Search Results (1 - 25 of 76 Results)

Sort By  
Sort Dir
 
Results per page  

Kline, ErinCeramic Architecture: Showcasing a Forgotten Architectural Medium Through Recycled Rubble
MARCH, University of Cincinnati, 2017, Design, Architecture, Art and Planning: Architecture
Vacancy has long been a struggle in the United States due to the cycle of urbanization and suburbanization. There has continuously been a large number of vacant properties across the country, and higher vacancy rates lead to increased rates of demolition. An increase in demolished structures, in turn, leads to a higher volume of waste entering the country’s landfills. Cincinnati is one of the many cities with a surge in re-urbanization. While redevelopment has quickly spread through the city’s derelict neighborhoods, many vacant properties still stand, and their futures are often uncertain. This thesis looks at an obsolete, vacant structure in Cincinnati’s downtown neighborhood, and proposes an alternative method of recycling to reduce the building industry’s waste production through repurposing building rubble and salvaged materials into dry ingredients for architectural ceramic clay bodies. The recycled clay is then translated into traditional and contemporary architectural ceramics that work together to form a designed spatial showcase of CERAMIC ARCHITECTURE. The program, a youth recreational facility, is intended to highlight the forgotten and unconventional applications of ceramics as a construction medium. Within each program space, ceramic becomes more than just a traditional finish material, but acts as both finish and architectural element [structure, partition, acoustic treatment, etc.] simultaneously.

Committee:

Aarati Kanekar, Ph.D. (Committee Chair); Katie Parker (Committee Member)

Subjects:

Architecture

Keywords:

ceramic architecture;recycling;ceramic;building rubble

Petty, Renee LynnCatalytic Decomposition of Nitric Oxide and Carbon Monoxide Gases Using Nanofiber Based Filter Media of Varying Diameters
Master of Science in Engineering, University of Akron, 2010, Chemical Engineering

Nitrogen Oxide (NO) and carbon monoxide (CO) are major pollutants in the exhaust streams of automobiles, power plants, and other combustion processes. The growing concerns for the environment have resulted in increasingly restrictive emission standards. The removal of NO and CO from exhaust gases is a challenging task.

One method for harmful gas removal is using a catalyst for dissociation. This work explored an alternative method for catalytic reduction of NO. Polymer solutions with palladium catalyst and ceramic precursors were electrospun to form polymer nanofibers. These nanofibers were heated to form ceramic nanofibers with catalyst nanoparticles and were mixed with microfibers to form a nonwoven fibrous catalyst support structure. The concentration of the polymer was varied to create nanofibers with diameters ranging from 100 to 700 nm with a constant mass of catalyst particles per mass of fiber. The effect of the fiber diameter on the corresponding catalyst structure performance was tested. A surface area comparison test was completed to determine whether the reactions occur strictly on the surface of the catalyst or if diffusion occurs. An aging comparison was also completed which tested 1 week old catalytic filters compared to 6 months old. A conventional catalytic converter was tested to verify the performance was similar to the catalytic fibrous filter media containing only palladium.

Experiments were carried out using a lab reactor to expose the media to a mixture of gases simulating an exhaust stream at room temperature to a maximum of 450°C. The reactor exhaust concentrations are measured using gas chromatography (GC) to determine the catalyst performance. Results indicated that the catalytic reaction performance was about the same for fiber sizes ranging from 100 to 700 nm on a mass basis with a reduction temperature of 325 – 350°C. The surface area comparison filter reduced at 275°C which showed that both surface catalyst particles and particles within the fibers are available for reaction. Furthermore, a conventional catalytic converter reduced at approximately 325°C which exhibits comparable catalytic performance with the catalytic filters. Model theory and equations were also developed for decomposition reactions of NO and CO using elementary reactions.

Committee:

George Chase, Dr. (Advisor)

Subjects:

Chemical Engineering

Keywords:

catalyst; polymer; palladium; ceramic precursor; electrospinning; nanofibers; ceramic; nanoparticles; catalytic filter; concentration of polymer; varying diameter; surface area; catalyst surface; elementary reactions; equations; catalyst effectiveness

Dagam, Sarah AThe Effects of Life Experiences
MFA, Kent State University, 2016, College of the Arts / School of Art
My thesis presents a series of pieces that transferred from the basic, natural form to be tougher, stronger, and abstract. These pieces are meant to present the idea of abstraction that inspired by my life, and embodied on these organic forms from the ocean. The idea of my work presents the changes that happened to me and reflect into my work. How I challenged myself to adjust no matter what happened during the period of my study abroad. Also, how I used these challenges, and life experiences as an inspiration.

Committee:

PETER JOHNSON (Advisor); JANICE LESSMAN (Committee Member); ISABEL FARNSWORTH (Committee Member); GIANNA COMMITO (Committee Member)

Subjects:

Fine Arts

Keywords:

The effects of life experiences, Ceramic art, MFA thesis in Ceramics, Ceramic thesis 2016, The abstractions, Ocean forms

Wolford, Ian MarkQuantifying Amorphous Content of Commercially Available Silicon Carbide Fibers
Master of Science in Materials Science and Engineering (MSMSE), Wright State University, 2016, Materials Science and Engineering
SiC/SiC ceramic matrix composites (CMCs) with potential applications at =2700°F (1482°C) are of significant interest to the Air Force. The high temperature performance of SiC fibers used within these composites is greatly affected by the presence of amorphous SiOC and free carbon in the fibers. Therefore quantification of this non SiC material in commercially available SiC fibers is extremely important. In this work Hi Nicalon, Hi-Nicalon Type-S, Tyranno-SA3, Cef-NITE, and Sylramic SiC fibers were studied. Changes in mass, grain size, and amorphous content were measured as a function of processing temperature and time. The amorphous material in each fiber was quantified using the Spike-In method in conjunction with Rietveld refinement. Trends in amorphous content were observed, as well as trends in grain size and crystallized fraction. Transmission electron microscopy (TEM) was used to confirm changes in fiber microstructure.

