Materials Science and Engineering Commons^™

A Study Of Ti-Doped Wo3 Thin Films Using Comparative Theoretical And Experimental Approach, Aurelio Paez

Open Access Theses & Dissertations

Metal oxides like Tungsten Oxide (WO3) are well documented and characterized in the literature, with uses in darkening windows and mirrors, flat computer displays, solar panel cooling, and sensors (of interest in this study). Ti doping of WO3 is less documented and the focus of this study. Sample thin films of pure WO3 and varyingly Ti doped WO3 were prepared using Radio Frequency magnetron sputtering (RF) (13.56 MHz) to grow thin films on a silicon substrate. This study aims to compare multiple Ti doping percentages in WO3 theoretically and then compare with experimental data taken from thin films of various …

Repeated Load Relaxation Testing Of Pure Polycrystalline Nickel At Room Temperature Using Nanoindentation, D. E. Stegall, M. A. Mamun, B. Crawford, A, A. Elmustafa

Mechanical & Aerospace Engineering Faculty Publications

We present the results of repeated relaxation tests using nanoindentation to derive the activation volume of the dislocation velocity and the ratios of the dislocation density and dislocation velocity. An experimental technique, based on classical uniaxial relaxation experiments, was developed to establish a constant strain during repeated load relaxation transients and then to calculate the stiffness of unloading, and therefore the hardness, across the transients with acceptable results. We found that the activation volume of the dislocation velocity from our nanoindentation methodology was in good agreement when compared to the same reported for uniaxial experiments. © 2014 AIP Publishing LLC.

Electrospinning Applications Air Filtration And Superhydrophobic Materials, Negar Ghochaghi, Adetoun Taiwo

Graduate Research Posters

Electrospinning is a widely applicable technique that generates non-woven fibers in the micro and nano range. In this project two of its applications are highlighted namely filtration media and enhancement of wettability. The first project demonstrates that electrospinning can be used to produce new fiber filtration media with controlled microstructure. The bimodal and unimodal orthogonal and random filters were made and characterized against their filtration efficiency and pressure drop. Figure of Merit (FOM) was also calculated and discussed. It is shown that the FOM increases when the electrospun fibers are arranged into alternating layers of aligned course and fine fibers. …

The Environmental Performance Of Biobased Resin Within Phenolic-Urethane Nobake Binders: A Feasibility Study, Ian David Morgan Williams

Dissertations and Theses @ UNI

The objectives of this research were to investigate the discovery and development of a biobased nobake binder resin for use within the foundry industry toward improved energy efficiency and environmental performance. The performance of polysaccharides within biobased resins was evaluated using industry-accepted methods and standards such as cure rate, tensile-strength development, and casting performance based upon step cone core results. Biobased nobake resins comprised of polysaccharide raw materials cure at a rate that is comparable to conventional nobake sand binders. Upon reaching stripping time, the development of biobased resin reveals a rapid increase in tensile strength, reaching 80% of its …

Elevated Temperature Mechanical Properties Of Zirconium Diboride Based Ceramics, Eric W. Neuman

Doctoral Dissertations

"Research presented in this dissertation focused on the mechanical behavior of ZrB₂ based ceramic at elevated temperatures. Flexure strength, fracture toughness, and elastic modulus were measured at temperatures up to 2300ºC for three compositions: monolithic ZrB₂ (Z); ZrB₂ - 30 vol% SiC - 2 vol% B₄ C (ZS); and ZrB₂ - 10 vol% ZrC (ZC). In argon, Z, ZS, and ZC had strengths of 210 (at 2300ºC), 260 (at 2200ºC), and 295 MPa (at 2300ºC), the highest temperatures tested for each composition. Fractography was used extensively to characterize the strength limiting flaws as a function of temperature. Strength of ZS …

Electric-Field Induced Ferromagnetic Phase In Paraelectric Antiferromagnets, Maya D. Glinchuk, Eugene A. Eliseev, Yijia Gu, Long-Qing Chen, Venkatraman Gopalan, Anna N. Morozovska

Materials Science and Engineering Faculty Research & Creative Works

The phase diagram of a quantum paraelectric antiferromagnet EuTiO₃3 under an external electric field is calculated using Landau-Ginzburg-Devonshire theory. The application of an electric field E in the absence of strain leads to the appearance of a ferromagnetic (FM) phase due to the magnetoelectric (ME) coupling. At an electric field greater than a critical field, E_cr, the antiferromagnetic (AFM) phase disappears for all considered temperatures, and FM becomes the only stable magnetic phase. The calculated value of the critical field is close to the values reported recently by Ryan et al. [Nat. Commun. 4, 1334 (2013)10.1038/ncomms2329] …

