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Ox/ox CMC based on Nextel 610™ fibers with 75 wt% alumina – 25 wt% zirconia matrix have been joined by a glass-ceramic and tested in creep in four-point bending (DIN EN 820–4) up to 50 h at 850 °C and 1000 °C, between 32 and 41 MPa. As a comparison, the creep limit of the non-joined ox/ox CMC was investigated in this range and also at higher temperatures and stresses. The creep experiments at 850 °C did not show any significant difference between joined and ox/ox CMC after 50 h, while a certain one was detected at 1000 °C on joined ox/ox CMC, suggesting that its creep mechanism is dominated by visco-elastic flow of the glass-ceramic.

Municipal solid waste (MSW) production in the world has increased by 60 % in recent years. Incineration of MSW reduces their volume in conjunction with energy recovery. Incineration produces two residues, namely bottom ash (BA) and fly ash (FA), with high concentration of heavy metals and organic pollutants, especially for FA, making them an environmental concern. Vitrification is a costly, highly safe high temperature treatment, ensuring encapsulation of heavy metals. FA vitrification requires a source of silica to be able to get vitrified. In this study, we have proposed valorizing treated (vitrified) FA through the production of porous glass-ceramics, subsequently to MSWI. The entire process, from incineration to glass-ceramics production, was evaluated for several scenarios by Life Cycle Assessment (LCA) using Sima Pro 9.0. Three main scenarios were analysed; each one considering a different silica source: bottom ash (BA), glass cullet (G) and silica sand (S), and for each scenario, three thermal recovery subscenarios were assumed: no thermal recovery used to heat FA prior to vitrification (N), heating FA prior to vitrification using incineration gases thermal recovery (T) and methane-combustion-aided thermal recovery, which exploits methane combustion to further increase the gases temperature (M). Results proved that vitrification was a technically feasible and environmentally-energetically sustainable technology. The result indicates that the most eco-sustainable scenario was using bottom ashes as a silica source together with methane-combustion-aided recovery: 0.467 kgCO

Incineration is the most common way to reduce the mass and the volume of municipal solid wastes. One of the most dangerous by-products of the incineration process is fly ash that contains a considerable amount of heavy metals. Therefore, its treatment is crucial to prevent the leaching of heavy metals into the environment. In the present work, two different sources of municipal solid waste incinerator fly ash have been vitrified in order to inhibit the release of potentially toxic heavy metals. Two different sources of silica, i.e. silica sand and glass cullet, have been added to each type of fly ash in an attempt to obtain vitrifiable batches. The standard leaching test on vitrified products was performed according to EN12457-2 confirming no heavy metal leaching and, therefore, they all pass waste acceptance criteria to be classified as an inert material. Furthermore, the previously reported data for vitrification of fly ash was combined with the present work and their compositions were presented in the SiO2–Al2O3–CaO, and SiO2-ΣM2O3-Σ(MO + M2O) ternary phase diagrams to identify the region in which successful compositions are concentrated. This analysis could facilitate the attempt to find the right composition for vitrification of fly ash.

Since reliable long term operation of SOFC and SOEC devices depends critically on the mechanical behavior of the sealant material, the current work focuses on the characterization of the shear strength by a torsion test of two different glass-ceramic sealants that are used to join Crofer22APU substrates in an application relevant configuration. The two glass-ceramic sealants differ in terms of characteristic temperatures and crystalline phases with possible impications on the joining behavior. Statistically identical shear stress values were measured at room temperature for joined hourglasses of different size with both sealants, thus confirming a size independence of the measured strength values. Experimental post-test examination results confirm that the interfaces play a strong role regarding the measured shear strength and provide important insights with respect to integration of metallic and glass-ceramic components in SOFC/SOEC stacks.

This study fills a knowledge gap regarding neutron-irradiation resistance of SiC joints for nuclear applications, by investigating high-dose neutron irradiation effects on the strength of selected joints and low-dose neutron irradiation effects on recently developed joints fabricated by state of the art processing methods. The joining methods used for the high-dose radiation study included pressure-assisted liquid-phase sintering (LPS) of SiC nanopowder, pressureless calcia-alumina glass ceramics joining, and reaction sintering of Ti-Si-C powders with hot-pressing. The joints were neutron-irradiated at 530 °C to 20 displacements per atom (dpa). Other joining methods included low-pressure LPS of cold-pressed SiC green body, pressureless reaction sintered Ti-Si-C powder joint, spark plasma–sintered Ti diffusion bond, and hot-pressed Ti diffusion bond, which were irradiated at ∼500 °C to ∼2 dpa. There was no notable degradation of torsional strengths of the joints following the high-dose irradiation. The irradiation-induced degradation at low neutron dose was highly dependent on joint type.

