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This work focuses on the joining processes of oxide-based ceramic matrix composites (Al2O3f /Al2O3-ZrO2), which are used as radiant tube furnace components in the steel industry. These components have to operate in harsh environments, and under high temperatures, and they therefore have to resist corrosion, humidity, and combustion. Two glass-ceramics systems, which have Y2Ti2O7 as their main crystalline phase, as well as specific and optimized properties to withstand severe operating conditions, including temperatures of 900 °C, are here proposed as joining materials. The adhesion of the glass-ceramics to the composite was found to be excellent after mechanical and thermal tests in which they were in direct contact with a 900 °C flame and thermal cycling of between 400 °C and 900 °C.

The surface texturing of ceramics is generally performed through acid-based etching and machining; however, laser texturing may be considered as a more precise, reproducible and eco-friendly process. Furthermore, laser ablation may be used to produce complex patterns on ceramic surfaces, thus offering new surface engineering opportunities. The studies so far conducted on this topic have mainly been application-driven, and since a wide variety of lasers have been used for surface texturing, it is difficult to have a comprehensive understanding of this technique applied to ceramics and ceramic composite materials. Laser texturing requires a great deal of knowledge of the material and the laser source parameters to optimise the process in order to obtain the expected results. It is therefore important to expand the research on the laser texturing of ceramics and CMCs in order to build a relevant amount of literature that can be used to identify the most appropriate parameters for each application. This review provides an overview of most of the technological aspects considered relevant for the laser surface texturing of ceramics and CMCs, and includes the fundamentals of laser-material interactions and a summary of the used equipment and parameters. Furthermore, most of the techniques related to the modifications of surface material induced by a laser are critically reviewed, and the new horizons that are opening up, in the context of the modification of surfaces to improve the performances of materials for several applications, are discussed.

A key aspect of ceramic matrix composites integration is related to a reliable joining technique. An ytterbium disilicate based glass-ceramic material is processed by reactive viscous flow sintering between a barium aluminium borosilicate glass and ytterbium oxide and it is used to join SiC/SiC and C/SiC composites. The joining temperature and the in situ formation of the Yb2Si2O7 is optimised at 1200°C without pressure, on the basis of the sintering and crystallisation mechanisms. The mechanical characterization of SiC/SiC and C/SiC joined with the ytterbium disilicate-based glass-ceramic, tested by single-lap offset at RT, exhibits an apparent shear strength of 35 MPa, similar to their interlaminar shear strength. The proposed system displays self-healing behaviour at 1000 °C and 1150 °C, as demonstrated by the partial and complete sealing of induced cracks by Vickers indentation on its surface at different loads, thus suggesting that it can effectively be used as promising joining material for CMCs.

This work has focused on surface engineering coupled with brazing to join SiCf/SiC composites and to improve the joint strength. The surface engineering was carried out through the Selective Thermal Removal (STR) of SiC fibres from a SiCf/SiC composite to obtain “brush-like” surfaces; the modified composites were then joined by means of an AgCuTi braze alloy. In order to investigate whether a “brush-like” interface could enhance the mechanical strength of the joint by increasing mechanical interlocking with the brazing alloy at the micron scale, the joints were tested with and without surface engineering by means of single lap offset under compression. The treatment to form a roughened surface suitable for mechanical keying of the braze metal led to an improved ductility of the joint; the fracture surfaces demonstrated that the proposed method is promising, even though the treatment damages locally the composite.

Concentrated solar power (CSP) is an important option as a competitive, secure, and sustainable energy system. At the moment, cost-effective solutions are required for a wider-scale deployment of the CSP technology: in particular, the industrial exploitation of CSP has been so far hindered by limitations in the materials used for the central receiver—a key component in the system. In this context, the H2020 NEXTOWER project is focused on next-generation CSP technologies, particularly on advanced materials for high temperatures (e.g., &gt, 900 °C) and extreme applications environments (e.g., corrosive). The research activity described in this paper is focused on two industrial solutions for new SiC ceramic receivers for high thermal gradient continued operations: porous SiC and silicon-infiltrated silicon carbide ceramics (SiSiC). The new receivers should be mechanically tough and highly thermally conductive. This paper presents the activity related to the manufacturing of these components, their joining, and characterization.

