Engineering Commons^™

Surface Modification Of Aluminum Alloys By Plasma Electrolytic Oxidation, Vahid Dehnavi

Electronic Thesis and Dissertation Repository

Plasma Electrolytic Oxidation (PEO) is a surface treatment for the production of ceramic oxide coatings with great properties, such as high wear and corrosion resistance, on metal substrates, particularly aluminum and magnesium alloys. Formation of PEO coatings involves complex processes and mechanisms that are difficult to study. Currently, the PEO process is in a transition phase from research to commercial application, with a primary focus on the corrosion and wear protection of light alloys, and has recently generated interest as a promising surface treatment for biomedical applications.

To justify the industrial application of PEO, a more systematic and in-depth study …

A Rubric For Electrochemical Testing Of Metallic Biomaterials, Frederick G. De La Fuente

Master's Theses

Corrosion is a major factor for the failure of metallic medical implants. Testing a metal’s suseptability to corrosion prior to implantation is key to a successful implantation. Electrochemical processes were used in this study to evaluate the characteristics of corrosion of both AISI 316 stainless steel and titanium alloy Ti6Al4V, welded and non-welded. Linear, potentiodynamic, and cyclic polarization curves were produced by the PARC 2273 potentiostat showing the corrosion tendencies of the metals in four unique solutions 3.5% NaCl, 0.35% NaCl, phosphate buffered saline solution (PBS), and Butterfield phosphate buffered solution (BPS). The concentration of chloride ions in solutions affected …

Feasibility Of Application Of Cathodic Prevention To Cracked Reinforced Concrete In Marine Service, Kevin Williams

USF Tampa Graduate Theses and Dissertations

Corrosion can take place as chloride ions accumulate above a critical concentration (CT) at the surface of a reinforcing bar inside concrete in marine service. The initiation of corrosion can be delayed by polarizing the steel cathodically, which is known to increase the value of CT. That effect is the basis of the cathodic prevention (CPrev) method to control corrosion of reinforcing steel in concrete. However, concrete cracks are a common occurrence and at cracks, the buildup of chloride ions is accelerated to the extent that CPrev may be less effective. The findings from an ongoing investigation to determine the …

Friction Bit Joining Of Dissimilar Combinations Of Advanced High-Strength Steel And Aluminum Alloys, Lile P. Squires

Theses and Dissertations

Friction bit joining (FBJ) is a new method that enables lightweight metal to be joined to advanced high-strength steels. Weight reduction through the use of advanced high-strength materials is necessary in the automotive industry, as well as other markets, where weight savings are increasingly emphasized in pursuit of fuel efficiency. The purpose of this research is twofold: (1) to understand the influence that process parameters such as bit design, material type and machine commands have on the consistency and strength of friction bit joints in dissimilar metal alloys; and (2) to pioneer machine and bit configurations that would aid commercial, …

Flexural Behavior Of Reinforced Concrete T-Beams Strengthened With Nsm Composite System Under Accelerated Corrosion., Anes Bouchair

Theses

This research work aims at evaluating the effects of corrosion on flexural response of simply supported reinforced concrete (RC) T-Beams strengthened with near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) strips. The research comprised experimental testing and analytical modelling. Test parameters included concrete grade, amount of NSM-CFRP strips, presence of U-wraps along the beam span, and time of corrosion exposure. A total of eighteen reinforced concrete beams with a T-shaped cross section were tested. Fourteen beams were strengthened in flexure and four beams were not strengthened to act as benchmarks. The strengthening regime included installation of either two or four NSM-CFRP strips into …

Corrosion Assessment And Enhanced Biocompatibility Analysis Of Biodegradable Magnesium-Based Alloys, Luis Enrique Pompa

Theses and Dissertations - UTB/UTPA

Magnesium alloys have raised immense interest to many researchers because of its evolution as a new third generation material. Due to their biocompatibility, density, and mechanical properties, magnesium alloys are frequently reported as prospective biodegradable implant materials. Moreover, magnesium based alloys experience a natural phenomena to biodegrade in aqueous solutions due to its corrosive activity, which is excellent for orthopedic and cardiovascular applications. However, major concerns with such alloys are fast and non-uniform corrosion degradation. Controlling the degradation rate in the physiological environment determines the success of an implant. In this investigation, three grades of magnesium alloys: AZ31B, AZ91E and …

Influence Of Surface Modification On Corrosion And Biocompatibility Of Titanium Alloys, Zia Ur Rahman