Committee:

H. Daniel Young, Ph.D. (Advisor); Hong Huang, Ph.D. (Committee Member); Michael Cinibulk, Ph.D. (Committee Member); Robert E. W. Fyffe, Ph.D. (Other)

Subjects:

Aerospace Materials; Materials Science

Keywords:

silicon carbide; SiC; CMC; ceramic fiber; SiC fiber; ceramic composite; SiOC; amorphous

Miller, Robert JamesStoichiometric and compositional effects in cyrochemically processed barium ferrite ceramics /
Doctor of Philosophy, The Ohio State University, 1970, Graduate School

Committee:

Not Provided (Other)

Subjects:

Engineering

Keywords:

Ceramic magnets;Ceramic metals

Appleby, Matthew P.High Temperature Damage Characterization Of Ceramic Composites And Protective Coatings
Doctor of Philosophy, University of Akron, 2016, Mechanical Engineering
Novel high-temperature experiments were conducted in ordered to address some of the most critical life-limiting issues facing woven melt-infiltrated, silicon carbide (SiC) fiber-reinforced SiC ceramic matrix composites (CMCs) as well as protective thermal and environmental barrier coatings (T/EBC). Heating of specimens was achieved using laser-based approaches that simulate the high heat-flux thermal gradient environments that these materials will be subjected to in service. Specialized non-destructive evaluation (NDE) and inspection techniques were developed to investigate damage modes and material response. First, in order to examine the capabilities of utilizing the emerging technique of electrical resistance (ER) measurement for use in high temperature mechanical testing in SiC/SiC CMCs, the temperature dependent ER response of several systems was determined. A model was developed to establish the contribution to overall ER from the individual composite constituents and applied thermal gradient. Then, elevated temperature tensile tests were performed to characterize the damage of composite materials to localized stress concentrations. Further experiments were done to assess the differences in damage mechanisms and retained tensile strength properties of uncoated SiC/SiC CMCs and EBC-CMC systems after prolonged exposure to high pressure, high velocity water vapor containing environments. Differences in damage modes were described using ER monitoring and post-test inspection. Localized strain fields were measured using a novel digital image correlation (DIC) technique and stress-dependent matrix crack accumulation was monitored using in-situ modal acoustic emission (AE). Coupled AE and thermography measurements were also used to describe failure of protective ceramic coatings due to the life-limiting case of thermal cyclic loading. Due to the complex nature of T/EBC failure, the decrease in coating life and durability due to thermal stress concentrations and degradation via molten calcium-magnesium-aluminosilicate (CMAS) infiltration was also examined. Finally, the use of ER measurements for damage characterization was extended to the complex case of creep and stress-rupture of damaged and undamaged composites as well as the dramatic increase in stress-rupture life to SiC/SiC CMCs from environmental barrier coatings. Post-test microscopy was performed to further explain differences in material response and damage morphology.

Committee:

Gregory Morscher (Advisor); Manigandan Kannan (Committee Member); Kwek Tze Tan (Committee Member); Craig Menzemer (Committee Member); Alper Buldum (Committee Member)

Subjects:

Mechanical Engineering

Keywords:

ceramic matrix composites; environmental barrier coatings, thermal barrier coatings; non-destructive evaluation; electrical resistance; acoustic emission; digital image correlation

Leslie, James W.My Nature
MFA, Kent State University, 2007, College of Fine and Professional Arts / School of Music
This thesis explores my clay sculptures that celebrate the diversity of life that is revealed in natural objects and living organisms in and along the ocean and its shores. Each individual piece is inspired by the multitude of intricate details of sea-plants, coral, driftwood and ocean sea creatures that I have encountered throughout my life. The ocean is a place to explore, contemplate and relax, enjoying the variety nature has to offer. Through the process of creating, my work is at once familiar and strange, projecting a level of wonder and mystery. The pieces are static in the nature of sculpture, yet appear to possess a life of their own cultivating a unique, animated and sensuous presence. These sculptures suggest individuality, a fantasy creature that is inviting in form, texture and color. I chose ceramics as a medium to convey my ideas because of its organic composition and its ties to the environment. The pliable, plastic nature of clay allows me to be playful and spontaneous in my decision making. They are decisions that have been made to draw attention to the mysteries of the ocean and how it provides an endless source of inspiration. These sculptures are to be acknowledged as individual pieces representing a view into my nature, a nature that can be shared and enjoyed by those who are fascinated by the natural world of the ocean and the fantasy of the created object.

