Characterization Of Composites Research Articles

A comparative study on the effect of reinforcing boron nitride/alumina in epoxy-based hybrid composite with Millettia pinnata leaf powder and glass sheets: Experimental fabrication, mechanical and micro-structural characterization

The present study focuses on the fabrication and characterization of an innovative epoxy-based hybrid composite, designed to enhance its mechanical properties by incorporating three distinct reinforcing agents that are Millettia pinnata leaf powder, alumina/boron nitride particles, and glass sheets. This hybrid composite aims to combine the individual strengths of alumina/boron nitride particles reinforcements, ultimately achieving a superior material with enhanced mechanical strength. The selection of these reinforcements was based on their unique properties, such as biodegradability and eco-friendliness of Millettia pinnata leaf powder, high strength-to-weight ratio of alumina/boron nitride, and excellent mechanical properties of glass sheets. The optimized weight fraction of each reinforcement was determined through a series of experimental trials to maximize the composite's performance. The characterized thermo-mechanical properties included tensile strength, flexural strength, impact strength, and hardness. Additionally, microstructural analysis was performed using the scanning electron microscopy to examine the interfacial bonding between the matrix and reinforcements, offering insights into the composite's overall integrity. The findings revealed that the incorporation of Millettia pinnata leaf powder, alumina/boron nitride, and glass sheets led to significant improvements in the mechanical properties of this hybrid composite. The composite exhibited enhanced tensile and flexural strength, resulting from the reinforcing effects of alumina and glass sheets. Comparatively, the mechanical properties of boron nitride composites tend to be higher than that of the alumina composites. Maximum tensile strength, flexural strength, impact strength and hardness for the boron nitride composites are 312.21 MPa, 19.53 MPa, 53.68 kJ/m2 and 103.25 HRL, respectively at composition of 6 grams of boron nitride and 6 grams of Millettia pinnata leaf powder; whereas, for the alumina composites these values are 211.84 MPa, 15.46 MPa, 44.12 kJ/m2 and 101.23 HRL at composition of 6 grams of alumina and 6 grams of Millettia pinnata leaf powder. The results reported in this study will be helpful in accelerating the industrial applications of epoxy-based hybrid composites.

Influence of Nb and Mo Substitution on the Structure and Magnetic Properties of a Rapidly Quenched Fe79.4Co5Cu0.6B15 Alloy.

The importance of amorphous and nanocrystalline Fe-based soft magnetic materials is increasing annually. Thus, characterisation of the chemical compositions, alloying additives, and crystal structures is significant for obtaining the appropriate functional properties. The purpose of this work is to present comparative studies on the influence of Nb (1, 2, 3 at.%) and Mo (1, 2, 3 at.%) in Fe substitution on the thermal stability, crystal structure, and magnetic properties of a rapidly quenched Fe79.4Co5Cu0.6B15 alloy. Additional heat treatments in a vacuum (260-640 °C) were performed for all samples based on the crystallisation kinetics. Substantial improvement in thermal stability was achieved with increasing Nb substitution, while this effect was less noticeable for Mo-containing alloys. The heat treatment optimisation process showed that the least lossy states (with a minimum value of coercivity below 10 A/m and high saturation induction up to 1.7 T) were the intermediate state of the relaxed amorphous state and the nanocomposite state of nanocrystals immersed in the amorphous matrix obtained by annealing in the temperature range of 340-360 °C for 20 min. Only for the alloy with the highest thermal stability (Nb = 3%), the α-Fe(Co) nanograin grows, without the co-participation of the hard magnetic Fe3B, in a relatively wide range of annealing temperatures up to 460 °C, where the second local minimum in coercivity and core power losses exists. For the remaining annealed alloys, due to lower thermal stability than the Nb = 3% alloy, the Fe3B phase starts to crystallise at lower annealing temperatures, making an essential contribution to magneto-crystalline anisotropy, thus the substantial increase in coercivity and induction saturation. The air-annealing process tested on the studied alloys for optimal annealing conditions has potential use for this type of material. Additionally, optimally annealed Mo-containing alloys are less lossy materials than Nb-containing alloys in a frequency range up to 400 kHz and magnetic induction up to 0.8 T.

