TY - JOUR A1 - Nofz, Marianne A1 - Zietelmann, Christina A1 - Feigl, Michael A1 - Dörfel, Ilona A1 - Saliwan Neumann, Romeo T1 - Microstructural origin of time-dependent changes in alumina sol-gel-coated Inconel 718 exposed to NaCl solution T2 - Journal of sol gel science and technology N2 - Inconel 718 was spin coated twice and fourfold with a sol to obtain 200- and 400-nm-thick transition alumina films on the surface. Bare and sol–gel alumina-coated Inconel 718 samples were exposed to NaCl solution to study their corrosion behavior by means of electrochemical impedance spectroscopy. In combination with scanning electron microscopy, it was shown that bare Inconel 718 is after initial passivation prone to pitting corrosion. For the coated Inconel 718 samples, an improvement in the protective effect of the coatings with time was observed. This observation is in contradiction to the results of other authors who observed degradation of alumina coatings exposed to NaCl solution with time. Transmission electron microscopy revealed a formation of (1) a compacted region at the coating surface as well as (2) a chromium-rich region at the interface between coating and alloy during the contact with a NaCl solution. The last one mainly contributes to the observed chronological sequence of electrochemical characteristics of the samples. PB - Kluwer Academic Publ. CY - Dordrecht KW - Alumina coatings KW - Superalloys KW - Corrosion protection KW - EIS KW - SEM KW - TEM PY - 2015 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/33338 AN - OPUS4-33338 SN - 0928-0707 SN - 1573-4846 VL - 75 IS - 1 SP - 6 EP - 16 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany