Search Results (58)

This study aimed to evaluate the nanomechanical surface properties and water uptake of a flowable short-fiber-reinforced composite (SFRC) using various restorative techniques in order to assess its potential as a standalone restorative material. Nanoindentation and compressive creep testing were employed to characterize material performance. Three resin composites were examined: a flowable SFRC (everX Flow), a bulk-fill particulate filler composite (PFC), and a conventional PFC. Five experimental groups were established based on the restorative technique: layered PFC, layered SFRC, bulk SFRC, bulk PFC, and a bi-structure combining SFRC and PFC. Ninety standardized specimens (n = 18/group) were fabricated. Static and creep nanoindentation tests were conducted to assess surface properties, and water uptake was measured over a 30-day period. Data were analyzed using one-way ANOVA and Bonferroni post hoc tests. Nanoindentation revealed significant differences in hardness, with bulk PFC exhibiting the lowest values (p < 0.001). Creep testing indicated changes in modulus and viscosity following water storage. Notably, bulk SFRC showed the lowest water absorption (p < 0.001). Overall, bulk-applied SFRC demonstrated favorable nanomechanical properties and reduced water uptake, demonstrating its suitability as a standalone restorative material. Further clinical investigations are recommended to validate its long-term performance. Full article

Hybrid composite materials reinforced with both fibers and particulate fillers are increasingly used in engineering due to their favorable balance of mechanical strength, reduced weight, and enhanced tribological performance. This study investigated the effect of CuSn10 bronze powder additions (5%, 10%, and 15% by weight) on the mechanical and tribological properties of novel basalt fiber-reinforced polymer (BFRP) composites. The composites were fabricated via vacuum-assisted processing and tested under dry sliding conditions with varying loads (10, 20, and 30 N) and sliding speeds (0.1, 0.25, and 0.36 m/s). The results show that the optimal tensile strength (440.6 MPa) was achieved at 10 wt% CuSn10, while the best tribological performance was observed at 15 wt% CuSn10, under a 10 N load and 0.25 m/s sliding speed, where the coefficient of friction decreased by up to 38% and the specific wear rate was reduced by more than 50% compared to the unreinforced BFRP composite. These enhancements are attributed to the formation of a stable oxide-based tribolayer (CuO, SnO₂) and improved load transfer at the fiber–matrix interface. Statistical analysis (GLM) confirmed that CuSn10 content had the most significant influence on tribological parameters. The findings provide valuable insight into the design of high-performance hybrid composites for structural and tribological applications. Full article

Although dental resin composite restoratives offer a widely used direct-placement treatment option aimed at replacing the form and function of a natural tooth, there are several clinically relevant performance aspects of these materials that can be improved. The formulation of the resin matrix phase of dental composites for high-efficiency photopolymerization leading to polymers with excellent mechanical properties has always been a challenge that is addressed here through the use of structurally new and more reactive monomers as well as the formation of polymer networks that incorporate non-covalent reinforcing interactions. The purpose of this study was to validate that a set of tetraurethane diacrylates (TUDAs) with a novel configuration of their urethane linkages in coordination with acidic comonomers could be devised to obtain highly robust new composite materials. Due to the novel molecular design, this exploratory approach was conducted using reaction kinetics and three-point bend testing to assess the performance. Conversion and mechanical properties were measured to refine these formulations prior to the addition of filler. The initial formulations demonstrated outstanding dry mechanical test results that subsequently showed a major intolerance to water storage, which led to a model study using urethane diacrylate (UDA) followed by the addition of hydrophobic TUDA monomers. Once the resin formulations were optimized, silane-treated particulate filler was added to determine the effectiveness as composite materials. The final formulation used a hydrophobic, aromatic TUDA along with 4-methacryloxyethyl trimellitic anhydride (4-META) as a latent acidic comonomer and a mixture of acrylic acid (AA) and methacrylic acid (MAA). This formulation achieves a very high level of both reactivity and mechanical properties relative to current dental composite restoratives. Full article

Disposing of carbon fiber-reinforced polymers (CFRPs) has become a pressing issue due to their increasing application across various industries. Previous work has focused on removing silane coupling agent residues on recovered carbon fibers via microwave pyrolysis, making them suitable for use in new materials. However, the mechanical performance and structural characteristics of these fibers have not been fully reported. This study investigates the time–temperature curves of CFRPs treated through microwave pyrolysis and analyzes the mechanical and structural properties of silane-controllable recovered carbon fibers. Additionally, emissions—including carbon monoxide, carbon dioxide, and particulate aerosols—were measured using handheld monitors and thermal desorption–gas chromatography/mass spectrometry to determine the composition of fugitive gases around the microwave pyrolysis system. The pyrolysis process at 950 °C, with an additional 1 h holding time, reduced the crystallite size from 0.297 Å to 0.222 Å, significantly enhancing tensile strength (3804 ± 713 MPa) and tensile modulus (200 ± 13 GPa). This study contributes to more sustainable CFRP waste treatment and highlights the potential for reusing high-quality carbon fibers in new applications, enhancing both environmental and worker safety. Full article

