Ceramic Materials Commons^™

Ultra-Low Dosages Of Novel Graphene Types Enhance The Rheological Properties And Buildability Of 3d Printed Binders, Sahil Surehali, Akshay Venkatachalam, Ranjith Divigalpitiya, Aditya Kumar, Narayanan Neithalath

Materials Science and Engineering Faculty Research & Creative Works

The use of graphene as a high-performance concrete additive is attractive; but, its cost and concerns about production scalability and dispersion efficiency in concrete are impediments to widespread use. This study explores the impact of ultra-low dosages (≤0.02 % by mass of binder) of two novel graphene types—fractal graphene (FG) and reactive graphene (RG)—produced through a cost-effective, environmentally friendly, and scalable process, on the rheological properties of 3D-printable concrete. Both FG and RG significantly enhance the dynamic and static yield stresses and viscoelastic properties of the binder, with RG-modified mixtures exhibiting slightly more pronounced enhancements due to the presence of …

Mno2 Nanoscale Interface Modification, Alexander C. Skoppe

Doctoral Dissertations and Master's Theses

Interface modification of carbon fibers has been shown to improve the mechanical performance of composites. In addition, interface modification of carbon fiber composites can impart multifunctionality into the resulting composite. This work will explore ZnO and MnO2 as interface modifications for use on carbon fibers. When exposed to high temperatures, carbon fibers undergo fiber degradation, leading to the need for low-temperature hydrothermal processes. This work will develop and characterize a nanoscale ZnO and MnO2 interface modification for use on carbon fibers. These nanomodifications will be developed with low-temperature processes, minimizing the fiber degradation that the fibers undergo. Fourier transform infrared …

Thermomechanical And Thermal Characterization Of Pressureless Sintered Tib2, Simone Taraborelli, Simone Failla, Diletta Sciti, Steven M. Smith, Jeremy Watts, William G. Fahrenholtz, Greg E. Hilmas

Materials Science and Engineering Faculty Research & Creative Works

The impact of high-energy milling using WC[sbnd]Co media on the pressureless sintering and properties of TiB₂ was studied. After 30 mins of milling, samples sintered at 2200 °C achieved a high relative density (>98 %) and a fine mean grain size (<2 >µm). In the microstructure WxBy phases, often containing Co, were observed at triple points, due to contamination from the milling media. Moreover, core-rim structures with multiple rims were detected: the cores consisted of pure TiB₂ grains, the rims were (TixWy)B2 solid solutions. The core-rim formation was significantly more pronounced compared to a reference sample of …

Fire Fossils: Biomineral Infrastructures In Untangling Climates, Tanmayee More

Masters Theses

Diatoms drift, sediments sink, wildfires generate their own weather. Lightning strikes can blast sand into glass, and microscopic organisms do the same in the cold recesses of the ocean. What alchemies and metabolisms catalyze space, time, and energy? What are the thermodynamics of infrastructure in Climate Change?

Places, materials, and beings are afterimages. Through alchemical experiments, and multi-scalar imaging, I develop simulations of wildfires, and their profound, reverberating effects. In this thesis, a glass-meets-landscape experimental process enters these obscured conditions and renders new material relations for the built environment.

Reliability Of Cazro3 And Mgo Capacitors At High Temperatures, Alan Devoe, Hung Trinh, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Calcium zirconate and magnesium oxide have both been found to have useful dielectric properties at high temperatures. Multilayer ceramic capacitors (MLCCs) were made with these dielectrics and platinum electrodes. The relationship between the lifespan (mean-time to failure) and applied voltage was determined using Weibull statistics. CaZrO₃ capacitors were tested between 550◦C and600◦C while MgO capacitors were tested between 600◦C and 650◦C. The temperature coefficient Ea and the voltage coefficient n of the Prokopowicz Vaskas equation were determined under various test conditions. Activation energiesforcalciumzirconateandmagnesiumoxidewere3.25eVand3.48eV, respectively. Resistance degradation of CaZrO₃ and MgO capacitors, tested at 600◦Cand250V, were compared.

