Ceramic Materials Commons^™

In-Situ Investigations Of Calcium-Magnesium-Aluminosilicates (Cmas) Infiltration Effects On Thermal Barrier Coatings Under Extreme Environments Replicating Jet Engines, Zachary Stein

Doctoral Dissertations and Master's Theses

Calcium-magnesium-aluminosilicate (CMAS) particulates, such as sand or volcanic ash, are ingested by gas turbine jet engines during operation. When operating within high abundance regions, these particulates negatively interact and degrade the high temperature thermal barrier coatings (TBC) protecting underlying superalloy turbine blades vital to engine operation. These CMAS particulates melt within the engine and infiltrate into the ceramic coatings. In electron-beam physical vapor deposited (EB-PVD) TBCs, the CMAS within the intercolumnar gaps stiffens the coatings and causes thermomechanical induced high stress concentrations, risking crack formation. While molten, the CMAS thermochemically alters and destabilizes the coating, also risking coating failure. Premature, …

Thermal Properties Of High Entropy Dual Phase (Hf,Nb,Ta,Ti,Zr,)C-(Hf,Nb,Ta,Ti,Zr)B2 Ceramics: Comparison With The High Entropy Single-Phase Ceramics And The Effect Of Wc Additions, Rubia Hassan, William G. Fahrenholtz, Gregory E. Hilmas

Materials Science and Engineering Faculty Research & Creative Works

The heat capacity, thermal diffusivity and thermal conductivity of (Hf,Nb,Ta,Ti,Zr)C-(Hf,Nb,Ta,Ti,Zr)B₂ high entropy dual phase ceramics were evaluated from room temperature to 1800 °C and compared with the constituent high entropy single phase ceramics of the same nominal compositions. Thermal conductivity of the (Hf,Nb,Ta,Ti,Zr)C-(Hf,Nb,Ta,Ti,Zr)B₂ dual phase ceramic increased from 17.7 W m⁻¹ K⁻¹ at room temperature to 54 W m⁻¹ K⁻¹ at 1800 °C. The addition of WC to the dual phase ceramic reduced its thermal conductivity. For the addition of 5 wt% WC, room temperature thermal conductivity was 16.8 W m⁻¹ K^{−1 …}

Effects Of Wc Additions On The Phase Formation Of (Hf,Nb,Ta,Ti,Zr)C-(Hf,Nb,Ta,Ti,Zr)B2 High Entropy Dual Phase Ceramics, Rubia Hassan, William G. Fahrenholtz, Gregory E. Hilmas

Materials Science and Engineering Faculty Research & Creative Works

High entropy dual phase (Hf,Nb,Ta,Ti,Zr)C-(Hf,Nb,Ta,Ti,Zr)B2 ultra-high temperature ceramics were produced from powders synthesized by boro-carbothermal reduction. Systematic additions of 2.5 wt%, 5 wt%, and 10 wt% WC were incorporated after powder synthesis. Additions of 2.5 wt% and 5 wt% WC dissolved into the host ceramics, resulting in complete solid solution formation and nearly full densification. In contrast, a secondary monoboride phase evolved for the composition with 10 wt% WC, in addition to the main high entropy carbide and diboride phases. Thermodynamic analysis revealed that WB formation was favorable for WC additions in the presence of metal diborides at the sintering …

Micro/Nanomechanical Properties Of Top-Seeded Melt Grown Ybco Single Crystals Determined Using Depth Sensing Indentation, Ugur Kolemen, Cafer Mert Yesilkanat, Fikret Yilmaz, Fatih Dogan, Orhan Uzun

Materials Science and Engineering Faculty Research & Creative Works

Mechanical properties of the bulk YBa2Cu3O7-x (YBCO) single crystal superconductor, prepared by using the Top Seeded Melt Growth (TSMG) method, were determined. Property measurements were conducted by the nanoindentation method under various loads and the micro indentation method at different temperatures. Hardness (H) and reduced elastic modulus (Er) values were calculated by using the Oliver–Pharr method. According to hf/h max values found from load- displacement curves, there is a sink in behavior around outer rim of the indents that was confirmed by atomic force microscopy (AFM) analysis. Nanoindentation analyses conducted on upper section, middle section and subsection revealed that all …