Processing and characterization of porous composites based on CaAl4O7/CaZrO3

According to previous research, CaAl4O7/CaZrO3 composites present good refractoriness, mechanical resistance and low thermal expansion coefficient (good thermal shock resistance), characteristics that insulating materials and lightweight structural components require. In this work, porous ceramics based on CaAl4O7/CaZrO3 were prepared from commercial powder combinations of m-ZrO2, Al(OH)3 and CaCO3. The powder mixture was processed by high-energy milling at different times (from 3 to 24 h). Different composites were obtained by solid state sintering at 1400 °C. The reaction was studied using thermal analysis techniques (TG-DTA), and the crystalline phases were analyzed by X-ray diffraction (XRD) and the Rietveld method. The resulting composites were also characterized. CaAl4O7 and CaZrO3 were the main phases present in these composites, with c-ZrO2 as secondary phase, and some scarce m-ZrO2. Porosity values varied from 54 to 59%, and flexural strengths ranged from 16.5 to 23.6 MPa. The increasing milling time produced an effective particle size reduction that accelerated the reactivity of the starting mixtures and reduced the grain size. The composite obtained by 24 h milling and sintered at 1400 °C (ACZ2414) presented the highest flexural strength and the lowest coefficient of linear thermal expansion. The mean thermal expansion coefficient of CaAl4O7/CaZrO3 composites was ca. 6 10−6 °C −1. This indicated that it is possible to manufacture ceramic bodies with expansion properties comparable to those of mullite, making it a suitable for insulation.

Study of ethylene propylene diene monomer-lead monoxide-magnetite composites in radioactive waste disposal

In this study, ethylene propylene diene monomer (EPDM)-lead monoxide (PbO)-magnetite (Fe3O4) composite was prepared and changes in its properties with different gamma irradiation doses (50, 100, 200, 300, 500, and 1000 kGy) were investigated. Characterizations of irradiated EPDM-metal oxide composites were performed by X-ray Diffractometer (XRD), Field Emission Scanning Electron Microscope (FESEM) and Universal Testing Machine (UTM). It was observed that the synthesized sample shows an amorphous nature beyond the 500 kGy irradiation dose. The FESEM morphographs of irradiated samples show an increase in fracture size with an increase in irradiation dose. The mechanical tests have shown that prepared samples retain their mechanical strength up to ∼100 kGy. In addition, the effect of thermal and electrical properties on irradiation dose has also been studied. The synthesized samples show good thermal stability up to ∼500 kGy. The AC conductivity of the synthesized EPDM-metal oxide composites has been observed to increase slightly with an increase in irradiation dose. It was observed that synthesized EPDM-metal oxide composites are relatively good radiation resistant candidates and can be used for radioactive waste disposal management applications.

Mechanical and morphological characterizations of epoxy composites reinforced with surface modified woven cotton structures using vacuum bagging technique

Woven fabric structures facilitate the mechanical interlacement of textile yarns for increased strength, which leads to more balanced mechanical properties in a composite. This study worked on epoxy matrix composites reinforced with surface-modified cotton fabrics of different woven structures. The composites were fabricated using the resin vacuum bagging technique and mechanically characterized for tensile, three-point bending, and impact properties. Surface modification was conducted by alkali treatment using a 6% concentration of sodium hydroxide (NaOH). The interfacial adhesion of the various fabric structures and epoxy matrix was examined using a scanning electron microscope (SEM). The results obtained show that surface-treated composites yielded improved mechanical properties than untreated composites, with improvements of up to 14.4%, 36.2%, and 26.7% for impact, flexural, and tensile strengths, respectively. The different woven structures also significantly affected the mechanical performance of the composite. The composites of plain, herringbone, and twill woven structures presented better mechanical properties compared to the other woven composite structures in that order. The plain-woven composite structure, respectively, had the maximum impact, flexural, and tensile strengths of 80.03 KJ/mm2, 38.6 MPa, and 43.7 MPa. This was closely followed by the herringbone and twill-woven composite structures. SEM results revealed complete impregnation of fibers and a strong interfacial relationship between the thermoset matrix and the treated cotton fabrics in the composite laminate structures produced via the vacuum bagging technique. In conclusion, the study indicated that different weave structures and fiber surface treatments, as well as the vacuum bagging technique used, are of significant importance in enhancing the overall mechanical performance of woven fabric composites.

