Aplicação de espectroscopia de fotoelétrons ao estudo de processos de corrosão e oxidação de superfícies metálicas: Inconel 182, Fe/Cu(100) e U-Zr-Nb / Aplicação de espectroscopia de fotoelétrons ao estudo de processos de corrosão e oxidação de superfícies metálicas: Inconel 182, Fe/Cu(100) e U-Zr-Nb

Renato de Mendonça

In this work a study of the oxidation/corrosion process of three systems of metallic materials by Photoemission Spectroscopy is presented. In the first system, it was investigated the corrosion of Inconel 182 at simulated Pressurized Water Reactor (PWR) environment. Samples with and without surface chemical treatment were exposed to the simulated environment for until 8 weeks. The oxide layer formed on the surfaces of the samples at different conditions was characterized by Scanning Electron Microscopy and XPS coupled with argon ion sputtering. The comparison between the oxide films grown on the samples showed that the oxide layer formed on the chemically treated sample is thinner and relatively Cr-rich. In second system it was studied the initial oxidation at room temperature of epitaxial films of Fe evapored on Cu (100). The films were deposited with two different thicknesses in order to get the fcc Fe (100) and bcc Fe (110) surfaces. The results, obtained by photoemission spectroscopy at the TEMPO beamline of the Synchrotron Soleil, showed the formation of distinct oxides films. The surfaces also presented different kinetics of oxidation and the (110) Fe-bcc showed highest reactivity. The analysis of the data indicated the Fe1-xO formation on fcc Fe (100) and suggested the Fe1-xO and Fe3O4 formation on (110) Fe-bcc surface. In the last system, it was investigated the initial oxidation of U-Zr-Nb alloys at room temperature. For this experiment, the alloys were exposed to oxygen in ultra high vacuum. The analysis of the U 4f peak showed the fast formation of UO2 on the surfaces and similar kinetics of oxidation between the U and the U-Zr-Nb alloy. The alloying elements showed slower oxidation. The Zr 3d peak suggested the ZrO2 formation while the Nb 3d peak showed a remarkable enlargement that became necessary a deconvolution which indicated the formation of NbO, NbO2 and Nb2O5.

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