Environmental Fatigue Of Silicate Glasses In Humid Conditions, Zhongzhi Tang, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

Failure strains of commercial silica, soda-lime-silicate, and E-glass fibers were measured using two-point bending in room temperature humid air. Humidity dependence and dynamic fatigue behavior were studied, and the fatigue reaction orders in terms of humidity were determined. In the humidity range tested (~0.1% to ~100%), the dynamic fatigue parameters for silica and E-glass are found to be greater in lower humidity (~0.1% to ~10%), whereas the fatigue parameter for soda-lime-silicate is independent of humidity. The humidity dependence of failure strains for all three glasses was more pronounced in high humidity (~10% to ~100%) than in low humidity (~0.1% to …

Crystallographic Orientation Of The Ε → Α' Martensitic (Athermal) Transformation In A Femnalsi Steel, S. T. Pisarik, D. C. Van Aken

Materials Science and Engineering Faculty Research & Creative Works

The presence of a thermal ε- and α-martensite (α') in the as-cast structure of a Fe-_0.08C-_1.95Si-_15.1Mn-_1.4Al-_0.017N alloy has been revealed by electron backscattered diffraction analysis. The alloy exhibited two a thermal martensitic transformation described by γ → α' and γ → ε → α'. The Shoji-Nishiyama orientation relationship was observed between γ-austenite and ε-martensite, while α-martensite nucleated from γ-austenite exhibited a Kurdjumov-Sachs orientation relationship. Six crystallographic variants of α-martensite consisting of three twin-related variant pairs were observed in ε-bands. A planar parallelism of {0001}ε || {110}α' and a directional relation …

Nanocrystalline Rare Earth Phosphates From Glass Dissolution And Precipitation Reactions, Jaime George, Colin Ryan, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

A novel method is employed for the formation of rare earth phosphate solid solution compounds with unique mesoscopic structures. Europium- And lanthanum-doped sodium borate glass microspheres and particles, ranging in sizes from 50 to 300 μm, were reacted in 0.25 M K₂HPO₄ solution to form hollow spheres of nanocrystalline rare earth phosphate compounds by dissolution-precipitation reactions. The initially X-ray amorphous precipitated rare earth phosphate materials were heat-treated at 700°C for 2 h to form nanocrystalline compounds. Differential thermal analysis (DTA) experiments yield an average activation energy for crystallization of 394 ± 26 kJ/mol. X-ray diffraction (XRD) data …

An Evaluation Of Creep Behaviour In Friction Stir Welded Ma754 Alloy, Jiye Wang, Wei Yuan, Rajiv S. Mishra, Indrajit Charit

Materials Science and Engineering Faculty Research & Creative Works

Effect of friction stir welding (FSW) on microstructure and creep properties of oxide dispersion strengthened (ODS) alloy MA754 were investigated. Fine-grained microstructure developed in the weld zone. TEM results showed some degree of particle agglomeration as a result of intense material flow. Creep tests of the FSW material were carried out at 973 and 1073 K. Power law creep behavior was observed with stress exponent values of 6.9 and 6.3 at 973 and 1073 K, respectively. The results were compared to those of the as-received material. Creep resistance of FSW material was lower than that of as-received material associated with …

Development And Application Of Improved Shotctrete Refractory For Aluminum Rotary Furnace Applications, James G. Hemrick, Angela Rodrigues-Schroer, Dominick Colavito, Jeffrey D. Smith, Kelley O'Hara

Materials Science and Engineering Faculty Research & Creative Works

Oak Ridge National Laboratory, in collaboration with refractory manufacturer Minteq International, Inc., academic partner Missouri University of Science and Technology and refractory end users have developed novel refractory systems and techniques to reduce energy consumption of refractory lined vessels. The objective of this U.S. DOE funded project was to address the need for innovative refractory compositions by developing novel gunnable refractory compositions for use in high temperature and high alkali environments. Developed materials utilized new aggregate materials, bond systems, protective coatings, and phase formation techniques. Under this project, materials were developed specifically for aluminum rotary dross furnace applications and a …

Spinel-Based Refractories For Improved Performance In Coal Gasification Environments, James G. Hemrick, Beth Armstrong, Angela Rodrigues-Schroer, Dominick Colavito, Jeffrey D. Smith

