Symposium CF
ABSTRACTS
Session CF-1 Synthesis and processing
CF-1:IL01 Making UHTCMCs with Controlled and Variable Composition
B. STEADMAN, V. VINOTHINI, J. BINNER, School of Metallurgy and Materials, University of Birmingham, UK
Applications such as hypervelocity flight and rocket nozzles require materials that can survive the most extreme environments; temperatures can be between 2000 and 3000oC and this is combined with very high heat fluxes and extremely fast gas flows. A still relatively new class of materials, known as ultra-high temperature ceramic matrix composites (UHTCMCs), have been developed and are showing a lot of promise. At the University of Birmingham it has been demonstrated that UHTCMCs based on borides (hafnium and zirconium) reinforced with continuous carbon fibres can withstand such conditions. However, these borides are fundamentally dense materials and so it makes sense to only use them where they are really needed and to use lighter, less capable materials on the inside of components. Our work has thus focused on utilising an injection-based route for the manufacture of 2.5D and 3D woven Cf preform-based UHTCMCs in which the composition can be varied on demand, for example, to have ZrB2 or HfB2 at the surface and SiC in the interior, with a functionally gradient change between the two to avoid the presence of sharp interfaces that could form weakness in the structure. The thermo-ablative qualities of the resulting UHTCMCs have been determined.
CF-1:IL02 Phase Stability Regimes in Laser Chemical Vapor Deposited TiC Fibers
K.J. MITCHELL, M. PAVEL, G. THOMPSON, The University of Alabama, Alabama Materials Institute, Tuscaloosa, AL, USA
Laser Chemical Vapor Deposition (LCVD) is a process in which materials are deposited from a gaseous precursor into a solid phase. Using a laser, with its focused ‘hot spot,’ the deposition is localized, enabling fibers to be grown as the laser retracts. Here, we report the growth of titanium carbide (TiC) fibers using titanium tetrachloride, hydrogen, and ethylene gas at various mixtures and at various growth temperatures. As the hydrogen content increased, it became more difficult to produce a sequential series of fibers to form in a batch process, and the fibers were tubes created by the congregation of hydrogen in the deposition region, causing the solid deposit to form around it. In a hydrogen-lean mixture, the hydrocarbon gas precipitated carbon soot which coated the TiC fibers. In the hydrogen-balanced mixtures, the TiC fibers could be continuously deposited without either of these prior issues. The extent of TiC with graphite in the solid deposit was altered by changing the titanium tetrachloride and ethylene mixtures. This processing space is modeled through a series of thermodynamic maps that reveal these phase formations, with the kinetics captured through modeling thermophoresis effects during deposition.
CF-1:IL03 Ultra High Temperature Ceramics by Combustion Synthesis
A.S. MUKASYAN, University of Notre Dame, Notre Dame, IN, USA; A.S. ROGACHEV, Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia
The exceptional properties of ultra-high-temperature ceramics (UHTCs), such as thermal stability, oxidation resistance, and mechanical strength, make them ideal for a wide range of advanced applications, including aerospace, energy, defense, industrial processes, and emerging technologies. Their ability to withstand extremely high temperatures, typically above 2000 °C, positions UHTCs as crucial materials for pushing technological boundaries in these fields. The combustion synthesis (CS) method, also known as self-propagating high-temperature synthesis (SHS), offers a rapid and efficient alternative. It leverages the exothermic heat generated during chemical reactions to produce UHTCs without external heating sources. Indeed, essentially all carbides, borides, nitrides, and complex phases with operating temperatures exceeding 2000 °C have very high enthalpies of formation, enabling their production CS. This work overview the recent achievements of CS in synthesizing a wide range of UHTCs—from simple compounds to complex, multicomponent “high-entropy” ceramics—including materials with record-breaking melting points based on carbonitrides, binary carbides, and diborides.
CF-1:L05 Molten Salt Shielded Synthesis of WAlB and Mn2AlB2 MAB in Air
C. ROY, S. MONDAL, A. DASH, Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Kgs. Lyngby, Denmark
Transition metal-based boride-like layered MAB phases have recently emerged as promising materials owing to their unique combination of metallic and ceramic properties, including excellent thermal and electrical conductivity, oxidation resistance, thermal shock resistance, and superior wear resistance. Conventionally, WAlB can be synthesized using the aluminum flux method at high temperatures (around 1550 °C) with prolonged soaking durations (24 h), resulting in high costs and limited scalability. In contrast, Mn₂AlB₂ was recently prepared via molten salt shielded synthesis (MS³) using KBr at a relatively lower temperature (1000 °C), but it requires a longer soaking time (12 h), which increases the risk of oxidation. This study aims to synthesize WAlB and Mn₂AlB₂ MAB phases at relatively lower temperatures using a NaCl-KCl eutectic mixture instead of KBr, achieving high phase purity via a newly developed, simple, cost-effective, and environmentally friendly modified molten salt shielded synthesis method. The proposed approach enables the successful synthesis of both MAB phases with high yield and purity, at significantly reduced temperatures and processing times compared to previously reported literature.
CF-1:IL06 Synthesis, Properties, and Processing of Preceramic Polymer Grafted Nanoparticles: Versatile Hybrid Materials for Advanced Ceramics
M.B. DICKERSON1, J.L.S. ZACKASEE1,2, J.F. PONDER JR.1,2, K. MARTIN1,2, J.H. DELCAMP1, T.L. PRUYN1, 1Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, USA; 2AV Inc., Dayton, Ohio, USA
Preceramic polymers (PCPs) are an attractive class of materials as they allow for the fabrication of ceramic objects using polymer processing techniques, such as fiber spinning and the infiltration of carbon fiber-based preforms. Following shaping, PCPs are converted to polymer-derived ceramics (PDCs) via high-temperature heat treatment, resulting in inorganic fibers, composites, and components. PDCs have a number of desirable properties, including access to metastable compositions and processing at temperatures below service temperatures. Taking advantage of the numerous benefits of PCPs, we have utilized these macromolecules to create unique hybrid materials, termed preceramic polymer grafted nanoparticles (PCP GNPs). PCP GNPs typically possess an inorganic nanoparticle core (e.g., SiO2, SiC, or ZrO2), which is surrounded by a tightly associated layer of PCP. The anchored PCP layer serves to shield the nanoparticles from each other, minimizing nanoparticle-nanoparticle interactions. As a result of their captive PCP layer, PCP GNPs display distinct rheology from simple mixtures of nanoparticles and PCPs, often being flowable, room-temperature liquids. In this presentation, we will discuss the influence of PCP GNP constituents on the behavior of PCP GNPs and their resulting PDCs.
CF-1:IL07 Chemistry and Processing Effects on Preceramic Polymers Derived Ultra-High Temperature Ceramics
J.F. PONDER Jr.1,2, M.B. DICKERSON1, N.M. BEDFORD3,4, T.L. PRUYN1, 1Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, USA; 2AV Inc., Dayton, Ohio, USA; 3Energy and Environment Science Technology Directorate, Idaho National Laboratory, Idaho Falls, ID, USA; 4Department of Chemistry, Colorado School of Mines, Golden, CO, USA
Materials capable of withstanding ultra-high temperatures are becoming increasingly important for numerous aerospace applications, ranging from atmospheric re-entry shielding to aircraft brakes. Preparation of ultra-high temperature ceramics (UHTCs) using traditional inorganic powder methods limits the possible structural/compositional designs and is challenging for preparing composite components. Preceramic polymers (PCPs) have been used to address these challenges via the synthetic tunability and processing properties of PCPs prior to pyrolysis. Following pyrolysis of the PCP, a polymer derived ceramic (PDC) is obtained. By tuning the PCP structure, curing/pyrolysis conditions, and pyrolysis atmosphere, the composition of the PDC can be manipulated to obtain different properties. We report the functionalization of Si-based PCPs with Group IV/V transition metals to produce UHTC nanocomposites following pyrolysis. The effects of pyrolysis conditions on final ceramic composition/structure were explored using various techniques including synchrotron experiments. In addition to single metal systems, compositionally complex compositions were prepared to understand how the different materials blend/separate in PDCs.