Intermediate Stage Densification Kinetics Of High-Entropy Ceramics During Spark Plasma Sintering, Steven M. Smith, William G. Fahrenholtz, Greg E. Hilmas, Stefano Curtarolo

Materials Science and Engineering Faculty Research & Creative Works

The intermediate stage densification kinetics of (Hf, Nb, Ta, Ti, Zr) B2 and (Hf, Nb, Ta, Ti, Zr) C were studied using a Coble creep rate model. (Hf, Nb, Ta, Ti, Zr) B2 was synthesized by boro/carbothermal reduction and (Hf, Nb, Ta, Ti, Zr) C was synthesized by carbothermal reduction. Both ceramics were densified by spark plasma sintering at 1700–1850°C. The activation energies for densification were 575 ± 53 kJ/mol for the high-entropy boride and 646 ± 4 kJ/mol for the high-entropy carbide. The densification mechanisms were grain boundary diffusion for the high-entropy boride and lattice diffusion for the high-entropy …

Effects Of Processing And Microstructure On The Oxidation Of Zrb2-Sic In Co2, Marharyta Lakusta, Jeremy L. Watts, William G. Fahrenholtz, David W. Lipke

Materials Science and Engineering Faculty Research & Creative Works

Oxidation kinetics and oxide scale microstructures were compared for ZrB2-30 vol% SiC composites fabricated by hot press sintering of powders and by pressure less sintering of additively manufactured billets. Oxidation in CO₂ was conducted at temperatures up to 1400 °C with durations up to 900 h. All specimens exhibited parabolic oxidation kinetics. Materials with similar composition but different processing histories exhibited differences in oxidation behavior that become evident at extended durations (200–900 h) and higher temperatures (1200–1400 °C). Oxidation rates generally increased with grain size, e.g., at 1000 °C for 200 h, oxide scale thickness increased from 36 to …

The Evolution Of Nanoparticles In Nanoparticle Doped Optical Fibers, Mary Cahoon

All Dissertations

Optical fiber and fiber laser technologies based on silica glass are critical to many technologies today. One method to improve the optical performance of laser fibers is engineer the local environment around the active elements in the glass. To that end, this Dissertation focused on the fabrication and characterization of fibers made with nanoparticles incorporated into the glass to control the local composition. First, the nanoparticle composition and structure was analyzed as it evolved from from the initially-synthesized form to incorporation into the dense aluminum-silicate glass. The aluminum oxide in the glass was found to be important not only to …

Interfacial Defect Properties Of High-Entropy Carbides: Stacking Faults, Shockley Partial Dislocations, And A New Evans-Polanyi-Semenov Relation, Samuel E. Daigle, Stefano Curtarolo, William G. Fahrenholtz, Jon Paul Maria, Douglas E. Wolfe, Eva Zurek, Donald W. Brenner

Materials Science and Engineering Faculty Research & Creative Works

Using first principles calculations, {111} intrinsic stacking fault (ISF) energies in groups IVB, VB, and VIB high-entropy transition metal carbides (HETMCs) are shown to be predictable from an optimized rule of mixtures based on the atomic arrangement near the stacking fault. A composition-independent linear relationship is demonstrated between the ISF energies and the unstable stacking fault (USF) energies along the (112¯){111} γsurface slip path. This relationship represents a new application of the Evans-Polanyi-Semenov principle by treating the ISF and USF energies as analogous to the heat of reaction and transition state barrier in chemical reactions. Further, a full defect energy …

Advanced Manufacturing Of Multifunctional Shape Memory Polymer Composites And Self-Healing Systems, John B. Konlan

LSU Doctoral Dissertations

The need for multifunctional light weight structures for engineering applications is on the rise. Multifunctional composites are desired because of their ability to combine multiple functionalities into one structure. The advantages of a high strength-to-weight ratio of multifunctional composites make them desirable and suitable for use in energy-efficient applications. Shape-memory polymers (SMPs) have attracted interest over the past several decades because of their multifunctional nature. They have found use in many applications such as aerospace, satellites, automobiles, textiles, and biomedical devices, where lightweight and multifunctionality are key. The self-healing nature of most SMPs makes them suitable for use in lightweight …