Materials Science and Engineering Faculty Research & Creative Works

Oak Ridge National Laboratory, in collaboration with Minteq International, Inc., Missouri University of Science and Technology and refractory end users, has developed novel refractory systems and techniques to reduce energy consumption of refractory lined vessels. The objective of this U.S. DOE funded project was to address the need for innovative refractory compositions by developing MgO-Al₂O₃ spinel gunnable refractory compositions utilizing new aggregate materials, bond systems, protective coatings, and phase formation techniques. Materials have been developed specifically for coal gasification environments and work has been performed to develop and apply low cost coatings using a colloidal approach for …

A Preliminary Study Of Deformation Behavior Of Friction Stir Welded Ti-6al-4v, Jiye Wang, Jianqing Su, Rajiv S. Mishra, Ray Xu, John A. Baumann

Materials Science and Engineering Faculty Research & Creative Works

A preliminary study of deformation behavior of friction stir welded (FSW) Ti-6Al-4V was performed using two different tools with cylindrical and stepped spiral pin design for the welding process. The nugget regions experienced temperature above β transus and the matrix transformed to fine acicular α during cooling of the nugget. By using stepped spiral pin design, a local region with much refined grain structure and significant tool debris particles were observed. Room temperature tensile test showed increased strength and decreased ductility in the material from this region. Fractographic analysis revealed that tool debris particles served as void nucleation sites. Tensile …

Organic Ferroelectric Evaporator With Substrate Cooling And In Situ Transport Capabilities, Keith Foreman, C. Labedz, M. Shearer, Shireen Adenwalla

Shireen Adenwalla Papers

We report on the design, operation, and performance of a thermal evaporation chamber capable of evaporating organic thin films. Organic thin films are employed in a diverse range of devices and can provide insight into fundamental physical phenomena. However, growing organic thin films is often challenging and requires very specific deposition parameters. The chamber presented here is capable of cooling sample substrates to temperatures below 130 K and allows for the detachment of the sample from the cooling stage and in situ transport. This permits the use of multiple deposition techniques in separate, but connected, deposition chambers without breaking vacuum …

Practical Aspects Of Modern And Future Permanent Magnets, R.W. Mccallum, L. H. Lewis, Ralph Skomski, M. J. Kramer, I. E. Anderson

Ralph Skomski Publications

The mandate to reduce greenhouse gases will require highly efficient electric machines for both power generation and traction motor applications. Although permanent magnet electric machines utilizing Nd2Fe14B-based magnets provide obvious power-to-weight advantages over induction machines, the limited availability and high price of the rare earth (RE) metals make these machines less favorable. Of particular concern is the cost and supply criticality of Dy, a key RE element that is required to improve the high-temperature performance of Nd-based magnetic alloys for use in generators and traction motors. Alternatives to RE-based alloys do exist, but they currently lack the energy density necessary …

Functionally Graded Ti6sl4v And Inconel 625 By Laser Metal Deposition, Syamala Rani Pulugurtha

Doctoral Dissertations

"The objective of the current work was to fabricate a crack-free functionally graded Ti6Al4V and Inconel 625 thin wall structure by Laser Metal Deposition (LMD). One potential application for the current material system is the ability to fabricate a functionally graded alloy that can be used in a space heat exchanger. The two alloys, Inconel 625 and Ti6Al4V are currently used for aerospace applications. They were chosen as candidates for grading because functionally grading those combines the properties of high strength/weight ratio of Ti6Al4V and high temperature oxidation resistance of Inconel 625 into one multifunctional material for the end application. …

Dissolution Behavior Of Phosphate Glasses, Li Na Ma

Doctoral Dissertations

"The solubility of phosphate glasses in aqueous solutions can be tailored through compositional control to obtain a wide range of ion release rates required for a variety of applications. The principal objective of this dissertation is to advance the understanding of the dissolution behavior of phosphate glasses in aqueous environments.

Two families of glasses, sodium-iron phosphate (NFP) glasses and sodium-calcium phosphate (NCP) glasses, were evaluated. The dissolution behavior depends on the phosphate anions that constitute the glass structure and the associated metal (Me) cations. The phosphate glass structure, defined by the distribution and average size of phosphate anions and depending …

วัสดุไททาเนียผสมซีเมนต์เคลือบบนเม็ดแก้วซิลิกาสำหรับใช้เป็นตัวเร่งปฏิกิริยาเชิงแสงเพื่อแตกสลายสารประกอบฟีนอลในน้ำเสียที่นำกลับมาใช้ซ้ำได้, กมลวรรณ ปินะโต

Chulalongkorn University Theses and Dissertations (Chula ETD)