CF-1:IL08 High Temperature Coatings for SiCf/SiC Composites
JINGYANG WANG, Institute of Metal Research, CAS, China Liaoning Academy of Materials, China
SiCf/SiC composite is disruptive material for the hot-section components in new generation aviation engine. High temperature coatings, including thermal barrier coating, environmental barrier coating, as well as abradable coating, can protect various SiCf/SiC components against harsh thermal and chemical attacks in combustion environment. The request for service temperature for coatings has been critically increased up to 1350 to 1500oC, regarding the various combustion environments. The key technology depends on the whole chain advancement of intelligent design, feedstock production, coating fabrication, and coating evaluations. This talk presents the recent progresses of high temperature coating technologies for SiCf/SiC components in aviation engine. The developments support the explorations and applications of SiCf/SiC composite in high-thrust aeroengine.
CF-1:L09 Molten Salt Shielded Synthesis (MS3) of Ti3SiC2 with Various Precursors
S. MONDAL, C. ROY, A. DASH, Dept. of Energy Conversion and Storage, Technical University of Denmark, Kongens Lyngby, Denmark
The Ti3SiC2 MAX phase ceramic has attracted researchers’ attention due to its high temperature damage tolerance. The molten salt synthesis of this phase using elemental precursors has been reported so far. In this work, the Ti3SiC2 MAX phase is synthesized using carbide (TiC and SiC) and elemental (Ti, Si and C) precursors under the MS3 conditions. Potassium bromide (KBr) salt is used as the molten salt medium as well as the gas-tight shielding medium to prevent oxidation during heating. The temperature-wise phase evolution of various precursor mixtures is investigated by X-ray diffraction and quantified by Rietveld Refinement. With the aid of thermal analysis (TG-DSC) and scanning electron microscopy imaging, together with the XRD data, the reaction mechanisms leading to Ti3SiC2 are established. The highest amount of Ti3SiC2 (⁓ 88%) is obtained from the precursor mixture of Ti,/ Si/,C/TiC with 2:1:1:1 ratio. The average particle size of the Ti3SiC2 is 4-5 μm when SiC is used in the precursor mixture, but this average size increases to 15-35 μm when TiC is used in the precursor mixture, indicating a distinctive change in the reaction pathway. Therefore, the morphology and the particle size of the final product can be tuned with the right choice of the precursor mixtures.
CF-1:IL10 Polymer-derived Ceramics for Ultra-high Temperature Applications
KATHY LU, M. SHIRANI, S. KARTIK NEMANI, Department of Mechanical and Materials Engineering, University of Alabama at Birmingham, Birmingham, AL, USA
This study explores the integration of MXenes into polymer-derived ceramic (PDC) systems, specifically TiC/SiC composites. TiC and SiC, both highly covalent ceramics, typically demand elevated sintering temperatures or oxide-based additives to achieve full densification. In our work, synthesis, high temperature stability, and phase transformation of Ti3C2Tx MXene-polymer derived SiC have been studied. Spark plasma sintering (SPS) has been used for the densification of such carbide composites. By incorporating MXenes—exhibiting high electrical conductivity (~2×10⁴ S·cm⁻¹)—into TiC/SiC PDCs, we can lower sintering temperatures while enhancing densification kinetics. The resulting interlocked microstructure is expected to yield improved mechanical performance, including increased hardness, Young’s modulus, and fracture toughness. This presentation will highlight the synthesis strategy, processing-microstructure relationships, and comprehensive evaluation of electrical, thermal, and mechanical properties of MXene-reinforced TiC/SiC composites. The fundamental interactions of MXene with the evolving SiC phase will be elucidated.
CF-1:IL11 Synthesis, Microstructural Characterization and Physical Properties of High Entropy MAX phases
M. BERRABAH, V. GAUTHIER-BRUNET, S. DUBOIS, Institut Pprime, Chasseneuil du Poitou, France
MAX phases are compounds with the stoichiometry Mn+1AXn (n = 1, 2 or 3) where M is an early transition metal, A is an element of the groups 12 to 16 and X is carbon or nitrogen. They have an hexagonal nanolayered structure composed of near-close-packed layers of M6X octahedrons interleafed with A atom layers. They have attracted a particular attention due to their unusual combination of both metallic (machinability, high thermal and electric conductivity, mechanical damage resistance) and ceramic (high thermal stability, high stiffness, high resistance to corrosion) properties. In medium or high entropy MAX phases, 3 to 5 elements are used for M or A constituents. High-entropy alloys (HEA) and ceramics have attracted growing attention since solutes with different atomic radius and valence electrons in a unique structure can introduce unique physical and chemical properties. In this context, V4AlC3 MAX phase and (TiVCrMo)AlC3, (TiVNbMo)AlC3 HE MAX phase powders are sintered at 1400°C. Microstructures of the different samples are compared and characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Finally, electronic transport properties (electrical and thermal conductivities, Seebeck coefficient) of V4AlC3 and HE MAX phases are compared.
CF-1:L12 Eco-optimization and New Advanced Ceramic Solutions for Armor Protection Systems
M. CANTÙ, M. VALLE, G. PULCINI, U. LOSA, Petroceramics SpA, Italy
Advanced ceramics are among the most widely used materials for ballistic protection. Compared to metals, they offer the advantage of being relatively lightweight while providing comparable mechanical resistance. The current frontier in ceramic R&D for ballistic applications focuses on developing solutions for both personal and platform protection, capable of countering existing and emerging threats. These solutions must also meet critical requirements such as weight reduction and multi-impact resistance. In the framework of the European ECOBALLIFE Project, eco-design principles have been integrated into the development of new solutions and the optimization of existing ones. The initial results obtained from the use of recycled ceramics in body armor and tiles for both personal and platform protection will be presented, along with the development of new solutions using prestressed ceramics.
CF-1:L13 Synthesis, Microstructural Characterization, and Physical Properties of New Nanostructured Ternary Carbides: (TiNb)AlC0.91 and (Ti2Nb)AlC1.82 MAX phases
M. BERRABAH, T. CABIOC’H, P. CHARTIER, V. GAUTHIER-BRUNET, S. DUBOIS, Institut Pprime, Poitiers, France; E. EPIFANO, CIRIMAT, Toulouse, France
MAX phases are hexagonal nanolamellar carbides or nitrides composed of transition metals (M), elements from groups 13 or 14 of the periodic table (A), and carbon or nitrogen (X). They combine the best properties of metals and ceramics. New MAX phases derived from the Ti–Nb–Al–C system, [TiNb]AlC0.91 (211) and [Ti2Nb]AlC1.82 (312), were synthesized by Hot Isostatic Pressing from sub-stoichiometric TiCx, Nb, and Al powders, in the temperature range 1450 – 1700 °C. After synthesis at 1580 °C, the mass fraction of the 312 and 211 phases, determined by X-ray diffraction (XRD), is 98 wt% and 99 wt% respectively. The secondary phases consist of titanium and niobium, carbides and aluminides. The lattice parameter and the composition of the 312 and 211 phases were determined from Rietveld refinement of the XRD patterns and Energy Dispersive X-ray Spectroscopy (EDX), respectively. Thermal and electrical conductivities, as well as the Seebeck coefficient, were measured as a function of temperature (2–300 K). Hall effect measurements were used to determine the carrier concentration and mobility. Magnetoresistance measurements show that Kohler’s rule is satisfied, implying that the magnetoresistance is proportional to the square of the charge carrier mobility.
CF-1:L14 Polymer-Derived Si(Al)CN/Hf₆Ta₂O₁₇ Nanocomposites: A New Route to Thermal Barrier Materials for Harsh Environments
M. BOROOJERDI1, B. PRILL3, M. GALETZ3, R. RIEDEL1, E. IONESCU1,2, 1TU Darmstadt, Institute for Materials Science, Darmstadt, Germany; 2Fraunhofer IWKS, Alzenau, Germany; 3DECHEMA-Forschungsinstitut, Frankfurt am Main, Germany
In the present work, we report the synthesis and characterization of Si(Al)CN/Hf₆Ta₂O₁₇ nanocomposites obtained via a single-source precursor route. The commercial polysilazane Durazane 1800 was chemically modified with an organoaluminum compound to generate an Al-enriched preceramic polymer, as confirmed by NMR and FTIR spectroscopy. Nanoscaled Hf₆Ta₂O₁₇, synthesized through a sol–gel process, was homogeneously dispersed within the Al-modified matrix, followed by warm pressing and pyrolysis at 1000 °C under inert atmosphere to yield dense monolithic composites. Microstructural and phase analyses reveal the formation of a finely distributed ceramic network, combining amorphous Si(Al)CN domains with crystalline Hf₆Ta₂O₁₇ nanophases. The resulting hybrid architecture provides outstanding oxidation resistance, mechanical integrity, and thermal stability. The materials exhibit enhanced thermal conductivity control and structural durability up to 1600 °C, positioning these PDC-based nanocomposites as promising next-generation candidates for thermal barrier coatings (TBCs) and other high-temperature protection systems.
