Materials Science and Engineering Commons^™

Shape Memory Behavior Of Single And Polycrystalline Nickel Rich Nickel Titanium Alloys, Irfan Kaya

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTi is the most commonly used shape memory alloy (SMA) and has been widely used for bio-medical, electrical and mechanical applications. Nickel rich NiTi shape memory alloys are coming into prominence due to their distinct superelasticity and shape memory properties as compared to near equi-atomic NiTi shape memory alloys. Besides, their lower density and higher work output than steels makes these alloys an excellent candidate for aerospace and automotive industry. Shape memory properties and phase transformation behavior of high Ni-rich Ni₅₄Ti₄₆ (at.%) polycrystals and Ni-rich Ni₅₁Ti₄₉ (at.%) single-crystals are determined. Their properties are sensitive …

Precipitation, Orientation And Composition Effects On The Shape Memory Properties Of High Strength Nitihfpd Alloys, Emre Acar

Theses and Dissertations--Mechanical and Aerospace Engineering

NiTiHf high temperature shape memory alloys are attractive due to their high operating temperatures (>100 ^oC) and acceptable transformation strain compared to NiTi. However, NiTiHf has limitations due to their lack of ductility and low strength, resulting in poor shape memory properties. In this study, Pd has been added to NiTiHf alloys in an attempt to improve their shape memory behavior. A combined approach of quaternary alloying and precipitation strengthening was used.

The characterization of a Ni_45.3Ti_29.7Hf₂₀Pd₅ (at. %) polycrystalline alloy was performed in compression after selected aging treatments. Transmission electron …

Microstructure And Chemistry Evaluation Of Direct Metal Laser Sintered 15-5 Ph Stainless Steel, Kevin Coffy

Electronic Theses and Dissertations

15-5PH stainless steel is an important alloy in the aerospace, chemical, and nuclear industries for its high strength and corrosion resistance at high temperature. Thus, this material is a good candidate for processing development in the direct metal laser sintering (DMLS) branch of additive manufacturing. The chemistry and microstructure of this alloy processed via DMLS was compared to its conventionally cast counterpart through various heat treatments as part of a characterization effort. The investigation utilized optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffractometry (XRD), energy dispersive X-Ray spectroscopy (EDS) and glow discharge atomic emission spectrometry (GDS) …

Graphene Oxide Reinforcement In Plasma Sprayed Nickel-5%Aluminum Coatings, David Ward

Electronic Theses and Dissertations

Metallic plasma sprayed coatings are widely used in the aerospace industry for repair on worn engine components. However, the inherent defects in these coatings limit the variety of repairs and reduce the service life of the repaired parts. A potential solution to overcome this problem is to mix small amounts of inexpensive graphene oxide in the powder feedstock. The incredible strength to weight ratio of graphene oxide makes it a viable additive to improve mechanical properties of metallic plasma sprayed coatings. The powder system chosen for this research is Nickel-5Aluminum since it is a common coating for such repairs. The …

Processing And Characterization Of Multifunctional Thermoplastic Nanocomposite Films, Xin Wang

Electronic Theses and Dissertations

Nanoparticles reinforced polymer composite films have been widely studied for their enhanced mechanical, electrical and thermal properties compared with host polymer matrix. However, most research was conducted on incorporation of nanoparticles in polymer films to improve single property and there is a lack of research on the multifunctional polymer nanocomposite films. In this work, a scalable and continuous spray deposition process was developed for the production of nanoparticles reinforced multifunctional thermoplastic nanocomposite films. This process is capable of making a thin sheet of thermoplastic nanocomposites with high nanoparticle loadings. The smallest thickness can be 40um. The objective of this study …

The Effects Of Layer Thickness On Dry-Sliding Wear Of Binder Jet Additively Manufactured Stainless Steel And Bronze Composite, Cody Ingenthron

All Graduate Theses, Dissertations, and Other Capstone Projects

Pin on disk wear testing was used to compare additively manufactured binder jet metal matrix composites. The process parameters were changed. The layer thickness and applied forces were varied for the experimental study. Three different layer thicknesses used were, 50μm, 100μm, and 200μm. The pin used was a 420 stainless pin. The wear characteristics of the disk were examined using pin-on-disc method. The material tested was a composite of 420 stainless steel, and 90-10 bronze. Samples were weighed before, during, and after the test to determine differences in mass. Wear tracks were examined using a Scanning Electron Microscope. The results …

Development And Analysis Of Low Calcium Flyash Based Geopolymer For Structural Applications, Gaurav Nagalia

