Abstract: Illitic clays are one of the most important materials used in the ceramic industry. Carbonates support the densification and the sintering of ceramics. Five mixtures of illitic clay with calcite were prepared aiming for the crystallization of anorthite ceramics. The stoichiometric ratio of anorthite crystallization was determined at 21.6 wt.% of calcite content. To reveal the effect of calcite on the crystallization processes, two more mixtures were prepared below the stoichiometric composition (17.6 wt.% and 19.6 wt.%) and two more mixtures above the ideal composition (23.6 wt.% and 25.6 wt.%). X-ray diffraction revealed that gehlenite and Ca-feldspar were formed, what are the intermediate phases in anorthite crystallization. However, due to the low purity of illitic clay and the low firing temperature no anorthite formation was observed. The influence of calcite content on the Youngs modulus was negligible. However, a clear effect on the open porosity was revealed.

Abstract: In this study, an Acid-etching surface treatment technique is proposed for treating the surface of Carbon Fiber/Epoxy Composites to optimize its surface energy and chemical bonding ability for good bonding with thermoplastic resins (PA6), and consequently for high-quality resistance welding of Carbon Fiber/Epoxy Composites. It was shown that treatment of Carbon Fiber/Epoxy Composites surfaces with concentrated sulfuric acid for 45 min at 50°C significantly increased the single lap shear strength of Carbon Fiber/Epoxy Composites welded joints to 21.47 ± 1.2 MPa, which is 163.11% ± 14% higher than that of the welded joints of untreated samples. The Acid-etching surface treatment technique proposed in this study is low-cost, simple, easy to reproduce, and combines innovation, feasibility, and economy. By analyzing the surface morphology, wettability and chemical groups of the surface-treated samples, it can be seen that Acid-etching at appropriate temperature and reasonable time can improve the surface energy of the laminate and introduce oxygen-containing chemical groups on the surface of the laminate to enhance the physical embedding and chemical bonding ability of the laminate surface.

Abstract: Wood has been employed for millennia as a versatile structural material in various applications, from furnishings and household items to components in the automotive, aerospace, and energy sectors. However, its limited strength and toughness often constrain its use in highperformance applications. To address these limitations, numerous densification methods—often relying on aggressive chemical or thermal modifications—have been developed to improve wood’s mechanical properties and dimensional stability under moisture variation. In this study, a sustainable, low-cost hydrothermal densification method using a Teflon-lined system is proposed as a green alternative to conventional alkali-based processes. The investigation compares the effects of traditional alkali treatment and the proposed hydrothermal method on the structural integrity of oak wood cell walls. Various analytical techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Dynamic Mechanical Analysis (DMA), were employed to evaluate surface color changes, microstructural alterations, and chemical composition of both as received and treated wood samples. Results reveal that the degree of cell wall degradation varies significantly depending on the treatment and temperature. Alkali-treated samples exhibited the most pronounced structural damage, while the hydrothermally treated wood retained a porous microstructure with finer pore distribution. FTIR analysis confirmed hemicellulose degradation in both treatments, indicated by the reduction or disappearance of the C=O absorption peak. Importantly, the hydrothermal method achieved up to a 19.6% increase in storage modulus compared to alkali-treated samples, suggesting improved mechanical performance with lower environmental impact. These findings underscore the potential of the hydrothermal densification process as an environmentally friendly and effective pre-treatment for enhancing wood properties, making it a promising strategy for future integration into composite material manufacturing.

Abstract: Classical molecular dynamics simulation of cation diffusion in isolated crystals (UxPuyTh1xy)O2 bounded by a free surface was performed. It was shown that in the bulk of the same model crystallite the diffusion coefficients of cations of all types were practically identical. At the same time, the cation diffusion coefficients changed with the melting temperature of nanocrystals, which increased with increasing thorium content. At a given temperature, the diffusion coefficients were the higher, the lower were the melting points of the (UxPuyTh1xy)O2 crystallites. The temperature dependences of the diffusion coefficients in crystallites of different compositions converged when using coordinates normalized to the melting points.