This study was financially supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under project GRK 2561.
CF-1:IL15 Anomalous Metal Distribution in Dual Phase High Entropy Boride-carbide Ceramics
W.G. FAHRENHOLTZ, A. FELTRIN, G.E. HILMAS, Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO, USA; S. DIVILOV, S. CURTAROLO, Center for Extreme Materials, Department of Mechanical Engineering and Materials Science, Duke University, Durham, NC, USA
Dual phase, high entropy ceramics containing high entropy boride and high entropy carbide phases were produced by boro/carbothermal reduction. Compositions were formulated to contain either four or five different metals. All compositions contained Hf, Ti, and Zr with different combinations of group V and VI transition metals (Cr, Mo, Nb, Ta, V, and W). Metal distributions between the boride and carbide phases were characterized experimentally and compared to thermodynamic predictions based in first principles. In general, metal distributions followed predictions. However, V distribution was more complex and did not follow predictions while Mo and W additions led to the formation of third phases. Grain sizes and hardness values were measured with the goal of identifying compositions with the highest hardness. The role of composition on hardness and possible mechanisms that control V distribution between the boride and carbide phases will be discussed.
CF-1:IL16 Effect of Ti₂AlC MAX Phase Additive on the Densification and Properties of B₄C–SiC Ceramics
B. MATOVIC, Center of Excellence “CEXTREME LAB”, Vinča Institute of Nuclear Sciences - National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
B₄C–SiC composites with 0.3–1.0 wt.% Ti₂AlC MAX phase were consolidated by spark plasma sintering at 1950 °C, 70 MPa for 5 min in argon. The effect of Ti₂AlC on densification, microstructure, hardness, and ablation resistance was investigated. Ti₂AlC decomposed during sintering, forming secondary phases that promoted densification; all samples exceeded 99% relative density. With increasing Ti₂AlC, the microstructure evolved from a uniform B₄C/SiC system to a chemically active multiphase matrix, accompanied by changes in porosity and grain morphology. Hardness ranged from 34 to 45 GPa, with the highest value at 1.0 wt.% Ti₂AlC. Ablation tests in an oxyacetylene flame at 1850 °C for 60 s revealed that small Ti₂AlC additions improved ablation resistance through protective surface layers, while excessive content generated stress-inducing phases leading to degradation. These results define an optimal Ti₂AlC range for maximizing performance under extreme thermal loads and demonstrate the potential of B₄C–SiC–Ti₂AlC composites for aerospace and defense applications.
CF-1:L17 Formulation of Dielectric Inks Based on Preceramic Polymer and Alumina Nanoleaves for Aerosol Jet Printing of Ultra High-Temperature Strain Gauges
M. BOUZEGGAOUI, V. GAUBERT, Safran Tech, Magny-les-Hameaux, France; J. YUAN, LCMCP, Sorbonne Université, Paris, France
Despite advances in high-temperature strain gauges, the lack of resistance to extremely high temperatures and oxidation persists, limiting the sensitivity and lifespan of these gauges. Here we present an approach aimed at protecting the conductive layer of gauges by aerosol jet printing a dielectric layer consisting of a preceramic polymer filled with alumina nanoleaves. Alumina nanoleaves were first synthesised hydrothermally from aluminium chloride and sodium hydroxide as precursors, and CTAB as a surfactant. The resulting nanomaterials were characterised by XRD and SEM to verify the crystal structure and nanoleaves morphology, respectively. Organic and inorganic polysilazanes were used as preceramic polymer matrices for inks formulation. The printed resins underwent thermal treatment to convert polymeric precursors into ceramic materials. The achieved Si-based ceramics were characterised by ATR-IR spectroscopy, impedance spectroscopy, nanoindentation and contact angle test to identify their chemical nature, dielectric, mechanical and surface wetting properties. The high-temperature and oxidation resistance of the fully aerosol-jet printed strain gauge was tested at last to investigate the efficiency of the protective layer against oxygen diffusion under extreme environments.
CF-1:L18 Self-Assembling Block Copolymer Gels for Templating Ceramic Nanofibers
A.A. ADVINCULA, J.J. BOWEN, Air Force Research Laboratory & AV Inc., Wright-Patterson Air Force Base, OH, USA; J.H. DELCAMP, T.L. PRUYN, M.B. DICKERSON, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA
Polymer-derived ceramics (PDCs) offer a unique pathway to creating novel ceramic structures with tailored microstructures. Nanoscale patterning of preceramic polymers (PCPs) via block copolymer (BCP) self-assembly is a promising method to achieve this. By controlling parameters such as the PCP/BCP ratio, solution concentration, BCP block composition, and PCP chemistry, various morphologies (spherical, wormlike, bicontinuous) can be obtained in the cured state, which translate to diverse PDC microstructures after pyrolysis. These resulting PDCs can exhibit hierarchical ordering, low density, high specific properties, and multifunctionality. Our previous work demonstrated the fabrication of aligned, ultra-long PDC nanofibers by confining the PCP/BCP self-assembly within long-aspect ratio cylinders. This work expands upon this approach by investigating the influence of alternative confinement geometries and length scales on the resulting nanofiber morphology. Furthermore, we explore novel PCP chemistries compatible with BCP self-assembly for the creation of advanced ceramic nanofibers. Such precise control over nano- to meso-scale ceramic architecture holds significant potential for enabling next-generation aerospace applications.
CF-1:L19 Oxide-Oxide Ceramic Matrix Composites Based with an Alumina-Silica Matrix
T. CUTARD1, F. BOUTENEL2, T. CANET1, G. DUSSERRE1, 1Institut Clément Ader (ICA), Université de Toulouse, CNRS, IMT Mines Albi, INSA, ISAE-SUPAERO, UPS, Campus Jarlard, Albi, France; 2Université de Franche-Comté, SUPMICROTECHENSMM, CNRS, Institut FEMTO-ST, Besançon, France
Oxide/oxide ceramic matrix composites (CMCs) are materials that combine several advantages for thermostructural applications at temperatures between 400°C and 900°C in oxidising atmospheres (aerospace, industrial furnaces, etc.). More specifically, alumina-silica composites are of interest both for the processing route of such composites and for their final thermomechanical behaviour and properties. This talk presents the results of a predominantly experimental study carried out on the manufacture of ceramic matrix composites based on an alumina-silica matrix. Particular attention was paid to the influence of the alumina-silica ratio at different key stages of the manufacturing process: behaviour of the aqueous suspension and sintering behaviour in particular. More specifically, the aim of this work was to establish relationships between formulation, material, processes and properties based on the results of a detailed study of the behaviour of the aqueous suspension, the sintering behaviour of different matrix compositions, the mechanical properties of the latter, the development of a 1D CMC and the characterisation of its mechanical properties.
CF-1:IL20 Controllable Synthesis for Compositionally Complex MAX Phases
M. RADOVIC, Texas A&M University, College Station, TX, USA
Conventional synthesis of compositionally complex MAX phases containing two or more transition metals on the M-site is challenging due to numerous intermediate reactions and the formation of multiple competing phases, some of which are stable and difficult to suppress during sintering. These complexities often hinder control over reaction pathways and result in limited phase purity and compositional uniformity. To overcome these challenges, we developed a novel and controllable synthesis approach that employs pre-synthesized single M-element MAX phases as starting materials instead of elemental powders. This method enables diffusion-controlled reactions between structurally compatible layered precursors, significantly reducing the likelihood of forming unwanted intermediates and promoting homogeneous mixing on the M-site. Using this approach, a series of M₂AC (M = Cr, Ti, Ta, V, Nb, and their combinations) phases with two to five M elements were synthesized and systematically examined. Among the 26 compositions studied, only a few formed single-phase MAX phase solid solutions, while one showed spinodal decomposition. Importantly, this synthesis route provides a generalizable and controllable pathway that can be extended to other MAX systems with different stacking.