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.

This study aims at deposition and characterization of antibacterial, hydrophobic and semitransparent metal/plasma polymer nanocomposite coating, containing Ag nanoparticles, onto cotton fabrics intended to be used in medical applications. The nano composite coatings were obtained via a simple, one step and ecofriendly plasma based co-deposition approach where silver was magnetron sputtered simultaneously with plasma polymerization of hexamethyldisiloxane (HMDSO) monomer. The nanocomposite thin films containing different concentration of silver were deposited either by varying silver sputter rate or thickness of the plasma polymer matrix to obtain a good balance between optical properties of the coated fabric and its long term antibacterial performance. The obtained coatings were investigated in detail with respect to their composition, morphology, optical properties, nanoparticle size distribution, silver ion release efficiency, antibacterial performance, water contact angle and washing stability of the coating. The thickness of the plasma matrix was found to be more important in controlling the release of silver ions as well as affecting the optical properties of the coating. The water contact angle on the coated fabric was up to 145°, close to super hydrophobicity. The coating showed effective antibacterial efficacy against Staphylococcus epidermidis (a Gram positive bacterium) which was present even when fabric was subjected to 10 repeated washing cycles indicating good washing stability of the coating.

The invention of bioactive glasses has undoubtedly represented an important watershed in the history of biomedicine, innovatively revolutionizing the key concept of biomaterials. Although 50 years have passed since the first bioactive glass (45S5 Bioglass®), these materials still continue to inspire numerous generations of researchers all over the world, attracted by the promise of numerous possible fields of investigations given by the versatility of glass manufacturing and processing strategies. This allows obtaining final clinical products that are incredibly diverse in terms of chemical characteristics, shape and texture and, therefore, adaptable to different therapeutic needs. The possibility to tune textural properties and degradation rates, perform high-temperature sintering processes without or minimally altering the original properties of the glass, as well as the facile introduction of therapeutically active ions within the composition and the easy surface functionalization led, over year, to the development of multiple pruducts to be used in various clinical fields, including the regeneration of both hard and soft tissues, bacterial/viral infection treatments and development of antitumoral strategies. This chapter opens a wide window on the world of bioactive glasses, starting with the description of their peculiar chemical properties, discussed in relation to the most commonly used manufacturing processes to obtain glass monoliths or particles. Then, an overview on the most common applications of BG-based products will be provided, paying particular attention to porous scaffolds for bone tissue engineering, bioactive coatings, antibacterial glasses and surface functionalization. In conclusion, a comprehensive overview on clinical applications updated to the state of the art will be provided.

Following the general increase of population and industrial development, the management of resources through use of secondary source of raw materials, recycling and energy recovery from waste products are growing in importance. There are many challenges associated with each approach in which waste treatment and handling its by-products are among the most environmentally concerned matters. This chapter is divided into two main parts for two types of waste management: municipal solid waste management, and wastewater management. In the first part, management of municipal solid waste, incineration as a tool for energy recovery and its hazardous by-products fly ash and bottom ash are introduced. It has shown that vitrification of these ashes could open lots of potential for their utilization in various products such as cement and clinker substitution, or preparation of foam glass–ceramics as construction materials. In this chapter, a guide to successfully vitrify fly ash is also introduced and discussed. The second part of this chapter is dedicated to wastewater management, focusing on the potential use of rice-husk, an agricultural by-product to be utilized as an adsorbent for removal of heavy metals from wastewater. The final heavy-metal containing rice husk introduces new environmental concerns prior to landfill, and we have shown that vitrification has the potential to safely encapsulate this material and even give the opportunity to prepare foam glass–ceramics after its vitrification.

In this study, multifunctional stratified antibacterial and bioactive coatings were deposited and characterised. Initially, PEEK/bioactive glass (BG)/ mesoporous bioactive glass nanoparticle (MBGN) layers with a thickness of 110–120 μm were deposited on stainless steel substrates using electrophoretic deposition (EPD). Thin silver nanocluster-silica composite layers with a thickness of 70–155 nm were then deposited by radio frequency (RF) co-sputtering on the previously deposited EPD coatings. The deposition was carried for two different sputtering times (20 min and 40 min), which led to different layer thicknesses. PEEK/BG/MBGNs coatings were also deposited via single-step EPD. A comparison between the physicomechanical and biological characteristics of single layer PEEK/BG/MBGNs composite coating and bilayer Ag-PEEK/BG/MBGNs is presented. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) indicated that silver nanoclusters were homogeneously distributed in the multilayered EPD/RF coatings. An apatite-like structure was formed on the surface of the coatings upon immersion in simulated body fluid (SBF) after 1 day. Silver nanoclusters embedded in the silica matrix as a top layer provided controlled release of silver ions which led to a potent antibacterial effect against E. coli and S. carnosus. Single layer coatings exhibited a burst release of Ag ions, which led to antibacterial effects but were toxic to osteoblast cells. Finally, the results of WST-8 assays confirmed that the multi-structured coatings allow osteoblast-like cells to proliferate and attach strongly on the surface of the coatings.

