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Full-Text Articles in Mechanical Engineering
Modeling Stress Distributions In Anodic Alumina Films Prior To The Onset Of Pore Formation, Kurt R. Hebert, Ömer Ö. Çapraz, Shinsuke Ide, Pranav Shrotriya
Modeling Stress Distributions In Anodic Alumina Films Prior To The Onset Of Pore Formation, Kurt R. Hebert, Ömer Ö. Çapraz, Shinsuke Ide, Pranav Shrotriya
Ömer Özgür Çapraz
Porous anodic oxide (PAO) films are produced when reactive metals such as Al and Ti are electrochemically oxidized in baths that dissolve the oxide. Research in PAObased devices has been stimulated by the self-organized hexagonally ordered pore arrays found for some anodizing conditions. The initiation and ordering of pores follows a morphological instability of the initially planar barrier oxide, upon reaching a critical oxide thickness.
Morphological Instability Leading To The Formation Of Self-Ordered Porous Anodic Oxide Films, Ömer Özgür Çapraz, Kurt R. Hebert, Pranav Shrotriya, Fanliang Gao, Wei Hong
Morphological Instability Leading To The Formation Of Self-Ordered Porous Anodic Oxide Films, Ömer Özgür Çapraz, Kurt R. Hebert, Pranav Shrotriya, Fanliang Gao, Wei Hong
Ömer Özgür Çapraz
Porous anodic oxide (PAO) films are grown by electrochemical polarization of Al, Ti, Zr, Nb, Hf, and W in baths that dissolve the oxide. Procedures to grow films with highly ordered arrangements of nanoscale pores have led to the extensive use of PAO films as templates for nanostructured devices. The porous film geometry may be controlled precisely via the film formation voltage and bath composition (1). Recently, tracer studies and modeling showed that transport in the amorphous oxide involves both electrical migration and plastic flow (2,3). The oxide seems to behave as an incompressible material during steady-state growth of the …
Stress Distributions In Anodic Alumina Films Prior To The Onset Of Pore Formation, Ömer Ö. Çapraz, Pranav Shrotriya, Kurt R. Hebert
Stress Distributions In Anodic Alumina Films Prior To The Onset Of Pore Formation, Ömer Ö. Çapraz, Pranav Shrotriya, Kurt R. Hebert
Ömer Özgür Çapraz
Porous anodic oxide (PAO) films are grown by electrochemical oxidation of valve metals in baths that dissolve the oxide. The self-organized hexagonal patterns of pores in these films have led to many investigations of PAO-based devices. However, the mechanisms of pore formation and ordering have not yet been fully explained. Recent experimental and modeling results indicate the importance of plastic flow during growth of self-ordered PAO.1 Here we investigated the origin of stress driving plastic flow, and the possible role of stress in the morphological instability leading to pore formation. We report the first measurements of the evolution of stress …
Tensile Stress Induced By Aluminum Corrosion, Ömer Ö. Çapraz, Kurt R. Hebert, Pranav Shrotriya, Gery R. Stafford
Tensile Stress Induced By Aluminum Corrosion, Ömer Ö. Çapraz, Kurt R. Hebert, Pranav Shrotriya, Gery R. Stafford
Ömer Özgür Çapraz
Stress corrosion cracking (SCC) is a critical problem affecting the safety and viability of both existing energy conversion systems and ones under consideration for future development. In SCC, chemical interactions of a metal with the environment during corrosion accelerate degradation of materials under tensile applied stress, by reducing the critical stress intensity for crack propagation. Many competing mechanisms for the effect of corrosion in SCC have been put forth, including formation of brittle oxide or hydride phases, stress concentration at corrosion pits, and absorption of hydrogen. An additional mechanism is based on observed generation of tensile stress during corrosion of …
Curvature Interferometry Based In-Situ Measurement Of Stresses Associated With Electrochemical Reactions, Ömer Ö. Çapraz, Pranav Shrotriya, Kurt R. Hebert
Curvature Interferometry Based In-Situ Measurement Of Stresses Associated With Electrochemical Reactions, Ömer Ö. Çapraz, Pranav Shrotriya, Kurt R. Hebert
Ömer Özgür Çapraz
Anodization1 as well as dissolution2 of reactive metals such as aluminum results in buildup of significant levels of stresses on the reacting surface. In-situ measurement of stress evolution can provide remarkable insights into the associated electrochemical reactions and help in understanding the governing mechanisms. We report a curvature interferometry based technique for in-situ monitoring of stress evolution. Curvature interferometer is incorporated into the electrochemical cell and is used to monitor the curvature changes of the samples in order to determine the stress-thickness product of the film formed on the reacting surface.
Electrochemical And Metal-Phase Processes Accompanying Hydrogen Absorption In Aluminum During Aqueous Corrosion, Kurt R. Hebert, Ömer Ö. Çapraz, Pranav Shrotriya, Guiping Zhang
Electrochemical And Metal-Phase Processes Accompanying Hydrogen Absorption In Aluminum During Aqueous Corrosion, Kurt R. Hebert, Ömer Ö. Çapraz, Pranav Shrotriya, Guiping Zhang
Ömer Özgür Çapraz
Alkaline corrosion of aluminum results in large supersaturations of hydrogen, and formation of hydride and subsurface voids.1-4 Aluminum itself is not susceptible to stress corrosion cracking (SCC), but hydrogen and hydride effects are significant for SCC mechanisms on Al and Mg alloys. Chu found evidence that corrosion-induced tensile stress in several alloys additively combines with external tensile stress to promote SCC, and attributed the former to lattice contraction associated with vacancies injected during corrosion.5 Evidence for vacancy injection on Al was found from X-ray diffraction and in situ curvature measurements on Al thin films undergoing corrosion.1,6 Here we report new …
In Situ Stress Measurement During Aluminum Anodizing Using Phase-Shifting Curvature Interferometry, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya
In Situ Stress Measurement During Aluminum Anodizing Using Phase-Shifting Curvature Interferometry, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya
Ömer Özgür Çapraz
Stress measurements yield insight into technologically relevant deformation and failure mechanisms in electrodeposition, battery reactions, corrosion and anodic oxidation. Aluminum anodizing experiments were performed to demonstrate the effectiveness of phase-shifting curvature interferometry as a new technique for high-resolution in situ stress measurement. This method uses interferometry to monitor surface curvature changes, from which stress evolution is inferred. Phase-shifting of the reflected beams enhanced measurement sensitivity, and the separation of the optical path from the electrochemical cell in the present system provided increased stability. Curvature changes as small as 10−3 km−1 were detected, at least comparable to the resolution of state-of-the-art …
Morphological Instability Leading To Formation Of Porous Anodic Oxides, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya
Morphological Instability Leading To Formation Of Porous Anodic Oxides, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya
Ömer Özgür Çapraz
No abstract provided.