Theses and Dissertations - UTB/UTPA

Titanium alloys enhance the quality and longevity of human life by replacing or treating various parts of the body. However, the aggressive body fluids lead to corrosion and metal ions dissolution. These ions leach to the adjacent tissues and causes adverse reactions. Surface modifications improve corrosion resistance and biological activity. In this investigation, electropolishing, magnetoelectropolishing, titanium coating and hydroxyapatite coating were carried out on commercially pure titanium (CPTi), Ti6Al4V and Ti6Al4V-ELI (Extra Low Interstitials). These surface modifications are known to affect surface chemistry, morphology, wettability, corrosion resistance and biocompatibility of these materials. In vitro cyclic potentiodynamic polarization tests were conducted …

Sensitivity Of Electrochemical Impedance Spectroscopy Measurements To Concrete Bridge Deck Properties, Hillary Mckenna Argyle

Theses and Dissertations

Numerous methods have been developed to measure corrosion potential relating to chloride infiltration in concrete, including an emerging application of electrochemical impedance spectroscopy (EIS). EIS involves measurements of electrical impedance to evaluate the corrosion potential of steel reinforcement in concrete. With EIS, current is injected vertically into the concrete bridge deck between the surface and the embedded reinforcing steel, usually the top mat, to evaluate the degree to which the reinforcing steel is protected from chloride infiltration by the entire bridge deck system. The objectives of this research were to 1) investigate the sensitivity of EIS measurements obtained at various …

Development Of A Chloride Concentration Sampling Protocol For Concrete Bridge Decks, Sharlan Renae Montgomery

Theses and Dissertations

As the primary cause of concrete bridge deck deterioration in the United States is corrosion of the steel reinforcement as a result of the application of chloride-based deicing salts, chloride concentration testing is among the most common techniques for evaluating the condition of a concrete bridge deck. The objectives of this research were to 1) compare concrete drilling and powder collection techniques to develop a sampling protocol for accurately measuring chloride concentrations and 2) determine the number of chloride concentration test locations necessary for adequately characterizing the chloride concentration of a given bridge deck. Laboratory experiments on concrete drilling and …

Magnesium-Titanium Alloys For Biomedical Applications, Ilona Hoffmann

Theses and Dissertations--Chemical and Materials Engineering

Magnesium has been identified as a promising biodegradable implant material because it does not cause systemic toxicity and can reduce stress shielding. However, it corrodes too quickly in the body. Titanium, which is already used ubiquitously for implants, was chosen as the alloying element because of its proven biocompatibility and corrosion resistance in physiological environments. Thus, alloying magnesium with titanium is expected to improve the corrosion resistance of magnesium.

Mg-Ti alloys with a titanium content ranging from 5 to 35 at.-% were successfully synthesized by mechanical alloying. Spark plasma sintering was identified as a processing route to consolidate the alloy …

Fabrication And Enhancement Of Aluminum-Based Microchannel Devices, Paul Joseph Hymel

LSU Master's Theses

Microscale molding replication and transient liquid phase (TLP) bonding were used to fabricate Al-based microchannel heat exchangers (MHEs) and micro gas chromatograph (mGC) columns. Metal-based microchannel heat exchangers often experience corrosion as a result of their operating conditions. To address this problem, an internal anodization method was developed in Al microtubes by pulsing the flow of electrolyte through a microtube when the current dropped below a set value. The anodic aluminum oxide (AAO) films were characterized by scanning electron microscopy (SEM), focused ion beam (FIB) cross sections, and X-ray energy dispersive spectroscopy (EDS) to determine their growth rate and morphology. …

Corrosion Prevention And Control Training In An Immersive Virtual Learning Environment, Rustin Deane Webster

All ETDs from UAB

The majority of military education and training has not veered far from the days of chalk and talk instruction. Often with technological breakthroughs comes the proposal of the next revolution in multimedia instruction. Motion pictures to radios to educational television programs have all seemed to come and gone. The next wave of multimedia learning may involve more than a PowerPoint® presentation and lecture. Researchers continue to propose that Virtual Reality (VR) will find its true application and/or market in education and training. The objective of the project was to develop and provide a low-cost, scalable, and portable VR system containing …

Phosphate-Doped Borosilicate Enamel Coating Used To Protect Reinforcing Steel From Corrosion, Xiaoming Cheng

Doctoral Dissertations

"Phosphate-doped sodium borosilicate glasses were developed for enamel coatings to provide corrosion protection for reinforcing steel in concrete. Phosphates have low solubilities in borosilicate glasses, generally less than about 4 mol%, and are incorporated mainly as isolated PO₄^3- and P₂O₇^4- anions, along with some borophosphate bonds. With the addition of P₂O₅, the silicate network is repolymerized and tetrahedral borates are converted to trigonal borates, because the phosphate anions scavenge sodium ions from the borosilicate network. The addition of Al₂O₃ significantly increases the solubility of P₂O …