Symposium CC
ABSTRACTS
Session CC-1 Interface science for integration of inorganic materials
CC-1:IL01 Adsorption, Anisotropy, and Equilibrium: Orientation Relationships at Metal-Ceramic Interfaces
W.D. KAPLAN, Department of Materials Science and Engineering, Technion - Israel Institute of Technology, Haifa, Israel
While the details of metastable orientation relationships of thin films on substrates depend on the kinetics of the specific deposition process, equilibrium (minimal energy) orientation relationships define the driving force for microstructural evolution during annealing of thin films. This study examines equilibrium orientation relationships of metals on sapphire and yttrium stabilized zirconia. Equilibrium conditions were reached by dewetting the thin films in the solid-state (annealing until the film ruptures and forms single crystal particles), and the influence of dopants and impurities on the equilibrium crystal shape of the metal, the low-energy orientation relationship of the metal with the substrate, and the interface energy, was assessed. This presentation will show that while specific low-index low-energy orientation relationships often exist, adsorption to the same metal-ceramic interfaces can result in a more isotropic distribution of orientation relationships at equilibrium in addition to a decreased interface energy and increased adhesion.
CC-1:IL02 Characterization of the Atomic-level Structure and Stability of Pt/Alumina Interfaces using a Combined Experimental and Computational Approach
M.K. SANTALA, Materials Science Program, Oregon State University, Corvallis, OR, USA
In this work, transmission electron microscopy (TEM) is used to guide and validate density functional theory (DFT) based models of Pt/alumina interfaces. Pt nanoparticles (NPs) are formed in dense alpha-, gamma- and theta-alumina by ion implantation of Pt into sapphire followed by thermal annealing. The NP orientation relationships and morphologies are determined by TEM and facets with the most prevalent interfacial relationships are selected for study with DFT modeling and atomic-resolution microscopy. Models of the Pt/alumina interfaces are developed with different alumina terminations (O, Al1, Al2), which are compared to atomic-resolution images of the interfaces. O-terminated interface models provide the best match to experiment for all three alumina polymorphs and is predicted to be the most stable for the processing conditions, based on thermodynamic calculations of the interfacial energies as a function of temperature and oxygen partial pressure. The Pt/gamma-alumina model does not capture the alumina structure as well the models with the other polymorphs. This is attributed to compromises in the gamma-alumina model made to limit the computational time required for the calculations, which were not required for alpha- or theta-alumina.
CC-1:IL03 Plasma Techniques in Surface Engineering: Boosting Adhesion in Ceramics and Ceramic Matrix Composites
V. CASALEGNO, M. SALVO, Politecnico di Torino, Department of Applied Science and Technology (DISAT) Torino, Italy
Ceramic Matrix Composites (CMCs, such as C/C, C/SiC, SiC/SiC) and monolithic ceramics (SiC, Si₃N₄) combine outstanding thermo-mechanical properties with low density, making them attractive for aerospace and energy applications. The full exploitation of CMCs in aerospace and energy systems requires effective joining technologies to assemble complex geometries and integrate ceramic parts with metals into hybrid structures. However, their low wettability and chemical inertness make reliable brazed joining particularly challenging. This work investigates advanced surface texturing and pre-treatment techniques—atmospheric-pressure plasma jet (APPJ), reactive ion etching (RIE), plasma etching, and thermal selective removal—to enhance surface reactivity and promote mechanical interlocking without impairing alloy wettability. Morphological characterization, mechanical testing, and post-mortem analyses were performed on reference and pre-treated samples. Results demonstrate significant improvements in adhesion and joint strength both in adhesively bonded and brazed specimens, confirming that surface texturing is a key enabler for robust, high-performance brazed and hybrid ceramic assemblies.
CC-1:IL04 In-operando Spectroscopy Methods to Study Gas Solid Interfaces in Ceramics
A. STAERZ, Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO, USA
High-temperature metal oxide electrochemical systems are used in a wide range of applications, including energy conversion (fuel and electrolysis cells) and gas sensing. In all of these systems, the metal oxide–gas interface is central to device functionality. We have developed a novel spectro-electrochemical setup to directly probe surface chemical species and the associated charge-transfer processes under reaction conditions. Our setup enables the measurement of infrared and UV–Vis spectroscopies simultaneously to impedance spectroscopy. This approach allows real-time monitoring of how electronic structure modifications influence adsorption and reaction intermediates. This presentation will cover results obtained from metal oxide gas sensors operated in harsh conditions, high temperature (>400 °C), low oxygen concentration and in the presence of extrinsic contaminants.