Committee:

Kirk Mangus (Advisor)

Subjects:

Fine Arts

Keywords:

Ceramics; Sculpture; Ceramic sculpture; Clay; Clay sculpture; Nature; My nature; Ocean; Cape Cod; Coral; Driftwood; Cayman Islands; Barbados

Miller, Larry M.A model for the prediction of thermo-oxidative mass loss of ceramic coated polyimide composites
Doctor of Philosophy (PhD), Ohio University, 1995, Chemical Engineering (Engineering)

The purpose of this work is to understand the mechanisms of high temperature decomposition for a ceramic coated polyimide (DP-29) composite by developing a model for each of the mechanisms. The model covers a temperature range of 340-380°C, an oxygen range of 0-21%, and a duration of 100 hours.

An oven reactor was used to obtain experimental data for the thermal and thermo- oxidative decomposition reactions of the polyimide composite. The data taken was used to develop a model of the decomposition process. The equation of continuity for oxygen was used to find the concentration profile of oxygen through the ceramic film. The solution to the equation of continuity was combined with the model of polyimide decomposition to form an overall model for the prediction of thermo-oxidative mass loss of a ceramic coated polyimide composite.

The kinetic model predicts the decomposition reaction of the polyimide composite to within 10% of the experimental data taken. The overall model shows that temperature has the greatest effect on the rate of decomposition of a ceramic coated polyimide composite. Surface coverage of the ceramic coating on the polyimide composite has the next greatest effect on the decomposition rate and oxygen concentration of the atmosphere has the smallest effect.

Committee:

Daniel Gulino (Advisor)

Subjects:

Engineering, Chemical

Keywords:

thermo-oxidative mass; ceramic coated polyimide composites; rate of decomposition; kinetic model

Loiacona, Dominic J.Synthesis of β-Alumina-Type Compounds and their Transformation Via the TCON Process
Master of Science in Chemistry, Youngstown State University, 2010, Department of Chemistry

Fireline TCON, Inc., a ceramics company in Youngstown, Ohio, has developed a unique method for producing co-continuous ceramic/metallic composite materials. These TCON composite materials are usually produced from a reaction of silica with molten aluminum via a process known as reactive metal penetration, producing an interpenetrating phase composite of aluminum oxide and aluminum metal, where silicon is alloyed with aluminum in the metal phase. These composite materials have a variety of interesting properties, such as extremely high tolerance of heat, resistance to corrosion, and high strength.

Theoretically, the TCON process can be altered in order to utilize a wide variety of metal oxides other than silica as sacrificial oxides. A class of compounds known as β-aluminas are of particular interest, as these compounds contain open channels within their crystal structure, which may facilitate the TCON reaction or produce a TCON composite with different morphology and properties than have previously been reported. Specifically, the possibility of producing a nano-scale composite is being investigated, due to the nano-scale features of the β-alumina crystalline structure itself. Several different β-alumina compounds have been prepared and transformed via the TCON process. Phases present in the product were analyzed via PXRD, and the morphology of the composite was analyzed via SEM. Several related spinel phases were prepared and transformed for comparison to results for transformed β-alumina.

In addition, attempts have been made to produce novel β-alumina structures that would be beneficial as sacrificial oxides in the TCON process. Novel compounds such as SrTi5Mg6O17 that would transform under TCON conditions would result in a number of beneficial properties in the produced composite. These benefits include the presence of aluminum-titanium alloys, which have excellent strength-to-weight ratios.

Committee:

Tim Wagner, PhD (Advisor); Virgil Solomon, PhD (Committee Member); Clovis Linkous, PhD (Committee Member)

Subjects:

Chemistry; Inorganic Chemistry; Materials Science

Keywords:

B-Alumina; Beta Alumina; Ceramic; Composite; TCON; Fireline; Materials; Spinel; SEM; XRD; Oxide

Hansel, Jason EdgarThe Influence of Thickness on the Complex Modulus of Air Plasma Sprayed Ceramic Blend Coatings
Master of Science in Engineering (MSEgr), Wright State University, 2008, Mechanical Engineering
Previous research suggests that damping of metallic beams that have a hard ceramic coating applied on them is proportional to the coating thickness. This indicates that the damping is a volume dependent material property. Since thickness variations are likely in an actual application, it is essential to understand the role that coating thickness plays in damping effectiveness. For this research, a series of tests were conducted using substrate beams of 90 mil Ti-6Al-4V, coated with 3 mils of an air plasma sprayed NiCrAlY bond coat followed by a Titania-Alumina ceramic blend coating applied via air plasma spray in one of three thicknesses (5 mil, 10 mil and 15 mil). Four specimens were coated at each thickness for a total of 12 specimens. The system loss factor and natural frequencies were measured for each specimen at each stage to determine the material properties of the bare beam, the bond coat and the ceramic coating. This information was used with the dimensions at each stage to determine the material properties (storage modulus, loss modulus and loss factor) for the bond coat and the ceramic. Differences in the results of different thickness specimens allow the ability to determine and quantify a thickness effect.