CF-1:IL21 Processing and Oxidation Behavior of Multicomponent Metal Diborides
R. ORRÙ1, M. CASU1, L. CAPPAI1, A.M. LOCCI1, R. LICHERI1, S. GARRONI2, G. CAO2, 1Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, Cagliari, Italy; 2Dipartimento di Scienze Chimiche, Fisiche, Matematiche e Naturali, Università degli Studi di Sassari, Sassari, Italy
The discovery of High Entropy Borides (HEBs) prompts the Ultra High Temperature Ceramics (UHTCs) community to address their studies to the synthesis and characterization of multicomponent solid solutions generated from the combination of different transition metal diborides. Along this line, various binary to quinary dense ceramics are produced in this work by Spark Plasma Sintering (SPS) using powders preliminarily prepared by Self-propagating High-temperature Synthesis (SHS). While the very short duration of the SHS process (seconds) does not allow for the complete conversion of initial precursors into the expected solid solution, this target is achieved when the resulting powders are processed by SPS. The use of small amounts of graphite has beneficial effects to remove oxides contaminants and improve powders reactivity. A detailed compositional and microstructural characterization of the sintered samples is performed to optimize process conditions for obtaining multicomponent diboride products as single-phase. Their oxidation behavior during high temperature tests conducted under flowing and stagnant air is compared to that displayed by their individual constituents. The role played by the formation of mixed oxides is discussed.
CF-1:L22 Molten Salt Synthesis of High Temperature MAX Phases in the Nb,V,Ta-Al-C System
A. DASH, C. ROY, Department of Energy Conversion and Storage, Technical University of Denmark (DTU), Kongens Lyngby, Denmark
The synthesis of MAX phases like Nb2AlC, V4AlC3, and Ta2AlC needs high temperature exceeding 1500°C. Recently, the synthesis of MAX phases are demonstrated by a molten salt shielded synthesis (MS3) route where molten salt is used both as a reaction medium and for the protection of the oxidation prone materials. Potassium bromide (KBr) is used as a salt medium as it can be compacted to high density at room temperature and can form a gas tight cladding around the reaction mixture of MAX phase. This strategy protects the MAX phase reactants from oxidation at a temperature below the salt melting point (734°C for KBr) up to 1300 °C due to an oxygen impervious salt melt pool. Synthesis temperatures beyond 1300°C is unattainable due to boiling point of KBr being 1435°C, resulting in evaporation of salt leaving behind the exposed MAX Phase leading to oxidation. Here, we show the synthesis of Nb2AlC, V4AlC3 and Ta2AlC with the aid of KCl-CaCl2 eutectic salt mixture with a low vapor pressure and high boiling point (~1900°C) salt system. The synthesis of high temperature oxidation prone ternary carbides is demonstrated at 1500°C in air.
CF-1:L23 Simplified Processing of Ceramic Matrix Composites through Polyaddition Curing Resins – C/C-SiC based on Commercial Cyanate Ester Resins
F. WICH1, F. EBRAHIMI2, M. DEMLEITNER2, N. LANGHOF1, S. SCHAFFÖNER1, 1Ceramic Materials Engineering, University of Bayreuth, Bayreuth, Germany; 2Department of Polymer Engineering, University of Bayreuth, Germany
To date only few polymers are known as suitable matrix precursors for manufacturing ceramic matrix composites. Predominantly, phenolic resins or high-performance thermoplastics are used. However, these polymer systems exhibit inherent processing disadvantages such as the pore formation tendency of phenolic resins or the formation of a melt during the pyrolysis of thermoplastics. To overcome the limitations of the currently known matrix precursors, commercially available polyaddition curing cyanate esters were investigated concerning their applicability for reactive melt infiltration (RMI) processing. Dilatometry, TGA, DMA, SEM and phase composition analysis were conducted to characterize the suitability of resins for CMC manufacturing. C/C-SiC based on phenolic resin, PEEK and 3 different cyanate ester resins were manufactured by liquid silicon infiltration. Damage tolerant C/C-SiC materials with bending strength > 130 MPa were acquired by using high-char yield (> 60%) cyanate esters. Correlations between the char yield of the resins, shrinking behaviour, phase composition and mechanical properties were derived. All cyanate ester based materials showed exceptional fibre protection properties during RMI characterizing them as very promising candidate for future CMC development.
CF-1:L24 Kinetic Modeling of (Hf,Nb,Ta,Ti,Mo)B₂ Formation: Insights from Linear Heating Experiments
M. ZAKARYAN, K. NAZARETYAN, S. AYDINYAN, S. KHARATYAN, A.B. Nalbandyan Institute of Chemical Physics, Yerevan, Armenia
Complex borides, a new class of ultra-high-temperature high-entropy ceramics, exhibit superior hardness and oxidation resistance compared to single-metal diborides, making them highly promising for aerospace, solar energy, and microelectronics. They feature a hexagonal lattice structure with mixed covalent-ionic bonding, uniting the benefits of high-entropy and ultra-high-temperature materials. Their synthesis typically involves high-energy ball milling, borothermal or borocarbothermal reduction, though impurities often necessitate purification. Major challenges remain in powder preparation, purity, densification, and grain growth, hindering their full optimization in demanding applications. Process modeling under controlled heating using thermal analysis, aimed at optimizing synthesis conditions, provides valuable insight into reaction pathways. This study investigates (Hf,Nb,Ta,Ti,Mo)B₂ formation at linear heating with dT/dt=100-5000 K/min and Tmax=2000 K. Ex-situ characterization linked kinetics and phase transitions, showing that above a certain threshold heating rate, interaction proceeds through a single-stage exothermic reaction resembling a thermal explosion, resulting in the direct formation of the high-entropy boride compound in a single step.
CF-1:L25 Influence of Reactive Sintering on the Mechanical Properties of Al2O3-Mullite-ZrO2 Composites
A. MAY1, N. SADLI1, M. HAMIDOUCHE2, 1Laboratoire Génie des Matériaux, Ecole Militaire Polytechnique, Algiers, Algeria; 2Emerging Materials Research Unit, Ferhat Abbass University of Setif 1, Campus El Bez, Setif, Algeria
The research aimed to synthesize an alumina-mullite-zirconia (AMZ) multiphase ceramic composite via the reactive sintering of α-alumina, MKDD1 meta-kaolinite, and zircon (ZrSiO4). The initial mixture contained 74.65 wt% alumina, 15.79 wt% zircon, and 9.56 wt% DD1 meta-kaolinite. We investigated the effects of sintering temperatures ranging from 1400 to 1600∘C on zircon decomposition, densification, and mechanical characteristics. Furthermore, the ballistic performance of the resulting composites was assessed using dynamic impact tests via the SHPB apparatus. X-ray Diffraction (XRD) confirmed the complete decomposition of zircon at a sintering temperature of 1550∘C, yielding the final AMZ composite. SEM images showed a highly homogeneous microstructure, featuring lath-shaped and equi-axed mullite, and rounded zirconia particles (both t- and m-ZrO2) dispersed within the alumina matrix, with virtually no glassy phase observed. The best results were achieved after sintering for 5 hours at 1600∘C, yielding a density of 3.16 g/cm3 , a hardness of 7.7 GPa, a flexural strength of 185.94 MPa, and a Young's modulus of 91.95 GPa. The SHPB dynamic tests demonstrated that the sample sintered at 1600∘C exhibited the highest dynamic compressive strength of approximately 1054.2 MPa.