CC-1:IL05 Molten High-Entropy Alloys (HEAs) on Ceramic Substrates: From Thermodynamic Prediction to Interfacial Reactivity and Joining Performance
S. GAMBARO1, L. FENOCCHIO1, G. CACCIAMANI1,2, F. VALENZA1, 1National Research Council, Institute of Condensed Matter Chemistry and Technologies for Energy (CNR-ICMATE), Genova, Italy; 2University of Genova, Chemistry and Industrial Chemistry Department (UNIGE-DCCI), Genova, Italy
HEAs are attracting growing interest as innovative materials for high-temperature (HT) coatings, composites, and joining of ceramic substrates, owing to their compositional flexibility and tunable interfacial behavior. Understanding HEA–ceramic interactions are crucial to control wettability, reactivity, and bonding integrity, yet predictive tools remain limited. To address this challenge, a thermodynamic database was developed through collaboration between Genova University and ICMATE-group [1,2]. This CALPHAD-based framework enables accurate prediction of interfacial phenomena in complex HEA systems. AlCoCrFeNi-based alloys with refractory additions were synthesized and characterized, showing a very good experiments-calculations agreement. High-temperature wetting tests on carbon substrates confirmed stable spreading and carbide formation, while Si-containing alloys allowed effective joining of SiC ceramics, mitigating excessive substrate dissolution. This integrated experimental–computational approach demonstrates the capability of HEAs to serve as HT-coatings and brazing fillers for ceramic systems, paving the way toward the predictive design of next-generation materials for extreme environments.
[1] S. Gambaro et al. Calphad 85, 2024 [2] S. Gambaro et al. Surf. Interf 2024
Session CC-2 Innovations in joining methods and materials
CC-2:IL06 Glass and Ceramics for Hydrogen Technologies: Challenges and Solutions in Joining
F. SMEACETTO, Politecnico di Torino, Torino, Italy
Advanced glass and ceramic materials are crucial for achieving enhanced efficiency and durable electrochemical energy conversion systems, including reversible solid oxide cells, electrolysers, and proton-conducting membranes. These technologies enable the efficient and high-purity production of green hydrogen. As the EU targets 10 million tonnes of renewable hydrogen production by 2030, advanced electrolysis technologies are crucial for diversifying the technological landscape, reducing reliance on critical raw materials, and meeting decarbonization goals in hard-to-abate sectors. Current solutions and challenges related to the design, processing, and microstructure-property-performance relationships of different glass and ceramic-based systems, as well as solutions for joining similar and dissimilar materials, are presented.
CC-2:IL07 Laser Supported Joining of Silicon Carbide for Different Applications
M. HERRMANN, W. LIPPMANN, A. HURTADO, Dresden University of Technology, Institute of Process Engineering and Environmental Technology, Chair of Hydrogen and Nuclear Energy, Dresden, Germany
Silicon carbide and SiC fiber-reinforced silicon carbide play an important role in high-temperature applications in energy technology, particularly in nuclear energy technology. A large number of studies have been published on the joining of components made from this material. These studies deal with various joining technologies on the one hand and with the development of corresponding brazing filler materials on the other. The work at TU Dresden focuses on both areas of development. A process has been developed in which laser radiation is used as a heat source for joining SiC components. This technology enables local heating and brazing of components in an extremely short time. The technical requirements and the necessary material properties required for laser-based heating are presented. Examples of brazed joints are shown in which glass and glass-ceramic materials from the group of rare earth aluminum silicates and metallic brazing materials are used. The quality of the brazed joints is illustrated by means of microstructure examples, mechanical strength, tightness, and corrosion resistance. The presentation also shows the possibilities of laser technology for nuclear applications, in particular for sealing fuel element cladding tubes. A concluding evaluation summarizes the the potential of laser brazing technology for applications with other ceramics in the high-temperature energy sector.