Material Science and Engineering Theses - Archive

Geopolymers are an innovative ceramic material composed of long chains and networks of inorganic molecules are being used as an alternative to conventional Portland cement for infrastructure construction, replacement of intersection and localized repairs. Some of the advantages of this material is due to its ultra-fast setting time, rapid strength development and the phenomenal reduction in carbon foot print as compared to Portland cement. However, this material is yet to be commercialized due to the variability in its mechanical strength when using flyash from different sources. In this study aluminosilicate geopolymers with different alkali oxides (feldspars) have been prepared by …

Zein Film: Effects Of Dielectric Barrier Discharge Atmospheric Cold Plasma, Shashi Pankaj, Carmen Bueno-Ferrer, N. Misra, Paula Bourke, Patrick J. Cullen

Articles

Dielectric barrier discharge atmospheric plasma is a novel non-thermal technology for the food and packaging industry. The effects of dielectric barrier discharge plasma on the surface, structural, thermal and moisture sorption properties of edible zein films have been examined. Plasma treatment increased the surface roughness and equillibrium moisture content of the zein film in a direct relationship with the applied voltage level. No significant difference in the thermal stability of the zein film is also observed after plasma treatment. Dielectric barrier discharge plasma treatments of zein film lead to a change in the protein conformation which is confirmed by X-ray …

In-Situ Tem Plasma Chip Nanofabrication And Characterization, Xuebo Cui

Dissertations, Master's Theses and Master's Reports - Open

A silicon-based microcell was fabricated with the potential for use in in-situ transmission electron microscopy (TEM) of materials under plasma processing. The microcell consisted of 50 nm-thick film of silicon nitride observation window with 60μm distance between two electrodes. E-beam scattering Mont Carlo simulation showed that the silicon nitride thin film would have very low scattering effect on TEM primary electron beam accelerated at 200 keV. Only 4.7% of primary electrons were scattered by silicon nitride thin film and the Ar gas (60 μm thick at 1 atm pressure) filling the space between silicon nitride films. Theoretical calculation also showed …

Nano-Engineering Of Composite Material Via Reactive Mechanical Alloying/Milling (Rma/M), Edward Andrew Laitila

Dissertations, Master's Theses and Master's Reports - Open

Attempts to strengthen a chromium-modified titanium trialuminide by a combination of grain size refinement and dispersoid strengthening led to a new means to synthesize such materials. This Reactive Mechanical Alloying/Milling process uses in situ reactions between the metallic powders and elements from a process control agent and/or a gaseous environment to assemble a dispersed small hard particle phase within the matrix by a bottom-up approach. In the current research milled powders of the trialuminide alloy along with titanium carbide were produced. The amount of the carbide can be varied widely with simple processing changes and in this case the milling …

Development Of Practical Applications For Reprap Style 3-D Printers In Engineering, Benjamin T. Wittbrodt

Dissertations, Master's Theses and Master's Reports - Open

The current rise in popularity of consumer level 3-D printers introduces a need to understand the application and material property capabilities of the technology. Presented here is data demonstrating the ability for the average U.S. consumer to recuperate the cost of a 3-D printer within one year of ownership. Additionally, using a consumer level 3-D printer, multiple photovoltaic (PV) racking systems were printed and produced with much lower cost compared to commercially available aluminum racking. Additionally, mechanical testing on 3-D printed components showed a temperature dependence on both percent crystallinity and ultimate tensile strength. Conclusions are drawn using the information …

Analysis Of The Influence Of Organic Corrosion Inhibitors On Corrosion Of Reinforcement In Concrete Bridge Structure Under Simulated Field Service Environment, Liang Shi, J. Ye, C. C. Chen, Y. Wu, J. Z. Liu

International Conference on Durability of Concrete Structures

For concrete bridge projects in marine environments, attention must be paid to the reinforcement corrosion problems caused by chloride intrusion. As kinds of functional admixtures, which can reduce the reinforcement corrosion rate, corrosion inhibitors are becoming very popular in China in new bridge projects. Corrosion inhibitors cover both inorganic and organic inhibitors. Nitrite is representative of inorganic corrosion inhibitors, but its carcinogenicity has hindered its further development. Organic corrosion inhibitors such as small-molecule-based alcohol amine series are becoming the focus of attention. To guide the scientific applications of organic corrosion inhibitors, China is carrying out broad applications technology research. But …

Processing And Characterization Of Continuous Basalt Fiber Reinforced Ceramic Matrix Composites Using Polymer Derived Ceramics, Sarah Cox

Electronic Theses and Dissertations

The need for high performance vehicles in the aerospace industry requires materials which can withstand high loads and high temperatures. New developments in launch pads and infrastructure must also be made to handle this intense environment with lightweight, reusable, structural materials. By using more functional materials, better performance can be seen in the launch environment, and launch vehicle designs which have not been previously used can be considered. The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer matrix composites can be used for temperatures …