Committee:

Joseph Slater, Ph.D., P.E. (Committee Chair); Peter Torvik, Ph.D. (Committee Member); Nathan Klingbeil, Ph.D. (Committee Member)

Subjects:

Engineering; Mechanical Engineering

Keywords:

Vibration Damping; Ceramic coatings; Titania-Alumina; Mechanical Properties; complex modulus

Raghavan, Bharath KumarNanofiber Filter Media for Air Filtration
Doctor of Philosophy, University of Akron, 2010, Chemical Engineering

Nanofibers have higher capture efficiencies in comparison to microfibers in the submicron particle size range of 100-500 nm because of small fiber diameter and increased surface area of the fibers. Pressure drop across the filter increases tremendously with decrease in fiber diameter in the continuum flow regime. Nanofibers with fiber diameter less than 300 nm are in the slip flow regime as a consequence of which steep increase in pressure drop is considerably reduced due to slip effect. The outlet or inlet gases have broad range of particle size distribution varying from few micrometers to nanometers. The economic benefits include capture of a wide range of particle sizes in the gas streams using compact filters composed of nanofibers and microfibers.

Electrospinning technique was used to successfully fabricate polymeric and ceramic nanofibers. The nanofibers were long, continuous, and flexible with diameters in the range of 200 300 nm. Nanofibers were added to the filter medium either by mixing microfibers and nanofibers or by directly electrospinning nanofibers as thin layer on the surface of the microfiber filter medium. Experimental results showed that either by mixing Nylon 6 nanofibers with B glass fibers or by electrospinning Nylon 6 nanofibers as a thin layer on the surface of the microfiber medium in the surface area ratio of 1 which is 0.06 g of nanofibers for 2 g of microfibers performed better than microfiber filter media in air filtration tests. This improved performance is consistent with numerical modeling. The particle loading on a microfibrous filter were studied for air filtration tests . The experimental and modeling results showed that both pressure drop and capture efficiency increased with loading time. Nanofiber filter media has potential applications in many filtration applications and one of them being hot gas filtration. Ceramic nanofibers made of alumina and titania nanofibers can withstand in the range of 1000°C. Ceramic nanofibers filter media were fabricated by mixing alumina microfibers (SAFFIL) and alumina nanofibers. The appropriate binders were tested for ceramic filter media. The ceramic filter media were tested for aerosol filtration.

Committee:

Chase George, Dr. (Advisor)

Subjects:

Chemical Engineering; Engineering; Materials Science

Keywords:

nanofibers; mass production of nanofibers; electrospinning; ceramic nanofibers; hot gas filtration; air filtration; filtration; nanofiber filter media; particle laoding on fibrous filter; alumina nanofibers;, nylon 6 nanofibers; Nanopsider machine

Myers, Kyle MInvestigation of Novel Precursor Routes for Incorporation of Titanium Alloys and Nano- Sized Features into Ceramic-Metallic Composites Formed via the TCON Process
Master of Science in Chemistry, Youngstown State University, 2012, Department of Chemistry
Fireline TCON Inc. has developed a technology for the creation of alumina/aluminum interpenetrating phase composites via a reactive metal penetration process. TCON composites are created by immersing silica based ceramic precursors into a reactive molten aluminum or aluminum alloyed melt. The molten aluminum metal reacts with the precursor leaving a near net shape alumina ceramic backbone with aluminum filling in the pores in the composite. The resulting composites have unique mechanical properties that are desired for many applications. The mechanical properties of TCON composites can be tuned for specific applications by varying the precursor material, metal composition, and temperature of reaction. Research has shown that the reactive metal penetration process does work with precursors that are not silica based ceramics. Currently Fireline TCON Inc. only works with silica based precursors that leave undesired aluminum-silicon alloys in the metal phase as the transformation takes place. The aluminum-silicon alloys are created from a reduction of the silicon metal cations in the silica based ceramic. The incorporation of titanium into the metal matrix is a more desired result for Fireline. Several titanium based ceramics were transformed using the TCON process to try and incorporate titanium into the metal phase. In addition, specific type materials were transformed in the TCON process in attempt to manifest a nano-sized interpenetrating phase composite. Current technology at Fireline TCON Inc leaves the resulting composites with particle sizes on the micron scale. A nano-scaled titanium-silicon oxide and a β-alumina-type compound, which already has nano-features, were transformed in the TCON process to investigate if a nano-scaled composite would manifest. All of the samples that were transformed were analyzed using optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction. Fireline TCON Inc decided that one of the precursor materials showed enough promising results that this sample was scaled-up to test bars to be tested for mechanical properties. The mechanical properties of this composite are compared to existing metal ceramic composites.

Committee:

Timothy Wagner, Ph.D. (Advisor); Matthias Zeller, Ph.D. (Committee Member); Clovis Linkous, Ph.D. (Committee Member); Virgil Solomon, Ph.D. (Committee Member)

Subjects:

Chemistry; Materials Science

Keywords:

Ceramic-Metallic Composites; Reactive Metal Penetration; Alumina Composites; Spinel Composites

Paulin, Henry SylvesterCeramic manufacturing industry : Implications for industrial arts curriculum development /
Doctor of Philosophy, The Ohio State University, 1964, Graduate School

Committee:

Not Provided (Other)

Subjects:

Education

Keywords:

Industrial arts;Ceramic industries

Kim, GunyoungThe Quiet Body
Master of Fine Arts, The Ohio State University, 2014, Art
I am interested in looking at the subtle and spiritual side of humanity. The body is both external and internal, we experience changes in mind and emotion with our body. The body as a subject can be a form through which we share our emotional experiences and remembrances. I try to capture inner psychological aspects through surreal facial expressions, subtle gestures and placement. The complexity and ambiguity of human feelings that come from the vulnerability and imperfection is a main idea of my work. I always attempt to investigate different narrative aspects of the figure and displays so as not to represent on a singular moment but to make space for a mysterious and changeable reading. Using subtle variations in form, texture and color the physical representation of an emotional state becomes changeable. My work consists of different sizes of figures and objects that interact with each other, creating connections and relationships, bringing new stories to the space. Complicated emotional interactions occur in human relationship. Nonverbal emotional cues, such as eye contact, facial expression, body posture, and interpersonal distance; these things speak broadly about the tangled thinking and feeling that occurs when we interact with other people. I'm interested in putting these ideas into physical forms by emphasizing them through placement and tactile manipulation.