CC-2:IL08 Ultrafast Joining of Ceramics via Flash Joining and UHJ Methods
CHUN LI, LONG ZHOU, BO YANG, XIAOQING SI, YAOTIAN YAN, JUNLEI QI, JIAN CAO, State Key Laboratory of Precision Welding & Joining of Materials and Structures, Harbin Institute of Technology, Harbin, PR China
The commonly used ceramic joining methods include brazing and diffusion bonding. However, the processing efficiency is limited by the long heating time and the high vacuum required to protect the filler from oxidation. Thus, novel ceramic joining methods need to be developed to improve the efficiency and flexibility of the process by reducing heating time and joining temperatures. In this study, two ceramic joining methods with high efficiency are proposed. The first one is flash joining, which could realise the joining of the ceramics in ~30 s by applying an electrical field to the ceramics being joined at a relatively low temperature. The ultra-fast joining of the YSZ, BSCF and SiC has been achieved. The evolution of the voltage, the current and the temperature at the interface during the flashing joining process is monitored, which is found to be similar to the flash sintering process. The second high-efficient ceramic joining method to be introduced is the ultrafast high-temperature joining (UHJ) method, which could also join the ceramics in a short time by heating the samples using carbon felt. The UHJ method is utilised to obtain the joining of SiC, Ti3SiC2 and high entropy ceramics. The microstructure and the mechanical properties of the joints are characterised.
CC-2:L09 The Industrial Practice of Joining Ceramics to Metals Using Ultra-active Brazing Filler Metals: Technical Solutions and Future Work
A.E. SHAPIRO, Titanium Brazing, Inc., Columbus, OH, USA
Both active and ultra-active brazing alloys are used for joining ceramics and carbon materials. Active brazing alloys (ABA) of the systems Ag-Cu-Ti or Cu-Sn-Ti containing <10% of Ti have been successfully used for last 70 years. However, they exhibit a low mechanical strength, corrosion- and irradiation resistances. Therefore, ultra-active brazing alloys (UABA) based on Ti- or Zr-alloys were designed and typically contain >40% of active components such as Ti, Zr, and Nb. Over the past 25 years, we have accumulated extensive experience in using ultra-active brazing alloys, which exhibit higher reliability in many applications, e.g, metal-ceramic multilayer joints of fuel cells or liquid metal batteries. This presentation addresses the following issues: (1) The difference between UABA and ABA , (2) Applications of UABA, (3) Interfacial reactions with ceramics and graphite, (4) Irradiation resistance of potential brazing alloys, (5) High-entropy compositions of UABA, (6) Suitable designs of brazed joints. Also, prospective future work will be discussed: application of UABA for brazing refractory ceramics, high-temperature mechanical testing of brazed joints including creep resistance, improving hot strength of brazed joints by the post-braze diffusion heat treatment.
CC-2:L10 Physico-chemical and Mechanical Characterizations of Brazed Interfaces Alumina or Zirconia / Gold / Titanium for Biomedicals Applications
A.L. CÉNAC LAHON DEBAT, C. LE FESSANT, J. CHEVALIER, L. GREMILLARD, P. STEYER, SCT Ceramics, Bazet, France; INSA Lyon, MATEIS UMR CNRS 5510, Villeurbanne, France
SCT manufactures brazed ceramic-metal assemblies for several industrial fields and for biomedical market (cardiac, cochlear or neurostimulation implants). Active implantable medical devices need biocompatible materials, hermetic and resistant assemblies. Alumina or zirconia are used for ceramics parts, titanium for metallic parts and gold as metal filler. A preliminary metallization of the ceramic is required to increase the wettability of gold. A deeper understanding of the physico-chemical mechanisms involved during brazing is crucial for design-based innovation in ceramics brazing. Hence, brazed interfaces of these two ceramics with gold and titanium were analyzed and mechanically tested. Physico-chemical characterizations were carried out using different microscopy technics to determine which phases were formed. The relationships between the formed phases and the mechanical properties (shear strength) of the brazed assemblies will be discussed.