Numerical Simulation Of Heat Transfer In Self-Propagating High-Temperature Synthesis (Shs)-Based Calcination Of Limestone, Sayee Srikarah Volaity, Shubham Agrawal, Srinivas Kilambi, Patrick Phelan, Aditya Kumar, Narayanan Neithalath

Materials Science and Engineering Faculty Research & Creative Works

Calcination of limestone, a high temperature (∼900 °C) process that emits 44 % of the mass of limestone as CO₂, is a critical process in the production of many industrially important materials. To soften the CO₂-related impacts of traditional calcination, and to enable ultrafast synthesis of lime, a novel approach based on self-propagating high-temperature synthesis (SHS) has been put forward. SHS uses exothermic heat released by the combustion of fuel intermixed with the reactants to advance the reaction, and hence requires the provision of lower external temperatures. This study introduces a microstructure-guided modeling approach to understand …

Compositionally Complex Diborides: Competing Solubility During Sintering And Properties, Laura Silvestroni, Carlo Baldisserri, Jacopo Matteo Tabaglio, Nicola Gilli, Jeremy Watts, Steven M.I. Smith, Gregory E. Hilmas, William G. Fahrenholtz

Materials Science and Engineering Faculty Research & Creative Works

An ultra-high temperature ceramic based on ZrB2, TiB2, and SiC was hot pressed to full density at 1850 °C. Addition of 5 vol% of different metal-compounds, in the form of HfC, VC, NbC or CrB2, increased the densification temperature to 1910 °C. The resulting compositionally complex ceramics had homogeneous microstructures with boride grains exhibiting core-shell features. The shell was a solid solution containing variable amounts of the three metals. Notably, TiB2 remained as a discrete phase in the reference material and in the presence of the V- and Cr- based additions, whilst it dissolved into the main ZrB2-based grains for …

Fabrication Of Ultra High-Temperature Compact Heat Exchanger By Extrusion-Based Ceramic Additive Manufacturing, Abid Hasan Rafi, David W. Lipke, Jeremy Lee Watts, Greg Hilmas, Ming-Chuan Leu

Miners Solving for Tomorrow Research Conference

No abstract provided.

Sustainable Solutions To Eutrophication: The Role Of Glass Fertilizers, Lucas Greiner, Charmayne Lonergan

Miners Solving for Tomorrow Research Conference

No abstract provided.

Microstructural Evolution Of High-Entropy Carbide Ceramics, Elizabeth Pritchett, William Fahrenholtz, Greg Hilmas, Steven Smith

Miners Solving for Tomorrow Research Conference

No abstract provided.

Synergy In Materials: Leveraging Phosphosilicate Waste Forms For Electrochemical Salt Waste, Jonathan S. Evarts, Brian J. Riley, Charmayne E. Lonergan, Michaella S. Harris, Jincheng Bai, Eric W. Bohannan, Iheanyichukwu Ajoku, Saehwa Chong, John S. Mccloy

Materials Science and Engineering Faculty Research & Creative Works

Waste forms containing glassy and crystalline phosphate and silicate phases were produced to immobilize salt waste simulants from pyro processing and characterized by using Raman spectroscopy, Mössbauer spectroscopy, X-ray diffraction, scanning electron microscopy, heat capacity, and chemical durability measurements. In this work, a phosphosilicate waste form is presented to leverage the benefits of both borosilicate glasses and iron phosphate glasses. To improve waste loading, prior to immobilization, salt simulants were successfully dechlorinated using ammonium dihydrogen phosphate, mixed with a borosilicate frit (5–30 wt. %) and Fe2O3, and vitrified. Additions of 2.5–15 wt. % borosilicate glass (NBS3) improved normalized release rates …