During the current pandemic of COVID-19 caused by the new Coronavirus SARS-CoV-2, the confinement measures slowed down the contagion, but did not completely avoid the disease diffusion for health workers, patients and the remaining population. The individual protection equipment (e.g. facial masks), filters for air conditioning systems and for medical respiratory devices do not possess an intrinsic antimicrobial/virucidal action and they are susceptible to microbial/viral colonization. An efficient antimicrobial/virucidal technology on air filtering media is crucial for maintaining a safe air environment and protecting people, in particular when lockdown is eased. This short communication reports about the virucidal effect, preliminary verified towards Coronavirus SARS-CoV-2, of a silver nanocluster/silica composite sputtered coating, directly applicated on a FFP3 mask., Graphical abstract Image 1, Highlights • Sputtered antimicrobial/virucidal silver nanoclusters/silica composite coating. • SARS-COV-2 titre reduction till zero on coated face mask. • Suitable for coating several air filters and other surfaces.

Silicon carbide (SiC) fiber reinforced SiC matrix composites continue to undergo development for fusion applications worldwide because of inherent advantages of the material including low activation, high temperature capability, relatively low neutron absorption, and radiation resistance. This paper presents an international overview of recent achievements in SiC-based composites for fusion applications. Key subjects include applications in fusion reactors, high-dose radiation effects, transmutation effects, material lifetime assessment, and development of joining technology (processing, test method development, irradiation resistance, and modeling capability). This paper also discusses synergy among research for fusion materials and non-fusion materials (for fission and aerospace applications). Finally, future research directions and opportunities are proposed.

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.

Bioactive and antibacterial coatings on stainless steel substrates were developed and characterized in this study. Silver nanocluster-silica composite coatings of 60-150 nm thickness were deposited using radio frequency (RF) co-sputtering on PEEK/bioactive glass (BG) layers (of 80-90 ?m thickness) which had been electrophoretically deposited onto stainless steel. Two sputtering conditions were used by varying the deposition time (15 and 40 min); the resulting microstructure, composition, adhesion strength, in vitro bioactivity, and antibacterial activity were investigated. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopy (EDX) confirmed the presence of silver nanoclusters, which were homogeneously embedded in the silica matrix. The isoelectric point of the coatings and their charge at physiological pH were determined by zeta potential measurements. The presence of BG particles in the PEEK/BG layer allows the coatings to form apatite-like crystals upon immersion in simulated body fluid (SBF). Moreover, silver nanoclusters embedded in the silica matrix as a top layer provided an antibacterial effect against Escherichia coli and Staphylococcus carnosus.

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.

To obtain an Aluminium Foam Sandwich (AFS), Al-6016 sheets were successfully joined to a 9 mm thick Aluminium (Al) foam, by using Zinc (Zn) based joining materials (pure Zn and Zn alloy with 2% Al) at 430 °C in argon atmosphere. The microstructure of the joints was analysed by Optical Microscope (OM), Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS). Moreover, three-point bending tests were carried out to evaluate the flexural properties of the AFS components. Current experimental work is focused on optimization of the AFS joining process and the mechanical properties of AFS components.

Antibacterial functionality of cellulosic fibers has become an integral requirement for various applications. Silver is widely studied to functionalize textiles with antimicrobial properties and it can be applied via different routes, classified in wet and dry processes. Wet treatments can potentially influence the bulk properties of the textiles negatively and cause environmental concerns and high water and energy consumption. Dry routes including sputtering are considered ecofriendly processes and offer the advantage of modifying only the textile surface. In this study, antimicrobial silver nanoclusters/silica composite coatings of different thicknesses were deposited by radio frequency co-sputtering on cotton fabric. The samples were characterized in terms of morphology, composition, silver contents, silver leaching behaviour in water, antimicrobial properties, in vitro silver permeation through human skin, water contact angle, moisture management properties and air permeability. FESEM, EDX and XPS analysis confirmed the successful deposition of the coating composed of silver nanoclusters uniformly distributed and embedded in the silica matrix. Silver leaching test showed a gradual release of ionic silver in water. The composite coating exhibited antimicrobial activity against the tested microbial strains of Staphylococcus aureus, Escherichia coli and Candida albicans in disk diffusion test. The total amount of silver permeated through the human skin was found to be 3.21 ± 0.63 ngcm−2 during 24 h in vitro skin diffusion test. The water wettability of the fabric increased whereas air permeability was found to be unchanged after coating deposition.