CC-2:IL11 Innovations in Ceramic Joining
M. FERRARIS, Politecnico di Torino, Torino, Italy
Ceramics and ceramic matrix composites (CMC) have significant potential for industrial and energy applications. However, their reliable and energy-efficient joining methods remain a critical challenge. This talk explores several strategies for joining ceramics and CMC using glasses, brazing alloys and polymer-derived ceramics. Innovation in processing and characterization of CMC-based joined components developed at GLANCE-Glasses, Ceramics and Composites research group at Politecnico di Torino, Italy, will be presented and discussed. The combination of advanced design of interfaces and joining materials/technologies, selective matrix removal from the composite surface, laser structuring and mechanical machining of the composite/metal surfaces will be discussed and compared to existing solutions. The work done with the aim of developing reliable and user-friendly international standard test to measure the shear strength of joined components will also be reviewed. Finally, J-TECH@PoliTO (https://www.j-tech.polito.it/) , Advanced Joining Technology research center at Politecnico di Torino, will be described together with collaboration actions and opportunities for common research activity on joining.
CC-2:L13 Mixed Rigid/Compliant Glass Seal for Electrochemical Cell
F.O. MEAR, R. VOIVENEL, Univ. Lille, CNRS, Centrale Lille, Univ. Artois, UMR 8181 – UCCS – Unité de Catalyse et Chimie du Solide, France; R. PODOR, ICSM, Univ Montpellier, CNRS, ENSCM, CEA, Marcoule, France
Sealing is an ongoing concern for the development of pSOFC and pSOEC systems, mainly because gas tightness largely drives performance and is a critical key to develop these technologies. The main difficulties are due to the fact that gas tightness must be achieved at high temperature ( 800°C). Among the different technologies, we find glass seals: rigid (Tsoft > TpSOC) and compliant (Tsoft < TpSOC). Rigid glass seals have good durability and resistance to crystallization, and therefore good stability at high temperatures. However, it’s required high forming temperatures. In contrast, compliant glass seals, which are generally less stable with respect to thermal and chemical aging, have the advantage of being able to be formed at a temperature lower than the stack's operating temperature (800°C). To tackle this question, we report on self-healing hybrid glassy seals, which represent an interesting alternative to compliant or rigid seals. In this lecture, we present our work on mixed rigid and compliant glass seal, particularly with the influence of the compliant glass content in the rigid matrix on the physicochemical properties, forming, resistance to crystallization and the ability of the seal to self-repair at 800°C.
CC-2:L15 Joining SiC to the TZM Alloy by Hot Pressing (HP)
B. CONTRI, S. VALETTE, P. LEFORT, IRCER (European Ceramics Center), UMR CNRS 7315, University of Limoges, Limoges, France
Joining ceramics to metals requires au proximity of the CTEs of the materials. Previous attempts for bonding SiC (RBSC) to TZM have not yielded good results CTEs being not very close (4.5x10-6 K-1 and 5.3x10-6 K-1 respectively), and we revived this study using the HP which often produced strong bonding. The influence of temperature between 1300 and 1700 °C under 60 MPa for 1 h showed that the assemblies occurred from 1600 °C but were brittle. Liquid MoSi₂ & Mo₅Si₃ formed at the interface and solidified when cooling. They resulted from the reaction of the alloy with liquid silicon (10 wt.% present inside the industrial RBSC). These silicides were unable to withstand the thermomechanical stresses during cooling and cracked. Above 1675 °C, the strength of the assembly was sufficient to keep the materials more firmly bonded after HP. The interphase was still composed of MoSi₂ and Mo₅Si₃, but significant cracks remained, even deep into the ceramic, making the joint still relatively brittle. By optimising the thermal/pressure cycle and duration, a continuous interface was achieved between the TZM alloy, Mo5Si3, MoSi2, and SiC ceramic, with fewer cracks within the interphase and much higher bonding strength, which is an encouraging result.
CC-2:IL16 Mechanical Characterisation of Joined Ceramics and Composites
S. DE LA PIERRE, A. BENELLI, M. FERRARIS, Politecnico di Torino, Torino, Italy
The mechanical characterisation of joined ceramics and composites is crucial for assessing their structural reliability in extreme environments. This study summarises testing methods applied to both similar (ceramic–ceramic) and dissimilar (ceramic–metal) joints produced through different joining technologies. Shear, flexural, torsion and indentation tests were used to evaluate joint strength, adhesion, and failure mechanisms, supported by X-ray computed tomography, SEM and Impulse Excitation Technique analyses. The comparison of results reveals the strong influence of joint geometry, filler composition, manufacturing process and residual stresses on mechanical behaviour. Due to the current lack of standardised testing procedures, a wide variety of methods is employed, often leading to non-comparable results. Establishing a unified testing methodology—particularly for the determination of joint shear strength—would enable reliable data generation for design and qualification of structural ceramic and composite components in high-temperature and harsh operating conditions.