Converting polymer-wastes to green nanocomposites in Saudi Arabia: Investigation of fracture parameters (KIc, KIIc, θc, σc) for quality and sustainability evaluation

The intrinsic fracture-parameters including fracture-envelope (KI-KII), fracture-direction (θc) and fracture-load (σc), are predicted experimentally at different crack inclination-angle (β) for each of pure-original polyethylene (HDPE, LDPE) and advanced green-nanocomposite CPNC made of (95%) recycled waste polyethylene (HDPE, LDPE) and (5%) montmorillonite MMT nanoclay NC. These fracture factors represent evaluation of material quality and sustainability. These fracture parameters are investigated experimentally and compared with characterization of microstructure, interfacial-bond, chemical composition, and crystallinity. These parameters are depending on material type, crack type, crack-location, crack-shape, crack-geometry, crack-orientation, crack-dimensions, and loading type. Nanocomposite called clay-based polymer nanocomposite CPNC is produced of recycled polymers with special mixing technique with (5%) surface modified natural nanoclay. Pre-cracked recycled-CPNC, HDPE and LDPE samples are tested with different crack-orientations of central cracks and edge cracks under far-field tension load. Characterizations of microstructure, bond and chemical composition are conducted by SEM and EDAX for investigating the differences between original and recycled materials. The results are compared to each other with detailed discussion showing good results of converting of contaminated waste-materials to valuable advanced green ecofriendly nanocomposite suitable for different fields like medical applications, dental biomaterials for orthodontics, dental-restoration for fracture under caries and occlusal stresses and other industrial applications.

Mechanical characterization of natural hybrid composites for automotive applications

Mechanical characterization of natural hybrid composites for automotive applications

Enhancement of thermal and mechanical properties of polymer composite using a novel milled bamboo filler

AbstractThis work presents the thermal and mechanical characterization of epoxy composites reinforced with different fillers developed by modifying thermo‐mechanically extracted bamboo micron fibers. The modification of bamboo fibers was done by adding carbon nanoparticles to their surface and also by making powdered fillers using the process of ball milling. A decrease in water absorption in case of surface coated bamboo fibers was observed. The glass transition behavior was enhanced for composites filled with milled bamboo fillers as compared to neat epoxy. Better mechanical properties were observed for composites reinforced with milled bamboo fillers compared to that of composites filled with bamboo fibers. The highest tensile strength (90.258 MPa) was observed for composites reinforced with 5 wt% of milled bamboo fillers depicting an increase of 93.01% compared to that of neat epoxy (46.762 MPa).Highlights Bamboo fibers were modified with a sizing agent and carbon nanoparticles. A novel “milled bamboo filler” was produced and incorporated in composites. Thermal properties of epoxy composite were enhanced by the novel filler. Tensile strength of the composite was significantly enhanced. The novel filler has the future scope of application in various composite products.

Synthesis and characterization of biowaste-based porous carbon nanoparticle-polymer dispersed ferroelectric liquid crystal composites

Herein, porous carbon nanoparticles (PCNPs) were synthesized using magnolia champaca seed pods and studied their doping effect on the polymer-dispersed ferroelectric liquid crystal (PDFLC) properties. The effect of PCNPs concentration (≤0.75 wt.%) on the morphology of PDFLC, polarization, and permittivity are investigated in thin sample cells. Field emission scanning electron microscope image results indicate the spherical shape of PCNPs of particle size ∼27 nm diameter. Temperature-dependent electro-optic and dielectric properties are also investigated in the wide SmC* phase and near transition temperature of SmC*-SmA*. Polarising optical microscope textures confirm the non-homogeneity of FLC molecules in the polymer matrix as a function of PCNPs concentration. Thespontaneous polarization and anchoring energy coefficients increase with increasing the doping amount of PCNPs.The phase transition temperature is found unaffected by PCNP doping in all prepared samples. In PDFLC and PCNPs doped PDFLC composites, usualbehaviourof permittivity as a function of temperature is observed. Fluorescence spectra show an enhanced two-fold increase in emission intensity peak at 412 nm wavelength for 0.5 wt.% PCNPs doped PDFLC while concentration-dependent quenching and slight redshift have been observed for the 0.75 wt.% PCNPs doped PDFLC. The enhanced electro-optic and dielectric properties observed in the composites suggest potential applications in displays, sensors, and optical devices. The findings open doors for further exploration and utilization of these functional materials in advanced electronic and photonic technologies.