Variable-Temperature Plasmonic High-Entropy Carbides, Simon Divilov, Sean D. Griesemer, Robert C. Koennecker, Michael J. Ammendola, Adam C. Zettel, Hagen Eckert, Jeffrey R. Shallenberger, Xiomara Campilongo, William G. Fahrenholtz, Arrigo Calzolari, Douglas E. Wolfe, Stefano Curtarolo

Materials Science and Engineering Faculty Research & Creative Works

Effective thermal management at variable and extreme temperatures face limitations for the development of novel energy and aerospace applications. Plasmonic approaches, shown to be capable of tailoring black-body emission, could be effective if materials with high-temperature and tunable plasmonic resonance were available. Here, we report a synergy between experimental and theoretical results proving that many high-entropy transition metal carbides, consisting of four or more metals at equal molar ratio, have plasmonic resonance at room, high (>1000∘C) and variable temperatures. We also found that these high-entropy carbides can be tuned and show considerable plasmonic thermal cycling stability. This paradigm-shift approach …

Data Driven Design Of Ultra High Performance Concrete Prospects And Application, Bryan K. Aylas-Paredes, Taihao Han, Advaith Neithalath, Jie Huang, Ashutosh Goel, Aditya Kumar, Narayanan Neithalath

Electrical and Computer Engineering Faculty Research & Creative Works

Ultra-high-performance concrete (UHPC) is a specialized class of cementitious composites that is increasingly used in various applications, including bridge decks, connections between precast components, piers, columns, overlays, and the repair and strengthening of bridge elements. The mechanical and durability properties of UHPC are significantly influenced by factors such as low water-to-binder ratios, the inclusion of supplementary cementitious materials (SCMs), and fiber reinforcement. Machine learning (ML) has been employed to predict the performance of UHPC and optimize its mixture designs by using various raw materials. This study first provides a comprehensive review of ML applications in UHPC, focusing on predicting workability, …

Elucidating The Effects Of Water Activity On The Hydration Kinetics And Thermodynamics Of Ye’Elimite–Calcium Sulfate Hydrate Systems, Godwin I. Ogbuehi, Rupack R. Halder, Aditya Kumar, Gaurav Sant, Monday U. Okoronkwo

Materials Science and Engineering Faculty Research & Creative Works

Relative humidity and water activity (aH) reductions have been known to suppress the hydration of anhydrous cement clinker phases. However, the relationship between ye'elimite (C4A3$) hydration kinetics and water activity remain unclear. This study employs experimental and thermodynamic modeling approaches to investigate the influence of water activity on ye'elimite hydration in the "C4A3$ + water", and "C4A3$ + gypsum + water" systems. Experimental findings indicate that as water activity decreases, C4A3$ hydration diminishes until the reaction is brought to a halt at a threshold aH. The critical aHand corresponding solubility constant of C4A3$ (KC4A3S¯) estimated from thermodynamic analysis are 0.46 …

Effects Of Yttrium And Barium Trace Impurities On The Dielectric Properties Of  Srtio3 (111) Single Crystals At Cryogenic Temperatures, Hung Trinh, Alan Devoe, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Commercially available single crystals of (111) SrTiO₃ were found to contain impurities of varying amounts that strongly affected their dielectric performance at cryogenic temperatures. Three crystals with total impurities of 111, 126, and 625 ppm, primarily of barium and yttrium, were analyzed. Relative permittivity (εr) and loss tangent were investigated with high resolution as a function of temperature (4 K to 100 K), DC voltage (0 V/cm to 800 V/cm), and frequency (100 Hz to 1 MHz). An impurity level as low as ≈500 ppm barium resulted in an increase of the maximum permittivity (εm) to approximately 50,000 at …

Active Measurement Of A Micron-Order Gap Under High-Speed And High-Temperature Conditions, Andrew Becker

