IC-1 - 10th International Conference
Advanced Inorganic Particulates and Fibre Composites for Structural and Thermal Management Applications
ABSTRACTS
Session IC-1.A Production and properties of reinforcements, preforms, and matrix materials
IC-1.A:IL01 Polymer Derived Ceramics and Composite Matrices for Ceramic Composites
RAVI KUMAR, Laboratory for High Performance Ceramics, Indian Institute of Technology Madras (IIT Madras), Chennai, India
Polymer derived ceramics (PDC) as structural ceramics for high temperature applications have been intensely studied for more than two decades. The transformation from a polymeric precursor to the corresponding ceramic is achieved via. solid state thermolysis (SST). The as-thermolysed ceramic is often amorphous and is found to possess exceptional thermo-mechanical properties such as high temperature stability, oxidation and creep resistance. At higher temperatures, these ceramics undergoes phase separation and crystallization, leading to the formation of ceramic nanocomposites. Precursor-derived ceramic containing Zr, La, B, and C was synthesized through precursor modification of phenol formaldehyde resin. The thermal stability and resistance to crystallization of the ceramic at a temperature of 1600 °C was investigated and was found to be profoundly influenced by the boron content in the starting precursors. The ceramics remained amorphous at 1600 °C for 2 h in argon and upon sustained heat-treatment for up to 16 h resulted in nano-crystalline ultra-high temperature phases such as ZrB2, ZrC, LaB6 and La2Zr2O7. Thermodynamic equilibrium phase calculations show that even longer durations of heat treatment may be required to achieve thermodynamic equilibrium.
IC-1.A:IL02 Efficiency of the Thermal-gradient Chemical Vapor Infiltration Process for CMCs Manufacturing: Practice and Theory
G.L. VIGNOLES, University of Bordeaux, LCTS, Pessac, France
Introducing thermal gradients in the Chemical Vapor Infiltration (CVI) process has been made since many years, especially for the fabrication of C/C and SiC/SiC composites. The basic idea is that the thermal gradient helps infiltrating the fibrous preform from the inside out, minimizing the amount of trapped porosity. However, practical implementations of the process are not always totally successful. This presentation will discuss, from a chemical engineering point of view, the existence of optimal sets of processing parameters that ensure the existence of a fully formed infiltration front. Confrontation of these relationships with actual cases of thermal-gradient CVI and with more detailed numerical simulations has been made with success. Some guidelines towards optimizing the process are given.
Funding from the European Union (H2020-NMBP program) under the CEM-WAVE project (grant agreement no. 958170) is acknowledged.
IC-1.A:IL03 Theoretical Prediction, Synthesis and Mechanical Properties of Non-equimolar (Ta-Hf-Zr-Nb-Ti)B2 Entropy-stabilised Borides
I. ZHUKOVA, M. TATARKOVÁ, P. TATARKO, Institute of Inorganic Chemistry SAS, Slovakia; D. ZAGORAC, M. PEJIC, B. MATOVIĆ, Vinča Institute of Nuclear Sciences - National Institute of thе Republic of Serbia, Serbia; Z. CHLUP, F. ŠIŠKA, I. DLOUHÝ, Institute of Physics of Materials, Czech Academy of Sciences, Czech Republic
This study investigates the prediction and synthesis of non-equimolar entropy-stabilised borides based on the (TaxHfxZrxTixNbx)B2 structure. Using Density Functional Theory (DFT) calculations combined with Special Quasirandom Structures (SQS), formation energy was applied to identify stable single-phase compositions. Three compositions were selected for experimental study: (Ta0.6Hf0.1Zr0.1Ti0.1Nb0.1)B2, (Ta0.6Hf0.25Zr0.05Ti0.05Nb0.05)B2, (Ta0.6Hf0.2Zr0.1Ti0.05Nb0.05)B2. The effect of different transition metal concentrations on the synthesis and mechanical properties of entropy-stabilised borides was investigated. These compositions exhibited hardness between ~ 22 and 23 GPa, significantly higher when compared to the equimolar counterpart (~ 19 GPa). Similarly, the specific wear rate was markedly reduced to 4.03 × 10-9 mm3/N·m, compared to 5.16 × 10-8 mm3/N·m for the equimolar sample. These results demonstrate that refining the high-entropy concept towards non-equimolar, medium-entropy, compositions through precise molar ratio selection enhances mechanical performance in transition metal diborides.
This work was supported by the Slovak Research and Development Agency under the Contract no. APVV-21-0402 and the project SAS-TUBITAK/JRP/2023/807/HiTemCom (No. 720464).
IC-1.A:IL04 Synthesis of Zr-based Polymer Precursor for PIP Method using the Sol-Gel Method
SEA-HOON LEE, JAEIL SO, KEON-HO LEE, Korea Institute of Materials Science, Changwon, Republic of Korea
Their unique properties, including high heat resistance and ablation resistance, have made UHTC indispensable materials in the aerospace industry. Among UHTC, Zr-based ceramics (ZrO2, ZrC) are widely used due to their high melting points exceeding 2800℃. One of the densification methods for Zr-based ceramics is the polymer infiltration & pyrolysis (PIP) method. In the PIP method, a liquid polymer precursor with low viscosity is necessary for efficient infiltration into matrix. Typically, Zr-based ceramic precursors have been synthesized through sol-gel reactions with zirconium alkoxides and carbon sources. These carbon sources often contain hydroxyl functional groups, which facilitate the sol-gel reaction but can complicate control over the molecular weight of the product, resulting in significantly increased viscosity. Therefore, new synthetic strategies are required to increase ceramic yield while reducing precursor viscosity. In this present versatile, enabling the production of both ZrC and ZrO2 depending on the carbon source’s presence, we will introduce a novel oxidized precursor for the fabrication of ZrC and ZrO2. The carbon source used in our study acts as a solvent, effectively decreasing the viscosity of the precursor and promoting a stable infiltration process.