In sustainable construction and packaging, the development of novel bio-based materials is crucial, driving a re-evaluation of traditional components. Lightweight, biodegradable materials, including xerogels, have great potential in architectural and packaging applications. However, reinforcing these materials to improve their mechanical strength remains a challenge. Alginate is a promising matrix material that may be compatible with inorganic fibrous or particulate materials. In this study, biocomposite xerogel-structured foam materials based on an alginate matrix with expanded perlite reinforcement are improved using certain additives in different weight ratios. The plasticizers used include glycerol and gum arabic, while chitosan was added as an additional reinforcement, and iota carrageenan was added as a stabilizer. The tested specimens, with varying weight ratios of the added components, showed good mechanical behavior that highlights their potential use as packaging and/or architectural materials. The influence of the presence of different components in the composite material specimens on the modulus of elasticity was investigated using SEM images and FTIR analyses of the specimens. The results show that the specimen with the largest improvement in the elastic modulus contained a combination of chitosan and glycerol at a lower percentage (1.96 MPa), and the specimen with the largest improvement in tensile strength was the specimen containing chitosan with no plasticizers (120 kPa), compared to cases where combinations of other materials are present. Full article

Manufacturing sectors, including automotive, aerospace, military, and aviation, are paying close attention to the increasing need for composite materials with better characteristics. Composite materials are significantly used in industry owing to their high-quality, low-cost materials with outstanding characteristics and low weight. Hence, aluminum-based materials are preferred over other traditional materials owing to their low cost, great wear resistance, and excellent strength-to-weight ratio. However, the mechanical characteristics and wear behavior of the Al-based materials can be further improved by using suitable reinforcing agents. The various reinforcing agents, including whiskers, particulates, continuous fibers, and discontinuous fibers, are widely used owing to enhanced tribological and mechanical behavior comparable to bare Al alloy. Further, the advancement in the overall characteristics of the composite material can be obtained by optimizing the process parameters of the processing approach and the amount and types of reinforcement. Amongst the various available techniques, stir casting is the most suitable technique for the manufacturing of composite material. The amount of reinforcement controls the porosity (%) of the composite, while the types of reinforcement identify the compatibility with Al alloy through improvement in the overall characteristics of the composites. Fly ash, SiC, TiC, Al₂O₃, TiO₂, B₄C, etc. are the most commonly used reinforcing agents in AMMCs (aluminum metal matrix composites). The current research emphasizes how different forms of reinforcement affect AMMCs and evaluates reinforcement influence on the mechanical and tribo characteristics of composite material. Full article

This research investigates the manufacturing and characterisation of polyester-based composites reinforced with jute fibres and red mud particulates. The motivation stems from the need for sustainable, high-performance materials for applications in industries, like aerospace and automotive, where resistance to erosion is critical. Jute, a renewable fibre, combined with red mud, an industrial byproduct, offers an eco-friendly alternative to conventional composites. The composites were fabricated using compression moulding with varying red mud contents (10, 20, and 30 wt.%) and a fixed 40 wt.% of jute fibre. Fibre treatments included sodium hydroxide (NaOH) and silane treatments to improve bonding and performance. Erosion tests were performed using an air-jet erosion tester, examining the effects of the red mud content, fibre treatment, and impact angles. Scanning Electron Microscope (SEM) analysis provided insights into the erosion mechanisms. A distinctive reduction in erosion rates at higher impact angles (30°–60°) was observed, attributed to the semi-ductile nature of the composites. The addition of red mud enhanced erosion resistance, although an excess of 30 wt.% reduced resistance due to poor surface bonding. Silane-treated composites showed the lowest erosion rates. This study provides new insights into the interplay among material composition, fibre treatment, and erosion dynamics, contributing to the development of optimised, eco-friendly composite materials. Full article

Aluminum alloy–graphene metal matrix composite is largely used for structural applications in the aerospace and space exploration sector. In this work, the preprocessed powder particles (AA 2014 and graphene) were used as a reinforcement material in a squeeze casting process. The powder mixture contained aluminum alloy powder 2014 with an average particle size of 25 μm and 0.5 wt% graphene nano powder (Grnp) with 10 nm (average) particle size. The powder mixture was mixed using the high-energy planetary ball milling (HEPBM) technique. The experimental results indicated that the novel mixture (AA 2014 and graphene powder) acted as a transporting agent of graphene particles, allowing them to disperse homogeneously in the stir pool in the final cast, resulting in the production of an isotropic composite material that could be considered for launch vehicle structural applications. Homogeneous dispersion of the graphene nanoparticles enhanced the interfacial bonding of 2014 matrix material, which resulted in particulate strengthening and the formation of a fine-grained microstructure in the casted composite plate. The mechanical properties of 0.5 wt% graphene-reinforced, hot-rolled composite plate was strengthened by the T6 condition. When compared to the values of unreinforced parent alloy, the ultimate tensile strength and the hardness value of the composite plate were found to be 420 MPa and 123 HRB, respectively. Full article

