanostructured Co-Al coatings on Superni-718 superalloy substrate were deposited by DC/RF magnetron sputtering in the present work. The microstructure and cyclic hot-corrosion behavior of nanostructured Co-Al coatings on Superni-718 superalloy were investigated in molten salt of 40 wt% Na 2 SO 4 ? 60 wt% V 2 O 5 at 900°C. The results showed that a dense scale formed on the coated samples exposed to corrosive environment during thermal cycling. The spinel phases of CoCr 2 O 4 , CoAl 2 O 4 and NiCr 2 O 4 were found in the corroded scale of the coatings, resulting in an effective inhibition of O and S diffusion. The sputtered Co-Al coatings exhibited high hot corrosion resistance due to the formation of b-CoAl phases in the coating. The relevant corrosion mechanisms substantiating the role of coatings are discussed.

Oxidation of Al-Co Alloys at High Temperatures

“…The formation of alumina scales may be achieved by pack aluminizing the alloy’s surface [ 13 , 14 , 15 ]. The application of Al-Co coatings could significantly extend the alloy’s lifetime [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

The degradation behaviour of nickel-based superalloys in the medical waste incineration plant

“…Most of the high temperature degradation studies have been carried out in simulated environment [10][11][12][13][14][15][16][17][18][19] and very few in-situ studies on superalloys have been carried out in a medical waste incinerator. Hence the aim of present study is to evaluate the degradation behaviour of nickel-based superalloys Superni-75, Superni-750 and Superni-718 hung inside the secondary chamber of a medical waste incinerator at SKIMS Hospital, Soura, Jammu and Kashmir, India which is a tertiary care 600 bedded teaching hospital, catering to the average socioeconomic class.…”