Session IC-1.B Interfaces / Interphase
IC-1.B:IL05 Structure and Properties of CVD Fiber Coatings for SiC/SiC Composites
K. SCHÖNFELD, M. KRUG, C. STEINBORN, Fraunhofer IKTS, Dresden, Germany
Hot gas stable SiC/ SiC composite materials require a dense matrix to prevent degeneration effects caused by hot gas contact. Toughness-enhancing mechanisms for the composite material, like crack deflection and fiber pull-out, require an interphase between the fiber material and the matrix acting as a predetermined breaking point. State of the art interphase materials are coatings of the fiber materials applied by wet-chemical processes or gas phase processes as chemical vapor deposition (CVD), like PyC or BN. The layered crystal structure of the materials favors a deformation due to slip processes. However, the limited stability of the interphase material in oxygen containing atmospheres at elevated temperatures (> 900 °C) is critical. At these conditions oxygen migration through microcracks in the matrix or by diffusion leads to oxidation of the interphase material (borate glass formation) resulting in a decrease of the material strength and an enhancement of brittleness. Therefore, it is crucial for applications in hot gas atmosphere to develop an interphase material which is more advantageous compared to currently available BN fiber coating. Within the present contribution, initial results for modified BN fiber coatings in combination with a SiC top coating by thermal CVD.
IC-1.B:IL06 Synergistic Effect of Nanotubes and Graphenes in ceramic Composites: Role of Interfaces
C. BALÁZSI, K. BALÁZSI, HUN-REN Centre for Energy Research, Institute for Technical Physics and Materials Science, Budapest, Hungary
The lecture will give a comprehensive view on innovative developments made in the field of nanocarbons e.g. carbon black, carbon nanotubes (CNTs), graphene added ceramics highlighting the key issues related to integration technology and improvements in the mechanical, tribological or functional properties as a result. Among non-oxide ceramics the silicon nitride based ceramics are well-known as low density materials with high strength and toughness. Silicon nitride, known as a typical dielectric material, is an ideal candidate for several structural applications, even at high temperatures. The addition of graphene or carbon nanotubes to silicon nitride to create ceramic nanocomposites gives rise to promising applications in a wide range of fields such as electronics, biomedical aids, membranes, flexible wearable sensors and actuators, energy systems. The presentation will show how the use of different reinforcing phases, theri dispersion grade, ceramic matrix – CNTs, graphene interphases and sintering methods influence the microstructure and as a result, mechanical properties, electrical, thermal conductivity and tribological properties of the final silicon nitride nanocomposites. The prospective future applications will be also discussed.
IC-1.B:IL07 Micromechanical and Microstructural Analysis of the Interphase in SiC/SiC
K. BOCK, K. POSTLER, D. KOCH, J. MOOSBURGER-WILL, Institute of Materials Resource Management, University of Augsburg, Augsburg, Germany
In SiC fiber-reinforced SiC composites (SiC/SiC), the interfacial region between fiber and matrix, typically featuring a chemical vapor deposited BN-SiC coating system, plays a pivotal role in determining composite behavior. The BN layer establishes weak interfacial bonding that enables quasi-ductile failure behavior, while the SiC layer protects both the BN coating and the SiC fibers from degradation. Optimizing interphase design requires a thorough understanding of the correlations between microstructure, chemical composition, and mechanical properties. This work investigates these relationships through high-resolution microstructural characterization and micromechanical testing of SiC/SiC composites fabricated via liquid silicon infiltration. Transmission electron microscopy is employed for detailed microstructural evaluation, complemented by analytical techniques to determine elemental composition, chemical bonding characteristics, and crystalline structure. To quantify fiber-matrix adhesion, single-fiber push-out tests are conducted. This comprehensive approach provides fundamental insights into structure-property relationships, enabling targeted optimization of interfacial design for enhanced composite performance.
Session IC-1.C Processing and fabrication of MMCS, CMCS, and C/C composites
IC-1.C:IL08 New Methods for the Manufacture of C/C-SiC Thrusters for Space Propulsion
B. HEIDENREICH, R. JEMMALI, R. PERRIER-GUSTIN, D. CEPLI, M. SMOLEJ, D. CEPLI, F. VOGEL, J. PEICHL, DLR, Institute of structures and design, Stuttgart, Germany; M. KURILOV, T. HÖRGER, DLR, Institute of Space Propulsion, Lampoldshausen, Germany
In the frame of DLR interdisciplinary projects, C/C-SiC thrusters have been developed for space propulsion systems. Thereby, efficient manufacturing, as well as testing with green propellants, was in the focus. C/C-SiC composites are based on carbon (C) fibers, embedded in C and silicon carbide (SiC) matrix, and are manufactured via the liquid silicon infiltration (LSI) process. In the first step, a carbon fibre reinforced polymer (CFRP) is manufactured, and subsequently pyrolyzed in inert atmosphere. The resulting, porous C/C (C fiber reinforced C) preform finally is siliconized in vacuum. Two design concepts have been used. In a differential design, the thruster was separated into three components, a tubular combustion chamber, a tubular flange and a double conic nozzle insert. Thereby, different methods could be selected for the efficient manufacture of the CFRP preforms. Whereas the nozzles were manufactured via warm pressing of short fibres, 2D fabrics were used for prepreg wrapping of the tubular components. Small thrusters were realized in an integral design. Thereby, the thrusters were manufactured as single parts in near net shape geometry by warm pressing. In this presentation, the manufacture, as well as the results from mechanical and hot firing testing are shown.
IC-1.C:IL09 Fabrication of Oxide/Oxide Composites
M. SINGLARD, IRT Saint Exupéry, Talence, France
Oxide/Oxide ceramic matrix composites (O-CMCs) are attracting a growing interest for intermediate-temperature applications (800-1000 °C) in oxidizing environments. Their oxide nature allows the use of the weak-matrix concept without the need for costly fiber coatings. A wide range of processing routes are available for manufacturing O-CMCs, and IRT Saint Exupéry focuses on liquid-based processes: tow impregnation (towpreg) for subsequent AFP deposition, fabric impregnation (prepreg) for manual lay-up, and injection (derived from RTM process) of fibrous preforms. The first two routes rely on the production of semi-finished products that must remain stable and suitable for lay-up, whereas the injection route starts from a fibrous preform before matrix build-up. The associated constraints on the matrix are discussed in detail. Subsequently, examples of part manufacturing are presented, with a particular attention on microstructural and mechanical properties. Finally, the industrial perspectives for these processes are outlined.