Session CF-2 Corrosion, oxidation, and testing
CF-2:IL26 Influence of Compositional Complexity on the Thermal Stability and Oxidation Behavior of Transition Metal Nitride and Boride Coatings
E. MAYER, D. NEUSS, S. LELLIG, RWTH Aachen University and Empa, Thun, Switzerland; J. MICHLER, Empa, Thun, Switzerland; A. NAVIDI KASHANI, S. MRAZ, M. HANS, J.M. SCHNEIDER, Materials Chemistry, RWTH Aachen University, Germany
The thermal stability and oxidation behavior of transition metal nitride and boride coatings with systematically varied compositional complexity are investigated. Magnetron sputtering from multiple plasma sources is employed to synthesize coatings with controlled compositional complexity. Advanced characterization techniques are used to assess how variations in elemental diversity influence phase formation, thermal stability, and oxidation behavior in comparison to TiAlN and TiAlB₂ benchmark systems[1,2]. The results provide insights into the relationship between compositional complexity and high-temperature performance, supporting the design of refractory coatings for use in harsh environments.
[1]Lellig, S., Navidi Kashani, A. H., Schweizer, P., Hans, M., Nayak, G. K., Michler, J., & Schneider, J. M. (2025). Passivating oxidation behavior of Ti₀.₁₂Al₀.₂₁B₀.₆₇ coatings investigated by scanning transmission electron microscopy and chemical-environment-dependent density functional theory simulations. Acta Materialia, 285, 120662. https://doi.org/10.1016/j.actamat.2024.120662
[2]Navidi Kashani, A. H., Hans, M., Lellig, S., Holzapfel, D. M., Löfler, L., Mráz, S., Primetzhofer, D., Michler, J., & Schneider, J. M. (2024).
CF-2:IL27 Plasma Wind Tunnel Testing of UHTCs, CMCs, and UHTCMCs
M. DE STEFANO FUMO, Italian Aerospace Research Centre, Capua, Italy
High-temperature materials and structures remain one of the primary challenges in the design of space transportation and hypersonic systems. Re-entry vehicles typically feature blunt nose geometries to enable rapid deceleration at high altitudes, where significant thermal heating occurs in a low-pressure environment. In such conditions, C/SiC thermal protection systems can be employed, as they provide a good balance between thermal resistance, structural integrity, and weight efficiency. Conversely, hypersonic vehicles require sharp leading edges to meet aerodynamic performance requirements. These configurations experience much higher heat fluxes and surface temperatures, combined with elevated stagnation pressures. Under these extreme conditions, the environmental loads can exceed the operational capabilities of CMC. Therefore, Ultra-High Temperature Materials technologies are considered promising solutions to meet these stringent demands. In both cases, comprehensive material and structural qualification is essential before transitioning to flight hardware. One of the key experimental activities supporting this qualification process is ground testing in relevant environment, achievable through plasma wind tunnel facilities. This paper presents the development and qualification.
CF-2:L28 On the High Temperature Water Vapor Corrosion of Directionally Solidified Garnet/Al2O3 Eutectic Ceramics at 1500 ℃
CUI ZHOU1, LUCHAO SUN2, JINGYANG WANG2, 1Institute of Coating Technology for Hydrogen Gas Turbines, Liaoning Academy of Materials, Shenyang, China; 2Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
Garnet/Al2O3 directionally solidified eutectic (DSE) ceramics exhibit outstanding potential for high-temperature structural applications owing to their exceptional thermal stability, excellent high-temperature strength and inherent oxidation resistance. To further investigate the reliability and durability of garnet/Al2O3 DSE ceramics under extreme conditions, thereby providing support for their practical applications. In this work, corrosion resistance of garnet/Al2O3 DSE ceramics was investigated under high-temperature water vapor environments (1500℃, 90 vol.% H2O(g) and 10 vol.% Air(g)). The results show that Al2O3 phase in garnet/Al2O3 DSE ceramics serves as corrosion-active component, whereas garnet phase exhibits corrosion resistance and structural stability. The maximum corrosion depth demonstrates a positive linear correlation with size of Al2O3 phase. Additionally, significant water vapor corrosion in high-entropy garnet/Al2O3 DSE ceramics is primarily confined to the initial 50 hours, whereas YAG/Al2O3 DSE ceramic undergoes continuous degradation. Furthermore, crystallographic orientation of garnet/Al2O3 DSE ceramics remains stable, preserving preferred orientation observed prior to water vapor corrosion, as consistently evidenced from matrix to corrosion front.
CF-2:L29 Oxidation and Ablation Resistance of ZrB2-SiC-LaB6 based Ultra-High Temperature Ceramic Composites
S.K. KASHYAP1,2, R. MITRA2, 1Materials Engineering Department, Indian Institute of Technology Jammu, India; 2Metallurgical and Materials Engineering Department, Indian Institute of Technology Kharagpur, India
The effect of LaB6 (7, 10, or 14 vol %) addition to the ZrB2-20% SiC composites containing 5.6% B4C and 4.8% C as additives, on isothermal oxidation and ablation resistance has been examined. The isothermal oxidation tests were conducted by exposing the composites in air at 1500°C for 24 h and the evolved oxide scale was examined by scanning and transmission electron microscopy. The detailed investigation of the cross-section of the oxide scale has revealed the formation of a layered microstructure formed by growth involving partial crystallisation of boro-silicate glass forming ZrSiO4 along with reprecipitation of La2Si2O7 and ZrO2 after prior dissolution of La2O3 and ZrO2 in the glassy matrix. The ablation resistance assessed by heating the sample surfaces to 1900-2200oC by a neutral oxy-acetylene flame, is found to be the maximum for the 14 vol% LaB6 containing composite as a dense and adherent oxide scale comprising ZrO2 forms with La2Si2O7 at grain boundaries.
CF-2:L30 Refractory Metals Impact on Harsh Environment Stability of Oxide Phases for a Functionally Graded Material
G. PERNETTE, DMAS, ONERA, Université Paris-Saclay, Châtillon, France and Université Marie et Louis Pasteur, UTBM, CNRS, Laboratoire Interdisciplinaire Carnot de Bourgogne ICB UMR 6303, Belfort, France; L. SÉVIN, J.-F. JUSTIN, A. JULIAN-JANKOWIAK, DMAS, ONERA, Université Paris-Saclay, Châtillon, France; P. BERTRAND, C. LANGLADE, Université Marie et Louis Pasteur, UTBM, CNRS, Laboratoire Interdisciplinaire Carnot de Bourgogne ICB UMR 6303, Belfort, France and Université Bourgogne Europe, CNRS, Laboratoire Interdisciplinaire Carnot de Bourgogne ICB UMR 6303, Dijon, France
In the satellite propulsion sector, there is a lack of thermostructural materials working under oxidising environment at Ultra-High Temperature. ONERA, in collaboration with CNES and ICB-PMDM works on a Functionally Graded Materials (FGM) to fulfil the specifications of harsh combustion conditions. Yttria stabilised hafnia/tungsten FGM materials, manufactured by Atmospheric Plasma Spray, have been tested under a laser bench in oxidative atmosphere to study the degradation mechanisms. At temperatures higher than 1700°C, FGM failure can be explained by the presence of different reaction products with low thermal stabilities. To assess a better oxidation resistance, the stability of alternative high temperature materials is investigated. More particularly, tantalum is investigated and reactions with yttria stabilised hafnia in are studied. First, powders were mixed and reactions under air were studied up to 1750°C. Then, phases were characterised using XRD, Raman, SEM and TEM coupled with EDS analyses. Preliminary, yttria stabilised hafnia phases (12 and 33 mol. %) were investigated with this protocol in presence of tungsten. From 1200°C, disruption of cubic phases in presence of WO3 form Y2W3O12. SEM-EDS analyses reveal growth of the reaction product with temperature, encircling yttria stabilised hafnia phases and will be compared with other ceramic/metal mixtures. Also, thermodynamic calculations of by-product formations were performed to better understand experimental results.
CF-2:L31 Thermodynamic Study of the HfO2-Y2O3-Ta2O5 Materials System for Future Thermal Barrier Coating Applications
A. HABERMANN1, A.L. SCHOLL1, O. FABRICHNAYA2, M. LEPPLE1, 1Justus Liebig University Giessen, Giessen, Hesse, Germany; 2TU Bergakademie Freiberg, Freiberg, Saxony, Germany
New thermal barrier coating materials, which protect the Ni-based superalloys used in the hot sections of the gas turbines are urgently needed to increase the turbine efficiency by increasing the operating temperature. Therefore, the new materials must exhibit several properties, with phase stability over a wide temperature range and low thermal conductivity being the most important ones. The state-of-the-art material is 7-8 wt% yttria-stabilized zirconia (YSZ), which exhibits excellent mechanical properties but a limited phase stability. Further substitution of Ta5+ to the YSZ system showed improved properties relating to low thermal conductivity, and phase and structural stability of the ZrO2 lattice. Furthermore, substituting Zr4+ with Hf4+ might lead to a shift of the phase transitions to higher temperatures. Therefore, this study investigates the HfO2-Y2O3-Ta2O5 system using the CALPHAD approach. Key compositions were prepared via co-precipitation synthesis and equilibrated at 1500 °C. The specific heat capacity was measured using differential scanning calorimetry and drop calorimetry. Phase relations were investigated using X-ray diffraction and energy dispersive spectroscopy. The experimental data is used as input for thermodynamic modelling of this material system.
