Engineering Commons^™

Reliability Challenges In Airside Economization And Oil Immersion Cooling, Jimil Manojbhai Shah

Mechanical and Aerospace Engineering Theses - Archive

The Datacom facility which comprises rooms or closets used for communication, computers/servers or electronic equipment requires cooling unit which consumes 31% (23% HVAC cooling + 8% HVAC fans) of overall energy. The ASHRAE TC9.9 subcommittee, on Mission Critical Facilities, Data Centers, Technology Spaces, and Electronic Equipment, has suited the data center’s executives by permitting brief period outings of the environmental conditions outside the prescribed temperature-humidity range, into passable extents A1-A4. To comprehend the expanding server densities and the required cooling vitality costs, data center operators are falling back on cost cutting measures. For instance, they are not firmly controlling the …

Novel Methods And Self-Reinforced Composite Materials For Assessment And Prevention Of Fretting Corrosion In Modular Tapers, Eric S. Ouellette

Dissertations - ALL

Novel methods for assessing the electrochemical and micromechanical performance of modular tapers were evaluated, and self-reinforced composite materials were developed for their potential to prevent the onset of mechanically assisted corrosion in modular taper devices.

A study of the seating and taper locking mechanics of modular taper samples was conducted, and the effect on taper engagement strength of seating load, loading rate, taper moisture, and taper design/material combination was studied. The load-displacement behavior was captured during seating, and the subsequent pull off load was correlated to seating displacement, seating energy, and seating load. The primary factor affecting taper engagement strength …

Interactions Between Inflammatory Cells And Cocrmo Alloy Surfaces Under Simulated Inflammatory Conditions, Huiyu Shi

Dissertations - ALL

Metallic biomaterials continue to be the primary materials for medical devices because of their excellent physical and mechanical properties especially for certain implants which need high strength (hip, spinal, shoulder, knee etc.). However there is no perfect material to meet all the requirements of a medical device. Metallic biomaterials are prone to corrosion and wear which has been associated with implant failure (osteolysis, aseptic loosening, pseudo tumor etc.) This study focused on investigating how inflammatory cells interact with CoCrMo alloy surfaces under simulated inflammatory conditions (H2O2 treatment). It is hypothesized that the presence of Reactive Oxygen Species (ROS) in cell …

Performance Assessment Of Deteriorated And Retrofitted Steel Hp Piles, Steven T. Stauffer

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Deterioration of aging bridges can be attributed to an assortment of mechanisms throughout the structure, with remediation policies also varying. This study focused on assessing the validity of the Nebraska Department of Roads’ (NDOR) reinforced concrete encasement retrofit for corroded steel HP piles. Experiments were designed and conducted to test the capacity of the NDOR retrofit and evaluate failure limit states. Two pile locations were considered: abutment and pile bent. For each location there was a non-deteriorated, deteriorated, and retrofitted case. These cases represented the pile at key stages during its life. NDOR’s concrete encasement retrofit provided the required stability …

Corrosion Of Rebar Under Carbonation And Salt Environment, Wei-Chung Yeih, Jiang-Jhy Chang, Yu-Ping Huang, Ran Huang

Journal of Marine Science and Technology–Taiwan

In this study, the behavior of reinforced concrete under carbonation and in a salt environment was investigated. Three types of cements- Type I cement, Type II cement and highalumina cement (HAC) - were used to study the influence of cement on reinforced concrete behavior. To simulate chloridecontaminated concrete, 1% NaCl (by cement weight) was added to some groups of specimens. Results revealed that the carbonation released chloride ions from Friedel's salt, which increased the chloride content near the carbonation front. The carbonation rate of HAC concrete was higher than that of Type I and Type II cement concrete. The corrosion …

Microgalvanic Corrosion Behavior Of Cu-Ag Active Braze Alloys Investigated With Skpfm, Armen Kvryan, Kari Livingston, Corey M. Efaw, Kyle Knori, Brian J. Jaques, Paul H. Davis, Darryl P. Butt, Michael F. Hurley

Materials Science and Engineering Faculty Publications and Presentations

The nature of microgalvanic couple driven corrosion of brazed joints was investigated. 316L stainless steel samples were joined using Cu-Ag-Ti and Cu-Ag-In-Ti braze alloys. Phase and elemental composition across each braze and parent metal interface was characterized and scanning Kelvin probe force microscopy (SKPFM) was used to map the Volta potential differences. Co-localization of SKPFM with Energy Dispersive Spectroscopy (EDS) measurements enabled spatially resolved correlation of potential differences with composition and subsequent galvanic corrosion behavior. Following exposure to the aggressive solution, corrosion damage morphology was characterized to determine the mode of attack and likely initiation areas. When exposed to 0.6 …