IC-1.C:IL10 Fabrication of CVI-SiCf/SiC Composite for Heat Exchanger Applications
DAEJONG KIM, J.-B. KIM, H.-G. LEE, W.-J. KIM, B.-H. JEON, KAERI, Daejeon, South Korea; H.S. MOON, Sewon Hardfacing Co. Ltd., Mokpo, South Korea; G. BIANCHI, A. ORTONA, SUPSI, Manno, Switzerland; V. PAPAGEORGIOU, IHI BERNEX AG, Olten, Switzerland
Sandwich-structured ceramic composites incorporating porous ceramics with excellent thermal conductivity can provide either superior thermal insulation or efficient heat transfer depending on the structural design, making them promising candidates for addressing diverse materials challenges in renewable energy and next-generation transportation systems. SiC-based composites not only possess high thermal conductivity but also maintain outstanding mechanical strength up to approximately 1500 °C. They can directly recover high-temperature heat. Therefore, SiC-based sandwich-structured composites are promising materials for high-temperature heat exchangers aimed at recovering waste heat generated in incineration and chemical processing environments. In this study, a cylindrical sandwich-structured SiC composite was fabricated using a high thermal-conductivity porous SiC core produced by additive manufacturing, combined with a dense fiber-reinforced ceramic composite skin. A SiC fiber preform was prepared by filament winding using Tyranno SA-grade fibers, followed by the deposition of a PyC or h-BN interphase layer via chemical vapor deposition (CVD). Subsequently, the SiC matrix was densified through chemical vapor infiltration (CVI).
IC-1.C:IL11 Advanced Manufacturing of Conical CMC Structures via Wet-laid Nonwoven Technology
F. KESSEL, M. FRIEß, O. HOHN, German Aerospace Center, Stuttgart, Germany
Ceramic Matrix Composites (CMCs) combine high-temperature stability, fracture toughness, and strength over wide temperature ranges, but their application is limited by complex manufacturing, especially for textile fiber reinforcements. Adapting fabrics to new shapes requires intensive manual preparation and often causes fiber damage. At the German Aerospace Center (DLR), wet-laid nonwoven technology was applied to produce three-dimensional preforms, focusing on conical geometries relevant for radome tips and nozzle components. Demonstrators based on carbon and alumina fibers were processed into Al₂O₃/SiCO (oxide-CMC) and C/C-SiC (non-oxide-CMC) using PIP and LSI methods. Both yielded defect-free parts with high shape fidelity, without additional machining. The oxide-based cone was tested in an arc-heated wind tunnel (L2K) under extreme conditions. A non-through-thickness crack appeared at the tip during peak load but did not cause failure, even after further cycles. Overall, the structure endured multiple loadings, with a total test time of 380 s and a maximum heat flux density of 500 kW/m².
IC-1.C:IL12 Additive Manufactured C/C-SiC based on FFF - Advances and Challenges
N. LANGHOF, W. FREUDENBERG, J. BEST, S. SCHAFFÖNER, University of Bayreuth, Chair of Ceramic Materials Engineering, Bayreuth, Germany
Ceramic matrix composites are materials that combine non-brittleness and thermal shock resistance with low densities and high wear resistance. The fiber reinforcement within the ceramic matrix is crucial and responsible for this remarkable combination of properties. However, due to the hardness of CMCs and the costly fibers, net-shape fabrication is one goal of the CMC development.
One way to handle this challenge is additive manufacturing. With fused filament fabrication fibers can be printed in a polymer matrix (thermoplastics). The fabricated green bodies must be converted into C/C during pyrolysis and C/C-SiC during liquid silicon infiltration.
Within this work the development of C/C-SiC based on FFF (C-fibers in PEEK-filament) is summarized. Thermomechanical properties like the CTE, the thermal conductivity, the impact behavior and the strength are presented. These properties are correlated, mainly with the printing parameters and the fiber content (15-30 wt.%). The question how thermoplastics can remain their shape during heating in pyrolysis and the critical fiber length are discussed. Do the ultra-short fibers (< 250 µm length) really provide a considerable reinforcement like they do in polymer composites? If not, can we easily switch to long or continuous fibers?
IC-1.C:IL13 Integration, Joining, and Repair Technology Development of Ceramic Matrix Composites for Aerospace Applications
M.C. HALBIG1, M. SINGH2, A. ALMANSOUR1, 1NASA Glenn Research Center, Cleveland, OH, USA; 2Ohio Aerospace Institute, Cleveland, OH, USA
Integration and joining technologies are critical for the wider application of ceramic matrix composites (CMCs) for demanding aerospace applications such as thermal protection systems, thermal management, and propulsion systems such as turbine engine, nozzle, and exhaust components. Integration technologies allow for the incorporation of CMC components with metal-based systems while joining technologies allow for the fabrication of large and complex shaped CMC parts. Every specific need for integration and joining requires a customized solution which must consider use temperature, environment, and stress states, bonding interlayer selection, component geometries, material compatibility, and life and reuse requirements. The ability to repair CMCs has also been pursued in order to prolong the use life and reduce the replacement costs of CMC components. NASA integration, joining, and repair technologies have been developed with an emphasis on processing and optimization, thermomechanical testing, and processing-microstructure-property correlations. Various technical challenges and opportunities for the integration, joining, and repair of CMCs will be presented.