CC-2:L17 Hot Explosive Welding of Non-oxide Ceramics to Metals using a Metal Powder Bed
RYUICHI TOMOSHIGE, SHIHO SATONAKA, Sojo University, Kumamoto, Japan
Ultra-high pressure and temperature environments often attract special attention because they can generate new compounds. The key point of our hot explosive weiding recently developed is the use of a chemical synthesis method called combustion synthesis. This synthesis method involves both highly exothermic reactions at temperatures reaching several thousand degrees Celsius, enabling the synthesis of various ceramics and intermetallic compounds. The novel process is achieved by simultaneously applying the high-temperature generated by this chemical reaction and the pressure of tens of GPa generated by the explosion. In this presentation, the results of fabricating a three-layer laminated material of TiN+TiB2/TiNi/Cu or Fe using this method will be reported. In the chemical reaction region in ouroriginal apparatus, a raw material powder mixture is placed on a Cu or Fe powder bed, and a two-layer structure consisting of TiN+TiB2 and TiNi is formed from the powder mixtures. Explosive welding was performed immediately on this composite material, which was maintained at a high temperature, using several types of explosives. As a result, we successfully achieved the bonding of ceramics and metal by using TiNi, an intermediate layer exhibiting a pseudoelastic effect.
CC-2:L18 Seamless Architecture: Design and Development of Functionally Graded Sustainable Materials for Building Construction
SHADI NAZARIAN, The University of Texas at Arlington, Arlington, TX, USA
Conventional buildings contribute nearly 40% of global CO₂ emissions, encompassing material production, construction, and operation. Despite advanced mechanical joints and chemical bonds, substantial heat loss persists through inefficient interfaces that fail to ensure impermeability. This research rethinks how materials are produced and integrated, demonstrating a seamless, impermeable transition between ceramized geopolymer (GP) concrete—engineered for structural performance—and transparent soda-lime glass. The GP matrix was tailored to match the glass’s coefficient of thermal expansion, enabling optimal fusion at the interface. GP, a sustainable alternative to portland cement, offers reduced embodied and operational energy while addressing critical environmental challenges. Our study investigates functionally graded materials (FGMs), focusing on sintering behavior, compositional tuning of GP–glass systems, and exposure effects. These findings guided the fabrication of graded composites, including a 400 mm column composed of 21 binary GP–glass layers. FGMs present transformative potential for construction technology on Earth and in extraterrestrial environments, minimizing vulnerable joints and advancing impermeable, energy-efficient building systems.
CC-2:L19 Superconducting Joints of MgB2 Composite Wires Made by Three Different Processes
P. KOVAC, I. HUSEK, T. MELISEK, D. BEREK, L. KOPERA, Institute of Electrical Engineering of Slovak Academy of Sciences, Department of Superconductors, Bratislava, Slovakia
Superconducting joints between MgB2 wires manufactured by internal Mg diffusion (IMD) process and by powder-in tube (PIT) in-situ and ex-situ techniques have been made by using of scarf joints architecture. Internal structure of these joints were analysed mostly bby an optical microscope and X-ray micro-tomography. It was found that the morphology and amount of powder added between the joined wires and also the applied pressing deformation affect the superconducting currents between the joined ends considerably. Joint’s transport currents were measured and compared with the currents of used MgB2 wires. The best current carrying capacity of joints of 72.3 % of critical current of single-core MgB2 wire and 57.3 % of six-core wire were measured. Presented results show simple joint technique allowing sufficiently high transport currents at low external magnetic field (~ 1 T), which can be used for MgB2 coils in persistent mode.