Two pressureless and reliable procedures for brazing SiC-based materials have been designed. The joining was obtained by the in-situ formation of a Ti3Si(Al)C2 MAX phase using simple Al-Ti interlayers. Wettability studies were conducted using several Al-Ti alloys in contact with SiC at 1500 °C. The interfacial microstructures and thermodynamic analysis demonstrated that liquid Al3Ti in contact with SiC formed a well-bonded Ti3Si(Al)C2 interfacial layer. These findings guided the design of two joining methods: one consisted of the simple infiltration of Al3Ti into the brazing seam, while an Al3Ti paste/Ti/Al3Ti paste interlayer assembly was designed for the second process. Sound interfaces without cracks were obtained in both processes. The average shear strength was very high, 296 MPa, for the infiltration method; the drawback was the presence of residual Al. Joining through Al3Ti/Ti/Al3Ti interlayers avoided the presence of low-temperature melting phases, with lower shear strength: 85 or 89 MPa depending on the testing method.

IR pulsed laser radiation in air was applied to Si3N4 and Invar to obtain reliable Si3N4/Si3N4 and Si3N4/Invar adhesive bonded components. The laser pre-treatment produced a homogeneous nanostructured oxide layer on the surfaces, which effectively increased the adhesion at the adhesive/adherends interface and led to cohesive failure in the joining material. The mechanical strength of Si3N4/ Si3N4 and Si3N4/Invar joined components was measured, with and without laser nanostructuring, before and after thermal cycling from room temperature to 50 K, and it resulted that the exposure to extremely low temperatures did not affect the mechanical integrity of the joints. It was also demonstrated that this laser pre-treatment did not alter the mechanical properties of the ceramic substrate.

SiC foams sandwiched between two Ceramic Matrix Composite (CMC) skins are of interest for several high temperature applications ranging from aeronautics to energy production. In this paper, SiC foams were joined to C/SiC composites by the “Mo-wrap” method to obtain sandwich structures. The Mo-wrap method is a recently developed joining technique: it consists of wrapping Si foils inside a Mo wrap in order to prevent molten silicon leaking from the joined area and infiltrating SiC foam and C/SiC during the joining process. Compression and thermal shock resistance tests were performed on the C/SiC – SiC foam – C/SiC sandwich obtaining sound results.

The aim of this work was to investigate and discuss the microstructure and interface reaction of a calcia-alumina based glass-ceramic (CA) with SiC. CA has been used for several years as a glass-ceramic for pressure-less joining of SiC based components. In the present work, the crystalline phases in the CA glass-ceramic and at the CA/SiC interface were investigated and the absence of any detectable amorphous phase was assessed. In order to provide a better understanding of the effect of irradiation on the joining material and on the joints, Si ion irradiation was performed both on bulk CA and CA joined SiC. CA glass-ceramic and CA joined SiC were both irradiated with 5.1 MeV Si2+ ions to 3.3 × 1020 ions/m2 at temperatures of 400 and 800 °C at DuET facility, Kyoto University. This corresponds to a damage level of 5 dpa for SiC averaged over the damage range. This paper presents the results of a microstructural analysis of the irradiated samples as well as an evaluation of the dimensional stability of the CA glass-ceramic and its irradiation temperature and/or damage dependence.

The joining of hypereutectic Al-Si alloy heat pipes to CRFP skins has been studied for radiator panel applications. Three different epoxy adhesives (two thermal conductive adhesives and one high-strength structural one) were used and mechanically characterised before and after thermal cycling. Two adhesives gave the most promising results, in terms of mechanical strength (apparent shear ~ 25 MPa for 100 µm thick lap joints). Thermal cycling (10 cycles between −30°C and +90 °C) did not significantly affect the mechanical properties of the joints or the failure propagation mode. The use of the thermal conductive adhesive could also guarantee good thermal conductivity of the designed panel.