Phase I Inspection Of The Stay Cable System On The Us 231 William H. Natcher Bridge Over The Ohio River, Theodore Hopwood Ii, Sudhir Palle, Danny Wells, Bobby W. Meade, Jared Fairchild, Christopher Goff

Kentucky Transportation Center Research Report

The US 231 Natcher Bridge was opened in 2002. By 2006 cracking was observed in the plastic piping that protected the stay cable strands from the environment at both the deck and tower anchorages. Over time the extent of cracking increased and an investigation was initiated to assess the types of deterioration impacting the cables, their causes and their impacts on the integrity of the stay cables.

From 2012-2015, a series of in-depth field inspections were performed using visual and nondestructive testing. Most of this work focused on the piping at the deck anchorages. The inspections disclosed voids in cable …

A Study Of The Mechanical Behavior Of Composite Materials Exposed To Corrosive Environments, Ryan Keith Hedgepeth

Electronic Theses and Dissertations

A collaborative study was conducted to examine the degradation of commercially pultruded uni-directional e-glass composites. The case study specimens, including a variety of commercially pultruded polyester/e-glass and vinylester/e-glass composites were exposed to corrosive environments, namely: distilled water (h2o), bleach (naclo), and hydrochloric acid (hcl) for a minimum of 60 days, and the degradation was analyzed. Such a study was chosen on two accounts, 1) to contribute viable data to industry and research and 2) to provide data to be used to develop a standardized practice to characterize the durability for pultruded composites used for structural applications. A control group was …

Microstructural Investigation Of Vintage Pipeline Steels Highly Susceptible To Stress Corrosion Cracking, Monica Adriana Torres

Open Access Theses & Dissertations

The use of pipelines for the transmission of gas offers not only efficiency, but a number of economic advantages. Nevertheless, pipelines are subject to aggressive operating conditions and environments which can lead to in-service degradation [1] and thus to failures. These failures can have catastrophic consequences, such as environmental damage and loss of life [2]. One of the most dangerous threats to pipeline integrity is stress corrosion cracking (SCC). Despite the substantial progress that has been achieved in the field, due to the complex nature of this phenomenon there is still not a complete understanding of this form of external …

Oxidation Resistance Of Nanocrystalline 316l Stainless Steel Processed By High Pressure Torsion, Kevin J. Meisner

Williams Honors College, Honors Research Projects

High Pressure Torsion (HPT) is a materials processing method used to refine the grain size of metallic materials through the application of simultaneous axial and torsional strain. HPT is reported to result in nanocrystalline structure, which the current scientific literature suggests may improve the high temperature oxidation resistance by enhancing diffusion of solutes, particularly Cr, to the surface to form a protective external oxide scale. If oxidation resistance is improved, this possibly allows the use of 316L in oxidizing environments where more expensive alloys are typically used. However, the influence of grain refinement to nanoscale on various properties have been …

Passivation And Potential Fluctuation Of Az31b Alloy In Alkaline Environments, Ana C. Bacco

Williams Honors College, Honors Research Projects

Magnesium (Mg) alloys are used in many industries because of their distinctive properties, but their high chemical reactivity and poor oxide film protection make them inferior. This project focused on investigating the effects of secondary phases and intermetallic particles (IMPs) on the corrosion behavior of AZ31B Mg alloy. The test solution was chloride free NaOH with varying pH levels between 10-14, as well as testing under deaerated conditions. The open circuit potential (OCP) measurements using AZ31B in static NaOH solutions showed potential fluctuation between approximately -1.6 V_SCE (active state) and -0.4 V_SCE (passive state) during the 24-h immersion. …

Stress Corrosion Cracking Evaluation Of Carbon Steel In Biodiesel And The Effect Of Ultrasonic Nanocrystal Surface Modification (Unsm) On 304 Stainless Steel, Josh Geyer

Williams Honors College, Honors Research Projects

The project that was performed was stress corrosion cracking (SSC) of carbon steel in biodiesel, petroleum diesel and a mixture. The project also included the effect of Ultrasonic Nanocrystal Surface Modification (UNSM) on 304 stainless steel. It included the assembly of a slow strain rate (SSR) machine and carrying out testing using the SSR machine. The assembly of the machine will require purchasing and building a stand to house the electrical equipment which includes the computer, actuator control panel and the actuator power supply. The assembly will also include designing and purchasing the connections to connect the actuator to the …