IC-1.C:L14 Role of Boron in the Si Melt-infiltrated Matrix of SiC/SiC Composites
G. CHOLLON, H. PLAISANTIN, J. ROGER, Laboratoire des Composites Thermostructuraux (LCTS), CNRS, Univ. Bordeaux, Safran Ceramics, CEA, UMR 5801, Pessac, France
During the synthesis of the SiC/SiC composite matrix, boron is usually added during liquid silicon infiltration (LSI) to limit corrosion of the SiC fibers and CVD SiC coating. Although well known, this effect has not yet been clearly explained. Here we examine the role of B towards CVD SiC via the synthesis and analysis of model composites prepared by LSI. Comparing SiC-Si,B and SiC-Si composites clearly demonstrates the B's protective role. Electron energy loss spectroscopy (EELS) and atom probe tomography (APT) were used to assess elemental composition at the atomic and trace scales, in volume and at SiC/Si,B interfaces. B diffuses into bulk SiC, but also concentrates at structural defects in polycrystalline CVD SiC. EELS and APT revealed a high B overconcentration over a few nanometers at SiC/Si,B interfaces. Raman spectroscopy also evidenced a microscale gradient of substituted B in the Si,B alloy, near SiC/Si,B interfaces, related to a high C concentration and an unexpected C environment. B cumulates three beneficial effects limiting SiC reactivity: a SiC volume effect stabilizing and accommodating structural defects, a SiC/Si,B interfacial effect: B atoms concentrating and stabilizing interfaces, and a Si,B alloy volume effect: B-C co-clusters inhibiting carbon diffusion.
Session IC-1.D Ultrahigh Temperature Ceramic Composites (UHTCCs) and Laminated Composite Structures
IC-1.D:IL15 Liquid-Phase-Sintered Cf–ZrB₂ UHTCMCs: Processing and Testing
D. SCITI, A. VINCI, M. MOR, S. FAILLA, L. ZOLI, CNR-ISSMC, Faenza, Italy
Zirconium diboride-based UHTCMCs are currently considered a promising class of materials for aerospace applications. One of the challenges in the production of these composites is the densification stage, carried out at very high temperatures. In this study, the liquid-phase sintering of ZrB2-Cf UHTCMCs was investigated to decrease the densification temperature, using liquid-forming sintering aids such as ZrSi2 and Si3N4. Both fiber-reinforced and non-reinforced systems were prepared and sintered by hot pressing and spark plasma sintering. Thermodynamic analyses and ad hoc interface experiments were conducted to reconstruct reactions at the matrix/fibre interface during matrix densification. The formation of a liquid phase lowered the sintering temperature; however, the accumulation of liquid at the matrix/fiber interface increased fiber corrosion. Compared to bulk systems, the addition of fibers slowed down densification. Microstructural analyses and mechanical tests up to 1500°C were conducted to assess the effect of sintering aids. The oxidation resistance was tested up to 1650°C in a bottom-up loading furnace.
IC-1.D:IL16 Processing and High Temperature Performance of UHTC-coated CMCs
H. ÜNSAL, M. HIČÁK, M. TATARKOVÁ, P. TATARKO, Institute of Inorganic Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia; Ş. ATEŞ, TUBITAK Marmara Research Center, Materials Technologies, Gebze, Kocaeli, Turkey; Z. CHLUP, I. DLOUHÝ, Institute of Physics of Materials, Czech Academy of Sciences, Brno, Czech Republic; R. KUMAR, Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, India
The superior thermal and mechanical stability of Ultra-High Temperature Ceramic Matrix Composites (UHTCMCs) renders them excellent candidates for structural applications in extreme environments. In this study, Cf/C and Cf/SiC ceramic matrix composites (CMCs) were developed and coated with a ZrB2-based ultra-high-temperature ceramic (UHTC) layer to enhance their ablation resistance. The coating was applied via a room-temperature deposition process and cured at 200 °C in multiple layers.The microstructural and phase composition analyses were conducted using SEM, EDS, and XRD, confirming uniform coating distribution and phase formation.The coated samples were annealed at 1400 °C under an Ar to remove organic compounds. Ablation performance was evaluated through an oxyacetylene torch test at surface temperatures of ~2300 °C for Cf/C and ~2050 °C for Cf/SiC. The results demonstrated a significant reduction in mass ablation rates, with the coated and annealed samples exhibiting up to 50% improvement in ablation resistance compared to uncoated counterparts.
This work was supported by the project SAS-TUBITAK/JRP/2023/807/HiTemCom (No. 720464). The support of the Slovak Research and Development Agency under the Contract no. APVV-21-0402 and APVV-24-0403 is also acknowledged.
IC-1.D:IL17 Fabrication and Oxidation Resistance of Coated and Uncoated UHTCMCs
A. VINCI, ISSMC - CNR, Faenza, Italy; J.-E. FOERSTER, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA; R. NARAPARAJU, German Aerospace Center (DLR), Cologne, Germany; D. SCITI, ISSMC - CNR, Faenza, Italy
Ultra-High Temperature Ceramic Matrix Composites are a new class of materials that combine the good mechanical properties of CMCs with the oxidation and ablation resistance of UHTCs. Preliminary studies on the oxidation resistance of C-ZrB2/SiC composites have shown the ability of these materials to survive harsh conditions with negligible erosion. The oxidation mechanism of the C-ZrB2/SiC system involves the oxidation of the outer fibres and the formation of a borosilicate layer that provides a barrier against further oxidation up to 1650°C. Above this temperature, B2O3 actively evaporates, leaving behind a ZrO2/SiO2 layer that becomes unstable at higher temperatures. In order to improve the oxidation resistance of UHTCMCs and allow reusability of these materials, reactive coatings have been investigated to delay the oxidation kinetics. In this work, niobium-based coatings were deposited on the surface of C-ZrB2/SiC composites via magnetron sputtering. Following the annealing procedure, a layered NbB2/NbC coating was formed. From the results of the oxidation testing at 1500 and 1700°C, the presence of the coating helped stabilizing and preserving B2O3 even above 1650°C, considerably slowing oxidation kinetics.