CF-2:IL32 SiC/SiC Composite Accident-tolerant (ATF) Cladding Materials for Light Water Reactors (LWRs)
K. LAMBRINOU1,2, C. SAUDER3, F. BOURLET3, M. GROSSE4, M. STEINBRÜCK4, J.A. HINKS1, PENG WANG5, SHUIGEN HUANG6, J. VLEUGELS6, 1School of Computing and Engineering, University of Huddersfield, Queensgate, Huddersfield, UK; 2IIT, Centre for Nanoscience and Technology, Milano, Italy; 3CEA, Service de Recherches Métallurgiques Appliquées, Université Paris-Saclay, Gif-sur-Yvette Cedex, France; 4KIT, Institute for Applied Materials (IAM-AWP), Eggenstein-Leopoldshafen, Germany; 5Nuclear Engineering & Radiological Sciences (NERS), Ann Arbor, University of Michigan, MI, USA; 6Department of Materials Engineering, KU Leuven, Leuven, Belgium
The 2011 Fukushima Daiichi event showed the need for improved nuclear energy safety, driving global investments in accident-tolerant fuels (ATFs). SiC/SiC composites are a promising ATF cladding material concept for light water reactors (LWRs) due to the attractive properties of SiC (e.g., refractoriness, pseudo-ductility). Unfortunately, the coolant compatibility of all state-of-the-art SiC/SiC composite claddings is still inadequate, challenging their deployment to market. In this work, bulk SiC ceramics were grain boundary (GB) engineered with compounds (i.e., yttrium aluminum garnet, Y3Al5O12, and yttrium monosilicate, Y2SiO5) that exhibit excellent compatibility with water and steam at high temperatures. All ceramics (i.e., bulk Y3Al5O12 & Y2SiO5; SiC GB engineered with Y3Al5O12 & Y2SiO5) were tested in PWR water (360°C, 28 days), steam (1600°C, 1 h), and under combined proton irradiation/aqueous corrosion (5.4 MeV protons, 320°C, 48 h, PWR water with 3 ppm H2). The performance of GB engineered SiC ceramics under proton irradiation in flowing PWR water was benchmarked against CVD (chemically vapor deposited) SiC tested under identical conditions. CVD SiC coatings are routinely deposited on SiC/SiC composites to minimize material losses under nominal LWR operation conditions.
CF-2:IL34 Mechanistic Study of Ultra-High Heat Flux Oxidation and Degradation in Compositionally Modified Zirconium Diboride
L. RUESCHHOFF1, J. KAUFMAN1,2, C. WYCKOFF1,2, A. GOURLEY1,3, P. LOUGHNEY1,3, 1Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH, USA; 2AeroVironment, Arlington, VA, USA; 3National Research Council Research Associate Program, Washington, DC, USA
Zirconium diboride (ZrB2) is an ultra-high temperature ceramic (UHTC) of interest for next-generation aerospace systems operating in extreme thermal and oxidative environments. Particular interest comes from the combination of favorable material properties and low cost and density relative to other UHTCs. To overcome the inherent oxidation and manufacturing limitations of conventional UHTCs, we present two synergistic approaches: compositional modification and advanced manufacturing. The first approach involves exploring a variety of dopants, selected using literature trends and first principal calculations, aimed at improving survivability in ultra-high heat flux environments. In parallel, we utilize the low-cost, net-shaping technique of material extrusion additive manufacturing (AM), incorporating chopped carbon fibers to form ZrB2 composites. Both conventional and AM samples were densified via pressureless sintering and exposed to a relevant ultra-high heat flux environment utilizing a robotic oxyacetylene torch. A detailed analysis of sample survivability and resultant oxidation phases formed will be presented, along with initial mechanical testing results.
CF-2:IL35 SiC as Ceramics for the UHTC Applications
P. SAJGALIK1, O. HANZEL1, M. HICAK1, A. KOVALCIKOVA2, 1Institute of Inorganic Chemistry, Slovak Academy of Sciences, Slovakia, Bratislava; 2Institute of Materials Research, Slovak Academy of Sciences, Košice, Slovakia
Freeze-granulated silicon carbide powder was densified to the full density without any sintering aids by rapid hot-pressing at temperatures from 1850 °C to 1900 °C. This densification temperature is at least 150-200 °C lower compared to the up to now known solid state sintered silicon carbide powders. This way prepared material has a high thermal conductivity of almost 200 W/mK Static and dynamic oxidation resistance of this way prepared ceramics is excellent. The static oxidation (parabolic rate constant) at 1450 °C for 204 h was 4.9×10-5 mg2/cm4h, which is almost negligible in comparison to the parabolic rate constant 7.0×10-5 mg2/cm4h of the LPS sintered SiC materials. In the dynamic regime the ceramics sustained 1900 °C for 60 s without substantial damage, weight loss was only 0.2 %. When the oxidation was prolonged to 300 s the damage was visible but still not crucial, weigh loss was 1.6 %. It seems that this material is really suitable for ultra-high-temperature applications.
CF-2:L36 Silicate-Particle-Induced Degradation of Ultra-high Temperature Ceramics
ZHIJIE HU, WENJIA SONG, Hangzhou International Innovation Institute, Beihang University, Hangzhou, China
Silicate particles such as dust, sand, and volcanic ash pose critical hazards to flight vehicles by inducing erosion and chemical degradation of thermal protection systems. Understanding the interaction between calcia–magnesia–aluminosilicate (CMAS) and thermal protection materials is crucial for ensuring safe operation of hypersonic vehicles. Here, the wetting and corrosion behaviors of a model artificial CMAS on ZrB2–MoSi2 ceramics were investigated between 1300 and 1500 °C. Sessile drop tests revealed rapid spreading of molten CMAS, with equilibrium contact angles decreasing from 14.5° to 7.3°. Cross-sectional analyses showed that CMAS not only dissolves protective ZrO2–SiO2 scales but also infiltrates grain boundaries, producing synergistic corrosion–oxidation damage up to ~50–90% deeper than oxidation alone. Notably, the most severe damage occurred at the triple junction among CMAS melt, ceramic substrate, and air. These results provide mechanistic insights into particle–ceramic interactions and highlight the vulnerability of ultra-high temperature ceramics under particle-laden environments.
CF-2:L37 Ultra High Temperature Creep of UHT PDC Ceramic Modified C/SiC Composites
XINGANG LUAN, Northwestern Polytechnical University, Xi’an, China
Carbon fiber reinforced silicon carbide matrix composites (C/SiC) have become thermal protection materials for hypersonic vehicles which may face ultra-high temperature （UHT）environments above 2000 ℃ during service. UHT Polymer Derived Ceramics (PDC) , i.e., SiHfBCN and HfC, were selected to be modified C/SiC . C/SiC-Si(Hf)BCN composites with different Hf contents were prepared by modifying C/SiC composites using CVI+PI-OP process. The UHT creep tests were carried out by laser in air. The residual strength and creep speed was compared. The C/SiC-SiHfBCN composites with 5:1 of the ratio of SiBCN and Hf source were found to have better ultra-high temperature oxidation resistance after ultra-high temperature oxidation assessment.