Alumina (Nextel™ 610) fibre reinforced YAG-ZrO2 matrix composites were successfully joined by using different brazing alloys, metallic interlayers and a glass-ceramic. All joints were mechanically stable and free of cracks. Three commercial brazing alloys and a new alloy based on Ti/Cu/Al interlayers were selected to join these composites for applications in a non-oxidizing environment. A glass-ceramic based on SiO2-Al2O3-CaO-MgO was developed in case the joined component needs to be oxidation resistant. To evaluate the thermal stability, all joined composites were aged up to 100 h in air at 550 °C for brazing joints or 850 °C and 930 °C for glass-ceramic joints. The mechanical strength was measured using single lap and four point bending tests before and after ageing. Four point bending tests on glass-ceramic joined samples showed an average joint strength of about 70 MPa which is 35% of as-received composites.

Flash joining of CVD-SiC coated Cf/SiC samples with a Ti interlayer was achieved using a Spark Plasma Sintering machine. The influence of different heating powers and discharge times were investigated. The sample flash joined at a maximum heating power of 2.2 kW (peak electric current of 370 A) within 7 s showed the highest apparent shear strength of 31.4 MPa, which corresponds to the interlaminar shear strength of the composites. A maximum joining temperature of ∼1237 °C was reached during the flash joining. An extremely rapid heating rate of 9600 °C/min combined with a very short processing time hindered any reaction between the CVD-SiC coating and the Ti interlayer. The formation of a metallic joint (Ti based) in the absence of any detectable reaction phase is proposed as a new joining mechanism. For a conventionally joined SPS sample, the formation of titanium silicide phases inhibited the formation of a bond.

This study focuses on the design, characterization and testing of a new glass-ceramic sealant for Na-based batteries. The thermo-mechanical properties as well as the sintering behaviour of the new sealant have been characterized by thermal analyses and x-rays diffraction studies. The exothermic peak in the differential thermal analysis plots has been assigned to the crystallization of a calcium sodium aluminum silicate (anorthite sodian), as confirmed by the X-ray diffraction data. The activation energy for the crystallization was found to be 482.3 kJ/mol. The compatibility at the interface between the glass-ceramic sealant and beta- and alpha-alumina is examined before and after corrosion test with molten Na. Tests of this novel silica-based glass-ceramic sealant with Na at 300 °C for 250 h in a real battery operating conditions showed no reactions with Na or evidence of corrosion, as demonstrated by SEM post mortem examinations after cell disassembly.

We explore joining Si-Al-C-O fiber-bonded ceramics to Cu-clad-Mo using an Ag-Ti-Cu brazing alloy. A temperature of 900 °C and times in the range of 10–20 min are required to obtain sound joints irrespectively of the fiber orientation. The reaction layer is 1–2 μm thick and free of pores and defects. The thermal conductivity of the joined samples is well described considering that the metal and the ceramic are in series for thermal resistance. This implies that the joint is highly conductive and forms an almost perfect thermal interface between the two materials, confirming the quality of the obtained brazing layer. Ministerio de Economía y Competitividad MAT2016-76526-R

The Micro-Electrical Discharge Machining (Micro-EDM) technique has been employed to machine micro-patterns with shaped micro-slots on Ti6Al4V surfaces. Ti6Al4V substrates, with and without micro-slots, were bonded using a commercial epoxy adhesive. Optical microscopy and SEM were used to observe the micro-patterned Ti6Al4V surfaces before and after joining and to analyse the fracture surfaces after mechanical tests. The joints were mechanically characterised, with and without micro-patterns, by means of Single Lap Offset (SLO) shear tests under compression to understand the effect of differently shaped micro-slots. The effects of the shape of the micro-slots, their interlocking or overlapping, and their orientation, with respect to the applied load, are presented and discussed in terms of mechanical performance of the joints.