Committee:

Rebecca Harvey (Advisor); Todd Slaughter (Committee Member); Carmel Buckley (Committee Member)

Subjects:

Fine Arts

Keywords:

Ceramic figure

Mei, FangCOATING OF SILVER FILM ONTO THE INNER PORE SURFACES OF THE RETICULATED ALUMINA BY AN ELECTROLESS PLATING METHOD
MS, University of Cincinnati, 2000, Engineering : Materials Science
A novel electroless plating method had been employed to coat a silver film onto the inner surface of porous alumina substrate. While the original substrate was a very good insulator, the coated substrate became highly conductive. One of the possible applications of this coated porous material is to serve as a novel electrical charged filter (ECF). An evenly distributed silver film with a thickness of a few tens of micrometers had been successfully produced by the electroless plating method. Silver growth process was investigated to analyze its kinetics. The change of overall conductivity of the coated substrate with time was studied. An empirical equation was developed to fit the experimental data. Based on the physical model of the coating kinetics, the process was simulated animatedly by computer simulation. The morphology and other properties of the film was investigated by using SEM, XRD and other means. The newly formed film was found to have very weak bonding strength with the substrate. Annealing treatment was adopted to enhance the bonding. Experiments showed that while higher annealing temperature gave rise to higher bonding strength, the conductivity decreased. An optimized annealing condition was determined based on experimental results. The change in conductivity caused by annealing was attributed to the morphology change of the film. Preliminary experiments on water treatment capability of Electrical Charged Filter were also carried out and the results supported the validity of the ECF concept.

Committee:

Donglu Shi (Advisor)

Keywords:

porous; Pore; Coating; ceramic; Plating; porous material; ECF

Lee, Chong-HoonStudy of reversible electrode reaction and mixed ionic and electronic conduction of lithium phosphate electrolyte for an electrolchemical co2 gas sensor
Doctor of Philosophy, The Ohio State University, 2004, Materials Science and Engineering
An electrochemical CO2 gas sensor with lithium ion conductor was developed and characterized in order to examine the potential for real-life applications and understand its sensing mechanism. Li2CO3 and Li2TiO3+TiO2 mixture were used as a sensing and a reference auxiliary phase, respectively. This electrochemical cell with a solid state Li3PO4 electrolyte has shown good selectivity, sensitivity and linear response in laboratory and automobile exhaust tests. However, the sensor response to CO2 gas showed a systematic deviation from the Nernst equation. Measured EMF did not agree with that calculated from the Nernst equation, even though it followed logarithmic behavior. Moreover, high sensitivity was observed for high CO2 concentrations (5~50%), compared to that for concentrations (500~5000 ppm). Two possible reasons for this deviation are: (1) reversibility of electrode reaction and (2) mixed ionic and electronic conduction of the electrolyte. Unless electrode reaction is fast enough, electrode polarization can easily induce overpotential. Pure ionic conduction of electrolyte is also necessary to avoid EMF loss during open circuit potential measurement. EIS (Electrochemical Impedance Spectroscopy) was used to study electrode kinetics. We found that Li2TiO3+TiO2 mixture reference electrode reaction is sluggish showing large electrode impedance. This impedance, however, was not affected by gas concentration change. On the other hand, that at the Li2CO3 sensing electrode is relatively small and it increased with decreased CO2 and O2 concentration. It was also observed that these electrode impedances induced the overpotential when the current flowed through the sensor. This electrode overpotential problem was minimized by mixing gold powder or porous sputtered gold electrode increasing effective reaction sites of the electrode. New electrode design improved the sensor EMF closer to the Nernstian values, however, the discrepancy still remained. Moreover, at higher sensor operating temperatures (T>500°C), the sensitivity deviated even further from the Nernstian value. Therefore, the temperature dependence of the current sensor clearly indicates that the non-Nernstian behavior is not just due to non-reversible electrode reaction. More significant effect on the non-Nernstain behavior is due to mixed ionic and electronic conduction of Li3PO4 electrolyte. Based on the EMF measurement and a modified Nernst equation, the transference number was estimated and the conduction domain boundary separating the n-type from the ionic conduction was constructed. This calculation predicted that the sensing side Li activity would be such that the electrolyte would be a mixed conduction (electronic and ionic) domain. Hebb-Wagner (HW) DC polarization measurement also confirmed a significant n-type electronic conduction of Li3PO4 electrolyte. The transference numbers obtained from the EMF measurement and the HW DC polarization measurement were compared and the results confirmed that the origin of the non-Nernstian sensor behavior is mainly due to the mixed conduction of Li3PO4 electrolyte at high temperatures (>500°C).

