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Improved Meso-Scale and Atom-Scale Imaging for Atomic Force Microscopy Study of Corrosion.

Singjai, Pisith. (2000) Improved Meso-Scale and Atom-Scale Imaging for Atomic Force Microscopy Study of Corrosion. Doctoral thesis, University of Surrey (United Kingdom)..

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Abstract

In this thesis, both fundamental work and its applications will be presented. The course of the work is based on AFM analysis which has been recently established as a standard surface analysis tool. The study was aimed at aqueous corrosion of polycrystalline copper in both ex situ and in situ investigation. Recently published literature on initial corrosion, i.e. dissolution, deposition, adsorption and etc. of copper will be reviewed at the beginning. The first part of this work was carried out by means of computational calculation in order to enhance and make more pronounced AFM imaging on both a microscopic scale and a nanoscopic scale. Image convolution caused by a finite size of a probing tip and other sources of noises were examined and further protected or reduced in AFM imaging. A new filtering technique, as a so-called “closing filter” was developed to solve the problem of downward noise presented in a grey-scale image before a well known morphological de-convolution will be adopted. Computer simulation of rigid surface models scanned by an idealised probing tip was performed in order to optimise imaging conditions and probing tip selection. Consequently, the work could yield one the best AFM atomic image of HOPG ever published and further suggested a possibility of diamond-like structure of graphite induced by the probing tip load force. The second part dealt with experimental work in both ex situ micrometer scale examination and in situ observation at atomic level under dilute HCl solution. The standard method of sample preparation was adopted, in which the process clearly revealed crystal grain and other microstructure. An interesting relation between etching rate and its microroughness was found which could lead to estimate dissolution rate by using AFM. As a consequence of the work, the top-most grain was selected, which was assumed to be the most thermodynamic stable face, i.e. Cu(111) for examination on an atomic scale. The result found was that the adsorbed layer of Cl ions on a bare copper surface have the structure (3 x 3)R30-Cl, which is in good agreement to most literature on single crystals. This is the very first report that provided an alternative method for study of initial corrosion by AFM at atomic level, especially, to study engineering metals rather than the mostly published work using single crystals.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors : Singjai, Pisith.
Date : 2000
Additional Information : Thesis (Ph.D.)--University of Surrey (United Kingdom), 2000.
Depositing User : EPrints Services
Date Deposited : 14 May 2020 14:16
Last Modified : 14 May 2020 14:18
URI: http://epubs.surrey.ac.uk/id/eprint/856500

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