The effect of a pulsed laser irradiation (Nd:YVO4, 1064 nm) in air on the surface morphology and chemical composition of silicon carbide and on the adhesion with an epoxy adhesive was investigated. Scanning and transmission electron microscopies, atomic force microscopy, and X-ray photoelectron spectroscopy revealed that the laser treatment reduced the contamination level of the surface and induced the formation of a silica-based nanostructured columnar layer on the SiC surface. The mechanism for the formation of five different microstructural regions is described in this paper. In addition, the formation of a 5-10-nm-thick graphite layer between the oxide layer and SiC was observed. The joining test with Hysol® EA9321 showed that the nanostructured columnar silica layer was completely infiltrated by the adhesive, thus leading to a significant increase in the joined specific area and a mechanical interlocking at the adhesive/substrate interface. Nevertheless, the apparent shear strength of the joined SiC samples slightly decreased after the laser processing of the surfaces from about 42 MPa for lapped SiC to about 35 MPa for laser-nanostructured SiC. The formation of the graphite layer was found to be responsible of the poor adhesion properties of the SiC surfaces modified by the laser radiation.

The design of interfaces, coupled with suitable joining materials and joining technologies, is a key parameter in component manufacturing and surface pre-treatments are crucial steps for the production of robust and reliable bonds. In this work, plasma pre-treatments on SiC and Si3N4 are studied and discussed. The pre-treated joined samples have shown a higher mechanical strength than the reference value (lapped surfaces) and the increased adhesion at the ceramic/adhesive interface has led to cohesive failure of the adhesive.

Efficient joining materials and techniques are of critical importance for the integration of CMCs in high performance structures. Continuous oxide fiber Nextel™ 610/alumina-zirconia composites were successfully joined to themselves by using a novel glass-ceramic based on the SiO2-CaO-Al2O3-MgO-Y2O3-ZrO2 system.Crystallization kinetic of the novel glass-ceramic was studied using Matusita, Sakka and Ozawa equations. Single lap off-set shear tests and four-point bending tests were performed at room temperature and at 850 °C to investigate the mechanical strength of the joints. Thermal ageing was performed at 850 °C for 100 h in air to check the thermal stability of the joined components. The results showed that the joints were oxidation resistant and the joined interfaces were well bonded. Single lap off-set shear tests on joined samples resulted in delamination of the composites. The average flexural strengths of the joined samples were 71 MPa and 81 MPa, at room temperature and at 850 °C, respectively.

Alumina dispersion-strengthened copper, Glidcop, is used widely in high-heat-load ultra-high-vacuum components for synchrotron light sources (absorbers), accelerator components (beam intercepting devices), and in nuclear power plants. Glidcop has similar thermal and electrical properties to oxygen free electrical (OFE) copper, but has superior mechanical properties, thus making it a feasible structural material, its yield and ultimate tensile strength are equivalent to those of mild-carbon steel. The purpose of this work has been to develop a brazing technique to join Glidcop to Mo, using a commercial Cu-based alloy. The effects of the excessive diffusion of the braze along the grain boundaries on the interfacial chemistry and joint microstructure, as well as on the mechanical performance of the brazed joints, has been investigated. In order to prevent the diffusion of the braze into the Glidcop alloy, a copper barrier layer has been deposited on Glidcop by means of RF-sputtering.

The thermal performance of a carbon fibre composite-copper monoblock, a sub-component of a fusion reactor divertor, was investigated by finite element analysis. High-accuracy simulations were created using an emerging technique, image-based finite element modelling, which converts X-ray tomography data into micro-structurally faithful models, capturing details such as manufacturing defects. For validation, a case study was performed where the thermal analysis by laser flash of a carbon fibre composite-copper disc was simulated such that computational and experimental results could be compared directly. Results showed that a high resolution image-based simulation (102 million elements of 32 μm width) provided increased accuracy over a low resolution image-based simulation (0.6 million elements of 194 μm width) and idealised computer aided design simulations. Using this technique to analyse a monoblock mock-up, it was possible to detect and quantify the effects of debonding regions at the carbon fibre composite-copper interface likely to impact both component performance and expected lifetime. These features would not have been accounted for in idealised computer aided design simulations.