Effect Of Niobium Dopant On Zno Thin Films Prepared Via The Sol–Gel Spin Coating Method, Kevin Alvin Eswar, Nur Fairuz Rostan, Maryam Mohamad, Rabiatuladawiyah Md Akhir, Rosfayanti Rasmidi, Muliyadi Guliling, Najwa Ezira Azhar, Irmaizatussyehdany Buniyamin, Mohd Firdaus Malek, Mohamad Rusop Mahmood, Husairi Fadzilah Suhaimi, Saifollah Abdullah

Makara Journal of Science

Thin films of zinc oxide (ZnO) and niobium (Nb)-doped ZnO were deposited on a glass substrate using the sol–gel spin coating method. Diethanolamine, isopropyl alcohol, and zinc acetate served as the stabilizers, solvent, and starting ma-terial, respectively. Niobium pentachloride was employed as the dopant source. Energy-dispersive X-ray analysis con-firmed Nb incorporation. Field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and ultravio-let–visible spectroscopy (UV–Vis) analyses characterized the morphology, structure, and optics of the films, respective-ly. Both films, comprising nanoparticles, were visible in FESEM. Nb doping reduced the particle size from 44.2 nm to 35.8 nm. The XRD peaks at 31.23°, …

Mg And Fe Co-Doped Perovskites For The Electrochemical Oxidative Coupling Of Methane In Solid Oxide Electrolyzers, Luke H. Denoyer

Chemical and Biological Engineering ETDs

More efficient usage of shale gas reserves and natural gas resources will allow for higher olefin yields and lower greenhouse gas emissions. The oxidative coupling of methane (OCM) is a direct pathway for converting methane to ethylene at temperatures >700 °C. The OCM process is typically regulated via the choice of catalyst, reactor conditions, temperature range and gas mixing. The electrochemical oxidative coupling of methane (E-OCM) is a modification to the OCM reaction by controlling the oxygen content via externally applied potentials to an SOEC. Perovskite oxide catalysts are useful for E-OCM due to their flexible bond networks and desired …

Design And Function Of Thermoresponsive-Ultrafast Stiffening Suspension Formulations For 3d Printing, Sharu Bhagavathi Kandy, Sebastian Remke, Thiyagarajan Ranganathan, Shubham Kiran Wani, Xiaodi Dai, Narayanan Neithalath, Aditya Kumar, Mathieu Bauchy, Edward Garboczi, Torben Gädt, Samanvaya Srivastava, Gaurav Sant

Materials Science and Engineering Faculty Research & Creative Works

An inability to accurately control the rate and extent of solidification of cementitious suspensions is a major impediment to creating geometrically complex structural shapes via 3D printing. In this work, we have developed a thermoresponsive rapid stiffening system that will stiffen suspensions of minerals such as quartz, limestone, portlandite, and Ordinary Portland Cement (OPC) over a wide pH range. When exposed to trigger temperatures between 40 °C and 70 °C, the polymer binder system undergoes a thermally triggered free radical polymerization (FRP) reaction, leading to an ultrafast stiffening of the suspension at an average rate on the order of 1 …

A Low-Carbon Approach For Lime Production Using Self-Propagating High Temperature Synthesis-Driven Limestone Calcination, Shubham Agrawal, Sayee Srikarah Volaity, Srinivas Kilambi, Aditya Kumar, Narayanan Neithalath

Materials Science and Engineering Faculty Research & Creative Works

Limestone calcination produces calcium oxide (or lime), that forms the basis for the manufacturing of many critical engineering materials such as cement and iron-and-steel. Limestone calcination—an endothermic reaction—is regarded as one of the most energy-and-CO₂ intensive industrial chemical reactions, and is facilitated by fossil fuels, since the high temperature requirement (∼900 °C) renders it less conducive to electrification through renewable energy sources. In this study, a novel, low-temperature (∼450 °C) pathway for ultrafast calcination of limestone using combustion synthesis or self-propagating high-temperature synthesis (SHS) is developed. SHS leverages exothermic heat from the combustion of lignin or biomass—as low-carbon fuels—mixed …