Effect of Aluminum Content on Corrosion Behavior of Ni-Al Alloys in Dilute Sulfuric Acid Solution
Ni-based high-temperature alloys(NiCrAlY)are commonly used in the hot sections of aerospace engines.Hot section components such as combustion chambers,guide vanes,and turbine blades require thermal barrier coatings(TBCs)for protection.TBCs consist of an oxidation-resistant met-al bond coat(BC)and a ceramic top coat(TC)that provides thermal insulation.The BC material is also NiCrAlY alloy,with Al and Cr content higher than the substrate Ni-based high-temperature alloys,leading to a 53 mV lower corrosion potential for BC compared to the substrate,therefore,resulting in galvanic couple with the BC.Herein,the influence of different Al contents in NiAl alloys on their corrosion behavior in dilute H2SO4,simulating the corrosive environment was studied.The result reveals that Ni95Al5 exhibits the highest corrosion potential and the lowest corrosion current density,while Ni75Al25 has a lower corro-sion potential.The research demonstrates that a high Al content in the BC is the primary cause of corro-sion in conditions of natural environment.
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