IC-1.D:IL18 B4C Laminated Ceramics Composites with Enhanced Comprehensive Mechanical Properties
WEIMIN WANG, XIZHAO CHEN, ZHENGYI FU, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, China
This presentation designed and prepared a novel symmetrical sandwich-structured B4C laminated composite ceramic with strong interfacial bonding using particle dispersoid-strengthened B4C composite ceramics (B4C/SiC, B4C/TiB2) as the unit layer. By altering the reinforcement phase types in the B4C ceramic, the performance of the layered composite ceramic can be significantly modified. This sandwich structured laminated composite ceramic exhibits excellent strength, toughness, and Vickers hardness. By optimizing the laminated structure and preparation process, the laminated composite ceramics with excellent comprehensive performance were prepared. The material's density, flexural strength, hardness, and fracture toughness were 2.64 g/cm3, 834 MPa, 37.1GPa, and 5 MPa · m1/2, respectively， compared with B4C unit ceramics, the bending strength, fracture toughness, and hardness of the material have increased by 12.5%, 35.1%, and 6.6%, respectively. The study reveals that the surface layer of laminated composite ceramic contains substantial compressive residual stress. By adjusting the composition of each layer of material, the compressive stress values of the surface layer can be changed, resulting in changes in the mechanical properties of laminated composite ceramics.
IC-1.D:IL19 Processing and Structural Optimization of Short Fibre-Reinforced UHTCMCs
M. MOR, A. VINCI, S. FAILLA, L. ZOLI, D. SCITI, CNR-ISSMC, Faenza, Italy
In recent years, various methods have been explored to incorporate short fibre reinforcement into ceramic matrices, such as ball milling and tape casting, for the production of Ultra High Temperature Ceramic Matrix Composites (UHTCMCs). However, drawbacks like fibre damage and the need for large volumes of solvents have significantly limited the applicability of these techniques. To address these issues, a novel water-based process has been developed, enabling the homogeneous dispersion of short carbon fibres within the ceramic matrix while preserving their original dimensions and minimizing damage. UHTCMCs are typically densified through hot pressing or spark plasma sintering. While these techniques are effective, they generally produce simple geometries that require costly machining with diamond tools or specialized equipment to achieve the final shape. In contrast, the flexibility of the water-based process used for short fibre-reinforced UHTCs opens up the potential for producing more complex structures and shapes using both hot pressing and pressure-less sintering. This study explores the feasibility of fabricating UHTCMC samples with non-standard geometries. Specifically, dual composition square- and disc-shaped tiles, wedges and cones were produced via hot pressing.
Session IC-1.E Property, modeling and characterization
IC-1.E:IL20 Design of Advanced Environmental Barrier Coatings
JIE ZHANG, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, China
Environmental barrier coatings (EBCs) are needed to protect SiCf/SiC ceramics from degradation advanced modern gas turbines. Multifunctional requirements were established for EBC, including matched coefficient of thermal expansion (CTE), low thermal conductivity as well as corrosion resistance to both steam and calcium-magnesium-aluminum-silicate (CMAS) deposits. In the current talk, tailoring thermal expansion behavior of rare earth silicates by means of local disordered structure was illustrated. Coordinative local disturbances introduced by strategic high-entropy design have been proposed as the key method for CTE regulation. To achieve thermomechanical robustness against CMAS deposits, thermochemical equilibrium between rare-earth oxides and calcium-magnesium aluminum-silicate deposit was investigated. The variation of rare earth constituents results in the transformation of crystalline products from apatite/silicocarnotite to garnet/diopside, which accelerates the consumption of CMAS melt and facilitates corrosion mitigation. A pseudo-ternary phase diagram was established, which had a great potential to describe phase equilibrium in coating-deposit systems and could provide guidance for compositional design of corrosion-resistant coatings.
IC-1.E:L21 Non-destructive Evaluation of Elastic Properties of C/C-SiC at Different Temperatures
S. HÖNIG, J. SCHUKRAFT, German Aerospace Center (DLR), Institute of Structures and Design (BT), Stuttgart, Germany; J. ROßDEUTSCHER, German Aerospace Center (DLR), Institute for Frontier Materials on Earth and in Space (FM), Cologne, Germany; T. LEBER, Thorsten Tonnesen RWTH Aachen University, Institute of Mineral Engineering (GHI), Aachen, Germany; D. KOCH, University of Augsburg, Institute of Materials Resource Management, Augsburg, Germany
The reinforced ceramic matrix composite (CMC) C/C-SiC components are primarily employed in high-temperature conditions, such as in aerospace applications or brake discs. The accurate modelling of in-service behaviour is dependent on the correct characterisation of the elastic properties of C/C-SiC. It is standard practice to measure the elastic properties in a discrete way at fixed temperatures via quasi-static tests. The Resonant Frequency and Damping Analyser (RFDA) enables continuous, non-destructive acquisition of the flexural and torsional eigenfrequencies of material samples across a range of temperatures. The present research combined RFDA under quasi-inert atmosphere and numerical reverse analysis to estimate the in-plane elastic and shear moduli of 0/90° and ± 45° C/C-SiC materials continuously versus temperatures up to 1250°C. Furthermore, the impact of oxidation on these elastic properties was quantitatively assessed. The novel methodology proposed in this study allowed also to estimate out-of-plane shear modulus at room temperature and 1250°C. The methodology is compatible to the estimation of the elastic properties of other materials at room or high temperature.
IC-1.E:L22 Flexural Behavior Analysis (DIC, AE, FEA) of a Sandwich Structure based on Geopolymer-matrix Composites.
