Full text
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| Author(s): |
Sérgio Venancio da Silva
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 1999-08-27 |
| Examining board members: |
Stephan Wolynec;
Isolda Costa;
Zehbour Panossian
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| Advisor: | Stephan Wolynec |
| Abstract | |
The aim of presente investigation was to characterize both in terms of morphology and chemical composition the rust formed on carbono steels having different chemical compositions and to establish a correlation between these parameters. To attain this purpose 26 carbon steel samples were used. They were prepared for a doctor thesis research Project under way at EPUSP. These samples, produced according to a partial factorial type planning with different contentes of copper, phosphorus, molybdenum and nickel, were submitted to an atmospheric corrosion testa t the Atmospheric Corrosion Testing Site (Industrial Atmosphere) of Companhia Siderúrgica Paulista COSIPA, in Cubatão, SP. For morphology characterization of the rust formed on these steels the scanning eléctron microscopy (SEM) was used, both with and without carbono deposition. Its chemical analysis was attempted with Raman spectroscopy, reflectance spectroscopy. Mössbauer spectroscopy, x-ray diffraction, and energy dispersive spectroscopy (EDS) (attached to SEM). The Raman spectroscopy and the x-raydiffraction analyses were performed directly on sample surfaces, without removal of rust (in situ analysis), while the Mössbauer spectroscopy analysis was undertaken with rust removed from the surface by scraping. In the in situ analyses the external componentes of the rust were preferentially detected. In virtually all analyses the hematite was the dominant compound. The Mössbauer spectroscopy analysis, on the other hand, using removed rust samples, identified more internal componentes of the rust. Even so it was not possible to detect the -Fe00H amorphous componente which is formed close to the interface with the metal, probably due to an incomplete removal of the rust from the metal surface. The EDS analysis supplied limited information,showing only that the four alloy elements are uniformly dispersed through the rust. For rust analysis the reflectance spectroscopy technique was inadequate. It was not possible to establish a correlation between the componentes identified in the rust and the alloy elements Cu, P, Mo and Ni. (AU) | |