Studies on the corrosion protection of metal by alloying and organic inhibitors /
On the Protectiviiy of Supersaturated Aluminum Alloys
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739887521&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | On the Protectiviiy of Supersaturated Aluminum Alloys The mechanism of the protectivity of the passive film of aluminum and supersaturated aluminum alloys such as Al-W, Al- Mo, Al-Ta and Al-Cu has been investigated in chloride environments. The PZC (potential of zero charge) of the passive film was determined by a method based on impedance spectroscopy. The chloride ion adsorption on the passive film surface was measured by means of an in situ radiotracer technique. Constituents of the passive film as a function of depth have been investigated by means of ex situ spectroscopic techniques such as XPS, ISS and SIMS. The PZC's of the passive films of Al and Al alloys were calculated from the flatband potentials. A linear correlation between the pitting potential and the PZC was found. Adsorption of the chloride ion on the Al-Ta surface starts at more anodic potentials compared with pure Al and this shift is in agreement with the anodic shift of the PZC. The mole fraction of the alloying elements in the surface region of the passive film is ca. 1 [] 8%. The structure of the passive film was modeled as two layers; an OH--rich top layer and an OH--poor inner layer. The adsorption of the chloride ion on the surface of the passive film is influenced by the anodic PZC shift which varies with the alloying element. However, retardation of the chloride penetration into the passive film by means of blocking of the entry site of the chloride seems to be the rate determining step in the mechanism of the protectivity of the supersaturated aluminum alloys. On the Organic inhibitors on Iron The corrosion inhibition efficiency of different groups of organic compounds such as linear alkyl compounds, indole derivatives, N-containing heterocyclic compound, N- containing heterocyclic compounds was investigated to understand the structure-inhibition relationship. The adsorption of the inhibitor-like organic compounds on the iron surface was determined by means of a radiotracer technique. A bell shaped adsorption curve as a function of the applied potential was obtained in C02 saturated brine solution and the maximum of the adsorption curve is in good agreement with the PZC of bare iron. Organic inhibitors mainly adsorb on bare iron surface and not on the iron carbonate film in C02 saturated brine solution. |
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| Item Description: | Vita. "Major Subject: Chemistry". |
| Physical Description: | xxi, 286 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 261-276. |