Session CF-3 Mechanical, thermal and optical properties
CF-3:IL39 Design of Continuous Fiber Reinforced Ceramic Matrix Composites for Extreme Environment
SHAOMING DONG, XIAOWU CHEN, DEWEI NI, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China
Continuous fiber reinforced ceramic matrix composites (CMCs) show outstanding properties, such as light weight, high strength, high temperature resistance, and oxidation resistance. They are widely applied in high-tech fields of aerospace, transportation, and new energy. Facing the advantages of ceramic matrix composites, Shanghai Institute of Ceramics, Chinese Academy of Sciences has designed and developed ceramic matrix composites and components that meet different application environments based on the scientific essence that restricts the performance and service life of materials. The research covers C/SiC, C/UHTC and SiC/SiC material systems. The matrix and interface strengthening strategies of ceramic matrix composites for extreme environment application has been put forward, and new methods of in situ reaction preparation with pore construction and sol-gel infiltration have been developed. The C/UHTCs show good ablation resistance under temperature above 2000°C.The SiC/SiC composites with excellent mechanical property and high-temperature oxidation resistance are obtained through fiber treatment, interfacial phase structure/composition regulation and design of multi-layer matrix, and they are expected to meet the application requirements of aero-engine hot components.
CF-3:IL40 Understanding Deformation to Failure in Single-Crystal MAX Phases
A. SRIVASTAVA, Texas A&M University, College Station, Texas, USA
The single-crystal-level mechanical response of MAX phases is characterized using small-scale mechanical testing of specimens machined from individual grains via focused ion beam milling or utilizing as-grown single crystals. Our results demonstrate that the onset of plastic flow in MAX phases is highly orientation-dependent and follows non-classical crystallographic slip, influenced strongly by the stress acting normal to the basal planes. We also analyzed the effects of different MX layers and stacking sequences on this non-classical slip behavior. Furthermore, our findings show that MAX phases tend to cleave easily along the basal planes, especially when the driving force for crystallographic slip is insufficient. However, when deformation is constrained normal to the basal planes, MAX phase crystals deform by kinking. The complete results of these experiments, as well as computational analyses to better understand the experimental observations and their implications on the macroscopic response of the material, will be presented.
CF-3:L42 Melting of Ultra-high Temperature Materials: Tantalum Carbonitrides
J. MANAUD1, D. ROBBA1, A. NAKAJO2, E. CORNIANI2, P. HAEHNER2, M. COLOGNA1, L. VLAHOVIC1, 1European Commission, Joint Research Centre (JRC), Karlsruhe, Germany; 2European Commission, Joint Research Centre (JRC), Petten, The Netherlands
Within the Ultra-High Temperature Ceramics (UHTC) class of materials, some carbides are of particular interest due to their melting temperature above 3500 K, especially tantalum carbide (TaC), i.e. > 4200 K. Recently, ab initio molecular dynamics calculations demonstrate that the addition of nitrogen into a carbide structure makes it harder to melt and a sub-stoichiometric hafnium carbo-nitride (HfC0.56N0.38) was predicted as the compound with the highest melting temperature, well beyond 4000 K. In this context, we performed a comprehensive analysis of the high-temperature properties and crystallographic behaviours of tantalum carbonitrides using advanced laser melting techniques and electron microscopy. The focus lies on deciphering the phase evolution, melting points, and solidification structures which are essential for applications in ultra-high temperature environments. Using PFIB-SEM and TEM, detailed microscopic investigations reveal structured transformations and accurate measurements of phase stability. The results demonstrate that the tetragonal Ta2CxNy phase exhibits remarkable thermal resilience, with a melting temperature of 4401 ± 69 K, making it a very interesting candidate, along with TaC (i.e. 4520 ± 73 K), for advanced thermal applications.
CF-3:L43 Fretting Wear Performance of a Novel B12(C,Si,B)3-SiC Composite Fabricated by Reactive Spark Plasma Sintering
A. FERNÁNDEZ-ORTIZ, V. ZAMORA RODRÍGUEZ, F. GUIBERTEAU CABANILLAS, A.L. ORTIZ, Universidad de Extremadura, Badajoz, Spain
The fretting wear behavior of an advanced B12(C,Si,B)3–SiC composite was investigated. This composite was fabricated using Reactive Spark Plasma Sintering (SPS) at low temperature (1400ºC) from a 80vol%B4C+20 vol% Si powder mixture. The composite was tested against three ceramic counterparts of varying hardness: diamond, Al2O3 and borosilicate glass (1 N and 5 N loads). The performance was benchmarked against two reference B4C monoliths: (at 1400ºC and at 2000ºC). The study revealed a clear inverse correlation related to hardness of the counterpart: the composite exhibited a higher SFR against softer ceramics. This effect is attributed to the greater damage, which in turn leads to greater wear residue generation. Despite this counter-body dependence, the B12(C,Si,B)3 –SiC composite demonstrated exceptional fretting resistance: Against diamond (two-body abrasion, SFR: 10−7 – 10−8 mm3/(N⋅m)), Al2O3 and borosilicate glass (three-body abrasions, SFR: 10−7 and 10−6 mm3/(N⋅m)). The fully dense, fine-grained microstructure and high hardness are key factors contributing to the composite's superior performance. The B12(C,Si,B)3–SiC composite proved to be more resistant to fretting than the porous B4C monolith SPS-processed at the same 1400ºC cycle and the reference sinterezed at 2000ºC.
CF-3:IL44 Plasmonic Response of Ultra-high Temperature Carbides
S. CURTAROLO, S. DIVILOV, A. CALZOLARI, Duke University, Durham, NC, USA; D.E. WOLFE, Penn State University, USA
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. In this presentation, 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 (>1000C) and variable temperatures. We also show that these high-entropy carbides can be tuned and show considerable plasmonic thermal cycling stability. This paradigm shift approach could prove quite advantageous as it facilitates the accelerated rational discovery and manufacturability of optically highly optimized high-entropy carbides with ad hoc properties.
CF-3:IL45 Mechanical Modelling of Damage, Fracture, Fatigue and Creep of CMCs
LONGBIAO LI, Nanjing University of Aeronautics and Astronautics, Nanjing, China
Ceramic-matrix composites possess high specific strength and modulus especially at elevated temperatures and have applied in hot section components in aerospace. To ensure the reliability and safety of CMCs hot-section components, it is necessary to develop multiscale theoretical models to perform stress, strength and lifetime analysis. In this lecture, Dr. Longbiao Li would present recent research about micromechanical modeling of damage, fracture, fatigue and creep of different CMCs. Experimental investigations on the tensile, fatigue and creep behavior of different CMCs were conducted at first, and the micro damage mechanisms of matrix cracking, interface debonding and fibers failure were analyzed using damage parameters of matrix cracking density, crack opening displacement, interface debonding length, and fibers pullout length, and fiber breaking displacements, etc. The composite’s tensile stress-strain curves, cyclic-fatigue hysteresis loops, and time-dependent strain responses were predicted using the developed micromechanical models. These models have already been adopted in the stress and strength analysis of different CMCs hot-section components.
CF-3:IL46 Thermomechanical Properties of Ultra-High and High Temperature Ceramic Matrix Composites for Hypersonic Applications
L. BAIER, M. FRIESS, N. HAIST, I. PETKOV, D. CEPLI, J. SCHUKRAFT, O. SCHATZ, O. HOHN, German Aerospace Center (DLR), Institute of Structures and Design *German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Stuttgart, Germany
Application of materials and structures at very high temperatures (e.g. hypersonics, re-entry vehicles, propulsion system) demand on very challenging requirements regarding corrosion resistance as well as sufficient thermomechanical performance and damage tolerance in changing atmospheric conditions. Therefore, only fibre-reinforced ceramic materials (CMCs) are the choice of selection. For short term applications carbon fibre-reinforced composites with silicon carbide (SiC) matrix) are the first choice due to their easy access for matrix built-up as well as formation of a passive protection layer of SiO2 under oxidation conditions during "mild" hypersonic flight conditions with the built-up of a protecting passive oxidation layer of SiO2. However, under more severe hypersonic flight or re-entry conditions this passive oxidation protection layer is no longer formed, moreover, active oxidation takes place on the aerodynamically exposed surfaces leading to mass loss as well as enhanced material recession and structural degradation. Therefore, new material systems had to be developed based on materials with pre-dominant active oxidation of Zr-compounds (ZrB2) and compared to C/C-SiC composites regarding thermomechanical behaviour and wind tunnel testing under hypersonic conditions.