Abstract: This paper deals with a comparative study of the effect of carbon nanotubes (CNTs) and expanded graphite (EG) on the thermal, mechanical, morphological, electrical, and piezoresistive properties of poly(ethylene-co-methacrylic acid) (EMAA) nano-composites. To this end, different amounts of carbonaceous fillers (5, 10, 15 wt% of CNT and 10, 15, 30 wt% of EG) have been added to the EMAA thermoplastic matrix. The electrical percolation threshold (EPT) was determined to know the percentages of nanofillers capable of forming a continuous electrical conductive network through the matrix. The thermogravimetric analysis (TGA) highlights that the conductive network behaves like a protective mesh against thermo-oxidative degradation. Differential scanning calorimetry (DSC) evidences how the presence of carbon nanoparticles af-fects the crystallinity of the EMAA matrix. From a mechanical point of view, the stress-strain curves, the storage modulus, and the graph of tan  demonstrate that both the fillers determine an enhancement in the Yang and storage moduli and in the glass transition temperature. A quantitative comparison between the different fillers evi-dences greater improvements for the bidimensional nanofiller, most likely due to the cumulative effect of more extended filler-matrix interactions. Field Emission Scanning Electron Microscopy (FESEM) and Tunnelling Atomic Force Microscopy (TUNA) were used to study the interaction between the filler nanoparticles and the polymeric chains of the hosting thermoplastic matrix. Among all the experimented filler concentrations, EMAA 10% CNT and EMAA 15% EG have been selected for studying the piezoresis-tive response of the formulated nanocomposites. The electrical parameters were found to depend sensitively on the aspect ratio and the structural and morphological features of the nanofillers. A very relevant difference was detected in the Gauge Factor (G.F.) of the two typologies of nanocomposites. The G.F. of EMAA 10% CNT and EMAA 15% EG, were found to be 0.5 and 165, respectively.

Abstract: The paper tackles the important issue of the flexural strength of continuous fibre reinforced ceramic composite. Estimates of flexural strength of 2D woven SiC/SiC composite are extracted from symmetric and asymmetric 3-point bending test results using three independent approaches: (1) the equations of elastic beam theory for homogneous solids, (2) finite element analysis of stress-state, (3) stress-strain relations in the tensile outer surface of specimens. Furthermore, the flexural strength is predicted from the ultimate tensile strength using a bundle failure model based on the fracture of the critical filament. It is shown that the equation of elastic beam theory significantly overestimates the flexural strength of the 2D SiC/SiC (620 MPa), while the alternate approaches, and the predictions from the ultimate tensile strength converged on ≈340 MPa. The variability of strength data was approached using the construction of p-quantile diagrams that provide unbiased assessment of the normal distribution function. Pertinent Weibull parameters are derived using the 1st moment equations. Important trends in the effects of size, stress gradient, tension-flexure relations, strength of critical filament in a tow and populations of critical flaws are established and discussed.

Abstract: Original compositions of electrical ceramics have been developed and tested using marshallite and wollastonite as raw materials. An analysis of the equilibrium states of the created porcelain masses at different temperatures in the Na2O-Al2O3-SiO2 and K2O-Al2O3-SiO2 systems has been carried out. The amount of melt in these systems has been calculated based on the equilibrium flux curves. The characteristics of the sintering process of the masses have been identified. A scheme for the formation of the very important secondary needle-like mullite during thermal treatment of the mass has been outlined, and the temperature intervals for the formation of intermediate compounds have been found. X-ray diffraction patterns and micrographs of the synthesized samples have been decoded, and the phase composition and microstructure of the samples have been analyzed. The effective influence of the dispersion of the silica component on the mineral formation processes during the sintering of porcelain masses on model samples of compositions of feldspar with quartz sand and marshallite has been noted. The optimal firing temperatures for full mineral formation and structure formation have been determined, as well as the physical-mechanical and dielectric properties of the obtained ceramic samples.

Abstract: With the global shift toward greener transportation, the automotive industry is rapidly adopting lightweight materials to enhance fuel efficiency and reduce greenhouse gas emissions. Weight reduction not only improves recyclability but also enhances vehicle performance, including driving dynamics, braking efficiency, and crash safety. A key enabler of this transition is the integration of lightweight, high-performance materials such as advanced polymer composites as sustainable alternatives to conventional automotive components. As the future of mobility increasingly leans toward electric vehicles (EVs), the demand for eco-friendly materials has never been greater. This review provides an extensive analysis of natural fibers and fillers derived from agro/food waste—such as banana, coir, corncob, date palm, pineapple leaf fiber (PALF), and sugar bagasse—as potential reinforcements for biocomposites in EV interior applications. It explores the extraction processes, as well as the physical, chemical, mechanical, and thermal characterization of these fibers and their reinforced composites. Additionally, the article presents a comprehensive review of automotive interior requirements, evolving market trends, and key considerations for adopting biocomposites in vehicle interiors. Finally, this review highlights the future research scope and challenges associated with integrating agriculture waste-based biocomposites into electric vehicle applications, paving the way for a more sustainable and environmentally responsible automotive industry.