Doctoral Dissertations and Master's Theses

The hypersonic regime poses numerous challenges that researchers face in the development of hypersonic flight vehicles. Due to their excellent thermomechanical properties, ultra-high-temperature ceramics (UHTCs) have risen as a promising solution to act as a protective barrier between the harsh environment and surface materials of these flight bodies. The mechanical operation of a portable hypersonic simulation device was developed in-house and tested at Argonne National Laboratories (ANL) to gather in-situ material response of prospective UHTC samples when exposed to a hypersonic regime. An edge detection-based algorithm was developed and used in LabVIEW to monitor the health and operation of the …

Extraction Of Aluminum From Lunar Regolith Through Molten Salt Electrolysis, Jacob N. Ortega, Todd P. Sander, Jeffrey D. Smith, Fateme Rezaei, David J. Bayless, William Schonberg, Daniel S. Stutts, Frank D. Han

Materials Science and Engineering Faculty Research & Creative Works

This paper presents the methodology, development, and results of an end-to-end regolith-to-metal concept for producing aluminum in-situ on the lunar surface, namely, the Lunar In-Situ Aluminum Production through Molten Salt Electrolysis (LISAP-MSE) method. Using electrolytic reduction, aluminum oxide (i.e., alumina) can be reduced into aluminum and oxygen via electrolysis in a molten salt bath. A steady supply of hydrogen chloride could allow this in-situ resource utilization (ISRU) method to supply several necessary materials consumed in the electrolytic reduction step of the process to produce bulk aluminum metal, oxygen, water, and silica from anorthite abundant in lunar highland regions. In this …

Microstructure Densification In Cement Pastes Enabled By Novel Graphene Types, Sahil Surehali, Taihao Han, Ranjith Divigalpitiya, Aditya Kumar, Narayanan Neithalath

Materials Science and Engineering Faculty Research & Creative Works

The primary barriers hindering graphene's widespread adoption as a performance-enhancing additive in cement-based systems have traditionally been its prohibitive cost and the sustainability concerns associated with conventional manufacturing processes. However, these impediments have recently been mitigated by advancements in detonation synthesis techniques, enabling scalable, cost-effective, and environmentally favorable production of novel graphene types—specifically fractal graphene (FG) and reactive graphene (RG). This paper explores the influence of ultra-low dosages of FG and RG (≤ 0.04 % by mass of cement, which results in ∼20 % increase in compressive strengths) on the pore-structure features of cement pastes. Compared to the control paste, …

Improvement Of Lithium-Metal Electrode All-Solid-State Batteries Performance By Shot Peening And Magnetron Sputtering, Atsuro Okumura, Manabu Kodama

15th International Conference on Shot Peening

To enable fast charging in lithium-metal anode all-solid-state batteries, suppressing lithium dendrite formation at the solid electrolyte (SE) interface is critical. Increasing fracture toughness via shot peening (SP) and improving interfacial contact with Au sputtering can inhibit dendrite growth. However, conventional sputtering may reduce toughness due to localized thermal damage. This study investigated magnetron sputtering as a low-damage, plasma-based Au deposition method. SEs with and without SP were fabricated and coated via normal and magnetron sputtering. Critical current density (CCD) and fracture toughness were evaluated. Without SP, CCD improvement was limited regardless of sputtering method due to poor bonding. With …

Antibacterial Activity Of Zno/Geopolymer Composite Granules And Their Potential Application In Water Treatment, Ziyan Tirta Maulitia, Putri Nur Angelina, Pipit Erlita Sari, Sri Sugiarti, Irma Isnafia Arief, Zaenal Abidin

Makara Journal of Science

Water pollution has become a major global concern owing to its complexity and widespread impact. Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are the most common bacterial contaminants in water sources, which pose significant threats to public health. To mitigate water contamination by these pathogenic microorganisms, developing and implementing effective water treatment technologies are essential. A promising approach involves using antibacterial water filtration systems. Herein, zinc oxide (ZnO) nanoparticles were synthesized via hydrothermal and precipitation methods as antibacterial agents for water treatment. These preparation methods required considerably low synthesis time. A capping agent was …

In Situ High-Temperature Raman Spectroscopy For Online Eaf Slag Analysis, Bohong Zhang, Hanok Tekle, Ronald J. O'Malley, Jeffrey D. Smith, Farhan Mumtaz, Jie Huang