Microwave has been applied to ignite the Self-propagating High-temperature Synthesis (SHS) of compacted Ni-Al mixtures, having 1:1 atomic ratio, in order to join Chemical Vapor Deposition (CVD) SiC ceramics and SiC/SiC composites. The average joint thickness of CVD SiC joint is about 200 μm and the Coefficient of Thermal Expansion (CTE) mismatch between CVD SiC and Ni-Al intermetallic compounds results in a interface bond strength inferior to that of the substrate and joining material; on the other hand, for the SiC/SiC composite joints, as a result of the porosity of SiC/SiC composites, the SHS products readily infiltrated into the pore spaces of the composite, leading to an increased porosity of the joint area and a better lower interface than the upper one. The mechanical strength of the joints has been evaluated by Single-Lap (SL) shear test at room temperature; neither of the ceramic joints nor the composites joint gave satisfactory results, but the ceramic joints reaching a maximum shear strength value of 56MPa exhibited a positive aspect for further experiments.

This work investigates the thermal performance of four novel CFC–Cu joining techniques. Two involve direct casting and brazing of Cu onto a chromium modified CFC surface, the other two pre-coat a brazing alloy with chromium using galvanisation and sputtering processes. The chromium carbide layer at the interface has been shown to improve adhesion. Thermal conductivity across the join interface was measured by laser flash analysis. X-ray tomography was performed to investigate micro-structures that might influence the thermal behaviour. It was found that thermal conductivity varied by up to 72%. Quantification of the X-ray tomography data showed that the dominant feature in reducing thermal conductivity was the lateral spread of voids at the interface. Correlations were made to estimate the extent of this effect.

Despite increasing interest in the use of natural biomolecules for different applications, few attempts of coupling them to inorganic biomaterials are reported in literature. Functionalization of metal implants with natural biomolecules could allow a local action, overcoming the issue of low bioavailability through systemic administration. In the present work, gallic acid was grafted to a pre-treated Ti6Al4V in order to improve its biological response in bone contact applications. The grafting procedure was optimized by choosing the concentration of gallic acid (1 mg/mL) and the solvent of the solution, which was used as a source for functionalization, in order to maximize the amount of the grafted molecule on the titanium substrate. The functionalized surfaces were characterized. The results showed that functionalization with Simulated Body Fluid (SBF) as solvent medium was the most effective in terms of the amount and activity of the grafted biomolecule. A key role of calcium ions in the grafting mechanism is suggested, involving the formation of coordination compounds formed by way of gallic acid carboxylate and Ti&ndash, O&minus, as oxygenated donor groups. Bioactive behavior and surface charge of the pre-treated Ti6Al4V surface were conserved after functionalization. The functionalized surface exposed a greater amount of OH groups and showed higher wettability.

A novel method based on the modification of a commercial brazing alloy was evaluated and used for joining CFC (carbon fiber reinforced carbon composite) to pure copper. This paper deals with the development of a flat and curved joint concept providing a versatile and cheap joining technology, i.e. a single step brazing process by using an innovative brazing alloy deriving from a commercial one. The brazing of CFC to Cu was performed by using a commercial non-active braze. RF-magnetron sputtering and galvanic processes have been used to modify the commercial non-active braze by coating it with Cr, an active element. The aim is to increase its wettability on CFC, instead of using an active braze, having potential embrittlement issues. Optical microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to evaluate the microstructure and composition of the CFC/Cu joints. In order to evaluate the mechanical strength of the joint, a lap test in compression has been performed.

Microwaves at 2.45 GHz have been applied to ignite the combustion synthesis of compacted Ti–Si–C powders mixtures, having 1:1:1 atomic ratio, in order to join SiC-based components. A mixture of different refractory phases such as TiC and TiSi 2 were obtained. Depending on the synthesis conditions, no residual silicon in the joint was detected, suggesting the suitability of the here proposed experimental joining approach for nuclear plants and high temperature applications. A simplified model was developed with the aim of obtaining a deeper understanding of the here proposed rapid, almost pressure-less and localized heating joining method. Experimental and numerical simulation results demonstrate that joining of SiC can be rapidly obtained with minimization of heat affected zones in the SiC substrates. Maximum apparent shear strength values of the joints ranged from 9.9 to 45.1 MPa, depending on the process conditions.