Abstract: Aim: Resin-based restorative materials have been the material of choice for direct dental restorations. However, the selection process remains multifaceted, while dentists often face the challenge of choosing the most suitable materials that not only meet clinical requirements but also align with their preferences, practice settings, and individual characteristics. This pilot study aimed to evaluate professional characteristics, knowledge levels, and selection criteria for resin-based restorative materials among dental clinicians at the National and Kapodistrian University of Athens.Materials and Methods: A cross-sectional questionnaire-based study was conducted between October 2023 and January 2025. A structured instrument comprising 23 closed-ended and 5 open-ended questions was administered to 87 dental clinicians. The questionnaire collected data on demographics, professional background, knowledge of resin materials, material selection preferences for anterior and posterior restorations, and influencing factors including economic and environmental considerations. Statistical analysis was performed using IBM SPSS version 29. Descriptive statistics, Spearman correlation coefficients, and Mann-Whitney tests were utilized to assess relationships between professional characteristics (e.g., clinical experience, age, postgraduate education) and material selection decisions.Results: Findings revealed that clinicians with over five years of experience demonstrated significantly higher knowledge of material composition (r = .230, p < .05) and shelf life (r = .223, p < .05). Less experienced practitioners prioritized anatomical and esthetic features, whereas experienced dentists favored specialized resin materials for anterior restorations. For posterior restorations, the majority (75.9%) selected packable composite resin for its superior mechanical properties and wear resistance. Additionally, procurement responsibility was associated with increased familiarity with industry specifications (r = .254, p < .05). Environmental considerations were noted as secondary factors, with notable gender-based differences observed.Conclusion: The study highlights that clinical experience and procurement involvement significantly influence the selection of restorative materials. While less experienced dentists focus on essential esthetic criteria, experienced clinicians incorporate a wider range of technical and regulatory factors. These insights report on the need for targeted educational interventions to bridge existing knowledge gaps and promote evidence-based decision-making in restorative dentistry.

Abstract: Nanostructures obtained as a by-product of the electrochemical synthesis of ZrO2 nanotube membranes have scarcely received any attention despite its enormous potential. This is mainly due to its size properties, morphology and composition. In the present work, we characterize these nanostructures and analyze its possible application as an additive in PVA-based coatings. The characterization was performed by XRF, SEM-EDS, TEM and XRD. The results showed that the nanostructures consist of tubular fragments generated during the formation of the ZrO2 membrane, with a dimension of 626.74 nm in width, a length of 1906.39 nm and a clear cubic structure. The ZrO2-PVA coating, which is prepared by using the spin coating technique, presented a uniform and homogenous particle distribution, which was later confirmed by FTIR, SEM and AFM. The optical transparency and thermal resistance were evaluated through UV-Vis and TGA, showing that the incorporation of ZrO2 as an additive improved its UV absorption properties and thermal stability during the pyrolysis stage. The results suggest that the ZrO2 nanostructures significantly improve the thermal and protective properties of the PVA-based coatings.

Abstract: Multifunctional self-healing supramolecular structural toughened resins, formulated to counteract the insulating properties of epoxy polymers and integrating auto-repair mechanisms, are morphologically and spectroscopically characterized using Tunneling Atomic Force Microscopy (TUNA) and Fourier-transform infrared spectroscopy (FT-IR), respectively. Specifically, the multifunctional resin comprises self-healing molecular fillers and electrically conductive carbon nanotubes (CNTs) embedded in the matrix. The selected self-healing molecules can form non-covalent bonds with the hydroxyl (OH) and carbonyl (C=O) groups of the toughened epoxy matrix through their H-bonding donor and acceptor sites. FT-IR analysis has been conducted to evaluate the interactions that the barbiturate acid derivatives, serving as self-healing fillers, can form with the constituent parts of the toughened epoxy blend. Tunneling Atomic Force Microscopy (TUNA) highlights the morphological characteristics of CNTs, their dispersion within the polymeric matrix, and their affinity for the globular rubber domains. The TUNA technique maps the samples' electrical conductivity at micro and nanoscale spatial domains. Detecting electrical currents reveals supramolecular networks, determined by hydrogen bonds, within the samples, showcasing the morphological features of the sample containing an embedded conductive nanofiller in the hosting matrix.