น้ำเสียจากโรงงานผลิตสารเคมีมักปนเปื้อนสารเคมีที่ใช้ในกระบวนการผลิตสูงเกินกว่ามาตรฐานอุตสาหกรรม จึงจำเป็นต้องควบคุมให้อยู่ในมาตรฐานก่อนปล่อยออกสู่สิ่งแวดล้อม น้ำเสียจากโรงงานผลิตฟีนอลปนเปื้อนสารอินทรีย์หลายชนิด เช่น คิวมีนไฮโดรเปอร์ออกไซด์ (CHP) ไดเมทิลฟีนิลคาร์บินอล (DMPC) และอะซิโตฟีโนน (ACP) ค่า pH มีค่า 12.7 งานวิจัยนี้มีจุดประสงค์ในการนำไททาเนีย (TiO2) ซึ่งเป็นตัวเร่งปฏิกิริยาเชิงแสงที่มีศักยภาพสูงและมีอายุการใช้งานยาวนานมาแตกสลายสารอินทรีย์ที่ปนเปื้อนในน้ำเสีย เพื่อความสะดวกในการนำกลับใช้ซ้ำ ไททาเนีย P25 จึงถูกนำมาเคลือบบนวัสดุรองรับ (Ecolite® sphere, EC) ด้วยเทคนิคแกรนูเลตและใช้แคลเซียมอลูมินาซีเมนต์ (AC) เป็นวัสดุเชื่อมประสานเกิดเป็น EC+AC+15wt% TiO2 P25 และศึกษาผลของปัจจัยต่างๆ ที่มีต่อการแตกสลาย CHP ได้แก่ แสงยูวี ปฏิกิริยาเชิงแสงของไททาเนีย P25 ความเข้มข้นเริ่มต้นและอัตราเร็วของ CHP พบว่าปฏิกิริยาเชิงแสงของไททาเนีย P25 ความเข้มข้นเริ่มต้นของ CHP และอัตราเร็วของ CHP มีบทบาทอย่างมากต่อการแตกสลายของ CHP จากนั้นศึกษาความสามารถในการใช้ซ้ำของ EC+AC+15wt% TiO2 P25 พบว่าเมื่อผ่านการทดสอบการแตกสลาย CHP 2,000 พีพีเอ็ม และน้ำเสียจากโรงงานผลิตฟีนอลจำนวน 7 ครั้ง พบว่ามีประสิทธิภาพการแตกสลาย CHP อยู่ในช่วง 90-100% และค่าคงที่อัตราอยู่ในช่วง 0.0089 ถึง 0.0171 ต่อนาที ต่อมาศึกษาประสิทธิภาพของ EC+AC+15wt% TiO2 P25 ในการแตกสลายสารอินทรีย์ชนิดอื่นๆได้แก่ DMPC ACP และฟีนอล พบว่าอัตราการเกิดปฏิกิริยาการแตกสลายสารอินทรีย์ของ EC+AC+15wt% TiO2 P25 คือ CHP > DMPC > ACP > Phenol ตามลำดับ ข้อมูลดังกล่าวสามารถข้อบ่งชี้ถึงประสิทธิภาพของวัสดุดังกล่าวในการนำไปใช้ในงานบำบัดน้ำเสียได้

Flame Retardant Property Improvement Of Polyester Fiber Using Inorganic Additives, Warunee Wattanatanom

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research focused on improving the flame retardancy of polyester and cotton/polyester blended fabrics using intumescent coating via layer-by-layer assembly technique with and without kaolin. The flammability, morphology, thermal stability and mechanical property of coated fabrics were investigated in comparison with uncoated fabrics. Branched polyethyleneimine and ammonium polyphosphate with and without kaolin were respectively used as polycationic and polyanionic to build up the multiple cationic/anionic pairs of layer by deposition technique. The SEM micrographs of coated fabrics compared with uncoated fabrics revealed as well as FT-IR analysis confirmed that layer-by-layer coatings were successfully applied onto the fabrics. The vertical burning …

Gadolinia Doped Hafnia (Gd2o3- Hfo2) Thermal Barrier Coatings For Gas Turbine Applications, Satya Kiran Gullapalli

Open Access Theses & Dissertations

Thermal efficiency of the gas turbines is influenced by the operating temperature of the hot gas path components. The material used for the hot gas path components can only withstand temperature up to a certain limit. Thermal barrier coatings (TBC) provide the additional thermal protection for these components and help the gas turbine achieve higher firing temperatures. Traditionally available yttria stabilized zirconia (YSZ) TBCs have a limitation up to 1200 C due to their phase transformation. The present work focuses on gadolinia based hafnia (GSH) TBCs to study their potential to replace the YSZ coatings. Different compositions of gadolinia doped …