In this paper, we report on the synthesis of pure silica (SiO2) nano- and microwires by a non-catalytic process. The structure, morphology and properties of the products were examined by scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy. The microstructural analysis shows that the SiO2 wires are high purity silica and are completely amorphous; their diameter ranges from 70 nm to 2 μm. The fiber length varies from 100 μm to several mm. The wire manufacturing process involves reduced temperatures and times (1000 °C, 30 min) compared to other processes, without needing any catalyst and has been carried out on different kinds of substrates (SiC and Si). Successful growth of SiO2 wires on the surface of silicon microcantilevers has been demonstrated; they could be used as an alternatively way to enhance the sensor performances.

A MoSi2/Si composite obtained in situ by reaction of silicon and molybdenum at 1450°C in Ar flow is proposed as pressure-less joining material for C/SiC and SiC/SiC composites. A new “Mo-wrap” technique was developed to form the joining material and to control silicon infiltration in porous composites. MoSi2/Si composite joining material infiltration inside coated and uncoated C/SiC and SiC/SiC composites, as well as its microstructure and interfacial reactions were studied. Preliminary mechanical strength of joints was tested at room temperature and after aging at service temperatures, resulting in interlaminar failure of the composites in most cases.

Monolithic high purity CVD β-SiC materials were successfully joined with a pre-sintered Ti 3 SiC 2 foil via solid-state diffusion bonding. The initial bending strength of the joints (∼ 220 MPa) did not deteriorate at 1000 °C in vacuum, and the joints retained ∼ 68 % of their initial strength at 1200 °C. Damage accumulation in the interlayer and some plastic deformation of the large Ti 3 SiC 2 grains were found after testing. The activation energy of the creep deformation in the temperature range of 1000 – 1200 °C in vacuum was ∼ 521 kJmol −1 . During the creep, the linkage of a significant number of microcracks to form a major crack was observed in the interlayer. The Ti 3 SiC 2 interlayer did not decompose up to 1300 °C in vacuum. A mild and well-localized decomposition of Ti 3 SiC 2 to TiC x was found on the top surface of the interlayer after the bending test at 1400 °C in vacuum, while the inner part remained intact.

Surface engineering based on the Selective Thermal Removal (STR) of SiC fibers from SiCf/SiC composites was used to obtain a brush-like surface in view of joining processes. As observed through 3D confocal microscopy, the thermal treatment led to a selective removal of the surface fibers so that the specific surface increased. Wetting tests were performed using a Ag-Cu-Ti brazing alloy. The STR led to a negligible increase in the contact angles, which ranged from 16° to 21° for as-received composites and increased to 28° for composites after STR. Microstructural observations showed that the brazing alloy perfectly adhered to the brush-like surfaces were giving a mechanical interlocking expected to enhance the strength of the joint.

This paper reports on the microstructure and properties of two glass–ceramics based on SiO 2 –Al 2 O 3 –MgO (SAMg) and SiO 2 –Al 2 O 3 –Y 2 O 3 (SAY), which have been designed to be used as pressure-less low activation joining materials for SiC/SiC and SiC based components for nuclear applications. Glass–ceramic pellets (SAY and SAMg) were irradiated for approximately 1 year in the reactor core of the LVR-15 research reactor at Nuclear Research Institute Rez, Czech Republic, at about 50 °C, 6.92 × 10 24 n/m 2 ( E > 1 MeV, about 1 dpa in steel); SiC/SiC composites joined by SAY were irradiated about 1 year at High Flux Reactor (HFR), Petten, The Netherlands, 550 °C, 9–11 × 10 24 n/m 2 ( E > 1 MeV, about 1.4–1.8 dpa in C), 600 °C, 16–22 × 10 24 n/m 2 ( E > 1 MeV, about 2.6–3.3 dpa in C) and 820 °C 31–32 × 10 24 n/m 2 ( E > 1 MeV, about 5 dpa in C). Optical microscopy with image analysis and scanning electron microscopy (SEM) with X-ray microanalysis (EDS) were used to investigate the glass–ceramics morphology and composition, showing a remarkable similarity before and after neutron irradiation for both glass–ceramics. Comparison of bending strength for irradiated and non-irradiated SAY joined SiC/SiC indicate that the mechanical strength is unaffected by irradiation at these conditions.