Abstract: Concrete-filled steel columns are increasingly recognised for their enhanced structural performance. This study investigates an innovative shear connector design with screw connectors as an alternative to conventional connection types. From push-out testing, the shear capacity of screw connectors in composite columns comprising cold-formed steel sigma sections and concrete infill was evaluated. Experimental push-out testing demonstrated the effectiveness of theoretical equations in estimating the shear strength of screw connections. The comparison indicates that established design methods provide reasonable predictions, supporting their applicability in practical scenarios. Theoretical equations in the literature for estimating shear strength were tested for suitability and gave comparable results. De-assembling of tested specimens showed that a concrete failure was the prominent mode of ultimate condition. Shear screws offer a novel design alternative to conventional shear connection methods. They demonstrate significant potential for structural applications when integrated with advanced composite column sections, such as the four-sigma built-up CFS sections. The study highlights screw connectors as a cost-effective, sustainable, and practical solution for innovative composite column designs, offering significant potential for construction and maintenance efficiency.

Abstract: This study explores the use of gypsum waste from civil construction as a partial replacement for cement in soil-cement formulations, aiming to produce eco-friendly bricks aligned with circular economy principles. Formulations were prepared using a 1:8 cement-to-soil ratio, with gypsum replacing cement in proportions ranging from 5% to 40%. The raw materials were characterized in terms of their chemical composition, crystalline phases, plasticity, and thermal profile. The formulations, molded by uniaxial pressing into cilindrical bodies and cured for 7 or 28 days, were tested for crystalline phases, compressive strength, water absorption, durability, and microstructure. Water absorption remained below 20% for all samples, with an average value of 16.20%. Compressive strength after 7 days decreased slightly with increasing gypsum content, from 16.36 MPa (0% gypsum) to 13.74 MPa (40% gypsum), still meeting the quality standard. After 28 days of curing, the formulation containing 10% gypsum achieved the highest strength (26.7 MPa), surpassing the reference sample without gypsum (25.2 MPa). Mass loss due to water immersion remained within acceptable limits for formulations containing up to 20% gypsum. Notably, samples with 5% and 10% gypsum exhibited superior mechanical performance, while samples with 20% gypsum showed comparable results to the reference. These findings suggest that replacing up to 20% of cement with gypsum waste is a viable and sustainable alternative, promoting circular economy practices and reducing the environmental impact of construction waste.

Abstract: This work presents a new approach for the fabrication of 316L/Al₂O₃ composites, based on the combination of spray-granulation, radio frequency (RF) plasma spheroidization and spark plasma sintering (SPS). Initially, a suspension containing 316L and alumina powders is formulated by precisely adjusting the pH and selecting an appropriate dispersant, thereby ensuring a homogeneous dispersion of the constituents. The spray‐granulation process then produces granules with controlled size and morphology. RF plasma spheroidization, carried out using a TekSphero-40 system, is investigated by varying parameters such as power, gas flow rates, injection position and feed rate, in order to optimise the formation of spherical and dense particles. The analysis reveals a marked sensitivity to heat transfer from the plasma to the particles, with a tendency for fine particles to segregate, which underscores the necessity for precise control of the processing conditions. Finally, SPS densification, performed under a constant pressure and a rigorously controlled thermal cycle, yields composites with excellent density and hardness characteristics. This study thus demonstrates that the proposed hybrid process offers an optimal synergy between a uniform distribution of alumina and a controlled microstructure, opening up promising avenues for the design of high‐performance composite materials for demanding applications.

Abstract: This paper provides the study results of influence of few-layer graphene obtained by self-propagating high-temperature synthesis from various biopolymers on the strength, thermophysical, and tribological properties of epoxy resin. The initial biopolymer's effect on synthesized few-layer graphene's structure is shown. In the studied composites, an increase in the glass transition temperature, thermal conductivity, and compressive strength is observed. The wear resistance of composites five times increase compared to the neat epoxy resin was also found due to a decrease in the coefficient of friction.

Abstract:

Semiconductors are often used in the energy conversion field, due to its electronic properties. One of the applications is for photovoltaic solar cells. Doping is a way of altering the properties of a material without significantly causing alterations in the structure of the materials. One of these properties that can be changed is the photon to current efficiency of a semiconductor. Many elements are being used for the doping of semiconductors, such as aluminum, cobalt, indium and lithium. This work doped zinc oxide with tin in the chloride form to try to increase the generated current inside a dye sensitized cell at different dye immersion times. The time used to immerse the film can affect the stability of the cell, and, by consequence, the efficiency of photovoltaic conversion. Ruthenium based dye was tested in this study. The results showed better current and efficiency values for a longer period of time, 3.38 mA/cm² and 0.52%; absorption peaks in the UV region and band gap around 3.0 eV, below the average 3.37 eV found for zinc oxide thin films, and crystalline size of 46.7 nm.