D. HABANS1, P. REYNAUD1, É. PRUD'HOMME1, G. FANTOZZI1, T. CUTARD2, G. DUSSERRE2, N. GODIN1, 1INSA Lyon, Claude Bernard Lyon 1 University, CNRS, MATEIS, UMR5510, Villeurbanne, France; 2Institut Clement Ader (ICA), University of Toulouse, CNRS, IMT Mines Albi, INSA, ISAE-SUPAERO, UPS, Campus Jarlard, Albi, France
Ceramic-matrix composites are interesting for structural applications due to their enhanced deformation compared to monolithic ceramics. Geopolymers are inorganic materials that first flow, then toughen rapidly at ambient temperatures. There have been many studies on geopolymer-matrix composites, as well as geopolymer foams. However, few structural applications have emerged for geopolymers outside of civil engineering despite their great polyvalence and their potential for sustainability. In this work, we present an innovative sandwich structure made of a geopolymer-matrix composite as external layers, and of a geopolymer foam as the inner core. The composites are made by impregnating continuous inorganic fibers with a geopolymer matrix. The geopolymer foam suspension is poured between two composite layers to form a sandwich by consolidating in-situ. We assessed the mechanical behavior of the sandwich structure using four-point bending tests assisted with digital image correlation and acoustic emission. A finite element model of the structure was also built based on a concrete damage plasticity behavior, to understand further the damage mechanism. Results show that cracks appear in the foam before propagating to the composites or being deviated at the foam/composite interface.
IC-1.E:IL23 Topology Optimization of Complex Ceramic Components: Integrating Computational Design and Additive Manufacturing for Functional Performance
A. ORTONA, SUPSI-DTI-MEMTi, Lugano, Switzerland
Silicon carbide (SiC) ceramics combine outstanding thermal, chemical, and mechanical properties, making them ideal for high-performance applications in heat transfer, process intensification, and thermo-mechanical systems. This talk presents an integrated approach that couples topology optimization with additive manufacturing to design and fabricate complex SiC architectures with tailored porosity, hierarchical structures, and optimized geometry. Computationally guided designs enable the simultaneous maximization of thermal conductivity, mechanical strength, and fluid flow, supporting compact, efficient, and resilient process equipment. Case studies illustrate cellular and lattice structures produced via additive manufacturing that enhance heat exchange, accelerate reaction rates, and withstand demanding thermo-mechanical loads. This work demonstrates how advanced SiC ceramics, informed by computational optimization and realized through additive manufacturing, provide a versatile platform for next-generation engineering solutions in thermal management, energy-intensive processes, and structurally demanding applications.
IC-1.E:IL24 Densification, Microstructure and Properties of Nano-ceramics Fabricated under Ultrahigh Pressure
WEI JI, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, China; ZHENGYI FU, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, China
Ultrahigh pressure sintering technology is one of the most important research scopes for advanced new ceramic materials. It can not only resolve the contradiction between high density and fine grain structure during ceramic sintering, but also lead to unique microstructure and fantastic properties. In traditional sintering theory, atomic diffusion is considered as the dominate densification mechanism in pressure sintering. But in our study, it has been found that the plastic deformation and creep etc. caused by high pressure could dramatically improve the densification. The related unique microstructure could contribute to the unique properties such as hardness, toughness and strength. Based on the new phenomenon, we investigated the densification behavior, microstructure evolution and interesting new properties of typical ceramics from ultra-fine grain powders under different pressure scales. Combined with the modeling results, the dominate densification mechanism of ultrahigh pressure and high temperature sintering technology, and the relationship between dominate sintering mechanism and properties were studied.
IC-1.E:IL25 Real time X-ray Tomography Imaging of Cracks Initiation and Propagation in CMCs at 1200°C
DONG (LILLY) LIU, Department of Engineering Science, University of Oxford, UK
Ceramic-matrix composites have complex microstrucutre therefore in-situ imaging technqiues are needed to investigate their deforamtion, crack initation and propagation in 3D. This work will showcase the range of CMCs, with and without coatings, studied using in-situ X-ray computed micro-tomography at elevated temperatures up to 1200°C. The loading configurations include short-beam flexural testing, C-ring compression and notched flexural testing. The tests were carried out over a range of temperatures and the impact of temperature on the mechanical behaviour of the different types of CMCs designs will be reported. Post-test data analysis inlcudes 3D image segmentation as well as digital volume correlation for 3D strain distribution to identify the 3D failure strain, strain localisation, crack initiation and propagation. The toughening mechanisms in the materials systems will be presented.
IC-1.E:L26 Environmental Deposits Corrosion on Thermal Barrier Coatings in Jet Engines
WENJIA SONG, School of Materials Science and Engineering, Beihang University, Beijing, China
Environmental deposits such as sand, dust, volcanic ash, and sea-salt aerosols severely degrade thermal barrier coatings (TBCs) in high-temperature turbine environments. Conventional CMAS model systems inadequately represent salt-bearing deposits encountered in marine and coastal service conditions.Here, a phase-informed strategy is applied to investigate salt-modified CMAS glasses and their interactions with yttria-stabilized zirconia (YSZ) TBCs. By incorporating marine salts into model CMAS compositions, we show that salt concentration, rather than regional compositional variability, dominates melt depolymerization, viscosity reduction, and spreading–infiltration kinetics at elevated temperatures. High-temperature wetting experiments, microstructural characterization, and first-principles simulations collectively reveal accelerated TBC corrosion induced by alkali species.A unified salt-bearing CMAS composition is proposed as a reference material for evaluating TBC performance in marine environments, providing guidance for the design of corrosion-resistant ceramic coatings.
IC-1.E:IL27 Thermal Aging of Oxide/Oxide CMC – Evolving Microstructural Features and their Relevance for Mechanical Properties
P. MECHNICH, G. ALKAN, F. FLUCHT, J. ROSSDEUTSCHER, German Aerospace Center (DLR) Institute for Frontier Materials on Earth and in Space, Cologne, Germany
Oxide/oxide ceramic matrix composites (OxCMC) consisting of Al2O3 and Al2O3/Mullite fibers and matrices are attractive for application in harsh thermal-mechanical-chemical environments. At DLR various types of OxCMC based on water-based Al2O3 matrix slurries and oxide fibers are manufactured by wet filament winding and textile-based vacuum assisted slurry infiltration. The specific OxCMC microstructure, i.e. submicron matrix grains and pores as well as nanosized fiber grains, is crucial for favorable mechanical performance. However, still lacking knowledge on the aging behavior of OxCMC during high-temperature operation hinders the full exploitation of their potential. OxCMC manufactured from Nextel 610 and Nextel 720 fibers were characterized mechanically after long-term annealing up to 1300°C. Post annealing mechanical tests and high-resolution electron microscopy were used to monitor degradation, especially in early stages. Aging of OxCMC can be attributed to the diffusion of SiO2 but also Al2O3 and the fiber-matrix interface. Matrix doping with small amounts of Mullite as secondary matrix phase was found a promising strategy to mitigate or minimize diffusion of SiO2 and Al2O3 thus decreasing the driving force for thermally induced degradation of the OxCMC.