From the European side, three directional carbon fiber composites (CFCs) are foreseen to be used as plasma facing material for the strike point region of the initial ITER divertor installed for the non-tritium operational phase. For such divertor components two designs, the flat tile and the monoblock concept, are feasible, comprising a joint of the CFC with a Cu/Cu-alloy heat sink. This paper deals with the qualification of a reliable and cheap joining technology for such components, i.e. the simultaneous joining of the CuCrZr heat sink to a compliant Cu layer for the accommodation of thermal stresses and of the Cu layer and the CFC using a non-active Cu–Ge brazing material. For this purpose flat tile and monoblock mock-ups were manufactured, microstructurally analyzed, and subsequently exposed to cyclic high heat flux tests in the electron beam facility JUDITH. Applying hundreds of cycles at up to 20 MW/m 2 the tested mock-ups underwent partial damaging, which was characterized in post-mortem microstructural investigations to analyze occurring degradation mechanisms, e.g. partial delamination at the CFC/Cu-interface.

Silicon carbide (SiC) samples have been joined by a pressureless slurry based method. The CaO–Al2O3 (CA) glass-ceramic joining material has been characterized in term of crystalline phases and thermal and mechanical properties. A torsion test based on miniaturized hourglass shaped specimens has been used as pure shear strength test method for joined ceramic samples. Torsion results are compared to those obtained by a single lap offset (SLO) test in compression on the same joined materials. Pure shear strength of 104 ± 25 MPa has been measured by torsion test, whereas single lap offset gave 36 ± 8 MPa.

The results of an experimental investigation on epoxy-joined silicon carbide tested in shear mode by four different configurations of torsion test are presented and compared to results obtained by asymmetric four-point bending and four different lap tests in compression. All samples have been joined by an epoxy adhesive (Araldite AV119) which is to be considered as a model brittle joining material chosen to obtain several joined samples in a reasonable time. Advantages and disadvantages of each configuration are discussed and compared to results previously obtained with epoxy-joined Carbon/Carbon composites and ceramics tested with the same methods.

The aim of this work was to develop a new joining/repairing material suitable to be easily applied at temperature not exceeding 300°C, in air atmosphere, on large surfaces of SiCf/SiC composites for aerospace applications. The joining/repairing material proposed here is based on a Carbon Fiber-reinforced commercial Adhesive (CFA) where silicon carbide particles were added. Mechanical strength of the joined SiC/SiC was tested before and after heat treatment at the maximum working temperature for these SiC/SiC. Flexural strengths higher than 200 MPa and 90 MPa, before and after heat treatment, respectively, were obtained by coupling mechanical and adhesive bonding techniques.

Over the past few years, significant progress towards implementation of environmentally sustainable and cost-effective thermoelectric power generation has been made. However, the reliability and high-temperature stability challenges of incorporating thermoelectric materials into modules still represent a key bottleneck. Here, we demonstrate an implementation of the Solid-Liquid Interdiffusion technique used for bonding Mmy(Fe,Co)4Sb12 p-type thermoelectric material to metallic interconnect using a novel aluminium⁻nickel multi-layered system. It was found that the diffusion reaction-controlled process leads to the formation of two distinct intermetallic compounds (IMCs), Al3Ni and Al3Ni2, with a theoretical melting point higher than the initial bonding temperature. Different manufacturing parameters have also been investigated and their influence on electrical, mechanical and microstructural features of bonded components are reported here. The resulting electrical contact resistances and apparent shear strengths for components with residual aluminium were measured to be (2.8 ± 0.4) × 10−5 Ω∙cm2 and 5.1 ± 0.5 MPa and with aluminium completely transformed into Al3Ni and Al3Ni2 IMCs were (4.8 ± 0.3) × 10−5 Ω∙cm2 and 4.5 ± 0.5 MPa respectively. The behaviour and microstructural changes in the joining material have been evaluated through isothermal annealing at hot-leg working temperature to investigate the stability and evolution of the contact.