Abstract: CuCrO₂ (mcconnellite) was synthesized using both the solid-state method and microwave dielectric firing. It was characterized as a novel black ceramic pigment for use in various industrial glazes. For the first time, the application of mcconnellite (CuCrO₂) and its coloured glazes as selective solar absorbers (SSA) for integral ceramic solar collectors has been reported. The addition of quartz or anatase was investigated as colour modifiers to prevent the bluing of the pigment in Zn-containing glazes, a phenomenon associated with the exsolution of copper. Furthermore, doping with lanthanide oxides was explored to address two key challenges: controlling the formation of pinhole defects in porcelain glazes, which are linked to the destabilization of Cu⁺, and adjusting the IR cut-off wavelength to improve its performance as SSA.

Abstract: Introduction: 3D printing resins have gained popularity in dentistry due to their practicality and reproducibility. However, differences in chemical composition have a direct influence on the mechanical properties of these materials and the various evaluation methods have generated different results which make it difficult to compare their properties. Objective: The aim of this study was to evaluate the influence of the orientation of the impression layers on the mechanical properties (flexural strength and flexural modulus) of biocompatible printed resins. Methods: 100 specimens (n=20) were made from bars measuring 2 x 2 x 25 mm, divided according to the angulation relative to the printing platform (V0, V22.5, V45, V67.5, V90). The bars were designed using Autodesk Meshmixer CAD software and printed on a 3D LCD printer. For the control group, composite resin specimens were made following the same patterns as the printed resins. These bars were subjected to 3-point bending tests on a universal testing machine and flexural strength (FS) and flexural modulus (MF) were evaluated. Results: The mean values of flexural strength and flexural modulus showed no statistically significant differences between the groups. The composite resin control group showed significantly higher mean values in both factors analyzed. Conclusion: It can be concluded that the groups showed minimal differences in the angles studied in both flexural strength and flexural modulus, showing the anisotropic behavior of the restorative material manufactured by 3D printing, suggesting that the choice of any printing angle can determine the applicability according to the characteristics and function of the object to be printed.

Abstract: This study focuses on reducing the weight of oxygen respirators in firefighters' personal protective equipment (PPE), which currently accounts for about 56% of the total weight. The heavy PPE, weighing between 20 and 25 kg, restricts movement and can lead to musculoskeletal injuries. To address this, the study investigates using a carbon fiber-reinforced composite for the backrest of the oxygen respirator to reduce weight while maintaining strength. The backrest was fabricated using a long-fiber thermoplastic (LFT) composite made with PA66 resin and 30wt.% carbon fiber content. Initially, the injection-molding process conditions were identified to achieve a tensile strength of 85 MPa or higher. Additionally, flame retardants were added to improve fire resistance, with AF-480 at 5 wt.% found to be the best option. Subsequently, optimal injection conditions were set by fabricating the back rest with the composite by applying the Taguchi method to satisfy the required tensile strength. As a result, the composite material achieved a 12.8% weight reduction while maintaining the required strength. This development is expected to significantly improve firefighter safety, leading to more effective firefighting and reduced human and property damage.

Abstract: Bio-based composites offer potential environmental benefits over fossil-based materials, but limited research exists on manufacturing processes with varying material combinations. This study performs a cradle-to-grave Life Cycle Assessment of five composite types to evaluate the role of fully and partially bio-based composites, focusing on the manufacturing stage. The composite materials include glass or flax fiber-based reinforcements embedded in polymer matrices based on a fossil epoxy, a partially bio-based epoxy or epoxidized linseed oil, fabricated using vacuum-assisted resin infusion. Flax fibers in a partially bio-based epoxy achieve lowest environmental impacts in most categories when assessed at equal geometry. Glass fiber composites exhibit higher fiber volume content and material properties, and thus, demonstrate competitive environmental performance at equal absolute and normalized tensile strength. Composites using epoxidized linseed oil are least advantageous with the manufacturing stage contributing a majority of environmental impacts due to comparatively long curing times. These results are based on methodological choices and technical constraints, which are discussed together with benchmarking against previous studies. While partially bio-based materials can provide a middle-ground for enhancing composite environmental performance, further optimization of bio-based material functionality regarding material properties and processability is pivotal to exploit the full potential of bio-based composites.