The study investigates the fabrication and analysis of nickel microparticle-reinforced composites fabricated using the digital light processing (DLP) technique. A slurry is prepared by incorporating Ni-micro particles into a resin vat; it is thoroughly mixed to achieve homogeneity. Turbidity fluctuations are observed, initially peaking at 50% within the first two minutes of mixing and then stabilizing at 30% after 15–60 min. FTIR spectroscopy with varying Ni wt.% is performed to study the alterations in the composite material’s molecular structure and bonding environment. Spectrophotometric analysis revealed distinctive transmittance signatures at specific wavelengths, particularly within the visible light spectrum, with a notable peak at 532 nm. The effects of printing orientation in the X, Y, and Z axes were also studied. Mechanical properties were computed using tensile strength, surface roughness, and hardness. The results indicate substantial enhancements in the tensile properties, with notable increases of 75.5% in the ultimate tensile strength and 160% in the maximum strain. Minimal alterations in surface roughness and hardness suggest favorable printability. Microscopic examination revealed characteristic fracture patterns in the particulate composite at different values for the wt.% of nickel. The findings demonstrate the potential of DLP-fabricated Ni-reinforced composites for applications demanding enhanced mechanical performance while maintaining favorable printability, paving the way for further exploration in this domain. Full article

In the present work, a metal–matrix composite was casted using the LM13 aluminum alloy, which is most widely used for casting automotive components. Such applications require materials to withstand high operating temperatures and perform reliably without compromising their properties. In this regard, particulate-reinforced composites have gained widespread adaptability. The particulate reinforcements used comprise of one of the widely available industrial by-products. which is fly ash, along with the abundantly available quartz. Hybrid composites are fabricated through the economical liquid route that is widely used in mass production. Though there are numerous published research articles investigating the mechanical properties of metal–matrix composites, very few investigated the thermal properties of the composites. In the present work, thermal properties such as thermal conductivity and thermal diffusivity of cast hybrid composites were evaluated. The particulate reinforcements were added in varied weight percentages to the molten LM13 alloy and were dispersed uniformly using a power-driven stirrer. The melt with the dispersed particulate reinforcements was then poured into a thoroughly dried sand mold, and the melt was allowed to solidify. The quality of the castings was ascertained through density evaluation followed by a microstructural examination. It was found that the composites with only the fly ash particles as a reinforcement were less dense in comparison to the composites cast with the quartz particulate reinforcement. However, the hybrid composite, with both particulate reinforcements were dense. The microstructure revealed a refined grain structure. The thermal diffusivity and thermal conductivity values were lower for the composites cast with only the fly ash reinforcement. On the other hand, the composites cast with only quartz as the particulate reinforcement exhibited higher thermal diffusivity and thermal conductivity. The specific heat capacity was found to be lower for the fly ash-reinforced composites and higher for the quartz-reinforced composites in comparison to the LM13 base matrix alloy. However, the highest value of thermal diffusivity and thermal conductivity were reported for the hybrid composites with a 10 wt.% inclusion of both fly ash and quartz particulate reinforcements. Full article

Mineralized connective tissues represent the hardest materials of human tissues, and polymer based composite materials are widely used to restore damaged tissues. In particular, light activated resins and composites are generally considered as the most popular choice in the restorative dental practice. The first purpose of this study is to investigate novel highly reinforced light activated particulate dental composites. An innovative additive manufacturing technique, based on the extrusion of particle reinforced photo-polymers, has been recently developed for processing composites with a filler fraction (w/w) only up to 10%. The second purpose of this study is to explore the feasibility of 3D printing highly reinforced composites. A variety of composites based on 2,2-bis(acryloyloxymethyl)butyl acrylate and trimethylolpropane triacrylate reinforced with silica, titanium dioxide, and zirconia nanoparticles were designed and investigated through compression tests. The composite showing the highest mechanical properties was processed through the 3D bioplotter AK12 equipped with the Enfis Uno Air LED Engine. The composite showing the highest stiffness and strength was successfully processed through 3D printing, and a four-layer composite scaffold was realized. Mechanical properties of particulate composites can be tailored by modifying the type and amount of the filler fraction. It is possible to process highly reinforced photopolymerizable composite materials using additive manufacturing technologies consisting of 3D fiber deposition through extrusion in conjunction with photo-polymerization. Full article

