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Application of electrochemical impedance spectroscopy as a non-destructive technique to characterize and detect degradation of carbon/nylon, 6 composites in aqueous environments
Title
Application of electrochemical impedance spectroscopy as a non-destructive technique to characterize and detect degradation of carbon/nylon, 6 composites in aqueous environments.
Creator
Haniyur, Ravishankar V., Florida Atlantic University, McIntyre, Jack F.
Abstract/Description
Experiments were conducted to investigate the degradative effects of ambient and high pressure aqueous environments on unidirectional carbon fiber nylon (AS4/nylon 6) composites. Electrochemical impedance spectroscopy (EIS) was selected for development as a non-destructive method to characterize the degradation phenomena in carbon/nylon composites as result of moisture absorption. EIS data was collected for composites and neat resins as a function of immersion time in ambient and pressurized ...
Show moreExperiments were conducted to investigate the degradative effects of ambient and high pressure aqueous environments on unidirectional carbon fiber nylon (AS4/nylon 6) composites. Electrochemical impedance spectroscopy (EIS) was selected for development as a non-destructive method to characterize the degradation phenomena in carbon/nylon composites as result of moisture absorption. EIS data was collected for composites and neat resins as a function of immersion time in ambient and pressurized (6.2 MPa) 3.5% NaCl solution. EIS was also utilized to understand degradative mechanisms when composites were subject to cathodically induced damage. Concurrent EIS and 3-point mechanical loading was also performed on composites to study the changes in the impedance response as a function of loading. A detailed equivalent circuit analysis is also presented in an attempt to elucidate the degradation phenomena in composites. Gravimetric and 3-point mechanical testing data is also presented to study the effect of ambient and pressurized aqueous environments on composites. Scanning electron micrographs of composites are also included to assist in morphological evaluation.
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Date Issued
1993
PURL
http://purl.flvc.org/fcla/dt/14907
Subject Headings
Impedance spectroscopy, Composite materials, Polymeric composites, Absorption, Environmental degradation--Moisture
Format
Document (PDF)
Evaluation of corrosion behavior of ion vapor deposited aluminum related coating systems
Title
Evaluation of corrosion behavior of ion vapor deposited aluminum related coating systems.
Creator
Hang, Ling., Florida Atlantic University, McIntyre, Jack F.
Abstract/Description
Experiments were conducted to investigate the effectiveness of ion vapor deposited (IVD) aluminum as a base coat for polyurethane topcoat systems in marine environments. Three test environments were used including marine atmospheric atmosphere, quiescent filtered seawater open to laboratory air and aerated seawater. Visual observation and electrochemical impedance spectroscopy techniques were primary testing methods; other characterizations included adhesion tape test, coating thickness...
Show moreExperiments were conducted to investigate the effectiveness of ion vapor deposited (IVD) aluminum as a base coat for polyurethane topcoat systems in marine environments. Three test environments were used including marine atmospheric atmosphere, quiescent filtered seawater open to laboratory air and aerated seawater. Visual observation and electrochemical impedance spectroscopy techniques were primary testing methods; other characterizations included adhesion tape test, coating thickness measurements, holiday detection, optical microscopy, open circuit potential measurements and potentiodynamic polarization. It was found that IVD aluminum was a good candidate for replacement of environmentally sensitive coatings on AA2219-T87 and AISI 4340 steel substrates, respectively. The IVD aluminum coating provided good sacrificial protection and served as a good base for polyurethane topcoat systems. Electrochemical impedance spectroscopy was a suitable method to predict coating performance in the early stages of exposure.
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Date Issued
1993
PURL
http://purl.flvc.org/fcla/dt/14970
Subject Headings
Aluminum coating, Corrosion and anti-corrosives, Metals--Corrosion fatigue, Electrochemical analysis
Format
Document (PDF)
Combined influence of heat treatment and immersion corrosion on the tensile-shear strength of aluminum-steel explosively welded plates
Title
Combined influence of heat treatment and immersion corrosion on the tensile-shear strength of aluminum-steel explosively welded plates.
Creator
Oberle, Hugues., Florida Atlantic University, McIntyre, Jack F., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
A series of experiments were performed on aluminum-steel explosively welded joints. The pub of this research was to better understand the synergism, if any, between thermal heat treatments and exposure to a seawater environment on the tensile-shear strength of the explosively welded joint. The effect of three different heat treatments on the tensile-shear strength of the bond was examined. The combined effect of two heat treatments and immersion in flowing aerated, natural seawater has been...
Show moreA series of experiments were performed on aluminum-steel explosively welded joints. The pub of this research was to better understand the synergism, if any, between thermal heat treatments and exposure to a seawater environment on the tensile-shear strength of the explosively welded joint. The effect of three different heat treatments on the tensile-shear strength of the bond was examined. The combined effect of two heat treatments and immersion in flowing aerated, natural seawater has been studied for two different corrosion times. For comparison purposes, some samples were also immersed in stagnant, aerated 3.5% weight NaCl solution. Open circuit potential measurements and microhardness profiles were also made. It was found that a heat treatment that would anneal the aluminum without causing the formation of an intermetallic layer at the aluminum steel explosively welded interface, was the best compromise between reduced mechanical properties and improved corrosion resistance.
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Date Issued
1991
PURL
http://purl.flvc.org/fcla/dt/14768
Subject Headings
Steel-aluminum alloys, Thermal stresses, Welded joints--Testing
Format
Document (PDF)
Study of corrosion-induced failure mechanisms of epoxy-coated reinforcing steel
Title
Study of corrosion-induced failure mechanisms of epoxy-coated reinforcing steel.
Creator
Lee, Seung-Kyoung, Florida Atlantic University, Hartt, William H., McIntyre, Jack F., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
A study of the corrosion protection afforded by epoxy coatings on reinforcing steel was performed. To accomplish this bars were acquired from ten sources and coatings were characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in various aqueous solutions at both ambient temperature and 80$\sp\circ$C and in chloride-contaminated concrete slabs under outdoor exposure. Direct pull-off adhesion testing was performed on tested and...
Show moreA study of the corrosion protection afforded by epoxy coatings on reinforcing steel was performed. To accomplish this bars were acquired from ten sources and coatings were characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in various aqueous solutions at both ambient temperature and 80$\sp\circ$C and in chloride-contaminated concrete slabs under outdoor exposure. Direct pull-off adhesion testing was performed on tested and virgin epoxy coated reinforcing steels (ECRs). Electrochemical impedance spectroscopy (EIS) scans were made periodically, and a curve fitting technique was employed to analyze coating parameters. Conventional electrochemical measurements were also made, and corrosion morphology of ECR specimens was examined. It was found that the density and size of coating defects was the primary factor affecting ECR performance. The circuit analysis indicated that poorly performing defect-free coatings absorbed water and oxygen; and these species reached the coating/substrate interface and electrochemical reactions at the interface caused coating degradation. By way of contrast, the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here also. Experimental results indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects developed during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment.
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Date Issued
1994
PURL
http://purl.flvc.org/fcla/dt/12389
Subject Headings
Corrosion and anti-corrosives, Epoxy coatings, Steel--Corrosion, Concrete--Corrosion
Format
Document (PDF)