IC-1.E:IL28 Prediction of Thermo-Mechanical Lifetime in Self-Healing Ceramic Particulate Composites via Combined Multiscale–Multiphysics Modeling and Machine Learning
S. ANUSUYA PONNUSAMI, Queen Mary University of London, UK; A. KUMTHEKAR, TU Delft, Netherlands; S. TURTELTAUB, TU Delft, Netherlands
Self-healing ceramic particulate composites offer significant potential for high-temperature structural applications by autonomously repairing damage and extending service life under thermo-mechanical loading. In these materials, encapsulated healing agents interact with evolving microcracks, enabling localized repair influenced by stiffness and fracture property mismatches, plasticity, and multiscale process zones. To capture these complex interactions, a coupled multiscale–multiphysics micromechanical framework incorporating a cohesive-zone-based crack healing model was developed to predict the thermo-mechanical lifetime of self-healing composites. Since deterministic modeling cannot fully address uncertainties in microstructural design, a data-driven surrogate model based on Polynomial Chaos Expansion and Gaussian Process Regression was trained using finite element simulations. The surrogate efficiently predicts lifetime statistics and sensitivity indices for variables such as particle size, volume fraction, and spatial distribution. The integrated modeling and machine learning approach provides critical insights for optimizing robust self-healing ceramic particulate and layered composites for demanding aerospace and energy applications.
IC-1.E:IL29 Designing Slurry Formulations for SiC/SiC Minicomposites: A Bayesian Optimization Approach to Maximize the SiC Content
K. POSTLER, J. MOOSBURGER-WILL, N. MEYER, N. JAIN, D. KOCH, Universität Augsburg, Augsburg, Germany
This study presents a sustainable, water-based slurry system for fabricating SiC/SiC minicomposites via Liquid Silicon Infiltration (LSI). The process avoids toxic or harmful materials and eliminates the need for pyrolysis, enabling a more environmentally friendly route to high-performance ceramic composites for high temperature applications. The slurries are based on mixtures of silicon carbide and carbon powders to promote in-situ formation of SiC and reduce residual silicon. To identify optimal formulations, a Bayesian Optimization framework was applied using BoTorch and integrated in digital lab book OpenBIS. The slurry design space included solid content, SiC/C ratio, additive type and amount, binder content, pH and mixing parameters. The key objective was to maximize the SiC yield in the matrix by balancing composition and processability. The SiC content was quantified from polished cross-sections using threshold-based image analysis. Trends indicate that slurry systems, both using SiC and C powders, with tailored additives can outperform single-powder slurries. This approach demonstrates how data-driven optimization can support the design of advanced aqueous slurries for aerospace-grade SiC/SiC, reducing experimental effort and environmental impact.
Session IC-1.F Composites for thermal management
IC-1.F:IL30 Additive Manufacturing of Oxide Fiber Composites
J. STILLER, D. NESTLER, Chemnitz University of Technology, Chemnitz, Germany
This work investigates the material extrusion-based additive manufacturing (AM) process chain of a pure alumina-based oxide ceramic matrix composite, starting from material selection, large-scale compounding to pellets, the AM process itself, debinding and sintering as well as microstructural and mechanical characterization. The compounded pellets have a volume share of 50% binder (polyvinyl butyral [PVB], polyethylene glycol [PEG], and stearic acid) and 50% alumina (Al2O3, alumina powder, and Nextel 610 alumina fibers) with an aimed fiber volume share of 40% after sintering. The material is compounded on an industrial scale with approximately 10 kg/h and the material extrusion-based AM process reaches speeds of up to 1000 mm/s. A variation of the feed rate leads to a significant increase in surface roughness and an increase in mass of 30%, in thickness of 12% and in width of 25%. The flexural behavior in the four-point-bending test can be described by a fast first peak and reaching higher flexural strength after the first crack subsequent with averages of 23.8 ± 3.6 MPa below .1% elongation. The fracture surfaces show the expected failure mechanisms like pull-out and crack deflection. The resulting fiber length in the printed samples is 140 μm in average.
IC-1.F:IL31 Oxide fiber Reinforced Ceramic Matrix Composites – The Right Choice for Challenging High-temperature Application
W. PRITZKOW, Walter E.C. Pritzkow Spezialkeramik, Filderstadt - Sielmingen, Germany
Replacing metal parts by oxide fiber reinforces ceramic matrix composites (O-CMC) is the aim of this new material group.
Why: • High temperature metals are losing strength rapidly beyond 800°C while O-CMC can work up to 1200°C without reduced strength; • Metal degrades in high-temp environments. They coke and deform which influences structural and process stability.
Advantages: • The specific tensile strength of O-CMC is higher than that of metal, especially at temperatures above 600°C, due to the much lower density of about 2,6 g/m²; • Utilization of lightweight parts due to thin-walled structures; • No negative chemical reactions due to chemical inertness of Aluminum oxide; • No shape distortions due to low thermal expansion coefficient; • Less energy consumption and faster process times due to less thermal mass and O-CMC isolation properties; • More stable processes due to less deterioration of parts (especially relevant with hole patterns of burners); • Much longer lifespans due to much less deterioration, thus fewer repair & replacement.
Challenges: • Re-design of parts from metal-centric to composite-friendly; • Attachment to the metallic system; • Higher initial cost due to raw material prices; • Convincing the customer to give it a try; • Educating the customer in handling of O-CMC parts.