Electrical and Computer Engineering Faculty Research & Creative Works

Real-time monitoring of slag chemistry is critical for optimizing Electric Arc Furnace (EAF) steelmaking operations, where dynamic variations in slag composition directly influence slag foaming, refractory degradation, and thermal efficiency. Conventional techniques such as X-ray fluorescence (XRF), Fourier-transform infrared (FTIR), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) are commonly used to analyze slag composition, but their offline nature and equipment constraints limit their applicability for online monitoring in harsh industrial environments. To address this challenge, we present an in situ, high-temperature analytical approach that integrates Raman spectroscopy with a custom-designed fiber-optic probe for real-time slag characterization at …

Enabling Carbon Dioxide Mineralization And Active Set Control In Portlandite-Based Cementitious Suspensions, Xiaodi Dai, Sharu Bhagavathi Kandy, Rui Xiao, Manas Sarkar, Shubham Wani, Thiyagarajan Ranganathan, Narayanan Neithalath, Aditya Kumar, Mathieu Bauchy, Edward Garboczi, Torben Gädt, Samanvaya Srivastava, Gaurav Sant

Materials Science and Engineering Faculty Research & Creative Works

The real-time control of concrete's stiffening allows users to better control pumping and extrusion during 3D-printing processes. Here, a portlandite-based cementitious formulation (i.e., slurry or suspension) that features the potential for rapid CO₂ uptake is adapted for 3D-printing applications. In particular, we showcase a portlandite-fly ash binder system combined with a thermo responsive polymer, wherein precise control via thermal activation allows set control and rapid solidification. Through the thermally induced polymerization of polyacrylamide, the hybrid binder system rapidly undergoes stiffening at trigger onset temperatures ranging from 60 °C to 80 °C, exhibiting average stiffening rates of up to 2600 …

Tensile Creep Of A Hybrid Polymer-Matrix/Ceramic-Matrix Composite At Elevated Temperature, Waleed S. Alshehri

Theses and Dissertations

Advanced aerospace systems require structural materials that can perform reliably in high-temperature environments for long durations. The performance of standard polymer matrix composites (PMCs) in these conditions is often limited by their susceptibility to time-dependent deformation, such as creep. The objective of this research is to characterize the high-temperature creep behavior of a novel unitized material system comprising a polymer matrix composite (PMC) and a ceramic matrix composite (CMC) co-cured together. The PMC part consists of the polyimide matrix reinforced with laminated carbon fibers woven in an eight harness satin weave (8HSW). The CMC part consists of a zirconia-based ceramic …

Investigation Of Solid-State Reactive Sintering And Rapid Laser Reactive Sintering For Al-Doped Li7la3zr2o12 Solid-State Electrolyte, Aaron Santomauro

All Dissertations

As a society, we’ve exhausted an extreme amount of fossil fuels and put an overwhelming strain on Earth’s natural resources. From this, it is critical to think about the successful future of our planet and ourselves by developing energy devices such as all-solid-state lithium-ion batteries (ASSLIBs). These devices offer a greener and more efficient alternative to power our daily lives, such as electric vehicles (EVs), portable electronics, medical devices, grid-scale energy storage, and aerospace/aviation. ASSLIBs are an excellent alternative to liquid-state batteries, which pose dangerous safety concerns (e.g., flammability, electrolyte leakage, etc.). These ASSLIBs are known to have generally high …

Discovery Of High-Performance Cathode Materials For Protonic Ceramic Fuel Cells, Liang Han

All Dissertations

Environmental pollution and rapid energy consumption have become common problems in global development and will continue to grow with the world population. PCFCs use proton-conducting ceramics as electrolytes, with low activation energy and high ionic conductivity at intermediate temperatures, enabling them to operate at intermediate-temperature conditions, which can effectively solve the problems of poor stability and high cost of exotic materials of traditional solid oxide fuel cells. However, as the operating temperature decreases, the electrocatalytic activity of the cathode decreases significantly, seriously affecting PCFC’s performance. Therefore, developing high-performance cathode material suitable for working under intermediate-temperature conditions has become the key …

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 …

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 …

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 …

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 …

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 …

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 …