Committee:

Sheikh Akbar (Advisor)

Subjects:

Engineering, Materials Science

Keywords:

Electrochemical sensor; Mixed Ionic and Electronic conductor; CO2; Reversible electrodes; Gas sensors; Ceramic

Harpster, StevenA Feasibility Study on Development of Dust Abrasion Resistant Gear Concepts for Lunar Vehicle Gearboxes
Master of Science, The Ohio State University, 2009, Mechanical Engineering
In this study, a feasibility analysis on development of dust abrasion resistant gear concepts for future lunar vehicle gearboxes was performed. Conventional gearbox design practices, lubrication methods, and gear materials are not suitable for this application due to a wide range of operating temperatures and the presence of fine lunar dust that is extremely abrasive. Operating lunar gearboxes in a marginally lubricated environment under these conditions promotes excessive gear tooth surface wear as the primary failure mode. In contrast to past missions where limited life cycles were expected from lunar gearboxes, long life cycle requirements for future lunar vehicles necessitates an investigation into alternative gear materials that have significantly higher wear resistance compared to gear steels. At the same time, they must meet other functional requirements of manufacturability, accuracy, and bending resistance. This investigation evaluates the feasibility of using ceramic materials for gears in lunar gearbox applications. For this purpose, a twin-disk contact test study was performed with steel and ceramic disks lubricated using grease with and without simulated dust contaminants. Wear performance of ceramic disks under combined rolling and sliding was evaluated against those of steel disks to establish a contact stress limit for no wear. Gear specimens made of a similar ceramic material were designed and procured. Loaded rotating gear tests were performed with the ceramic gears to assess their bending strength. These gear and roller tests indicate that ceramic materials can be considered for space gear applications where wear is a concern, provided they are designed to lower stress limits established in this study.

Committee:

Ahmet Kahraman (Advisor); Donald Houser (Committee Member)

Subjects:

Engineering; Mechanical Engineering

Keywords:

ceramic; wear; lunar; disks; contaminants; dust; gear; zirconia

Walton, Daniel K.Orthodontic Appliance Preferences of Children and Adolescents
Master of Science, The Ohio State University, 2010, Dentistry
Although attractiveness and acceptability of orthodontic appliances have been rated by adults for themselves and adolescents, children and adolescents have not provided any substantial data. Objective: To evaluate children and adolescent preferences and acceptability of orthodontic appliances. Methods: Images of orthodontic appliances previously captured and standardized for the research of Zuichkovski et al and Rosvall et al were selected and incorporated into a computer-based survey. Additional images of shaped brackets and colored elastomeric ties, as well as discolored clear elastomeric ties were captured and incorporated onto existing survey images with Adobe® Photoshop®. The survey displayed twelve orthodontic appliance variations to 135 children (n=45 of each 9-11 years, 12-14 years, 15-17 years). Subjects rated each image for attractiveness on a visual analog scale (VAS) and acceptability (yes/no). All images were displayed and rated twice to assess rater reliability. Results: Overall reliability for attractiveness rating was r=0.74 and k=0.66 for acceptability. There were significant differences in bracket attractiveness and acceptability in each age group. The highest rated appliances were clear aligners, twin brackets with colored ties, and shaped brackets with and without colored ties. Colored elastomeric ties improved attractiveness significantly over brackets without colored ties for children 12-14 years. There was a tendency for older subjects to rate clear orthodontic appliances higher than younger subjects. Ceramic brackets with discolored ties tended to be rated lower than ceramic brackets with new ties, and scored lowest in acceptability and attractiveness in all age groups. Female subjects rated shaped brackets significantly higher than male subjects. Conclusions: The results of this research demonstrate that children’s preference for orthodontic appliances differs by age and gender. Child and adolescent preferences differ from adult preferences.

Committee:

Henry Fields, DDS MS (Advisor); Stephen Rosenstiel, BDS (Committee Member); William Johnston, PhD (Committee Member); Allen Firestone, DDS MS (Committee Member)

Subjects:

Dental Care

Keywords:

orthodontic attractiveness bracket appliances children adolescent acceptability ceramic wildsmiles color elastomeric ties invisalign survey preferences

Hilbert, Timothy J.Factors associated with Reader Disagreement in a 20-year Radiology Study
MS, University of Cincinnati, 2009, Medicine : Epidemiology (Environmental Health)

Introduction: Studies have shown that there is considerable variability inherent in the reader interpretation of chest radiographs. Besides clinical implications, such disagreements can impact the validity of inferences from health studies. Factors contributing to this variability are not well understood. This study addressed three research questions. First, what worker-specific or test factors are significantly associated with differences in reader interpretations in a chest radiographic study? Second, does a change of one reader midway through a longitudinal chest radiographic study have a significant impact on study findings? Third, what was the radiologist's performance and agreement in this 20-year study?

Methods: Chest X-rays (n=6,392) were collected every three years between 1987 and 2008 from workers (n=1,570) participating in a longitudinal study assessing occupational exposure to Refractory Ceramic Fibers (RCF). RCF exposure has been shown to be associated with elevated rate of pleural and interstitial changes. All films were masked of personal identifiers and interpreted by three B-readers. Workers with two chest X-rays between 1987-1997 (n=1,084) were used to assess associations between the probability of agreement among three readers and several worker-specific and test factors. Worker-specific factors included age, body mass index (BMI), pack-years of cigarette smoking, cumulative RCF exposure, and asbestos exposure, while test factors evaluated were film quality and radiologist experience measured in years. The change in one of three readers was investigated by having the new reader re-evaluate the films (n= 193) with the potential to modify each worker's positive or negative longitudinal radiographic finding. Reader performance was assessed by calculating inter-reader agreement (kappa), sensitivity, specificity, and positive predictive value (PPV).