Galvanic Corrosion On Monel K-500 And 1018 Carbon Steel Couple, John K. Nnyanzi

Williams Honors College, Honors Research Projects

The purpose of this research project was to evaluate galvanic damage on 1018 Carbon Steel coupled to Monel K-500 at varying rotation speeds on a rotating cylinder electrode in an aerated solution of ASTM artificial seawater. The work in this project is and attempt to study corrosion behavior for a Monel fastener coupled to a Carbon Steel plate. Polarization curves of each material at different rotation speeds were created to predict the corrosion behavior for a galvanic couple of Carbon Steel and Monel. The Potentiodynamic sweeps predict an increase in the corrosion current density for the galvanic couple when then …

Probability-Based Hurricane Resilience Evaluation And Retrofitting For Residential Community, Yadong Dong

Dissertations, Master's Theses and Master's Reports

Wood residential construction is vulnerable to hurricanes, as evident in recent hurricane events. Many studies indicated that the changing climate may very likely alter hurricane patterns, which could lead to more severe hurricane damage to the wood residential construction that accounts for 90% of the residence in the USA. On the other hand, deterioration of material increases the chance of structural failure by reducing the structural capacity (e.g., corrosion of fasteners in roof panel could significantly reduce the withdrawal capacity of the roofing structure during hurricane events).

Currently, most hurricane damage estimations only focus on direct loss (e.g., structural loss). …

Distinction In Corrosion Resistance Of Selective Laser Melted Ti-6al-4v Alloy On Different Planes, Nianwei Dai, Laichang Zhang, Junxi Zhang, Xin Zhang, Qingzhao Ni, Yang Chen

Research outputs 2014 to 2021

Electrochemical measurements and microstructural analysis were performed to study the corrosion resistance of different planes of Ti-6Al-4V alloy manufactured by selective laser melting (SLM). The electrochemical results suggest that its XY-plane possesses a better corrosion resistance compared to XZ-plane in 1 M HCl solution, in spite of slight difference in 3.5 wt.% NaCl solution, suggesting that the different planes exhibit more pronounced distinction in corrosion resistance in harsher solution system. The inferior corrosion resistance of XZ-plane is attributed to the presence of more α′ martensite and less β-Ti phase in microstructure for XZ-plane than for XY-plane of the SLM-produced Ti-6Al-4V …

A Practical Anodic And Cathodic Curve Intersection Model To Understand Multiple Corrosion Potentials Of Fe-Based Glassy Alloys In Oh-Contained Solutions, Yingjie Li, Yonggang Wang, Bang An, Hui Xu, Yihua Liu, Laichang Zhang, Houyi Ma, Weimin Wang

Research outputs 2014 to 2021

A practical anodic and cathodic curve intersection model, which consisted of an apparent anodic curve and an imaginary cathodic line, was proposed to explain multiple corrosion potentials occurred in potentiodynamic polarization curves of Fe-based glassy alloys in alkaline solution. The apparent anodic curve was selected from the measured anodic curves. The imaginary cathodic line was obtained by linearly fitting the differences of anodic curves and can be moved evenly or rotated to predict the number and value of corrosion potentials. © 2016 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution …

The Effect Of Temperature And Relative Humidity On The Corrosion Rates Of Copper And Silver In Electronic Equipment In The Presence Of Sulfur Environment, Kanan Pujara

Mechanical and Aerospace Engineering Theses - Archive

Data center consume a significant amount of energy for the continuous air-conditioning of the servers with high internal heat loads and to maintain the indoor temperatures within recommended operating levels as recommended by ASHRAE. As an alternate source to air-conditioning, air-side economizers are used to reduce power consumption. However, there is a reluctance in using this technique due to undetermined equipment reliability by introducing outside air pollutants which over time could cause failures. There is a need to know the degree of reliability degradation when the equipment is operated, outside the recommended range, in the allowable temperature-humidity range in geographies …

Feasibility Of Cathodic Protection In Grouted Post Tensioned Tendons - Exploratory Model Calculations, Jacob Dharma Bumgardner

USF Tampa Graduate Theses and Dissertations

Recent corrosion related failures of grouted post tensioned tendons, even after the introduction of improved grouts, have led to renewed interest in supplemental or backup means of corrosion control for these systems. A finite element model is presented to explore feasibility of impressed current cathodic protection of strand in grouted tendons. The model examines polarization evolution as function of service time and includes consideration of anode placement and size, grout porosity, pore water alkalinity, electrochemical species diffusivity and applied voltage on the polarization efficacy and durability of such a system. The exploratory model projections suggested that, within the context of …

High Temperature Oxidation Kinetics Of Dysprosium Particles, Brian J. Jaques, Darryl P. Butt