Nowadays glass is widely used in building applications and coupled to steel through adhesive joining. Reliable mechanical characterization of these joints is necessary to design and predict the final structure performance.In this framework, the aim of this paper is to measure the pure shear strength and elastic modulus for design and modelling of adhesive joined glass-to-steel structures.Torsional shear strength and elastic properties of an adhesively bonded glass-to-steel component were measured on several joined steel-to-steel and steel-to-glass samples.An epoxy resin-based adhesive was used as joining material for AISI304 steel and soda-lime glass.The same steel and adhesive were used to obtain steel-to-steel joined sample bars to be tested in asymmetrical four-point bending, for comparison purposes.The indentation elastic modulus of the adhesive, both inside the joined region and as a bulk, was measured by nano-indentation and impulse excitation technique.Finally, the effect of etching on the glass was studied and correlated to the glass-steel joint strength.This study shows that torsion test can be used to provide reliable shear strength values for design and modelling glass-to-steel adhesive joined components.

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.

An original method to increase the mechanical strength of adhesively joined carbon fiber-reinforced plastics (CFRPs) and honeycomb CFRP sandwich structures by etching is proposed, based on sulfuric acid etching of the CFRP surface. Etched composites are joined by a novel phenolic resin-based adhesive and are cured, and their cross section is observed by FESEM. Etching of CFRP was aimed to obtain a “brush”-like composite to be infiltrated by the adhesive, giving a fiber-reinforced, stronger composite joint. This method gave a 100% increase in the lap shear strength for the adhesively joined etched CFRP, compared to the non-etched ones.

Indoor air quality has great impact on health and wellbeing of the occupants. Although modern air filtration systems assure high air quality, however the filtration media itself needs to be protected from microbial contamination. Low maintenance and dirt accumulation along with humid conditions in air ventilation systems create a suitable environment for the growth of microorganisms on the surfaces. Microbial proliferation undermines both the quality of the filtered air and the filtration apparatus. Contaminated air directly affects occupant’s health, comfort and productivity, with an augmented risk of infectious diseases. The aim of this work was the development of an air filter with innovative nanostructured coating, able to confer anti-pathogenic functionalities without altering filtration performance of the filter. The filter was accomplished by depositing a nanostructured composite silver/silica coating on the surface of a glass fibres based nonwoven filter. This developed air filter completely inhibited the growth of microorganisms even when exposed to bioaerosol of high bacterial concentration. The filter showed good antibacterial performance under practical conditions for extended period spanning one month. The innovative nanocomposite coating imparts long lasting antimicrobial properties to improve the performance of the filtration systems enabling them to perform better with minimal maintenance efforts.

Perovskite lead titanate PbTiO3 (PT) powder and ceramics were synthesized using solid state reaction technique. The PT single phase powder was detected by X-ray diffraction where the phase obtained by sintering at 700 °C for 2 h. Morphology of the ceramics powder were studied using SEM–EDS. It was found that the particle size tend to increase with increasing sintering temperature. Hot stage microscope has been used to investigate the sintering curve of the calcined powder. The pure calcined powder was prepared as humidity sensors by the screen-printing technique. Thereafter, DC resistance measurements were performed in the presence of relative humidity at room temperature where the powder shows a poor sensitivity towards relative humidity. The phase transition from ferroelectric to paraelectric was identified by differential thermal analysis, and was detected at 493 °C. The difference between using alumina and platinum crucibles during processing has been discussed.

Aluminum alloys are light-weight and one of the most interesting material solutions to optimize the strength/weight ratio to reduce car weight; however they are also relatively soft and therefore cannot be used for intensive wear applications. We developed an aluminum alloy part combined with hard and wear-resistant Al2O3-based ceramic plates on the surface for demanding mechanical parts for automotive industry such as disc brakes. Tribological tests of various engineering ceramic materials were performed in order to find a ceramic material with a combination of coefficient, wear resistance and thermal energy dissipation for the car brakes. Al2O3-based ceramic showed promising properties, as well as being cost effective. Two different approaches to braze ceramic on aluminum were investigated. A two-step brazing process using Cu-Sn-Ti-Zr filler alloy and a single step ultrasonic active soldering with Sn-Ag-Ti filler alloy. Larger areas of aluminum could be covered with a segmented brake design in which many ceramic plates were joined surface. Comparable tribological properties to those of the bulk ceramic material were achieved.