Session CC-3 Engineering applications
CC-3:IL20 YAS Crystallizing Glasses with Adaptable Properties for Joining Oxid and Non-Oxide Ceramics
J. MAIER, C. ECKARDT, A. KONSCHAK, J. SCHMIDT, Fraunhofer ISC, Center for High Temperature Materials and Design HTL, Bayreuth, Germany
Crystallizing glasses are promising materials for joining oxide and non-oxide ceramic matrix composites (CMC). These joining materials have relatively low firing temperatures, show good mechanical properties and there are simple methods for their application. A particularly interesting class are crystallizing glasses based on Y2O3-Al2O3-SiO2 (YAS). For a successful and long-lasting bonding, the properties of the joining material must be specifically tailored to meet the requirements of the CMC counterparts. One critical aspect for high temperature applications is that their coefficient of thermal expansion (CTE) must match that of the materials being joined. This presentation will introduce a new type of YAS glass-ceramic that can be utilized for both oxide and non-oxide CMCs without the need of modifying the composition, simply by tuning the thermal processes. The mechanical properties, phase composition, and microstructure of the joining material will be presented show-casing selected examples of joined CMCs.
CC-3:IL21 Innovative CMCs for the Manufacturing of Complex Parts of Thermal Protection Systems
M. VALLI, L. CAVALLI, L. DELLEDONNE, F. GIACOMETTI, Y. AKRAM, M. BOIOCCHI, M. CANTÙ, C. GIGANTE, G. PULCINI, M. ARNOLDI, A. BEDUINI, Petroceramics SPA, Stezzano, Italy
Ceramic matrix composites blend together peculiar properties – namely lightness, high thermal stability, resistance to thermal shocks, and stability in harsh environments – which are demanded for several aerospace applications. Cf-CMCs processed by means of Liquid Silicon Infiltration (LSI) can combine compliance with such requirements, with cost-effectiveness and processing ease. Among the materials developed by Petroceramics, ISiComp® and OxyComp® are two Cf-CMCs produced through LSI, which are suitable for the production of very large parts with complex shapes, thanks to an ad-hoc manufacturing technique. All processing phases – from lamination of the phenolic pre-preg to pyrolysis and LSI - have been designed in order to optimize dimensional stability and to enhance joining of the elements forming the large parts. ISiComp® has been selected to produce all the CMC components of the Thermal Protection System (TPS) and the control surfaces of the next reusable re-entry vehicle of the European Space Agency, named Space Rider. OxyComp®, with a high SiC content, is suitable for prolonged exposure to high temperatures in oxidizing atmospheres. This material is currently being used for the production of nozzle extensions and TPS for combustion environments.
CC-3:L22 High-temperature Joining Solutions for SiC/SiC Composites in Thermal Energy Storage
C. MALINVERNI1, V. CASALEGNO1, C. PRENTICE2, M. SALVO1, 1Department of Applied Science and Technology, Politecnico di Torino, Torino, Italy; 2Archer Technicoat Ltd, ATL, Unit E, High Wycombe, Bucks, UK
Ceramic matrix composites are advanced materials recognized for their outstanding resistance to oxidation at high temperatures. Among these, SiC/SiC composites exhibit excellent high-temperature performance, particularly in terms of thermo-mechanical properties, corrosion resistance, and low density. This work focuses on developing a reliable joining technique to enable the integration of SiC/SiC composites and their joints within thermal energy storage systems. The primary objective is to support the application of these composites as containers for high-temperature metallic phase change materials (mPCMs) and to study their performance while in direct contact with mPCMs, such as AlSi12 alloy and silicon. Specific criteria, including compatibility in thermal expansion coefficients, adequate wettability, and chemical stability with the selected mPCMs guided the selection of joining materials. Based on these factors, a SiC-based adhesive and a glass-ceramic system were chosen. The resulting samples and joints were examined through scanning electron microscopy and subjected to mechanical evaluation using single-lap offset shear tests. Furthermore, wetting behavior was assessed through dedicated tests on the SiC/SiC composites and joints in the presence of the molten mPCMs.
CC-3:L23 2D Modular Ceramic Joint Interlocking: A Pathway to Flexible, Thermoshock-resistant Assemblies
P. HOFFMANN, L. WAHL, T. FEY, Department of Glass and Ceramics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
Architectural interlocking materials offer superior adaptability compared to their monolithic counterparts, particularly under demanding conditions. Unlike traditional Topological Interlocking Materials (TIMs), which rely entirely on external peripheral forces for stability, this work presents an advanced two-dimensional modular system combining bidirectional Ceramic Joint Interlocking (CJI) with inherent structural integrity. To meet the requirements of high-temperature assemblies, our 2D-CJI approach achieves stability through integrated, self-supporting joints without external constraints or bonding phase. Using manual ceramic injection molding, 2D ceramic assemblies consisting of 25 detachable and individually replaceable building blocks were fabricated. Deflection analysis via laser scanning microscopy demonstrates superior reversible flexibility dependent on joint geometry while maintaining structural integrity. Indentation, impact, and thermal-shock tests confirm the localized failure behavior which prevents catastrophic fracture propagation due to the segmented modular design. This modular 2D-CJI system opens new possibilities for high-performance applications that require both structural integrity, flexibility and high-temperature resistance.