Non-Oxide Porous Ceramics From Polymer Precursor, Xueping Yang

Electronic Theses and Dissertations

Non-oxide porous ceramics exhibit many unique and superior properties, such as better high-temperature stability, improved chemical inertness/corrosive resistance, as well as wide band-gap semiconducting behavior, which lead to numerous potential applications in catalysis, high temperature electronic and photonic devices, and micro-electromechanical systems. Currently, most mesoporous non-oxide ceramics (e.g. SiC) are formed by two-step templating methods, which are hard to adjust the pore sizes, and require a harmful etching step or a high temperature treatment to remove the templates. In this dissertation, we report a novel technique for synthesizing hierarchically mesoporous non-oxide SiC ceramic from a block copolymer precursor. The copolymer …

Freeze Thaw Durability Of Internally Cured Concrete Made Using Superabsorbent Polymers, Wesley A. Jones, W. Jason Weiss

International Conference on Durability of Concrete Structures

The use of superabsorbent polymers (SAPs) to produce internally cured concrete has been shown to be effective in reducing the potential for restrained shrinkage cracking of high performance concrete mixtures. However, not much is known regarding the freeze–thaw durability of concrete mixtures that incorporate SAPs for internal curing (IC). When SAP particles desorb (or partially desorb) the “water” (pore fluid) they contain for the purposes of IC, some believe that the void space created by these particles can provide enough empty voids to accommodate the additional volume caused by water expansion upon freezing. This paper investigates the freeze–thaw durability of …

Influence Of Organic Inhibitor On Corrosion Resistance Of Steel In Simulated Concrete Pore Solution, Jingshun S. Cai, C. C. Chen, J. Z. Liu, J. P. Liu

International Conference on Durability of Concrete Structures

Organic corrosion inhibitor is one of lower cost technologies that limit the deterioration of concrete structures. The influence of a newly prepared organic corrosion inhibitor on the corrosion behavior of carbon steel in simulated concrete pore solution was investigated by polarization curves, electrochemical impedance spectroscopy, and so on. The effect of organic corrosion inhibitors on concrete working performance was also studied. The results show that the corrosion rate decreases with the concentration of inhibitor increase; when the content of inhibitor up to 1.5% versus water, the oxide film was completely passive. Organic corrosion inhibitor had no effect on work performance.

Co2 Sequestration In Cement-Based Materials During Mixing Process Using Carbonated Water And Gaseous Co2, Jacek Kwasny, P. A. Muhammed Basheer, Mark I. Russell, William Doherty, Kieran Owens, Neil Ward

International Conference on Durability of Concrete Structures

This paper presents selected findings from a recently completed research project, aimed at the investigation of CO₂ sequestration in cement-based materials during the early stages of hydration when the cement paste is being mixed. Portland cement pastes were carbonated during the mixing process, using both carbonated water and gaseous CO₂, and their properties were compared to the control non-carbonated mix. All mixes were prepared in a purpose-designed chamber that permitted carbonated water and gaseous CO₂ to be mixed with the cementbased materials during the mixing process, without losses of CO₂ to the external environment. Temperature …

Thermotropic Phase Boundaries In Classic Ferroelectrics, Tom T. A. Lummen, Yijia Gu, Jianjun Wang

Materials Science and Engineering Faculty Research & Creative Works

High-performance piezoelectrics are lead-based solid solutions that exhibit a so-called morphotropic phase boundary, which separates two competing phases as a function of chemical composition; as a consequence, an intermediate low-symmetry phase with a strong piezoelectric effect arises. In search for environmentally sustainable lead-free alternatives that exhibit analogous characteristics, we use a network of competing domains to create similar conditions across thermal inter-ferroelectric transitions in simple, lead-free ferroelectrics such as BaTiO₃ and KNbO₃. Here we report the experimental observation of thermotropic phase boundaries in these classic ferroelectrics, through direct imaging of low-symmetry intermediate phases that exhibit large enhancements …

Atomic Layer Deposition, Paul Kubicza

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.

Effect Of Er Doping On The Structural And Magnetic Properties Of Cobalt-Ferrite, Sateesh Prathapani, M. Vinitha, Tanjore V. Jayaraman, D. Das

Department of Mechanical and Materials Engineering: Faculty Publications

Nanocrystalline particulates of Er doped cobalt-ferrites CoFe_(2–x)Er_xO₄ (0 ≤ x ≤ 0.04), were synthesized, using sol-gel assisted autocombustion method. Co-, Fe-, and Er- nitrates were the oxidizers, and malic acid served as a fuel and chelating agent. Calcination (400–600 °C for 4h) of the precursor powders was followed by sintering (1000 °C for 4 h) and structural and magnetic characterization. X-ray diffraction confirmed the formation of single phase of spinel for the compositions x = 0, 0.01, and 0.02; and for higher compositions an additional orthoferrite phase formed along with the spinel phase. …