CF-3:IL47 High Temperature In Situ Mechanical Testing of Materials and Interfaces: New Insights into Deformation and Creep
SHEN DILLON, University of California, Irvine, CA, USA
Small scale mechanical testing has enabled the characterization of isolated microstructural features. Extending such experiments to high temperatures enables the creep response of the lattice and interfaces to be investigated systematically without microstructural complexities convoluting the analysis. Combining in situ TEM with laser heating allows such measurements to be performed. This work describes new insights into bulk and interfacial creep in oxides, metal-oxide interfaces, and metals resulting from such studies. Specifically, the work highlights the importance of interfacial dislocations in mediating interfacial creep and how Arrhenius models developed to treat this problem can be extended to understand lower temperature deformation.
Session CF-4 Characterization, analysis and simulation
CF-4:L48 Computational Pyrolysis of Polymers for Ultra-High Temperature Ceramics
P. KROLL, The University of Texas at Arlington, Arlington, TX, USA
The thermal conversion of zirconium-modified polycarbosilanes and polysilazanes produces multi-phase ZrSiCN ceramics for extreme environments. To explore directions and opportunities in chemical processing of these systems, we developed the first machine-learning interatomic potential (MLIP) for atomistic simulations in the Zr–Si–C–N–H system supported by our extensive library of molecular dynamics (aiMD) simulations. Polymer-precursor models are based on allylhydrido-polycarbosilane (AHPCS; e.g., SMP-10) and polyvinylsilazanes (PVZ; e.g., Durazane1800) co-reacted with varying amounts of zirconium amine complexes. Atomistic simulations reveal fundamental reactions during pyrolysis, including intra-chain and inter-chain coupling, cross-linking, and elimination. We also simulate the effects of reactive environments, such as hydrogen atmospheres, on the products’ chemical composition. Furthermore, large-scale multi-nanosecond simulations capture structural evolution during pyrolysis, including the formation of nanometer-sized graphitic segregations and the precipitation of ZrN nanocrystals. Our results demonstrate that the MLIP extends quantum-level accuracy to technologically relevant problems, providing new opportunities for predictive modeling of ceramic materials and their transformations.
CF-4:L49 Designing High-Entropy (Hf, Zr, Ta, Ti, Mo)B2 Ceramics for Enhanced Mechanical Strength and Oxidation Resistance in Extreme Conditions
A. PANWAR, S. KUMAR KASHYAP, Department of Materials Engineering, Indian Institute of Technology Jammu, India
High-Entropy Borides (HEBs) are characterized as solid solutions of five or more elements in near-equimolar ratios and have emerged as promising ultra-high-temperature ceramic (UHTC) materials. Their improved mechanical properties and oxidation resistance make them suitable for extreme temperature applications. Therefore, the design and development of HEB materials requires both theoretical and experimental investigation. Theoretical investigations encompass the study of (Hf, Zr, Ta, Ti, Mo)B2 ceramic by employing density functional theory (DFT). The quantitative and qualitative analyses carried out through DFT calculations have revealed that these materials have significant untapped potential. The high entropy of HEB has played a favorable role in stabilizing the solid solution. The results through thermodynamic calculations establish the stability of HEB. The mechanical properties calculated through the stress-strain method have confirmed that the HEB exhibited a higher Vickers hardness of 40.4 GPa and a bulk modulus of 343.5 GPa. The experimental synthesis of HEB with the addition of B4C, Graphite, and SiC may improve the mechanical properties and oxidation resistance of the material. Mo addition is further explored for its stabilizing effects on boria scales during oxidation.
CF-4:L50 Exploring the Interface-Driven Thermo-Mechanical Behaviour of Dual-Phase High-Entropy Boride–Carbide Ceramics
V. MISHRA, S. KUMAR KASHYAP, Department of Materials Engineering, Indian Institute of Technology Jammu, India
Compositionally complex ceramics (CCCs) have widened the field of high entropy ceramics (HECs) with tuneable thermo-mechanical properties. This concept led to the emergence of dual-phase high-entropy ceramics (DPHECs) for optimising properties through synergistic phase interaction. The properties of (Ti,Cr,Zr,Hf,Ta)B2- (Ti,Cr,Zr,Hf,Ta)C DPHECs were theoretically investigated using density functional theory (DFT) to illustrate the structural stability and evolution of properties at the boride-carbide multilayer interface. The interface was modelled in view of lattice mismatch and the presence of coincidence site lattices (CSLs) to minimise interfacial energy for randomly orientated boride-carbide powder. These DPHECs were found to have hexagonal and cubic crystal structures for the boride and carbide phases, respectively. The pinning effect in DPHECs leads to finer grain size (submicron), and the carbide-to-boride ratio enhances the hardness for a range of loads compared to individual boride-carbide phases.
CF-4:IL51 Pure and Compositionally Complex Transitional Metal Carbides and Carbonitrides for Extreme Environments: from Theory to the Experiment
D. ZAGORAC, Materials Science Laboratory, Institute of Nuclear Sciences “Vinča”, University of Belgrade, Belgrade, Serbia; and Center for synthesis, processing and characterization of materials for application in extreme conditions “CextremeLab”, Belgrade, Serbia
In the present study we will focus on pristine transitional metal carbide (Fe3C), as well as on a compositionally complex ceramic carbides and carbonitrides, i.e., (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)NxC1-x. While iron carbide is present in most high-temperature steels and cast irons, Fe based carbon materials are of highest interest because of their superior magnetic properties. On the other hand, complex transitional metal carbides and carbonitrides are possible candidates for ultra-high temperature usage and are known for their superior properties due to the high configuration entropy. A multidisciplinary approach is performed to study these pure and compositionally complex carbide systems, including experimental and theoretical investigations. In the current work, a straightforward method to achieve pure and compositionally complex carbides and carbonitrides was employed, which were characterized structurally by XRD, chemically and morphologically through SEM. Theoretical investigations were performed using the multi-methodological approach involving several computational methods and compared to the experimatal results. Structures were generated using the PCAE, supercell, SQS, and data mining approaches, and final DFT results are in good agreement with the experimental data.
CF-4:IL52 Fracture Behavior in Tantalum Carbides: Experiments and Modeling
S. HOSSAIN1, A. STUBBERS2, O. GRAEVE3, G. THOMPSON2, C. WEINBERGER1, 1Colorado State University, Fort Collins, CO, USA; 2University of Alabama; 3University of California UCSD
Tantalum carbides exhibit unique fracture properties across a wide range of stoichiometries. While stoichiometric TaC exhibit modest toughness and fracture on the cube planes, Ta2C exhibits higher toughness and the tantalum carbide zeta phase can show fracture toughness around 15 MPa-m1/2. To understand how different mechanisms contribute to fracture toughness across the chemistry space, we utilize both density functional theory calculations and targeted microcantilever experiments. The DFT simulations demonstrates that the toughness of these compounds depends on types of cleavage plane orientation and carbon content. Notably, the results demonstrate that the lower symmetry compounds should have many low cleavage planes, suggesting that classical microstructural toughening may not be the sole reason for the enhanced toughness of the zeta phase ceramics. Our microcantilever experiments show good agreement with the DFT simulations when plasticity is suppressed and clearly show that plasticity and microstructural toughening are operative in these ceramics in the bulk.
CF-4:IL53 Phase Stability in High Entropy Transition Metal UHTCs
T. DAVEY1,2, YING CHEN2, 1Bangor University, Bangor, UK; 2Tohoku University, Japan
High-entropy or multi-principal component ultra-high temperature ceramics (UHTCs), such as MC1-x carbides (where the cation M=Ti,Zr,Hf,Nb,Ta), may have potential improved or tuneable properties such as melting point, hardness, ductility, and oxidation resistance. At high temperatures, the configurational entropy in these multi-principal component mixtures is thought to overcome any opposing enthalpic effects inhibiting mixing, resulting in single solid solution phases. However, despite the individual group IV and V transition metal carbides having similar properties and behaviour on an atomic or electronic scale, the elemental differences result in the high entropy ceramics having complex local behaviour that depends on the local atomic environment. This work uses modelling approaches including density functional theory (DFT) calculations and CALPHAD (phase diagram) modelling to explore the MC1-x (M=Ti,Zr,Hf,Nb,Ta) composition space spanned by these systems, including variations in number and ratio of transition metal elements as well as carbon vacancy concentration.