D. Tech. Chemical, Metallurgical and Materials Engineering / Corrosion is the chemical or electrochemical interaction between a material, especially metals, and their environment resulting in mild to severe deterioration of the material and its properties. The economic impact and problems resulting from corrosion has drawn strong attention from scientists and engineers worldwide. Stainless steel is the most important engineering metal worldwide, and industrially stainless steel is used extensively due to its resistance to corrosion e.g. in acid pickling, industrial acid cleaning, acid descaling, oil well acidizing and the petroleum industry. The corrosion resistance of stainless steels is due to the formation of a protective film which covers the steel surface instantaneously when exposed to mild operational conditions in the presence of oxygen; however, the oxide is most often porous and insufficient to protect the steel from further oxidation and corrosion attack in harsh environments. It is hypothesized that: In-depth understanding of the electrochemical behaviour of ferrous alloys in interaction with selected organic compounds in acidic environments will enhance inhibitor application for corrosion control; Failure and poor performance of most inhibitor admixtures can be eliminated with comprehensive knowledge of electrochemical interaction at the metal-inhibitor interface, passive film formation, duration and breakdown, adsorption characteristics, bond formation and molecular structure effect; Optimization of the current electroanalytical method will enhance effective pitting corrosion detection, analysis and control with the use of organic inhibiting compounds. The primary aim of this research is to develop the science required for the effective assessment, development and confident use of organic compounds (heterocyclic compound, organosulphur compound, simple alcohol, aromatic amine compound, aromatic amine derivative and aminoalcohol) and tested alloys (austenitic stainless steel type 304 and mild steel) for applications in astringent environments through conventional and optimized corrosion monitoring techniques.

No description available.

No description available.

No description available.

Stress corrosion cracking (SCC) susceptibility of the phosphorus de-oxidized copper has been evaluated in synthetic seawater polluted by sulfides using slow strain rate test (SSRT). The effect of concentration of sulfide, temperature, and applied cathodic and anodic potentials on the final strain values and maximum stress were also studied. No cracks were found under the tested conditions. The final strain and maximum stress values decreased but not significantly, with increase in the temperature, applied anodic potential and sulfide concentration. The observed effect is due to the section reduction by uniform corrosion. Lateral cross section and microscopic examination of the fractured specimen ruled out the existence of the localized corrosion. Electrochemical measurements showed that the Cu2S film is not a protective film and also exhibits a mass transfer limitation to the inward diffusion of the sulfides. Based on these results the reasons for the absence of cracking are also discussed.

Stress corrosion cracking (SCC) susceptibility of the phosphorus de-oxidized copper has been evaluated in synthetic seawater polluted by sulfides using slow strain rate test (SSRT). The effect of concentration of sulfide, temperature, and applied cathodic and anodic potentials on the final strain values and maximum stress were also studied. No cracks were found under the tested conditions. The final strain and maximum stress values decreased but not significantly, with increase in the temperature, applied anodic potential and sulfide concentration. The observed effect is due to the section reduction by uniform corrosion. Lateral cross section and microscopic examination of the fractured specimen ruled out the existence of the localized corrosion. Electrochemical measurements showed that the Cu2S film is not a protective film and also exhibits a mass transfer limitation to the inward diffusion of the sulfides. Based on these results the reasons for the absence of cracking are also discussed.

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 149-158). Also available via World Wide Web.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1968. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

Scanning electrochemical microscopy is a method that incorporates an ultramicroelectrode capable of facilitating electrochemical reactions paired with an XYZ positioning system capable of micron-level movements. This study investigates the corrosion behavior of structural transition joint clad material that contains steel, pure aluminum, and an aluminum alloy blast welded into a single joint. This study will characterize the corrosion response of the structural transition joint and identify the galvanic activity measured between its layers. High-temperature coatings in this study are designed to be used effectively up to 1400?F. In this study, we characterized several commercial high-temperature coatings exposed to different levels of heat. General trends of decreasing barrier performance were observed with the exception when these coatings are exposed to their rated temperature limit of 1400?F, at which the barrier increased slightly, indicated by their low-frequency impedance modulus. The cause is a combination of sintering and oxide formation.