Metal-reinforced polymer composites are suitable materials for applications requiring special thermal, electrical or magnetic properties. Three-dimensional printing technologies enable these materials to be quickly shaped in any design directly and without the need for expensive moulds. However, processing data correlating specific information on how the metal particles influence the rheological behaviour of such composites is lacking, which has a direct effect on the processability of these composites through melt processing additive manufacturing. This study reports the compounding and characterisation of ABS composites filled with aluminium and copper particulates. Experimental results demonstrated that the tensile modulus increased with the incorporation of metal particles; however, there was also an intense embrittling effect. Mechanical testing and rheological analysis indicated poor affinity between the fillers and matrix, and the volume fraction proved to be a crucial factor for complex viscosity, storage modulus and thermal conductivity. However, a promising set of properties was achieved, paving the way for polymer–metal composites with optimised processability, microstructure and properties in melt processing additive manufacturing. Full article

The aim of this study was to assess adaptation and bonding to root canal dentin of discontinuous (short) glass fiber-reinforced composite to intra-radicular dentin (DSGFRC). Methods: Seventy virgin human teeth were extracted and then endodontically treated; then samples were randomly divided into 7 groups (n = 10), based on the materials’ combinations as follows: Group 1, a two-bottle universal adhesive + DSGFRC; Group 2, a single-component universal adhesive + DSGFRC; Groups 3 and 4, the same materials of Goups 1 and 2 were used but after cleaning of the canal walls with 17% EDTA and final irrigation with 5.25% NaOCl Ultrasound Activated (UA); Group 5, traditional prefabricated fiber posts were luted after being silanized with G-Multi Primer; Groups 6 and 7, like Group 5 but after ultrasonic irrigation (UA). All sample roots were cut 1 mm thick (n = 10) to be evaluated regarding root canal adaptation using a light microscope and scanning electron microscope (SEM) and push-out bond strength. These results were statistically analyzed by Kruskal–Wallis analysis of variance by ranks. The level of significance was set at p < 0.05. Results: Bond strength forces varied between 6.66 and 8.37 MPa and no statistically significant differences were recorded among the groups. By microscopic examination, it was noted that ultrasonic irrigation increased the adaptation of the materials to the dentin surface. Conclusions: Within the limitations of this in vitro study, it may be concluded that when DSGFRC was used for intracanal anchorage in the post-endodontic reconstruction, similar push-out retentive force and strength to those of traditional fiber posts cemented with particulate filler resin composite cements were achieved. Full article

SiC-particulate-reinforced aluminum matrix composites (SiCp/Al MMCs) are widely used in the aerospace field due to their high specific stiffness and strength, low thermal expansion coefficient, and good radiation resistance. In the process of application and promotion, there is a connection problem between the aluminum matrix composites and electronic glass. In this work, the lead-free SiO₂-B₂O₃-Na₂O glass filler was used to seal 65 vol.% SiCp/ZL102 composites and DM305 electronic glass in an atmospheric environment. The effects of the sealing temperature on the properties of the joints were studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Additionally, the causes of defects and the fracture mechanisms of the joints were analyzed. The results showed that the glass filler and base material were connected through a dual mechanism of an Al, Na, Si, and O element diffusion reaction and a mechanical occlusion. At a sealing temperature of 540 °C and a holding time of 30 min, the joint interface was dense and crack-free. Meanwhile, the average shear strength reached 13.0 MPa, and the leakage rate of air tightness was 1 × 10⁻⁹ Pa·m³/s. The brittle fracture features were revealed by the step-like morphology of the fracture, which originated from the brazing seam and propagated into the pore. The crack gradually propagated into the base material on both sides as the fracture area expanded, ultimately resulting in a fracture. Full article

The most important part of the wind turbine is the blade. From existing studies, it has been concluded that most wind turbine blades have a high rate of failure during operation due to fatigue, because of a lack of proper material selection processes. Materials such as fiberglass, wood, aluminum, and steel have been used but have not been able to qualify as sustainable materials. Therefore, this study focuses on the review of existing materials employed for developing metal matrix composites as ecological materials to produce wind blades. This study discusses the application of aluminium, silicon, and magnesium metal matrix alloys and the implementation of agro-waste materials (coconut rice, coconut shell, rice husk ash, and sugar Bagasse ash) and eggshell as reinforcement particulates for metal matrix composites for developing wind blades. The study also reviews the method of production of matrix composites. From the results obtained via the review, it is clear that the application of eggshells assists as a binding element for proper mixture, and the combination of Al–Si–Mg alloy with coconut rice and shell improves the strength of the material, since wind blades need durable materials and ductility due to their aerodynamic shape to convert enough energy from the wind. Full article