In this talk it will be shown how O-CMC parts are deployed in different applications, like high temperature kiln engineering, burner parts, induction furnaces, and chemical engineering, to improve these processes, save costs and ultimately become more sustainable.
IC-1.F:L32 Advancements of High Temperature Coating for SiCf/SiC Composite
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.
IC-1.F:IL32b Current Activated Reactive Ultrafast Joining (CARUJ) of Ceramics
D. SINGH, Applied Materials Division, Argonne National Laboratory, Lemont, IL, USA
This talk will discuss a novel Current Activated Reactive Ultrafast Joining (CARUJ) approach that utilizes carbon-based materials to resistively heat materials to be joined in addition to any interface material. Heat is applied directly to the joint interface or around the joint zone. CARUJ has been demonstrated in rapid joining of a commercial sintered silicon carbide. To facilitate joining a reactive interfacial precursor was synthesized and applied at the to be joined surfaces. Joining was conducted in matter of minutes as compared to hours using conventional methods for similar material systems. Compressive shear strengths of the joints ranged between 25-40 MPa, with some samples exhibiting strengths as high as 100 MPa. Role of additions of refractory metals to the precursor material was investigated. CARUJ was also demonstrated using commercial reactive brazes as interlayers. We further demonstrated CARUJ in successfully in joining complex changed sub-assemblies such as tubes via contact and non-contact heating of the joint interface. Finally, attributes of CARUJ will be discussed that make it a versatile joining technique for field applications.
This work was supported by the U.S. Department of Energy’s (DOE) Solar Energy Technologies Office (SETO) Award Number 38485 at Argonne National Laboratory operated under Contract no. DE-AC02-06CH11357 by the UChicago Argonne, LLC.
IC-1.F:L33 Thermal Conductivity of Carbon Fiber-reinforced Copper Matrix Composites Fabricated by Powder Metallurgy
V. GAUTHIER-BRUNET, M. CHARTEAU, V. AUDURIER, A. JOULAIN, Institut PPRIME, Poitiers, FRANCE; J.-F. SILVAIN, ICMCB, Pessac, France
Nowadays, the microelectronics industry uses higher functioning frequencies in commercialized components resulting in high operating temperatures limiting the component’s lifetime. Until now, heat-sink materials were composed of thermally-conductive metals. However, these metals often induce large coefficient of thermal expansion (CTE) mismatches and cause thermomechanical stresses at the interface between the heat sink and the nonmetallic components. Such differences in CTEs result in the device failure after several cycles. Carbon fiber-reinforced copper matrix composites with optimal thermo-mechanical properties are materials of choice for replacing the current metallic heat sinks. This study deals with the synthesis of carbon fiber-reinforced copper matrix composites by hot pressing using a solid-liquid process to produce in-situ a ZrC interphase at the Cu/C interface to optimize the transfer of properties. The microstructure and chemistry of the matrix, and those of the interphase, were analysed by transmission and scanning electron microscopies coupled with energy dispersive X-ray spectroscopy. Finally, the thermal conductivity of the composites was determined at room temperature, both experimentally and theoretically, in relation with their microstructure.
IC-1.F:L34 Engineering Segregated 3D Networks of MgO and BN Fillers for High-Performance Thermal Interface Materials
HYUNAE CHA, Korea Institute of Materials Science, Changwon-si, South Korea
With the continuous miniaturization and high-power operation of electronic devices, thermal interface materials (TIMs) have become indispensable for efficient heat transfer between sources and sinks. Ceramic/polymer composites incorporating thermally conductive fillers are recognized as promising candidates, particularly when configured into segregated 3D networks rather than random dispersions. Recent strategies such as polymer templating, NaCl sacrificial scaffolds, and protein foaming have been employed to engineer continuous ceramic frameworks that facilitate rapid phonon transport. Notably, segregated 3D architectures of MgO and BN fillers have demonstrated outstanding enhancement in thermal conductivity while maintaining electrical insulation, far surpassing conventional composites. This study summarizes recent advances in the design, processing, and application of functional ceramics, emphasizing innovative pathways for next-generation thermal management solutions in electric vehicles, power electronics, and emerging high-performance systems.
Session IC-1.G Applications
IC-1.G:IL35 CMCs at GE Aerospace: Engines and Beyond
J. WEAVER, B. DIX, D. DUNN, GE Aerospace, Niskayuna, NY, USA
For over 3 decades, GE Aerospace has been heavily invested in the development and commercialization of CMCs for applications in turbine engines. While the best-known product is the melt infiltrated SiC/SiC in the CFM LEAP and GE9X engines, GE now commercially produces Ox/Ox, C/SiC, and SiC/SiC CMCs for a variety of applications in turbine engines and other aerospace applications. Learnings from past efforts and products will be discussed, along with potential future opportunities and their associated challenges.
IC-1.G:L36 Development of Oxide / Oxide Ceramic Matrix Composites (CMCs) for Exhaust Sections: From the Components Choice, Fabrication and Characterizations to the First Ground Tests
N. EBERLING-FUX, J.-C. MALENFANT, A. PLANCKEEL, P. DISS, E. LESIZZA, Safran Ceramics, Mérignac, France
The introduction of CMCs in the next aero engines represents now a reality for military and for civil applications. Thanks to low density and service temperature increase, the ceramised engine can decrease kerosene consumption and pollutant emissions. Oxide / oxide CMCs are a good opportunity for exhaust parts of aero engines, lighter than superalloy solutions, with a higher temperature capacity in comparison with titanium alloy solutions. Taking the maturity level key issues for oxide / oxide into consideration (cost closed to metallic technologies, needs of acoustic treatment, metal/CMC attachments technologies), Safran Ceramics has developed and characterized different manufacturing routes. This presentation will detail how different studied routes were selected from the selection of raw materials, semi products, to the manufacturing and thermomecanical characterizations of composite materials and sub-element part for first engine ground test.