Materials Science and Engineering Faculty Publications and Presentations

Rare earth elements have been recognized as critical materials for the advancement of many strategic and green technologies. Recently, the United States Department of Energy has invested many millions of dollars to enhance, protect, and forecast their production and management. The work presented here attempts to clarify the limited and contradictory literature on the oxidation behavior of the rare earth metal, dysprosium. Dysprosium particles were isothermally oxidized from 500 to 1000 °C in N₂–(2%, 20%, and 50%) O₂ and Ar–20% O₂ using simultaneous thermal analysis techniques. Two distinct oxidation regions were identified at each isothermal temperature …

Analysis Of A Clinically Failed, Mechanically Intact, Reconstructive Compression Plate, Bharadwaj Cheruvu, Sunil Karmacharya, Richard T. Laughlin, Tarun Goswami

Biomedical, Industrial & Human Factors Engineering Faculty Publications

A reconstructive orthopedic bone plate was submitted for analysis. Traditional failure analysis methods were used to assess the mode of the plate failure. Metallographic investigation of the plate was carried out in this report. Since limited data was available in the literature and clinical data related to subject demography, date of removal as well as reasons for removal unknown, in depth analysis was not possible. However, the plate was received in in-tact condition with minor biological deposits and scratches, it is speculated that the failure of the plate may have been due to biological/clinical reasons, likely infection, rejecting the device …

Evaluation Of Deterioration Of Structural Concrete Due To Chloride Intrusion And Other Damaging Mechanisms, Sudhir Palle, Brian K. Howell, Theodore Hopwood Ii, Bobby W. Meade

Kentucky Transportation Center Research Report

Kentucky's bridges continue to age and experience distress. The intrusion of chlorides into concrete remains the primary mechanism for deterioration. It leads to reinforcing steel corrosion that damages the adjoining concrete structure. This study found problematic chloride concentrations in Kentucky concrete bridge elements (decks, pier caps, abutments). Chloride levels have been found at concentrations sufficient to initiate reinforcing steel corrosion. In some cases, chloride concentrations were sufficient to cause accelerated corrosion and produce major section loss of reinforcing steel. Advanced stages of corrosion such as these typically require costly repairs and maintenance to extend the service life of bridges.

Field …

Swelling-Etching Characterization Of Copper (I) Oxide - Pdms For The Development Of Micro/Nano - Particles Composite Mems Corrosion Sensor, Abdoul Kader Maiga

Graduate Theses and Dissertations

The primary objective for this thesis is to contribute to the understanding of the oxide removal process for a corrosion sensing device. The goal for designing such a device is for monitoring corrosion on metallic structures. The sensing material (6.35mm x 1mm discs) of the device is composed of copper (I) oxide particles mixed in some polydimethylsiloxane (PDMS). The PDMS, “housing,” is meant for controlling the oxidation rate through the sensing material. A solvent was used to facilitate the etchant diffusion through the PDMS matrix. Toluene and acetic acid were the ideal solvent and etchant, respectively, for carrying out the …

Fabrication And Material Characterization Of Copper And Copper-Cnt Micropillars, Siavash Ghanbari, Jeff Darabi

SIUE Faculty Research, Scholarship, and Creative Activity

In this work, copper micropillars and copper-carbon nanotube (CNT) composite micropillars were fabricated by incorporating an electrodeposition technique with a xurography process. In order to disperse carbon nanotubes in copper-CNT micropillars, various amounts of CNTs were added to the electroplating bath. Surface morphology and phase characterization of copper micropillars and copper-CNT composite micropillars were analyzed by optical microscopy and X-ray diffraction. In addition, the corrosion resistance (R_p) of a bare copper substrate, copper micropillars, and optimum copper-CNT micropillars were studied by electrochemical impedance spectroscopy (EIS) technique in a 3.5 wt. % sodium chloride. Experimental results yielded a corrosion …

On The Fe Enrichment During Anodic Polarization Of Mg And Its Impact On Hydrogen Evolution, D. Lysne, S. Thomas, M. F. Hurley, N. Birbilis

