Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8948440 | Ceramics International | 2018 | 14 Pages |
Abstract
Samarium strontium aluminate (Sm2SrAl2O7-SSA) and Yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) were developed on NiCrAlY bond coated Inconel 718 superalloy substrate using air plasma spray process. The hot corrosion study was conducted in simulated gas turbine environments (molten mixtures of 50â¯wt% Na2SO4 + 50â¯wt% V2O5 and 90â¯wt% Na2SO4 + 5â¯wt% V2O5 + 5â¯wt% NaCl) for two different temperatures of 700 and 900â¯Â°C. A developed SSA TBCs showed about 8% and 22% lower lifetime at 700 and 900â¯Â°C, respectively than YSZ TBCs in 50â¯wt% Na2SO4 +â¯50â¯wt% V2O5 (vanadate). The hot corrosion life of SSA TBCs being found about 13% and 39% lower than YSZ TBCs in 90â¯wt% Na2SO4 +â¯5â¯wt% V2O5 +â¯5â¯wt% NaCl (chloride) at 700 and 900â¯Â°C, respectively. X-ray diffraction results showed the formation of SmVO4, SrV2O6, and SrSO4 as a major hot corrosion product in 50â¯wt% Na2SO4 +â¯50â¯wt% V2O5 and 90â¯wt% Na2SO4 +â¯5â¯wt% V2O5 +â¯5â¯wt% NaCl environments respectively for SSA TBCs. Similarly, YSZ TBCs also showed YVO4 as hot corrosion product in vanadate and chloride environments. Both the TBCs suffer a more severe hot corrosion attack in chloride environment at 900â¯Â°C. The leaching of Sr2+ and Y3+ ions from SSA and YSZ respectively play a vital role in the destabilization of coating in vanadate and chloride environments at 700 and 900â¯Â°C. In both SSA and YSZ TBCs, the leaching of ion has significantly low influence as compared to attack by chloride ions at the bond coat-top coat interface in the presence of chloride environment. The hot corrosion resistance of SSA TBCs was improved three times higher in the presence of MgO and NiO inhibitor in vanadate environment at 900â¯Â°C mainly due to the formation of a stable Ni3V2O8 phase at the surface.
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Authors
T. Baskaran, Shashi Bhushan Arya,