High-temperature corrosion behaviour of Pt-modified aluminide coating with solid NaCl deposit in O2 + 10 vol% H2O and the influence of pre-oxidation treatment.

The electroplating and subsequent above-pack aluminisation were used to prepare a single-phase (Ni,Pt)Al coating on the second generation Ni-based single crystal superalloy. Corrosion behaviour of the (Ni,Pt)Al coating with and without pre-oxidation have been evaluated at1000 °C under simulated marine-environment. The results indicated that the pre-oxidised coating exhibited improved corrosion resistance compared with the one without pre-oxidation, due to the formation of stable and exclusive α-Al 2 O 3 layer. The synergistic effect of NaCl and water vapour plus oxygen on the corrosion mechanism of (Ni,Pt)Al coating was intensively discussed. [Display omitted] • Corrosion behaviour of (Ni,Pt)Al coating under environment of NaCl plus O 2 /H 2 O vapour is investigated. • Failure of (Ni,Pt)Al is related to formation of volatile metal chlorides and internal oxidation. • NaCl promotes α-Al 2 O 3 formation and induces formation of nodule-like oxide scale. • Pre-oxidation treatment can retard degradation and failure of (Ni,Pt)Al coating to some extent. [ABSTRACT FROM AUTHOR]