Results: Reader disagreement was significantly associated with increases in worker age, pack-years of cigarette smoking and cumulative RCF exposure. Agreement between readers was significantly associated with increases in reader experience. Film quality, BMI, and asbestos exposure were not significant in any model. The change in readers impacted the longitudinal positive or negative determination for three workers but did not significantly impact the findings of the original study evaluating the association between occupational RCF exposure and radiographic changes. There was moderate agreement among the readers regarding pleural changes (kappa, k=0.58) and 1/0 or greater interstitial changes (k=0.43). Agreement was fair (k=0.29) for 0/1 or greater interstitial changes. Sensitivity was 78% for pleural changes and 69% for 0/1 or greater interstitial changes. Specificity for both pleural and interstitial findings was extremely high, 99%, as expected for a study with few positive cases. PPV for pleural changes was 68%, 47% for 0/1 or greater interstitial changes and 59% for 1/0 or greater interstitial changes.

Conclusions: This study demonstrates that factors associated with radiographic changes, such as cigarette smoking, occupational exposures, and age, can increase disagreement among readers. Any research investigating subtle radiographic findings, such as 0/1 interstitial changes, should also anticipate radiologist disagreement. Researchers are advised to utilize at least three experienced readers when conducting radiographic studies in order to minimize measurement error and increase precision.

Committee:

Grace LeMasters, PhD (Committee Chair); James Lockey, MD, MS (Committee Member); Linda Levin, PhD (Committee Member); Tania Carreon-Valencia, PhD (Committee Member)

Subjects:

Epidemiology

Keywords:

reader agreement; chest radiograph; refractory ceramic fiber; pleural; interstitial

Nguyen, QuynhGiao N.High Temperature Volatility and Oxidation Measurements of Titanium and Silicon Containing Ceramic Materials
Doctor of Philosophy in Clinical-Bioanalytical Chemistry, Cleveland State University, 2008, College of Science
Titanium (Ti) and silicon (Si) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. A continuous exterior oxide layer is desirable to reduce the oxidation rate of these two materials. At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study first evaluated several hot-pressed Ti and Si-containing compositions at high temperatures as a function of oxidation resistance. This study also evaluated cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400°C - 1200°C in water containing environments to determine the volatile hydoxyl species using the transpiration method. The water content ranged from 0-76 mole % and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Results indicate that oxygen is not a key contributor at these temperatures and a volatile Ti-O-H species has been identified.

Committee:

Lily M. Ng, PhD (Committee Chair); James L. Smialek, PhD (Advisor); Kang N. Lee, PhD (Committee Member); John F. Turner II, PhD (Committee Member); Mary V. Zeller, PhD (Committee Member)

Subjects:

Aerospace Materials; Chemistry; Materials Science

Keywords:

aerospace; ceramic; combustion environment; high temperature; hydroxyl species; oxidation; materials; Si; silicon; titanium dioxide; TiO2; Ti-O-H; transpiration method; transpiration technique; volatility; water vapor

Nieh, Cuo-YoPriming and temperature loss of steel in a cellular ceramic filter
Doctor of Philosophy, Case Western Reserve University, 1990, Materials Science and Engineering
Ceramic filters have been accepted as a successful method of reducing or eliminating inclusions from steel and other metal castings. For a filter to function when it is placed in the gating system of the casting, it is necessary that the steel flow through this filter without freezing or that the filter prime properly. This priming and the factors that influence it is the subject of this thesis. Cellular ceramic filters of various cell sizes and thicknesses were used in this study to investigate the relationships among superheat, filter parameters and priming conditions. The heat loss was the major factor to cause freezing of metal and the cessation of flow at the filter. An increase of static head does not help much to improve priming. A solid shell model was proposed to describe the various primed flow rates. The priming or no priming was not a simple occurrence. Priming depends on the conditions in the overall metal mold-filter system and is considered as four categories: fully primed, gradually primed, gradually unprimed and completely unprimed. Criteria for priming were also discussed. The temperature loss of liquid steel across the filter under various conditions was studied. This temperature loss between the metal entering and leaving the filter was both measured and calculated using appropriate heat flow equations. The calcu lated temperature loss was proved to be a very good base line to obtain the required superheat for obtaining a fully primed condition under various conditions.

Committee:

John Wallace (Advisor)

Subjects:

Engineering, Metallurgy

Keywords:

Priming; temperature loss; cellular ceramic filter

Thomas, Andrew DANONIMITY
MFA, Kent State University, 2016, College of the Arts / School of Art
The definition of ANONYMITY is the idea that a person be non-identifiable, unreachable or untraceable. My work is based on the human form and its abstraction in clay. When looking at the physical human form, I try and focus on certain areas of the body and then express them within the clay pieces. I look at clay as a skin that can be shaped and molded, and just like skin, it can hold memories and emotions over time. I am intrigued by how the light plays across the pieces, how it touches a certain area and the shadow it causes on another, and how it changes as the viewer moves around the piece. The focus of this show is on the form and therefore I have been working with a variety of naked clay bodies to create physical abstraction. Just like humanity the different shades of the clay will bring out the unique qualities within each piece but will also show the similarities between these pieces.