CC-3:IL24 Vacuum Brazing of Lightweight Titanium Drill Bits to Cemented Carbides WC6Co Inserts
A.E. SHAPIRO, Titanium Brazing, Inc., Columbus, OH, USA
Lightweight drill bits are critically needed for space applications and in high-speed rotation drilling equipment. Brazed joints of cemented carbide WC-6Co with CP titanium and Ti6Al4V alloy were tested to select the most effective filler metals for manufacturing lightweight cutting tools. Two filler metals were used BTi5 (Ti20Zr20Cu20Ni wt.%) and TiBraze900V (Cu18Ti20Sn2V wt.%) to braze in vacuum at 920°C, followed by diffusion treatment at 850°C. Brazed joints of Ti made by TiBraze900V filler exhibited low shear strength 70-112 MPa, while joints of Ti6Al4V alloy showed higher strength 166-216 MPa. Brazed joints made by BTi5 are stronger: 109-241 MPa for Ti and 226-307 MPa for Ti6Al4V alloy. Niobium powder was added to filler metals to reinforce the joint metal and improve the strength. The resulting braze alloy TiBraze200Nb containing Ti-17Zr-17Cu-17Ni-17Nb wt.% is a high-entropy alloy. It was effective for joints of Titanium and carbides: the shear strength reached 346 MPa, while the strength of Ti-6Al-4V alloy joints went down to 190-213 MPa. Appropriate microstructures of brazed joints are reported to explain variations in mechanical properties. Mockups of titanium drills also were tested. Aluminum, titanium, or stainless steel can be drilled with titanium drill bits.
CC-3:IL25 CMCs for Aerospace Applications: An Insight on Microstructures and Properties in Use
M. VALLI, L. CAVALLI, L. DELLEDONNE, F. GIACOMETTI, Y. AKRAM, M. BOIOCCHI, M. CANTÙ, C. GIGANTE, G. PULCINI, M. ARNOLDI, A. BEDUINI, Petroceramics SPA, Stezzano, Italy
Among the solution that Petroceramics has developed for high temperatures, ISiComp® and OxyComp® are Cf-CMCs which are densified through Liquid Silicon Infiltration and can satisfy many requirements demanded for aerospace applications - including lightness, high thermal stability, resistance to high thermal shocks, stability in oxidizing atmospheres and combustion environments. Despite the similarity in processing phases, the two materials exhibit distinct properties. The good control on the evolution of the fiber-matrix interface throughout the manufacturing process lies behind the tailored microstructures of ISiComp® and Oxycomp®, which define their distinct properties in terms of thermo-mechanical behavior in use. Tests at high and ultra-high temperatures in different environments (including O2, H2O, CO or CO2 rich atmospheres) have revealed both the strengths and limitations of these materials, confirming their highly promising performance for the production of fully reusable TPS components. With its higher SiC content, OxyComp® is particularly well-suited for the production of parts intended to withstand prolonged exposure at high temperatures in oxidizing atmospheres. This material was selected to manufacture mufflers, nozzle extensions, TPS for combustion environments.
CC-3:IL26 Recent Advances in Joining Ceramics and CMCs to Metals at TWI
K. AMIN, N. LUDFORD, TWI, Cambridge, UK
Joining ceramics and CMCs to metals presents significant challenges due to mismatches in thermal expansion, material properties, and inherent ceramic defects which are commonly present. This presentation will showcase recent research conducted by TWI on ceramic matrix composites (CMCs), focusing on how variations in surface roughness and density influence joint formation and integrity. It will also highlight innovative strategies developed to mitigate thermal residual stresses arising from differences in coefficients of thermal expansion (CTE) between ceramics and metals. Additionally, the talk will address reliability concerns encountered when joining where sub-surface ceramic defects adversely affected joint performance and test outcomes.