Materials Science and Engineering Faculty Publications and Presentations

Iron (Fe) is an unintentional impurity present in pure magnesium (Mg) and Mg alloys, albeit nominally in low and innocuous concentrations (< 100 ppmw). Since Fe, like most metals, is more noble than Mg, the presence of Fe impurities can serve as cathodic sites within the Mg matrix. During anodic polarization of Mg, incongruent dissolution can lead to undissolved Fe impurities accumulating upon the Mg surface, permitting an increase in the overall rate of hydrogen evolution. The experimental manifestation of the incongruent dissolution of Mg, has not yet been clarified, wherein, the extent and efficiency of Fe enrichment during anodic polarization is not known, and also the increase in the hydrogen evolution rate due to Fe enrichment has not been quantified. In this work, Mg specimens with Fe concentration between 40 to 13,000 ppmw were examined in 0.1 M NaCl to obtain a quantitative relation between the Fe concentration and the rate of cathodic hydrogen evolution. These base-line alloys were then anodically polarized to facilitate surface Fe enrichment, and subsequently again cathodically polarized to determine the impact of prior dissolution and Fe enrichment on the subsequent hydrogen evolution. A simple model to predict Fe enrichment was used to analyze the electrochemical data and predict the extent and efficiency of Fe enrichment.

Weak Magnetic Field Accelerates Chromate Removal By Zero-Valent Iron, Pian Feng, Xiaohong Guan, Yuankui Sun, Wonyong Choi, Hejie Qin, Jianmin Wang, Junlian Qiao, Lina Li

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Weak magnetic field (WMF) was employed to improve the removal of Cr(VI) by zero-valent iron (ZVI) for the first time. The removal rate of Cr(VI) was elevated by a factor of 1.12-5.89 due to the application of a WMF, and the WMF-induced improvement was more remarkable at higher Cr(VI) concentration and higher pH. Fe2+ was not detected until Cr(VI) was exhausted, and there was a positive correlation between the WMF-induced promotion factor of Cr(VI) removal rate and that of Fe²⁺ release rate in the absence of Cr(VI) at pH 4.0-5.5. These phenomena imply that ZVI corrosion with Fe^{2+ …}

Mechanically- And Electrochemically- Induced Damage At Metal Interfaces Of Joint Replacements And The Biological Consequences, Pooja Panigrahi

All Dissertations

Retrieval analysis has emerged as one of the most direct and informative ways to analyze mechanisms of orthopaedic device failure. With a rising projected demand for revision joint arthroplasty, 268,200 revision total knee replacements (TKR) and 96,700 revision total hip replacements (THR) in 2030, metal interfaces in joint replacements are currently under intense scientific focus as the interactions among mechanical and electrochemical processes continue to challenge the orthopaedic device industry. The objective of these studies was to use implant retrieval and in in vitro analyses to determine the effects of material and mechanical properties on wear and corrosion, and to …

The Examination Of Stress Corrosion Cracking In High Strength Carbon Steel Through Combined Mechanical-Electrochemical Testing, Jacob Sines

Williams Honors College, Honors Research Projects

Through the analysis of materials and environments seen in industry a better understanding of the fundamentals behind degradation mechanisms can be observed. The scope of this project was to better understand the fundamentals behind the degradation of high strength pipeline steels in a lab setting to simulate an environment seen in industry. Specifically the degradation mechanisms of high and nearly neutral pH stress corrosion cracking were examined in environments that simulated oil and gas pipelines buried in soil. Experimentation was carried out utilizing X65 carbon steel specimen, a Gamry potentiostat, a CORTEST proof ring, a CORTEST slow strain rate machine, …

Metallic Encapsulation For High Temperature (>500 °C) Thermal Energy Storage Applications, Abhinav Bhardwaj

USF Tampa Graduate Theses and Dissertations

Deployment of high temperature (>500 °C) thermal energy storage in solar power plants will make solar power more cost competitive and pave the way towards a sustainable future. In this research, a unique metallic encapsulation has been presented for thermal energy storage at high temperatures, capable of operation in aerobic conditions. This goal was achieved by employing low cost materials like carbon steel. The research work presents the unique encapsulation procedure adopted, as well as various coatings evaluated and optimized for corrosion protection. Experimental testing favored the use of 150 μm of nickel on carbon steel for corrosion protection …

Reversing Sensitization Of Naturally Exfoliated 5456-H116 Aluminum Alloys, Ren-Yu Chen, Cheng-Chyuan Lai

Journal of Marine Science and Technology–Taiwan

5456-H116 Al-Mg alloy has been broadly used in the U.S. Navy in order to meet the demand of reducing ship hull weight while considering high specific strength, corrosion resistance, and weldability. A particular concern of these alloy is sensitization, which causes it to be sensitized when highly anodic β phase (Al3Mg2) is precipitated at grain boundaries especially in service exceeding 65~200°C, leading to intergranular corrosion (IGC), exfoliation and stress corrosion cracking (SCC). This study investigated the reversal of sensitization of a naturally exfoliated 5456-H116 alloy plate by planned heating treatment with a short exposure to 250°C. The properties of sensitized …

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 …