Committee:

peter johnson (Committee Chair); isabel farnsworth (Committee Member); janice lessman-moss (Committee Member)

Subjects:

Art Criticism

Keywords:

ceramic; sculpture; figure; naked clay; clay;art;kent state; body;abstract; vessel

Nowacki, Brenna M.Verification and Calibration of State-of-the-Art CMC Mechanistic Damage Model
Master of Science (M.S.), University of Dayton, 2016, Mechanical Engineering
Due to their low density, high toughness and elevated temperature performance, Ceramic Matrix Composites (CMCs) are attractive candidates for replacing metals in many high temperature applications, such as gas turbine engines and exhaust nozzles. While there are numerous benefits to CMCs, there are several limitations hindering the full-scale application within the aerospace industry. One significant limitation is the ability to accurately model and predict CMC damage behavior. A mechanistic approach to modeling the damage behavior in CMCs was previously developed by Structural Analytics. The damage model, CLIP (Ceramic Matrix Composite Life Prediction), is embedded in a software package that consists of an ABAQUS user-subroutine, as well as a standalone application. The current study verifies the model by calibrating it to a slurry melt-infiltrated SiC/SiC composite. A series of experimental tests were conducted at the Air Force Research Laboratory (AFRL) including montonic tensile tests at 23°C, 800°C and 1200°C, a creep test at 1200°C and a sequentially loaded tensile test at 23°C. The results from the experimental tests were used to calibrate the damage model. The calibration was concluded as successful when the model could produce matching stress-strain curves to the experimental data at the respective temperatures. Finally, the model was used to make predictions for intermediate temperature ranges of monotonic tension, sequentially loaded tension, and off-axis tension.

Committee:

Pinnell Margaret, Ph.D. (Advisor); Jefferson George, Ph.D. (Committee Member); Whitney Thomas, Ph.D. (Committee Member)

Subjects:

Materials Science; Mechanical Engineering

Keywords:

ceramic matrix composite; ABAQUS; CLIP; damage model; calibration; SiC-SiC; material characterization

Gordon, Neal AMaterial Health Monitoring of SIC/SIC Laminated Ceramic Matrix Composites With Acoustic Emission And Electrical Resistance
Master of Science in Engineering, University of Akron, 2014, Mechanical Engineering
Ceramic matrix composites (CMC) composed of Hi-Nicalon Type S™ fibers, a boron-nitride (BN) interphase, and pre-impregnated (pre-preg) melt-infiltrated silicon / silicon-carbide (SiC) matrix have been studied at room-temperature consisting of unidirectional and cross-ply laminates. Quasi-static, hysteretic and uniaxial tensile tests were done in conjunction with a variety of temporary, laboratory-based material health-monitoring techniques such as electrical resistance (ER) and acoustic emission (AE). The mechanical stress-strain relationship paired with electrical and acoustic measurements were analyzed to expand upon current composite knowledge to develop a more fundamental understanding of the failure of brittle matrix laminates, their constituents, and interactions. In addition, a simple but effective method was developed to allow visual confirmation of post-test crack spacing via microscopy. To enhance fidelity of acquired data, some specimens were heat-treated (i.e. annealing) in order to alter the residual stress state. Differences in location, acoustic frequency, and magnitude of matrix cracking for different lay-ups have been quantified for unidirectional and [0/90] type architectures. Empirical results shows complex hysteretic mechanical and electrical behavior due to fiber debonding and frictional sliding of which no general model exists to capture the essence of this CMC system. The results of this work may be used in material research and development, stress analysis and design verification, manufacturing quality control, and in-situ system and component monitoring.

Committee:

Gregory Morscher, Dr. (Advisor); Wieslaw Binienda, Dr. (Committee Member); Tirumalai Srivatsan, Dr. (Committee Member)

Subjects:

Aerospace Materials; Mechanical Engineering

Keywords:

Ceramic Matrix Composite,CMC;Aerospace;Non-Destructive Evaluation,NDE;Structural Health Monitoring,SHM;Composites;Acoustic Emission;Electrical Resistance

Brod, Undine“C” is for Ceramics – It Also Stands for: Collecting, Community, Content, Confusion, and Clarity
Master of Fine Arts, The Ohio State University, 2011, Art
The goal of this thesis was to elucidate the artists’ motivations, inspirations, sources, and reasons for creating visual art. An additional aim was to clarify the themes and content with which the artist works. This document serves as a reflection on the processes the artist underwent to fulfill the requirements for obtaining a Master of Fine Arts Degree. After spending two years studying visual art, maintaining a vibrant studio practice, and through a self-reflexive process of writing the author has gained clarity on the aforementioned goals of this thesis. Furthermore, this document serves as a record of the artist’s trajectory and will aide in guiding the artist forward in the continued pursuit of creativity.

Committee:

Mary Jo Bole (Advisor); Carmel Bucklye (Committee Member); Sergio Soave (Committee Member)

Subjects:

Art Education; Families and Family Life; Fine Arts

Keywords:

Undine Brod; ceramic sculpture; mixed media sculpture; art; visual art; memory; found object; animal; animals; family; mothers; self-reflective quesions; studio practice; art speak; art; clay; artist; American Artist; Female Artist; Narrative; Doilies

Next Page