Tribological Characterization of UHMWPE Composites Reinforced with MoS2 and Graphite: A Comparative Study

This study presents a comprehensive analysis of the microstructural, physical and tribological properties of Ultra-High Molecular Weight Polyethylene (UHMWPE) composites reinforced with micro MoS2 and nano Graphite. Microstructural evaluations through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDAX) reveal intriguing insights into the morphology and elemental composition of the reinforcement materials. SEM images unveil the nanoscale hexagonal lattice structure of nano graphite, affirming its suitability for composite applications. EDAX spectra confirm the purity of both nano graphite and micro MoS2, reinforcing their efficacy as reinforcement agents.Density assessments illustrate an increase in composite density with rising reinforcement percentages for both materials, attributed to their inherently higher densities. This increase in density is complemented by reduced porosity, signifying improved packing efficiency within the composite.Wear evaluations under various load and speed conditions elucidate the tribological behaviour of the composites. UHMWPE composites with micro MoS2 exhibit reduced wear rates, frictional forces, and coefficient of friction (COF) compared to neat UHMWPE, emphasizing the effective lubricating properties of MoS2. Conversely, UHMWPE composites with nano graphite outperform micro MoS2 counterparts across all parameters, showcasing superior wear resistance and friction reduction. This is attributed to nano graphite's lamellar structure, which facilitates enhanced lubrication and reduced friction.

Characterization of Polymeric Composites for Hydrogen Tank.

Carbon neutrality has led to a surge in the popularity of hydrogen tanks in recent years. However, designing high-performance tanks necessitates the precise determination of input material properties. Unfortunately, conventional characterization methods often underestimate these material properties. To address this limitation, the current research introduces alternative designs of ring tensile specimens, which enable accurate and reliable characterization of filament-wound structures. The advantages and disadvantages of these alternative designs are thoroughly discussed, considering both numerical simulations and experimental investigations. Moreover, the proposed ring tensile methods are applied to characterize thermoplastic composites for hydrogen storage tanks. The results indicate that the mechanical strengths and stiffness of carbon fiber-reinforced thermoplastic Elium® 591 composites closely match those of epoxy-based composites. This newfound accuracy in measurement is expected to contribute significantly to the development of recyclable hydrogen tanks.

Damage mechanism characterisation of plain weave ceramic matrix composites under in-plane shear using in-situ X-ray micro-CT and deep-learning-based image segmentation

This paper investigates the microstructure and damage evolution of plain weave ceramic matrix composites under in-plane shear using the in-situ X-ray computed tomography approach. The actual microstructure and damage evolution of material under several successive loading levels have been revealed precisely. A deep-learning-based image segmentation method has been employed to accurately identify material damages, including matrix cracks, delamination, fibre pull-outs and interface debonding. Besides, three-dimensional visual characterisation and quantitative analysis of damage have been carried out to gain a better understanding on the failure mechanisms. For longitudinal tows under shear, the cracks propagate along the loading direction and cause the splitting and sliding failure of tow; For transverse tows under shear, they undergo coupling effects of shear and tension, which results in kink band damage with fibre bridging mechanism. Finally, the connection of longitudinal tow splitting and transverse tow kinking leads to the catastrophic fracture of CMCs under in-plane shear.

Sustainable biobased epoxy thermosets with covalent dynamic imine bonds for green composite development

The widespread use of thermoset composites has raised great environmental and economic awareness, due to the lack of recyclability of the resins and fibres. This work is focused on the development of a sustainable, recyclable and reprocessable epoxy vitrimer by using an epoxidized linseed oil resin and a vanillin derived Schiff base as dynamic hardener. Different epoxy:dynamic hardener ratios have been employed, analyzing its influence in the final physico-chemical properties of the thermoset resin. The reprocessability and the recyclability of the vitrimers have been demonstrated. This work also describes the manufacturing and characterization of greener composites obtained with these vitrimers and flax yarn fibres. A good adhesion between the fibres and the vitrimer is observed. Moreover, the characterization of developed composites indicated that their thermal and mechanical properties allow their use in lightweight engineering applications. Finally, chemical recyclability and compostability of the flax fibre vitrimer-based composite have been demonstrated.

Tribological performance and mechanical behavior of graphite based hybrid composites reinforced with silicon carbide particulate

This study aimed to investigate the mechanical and Tribological Characterization of aluminum metal matrix composites reinforced with silicon carbide particulates ranging from 10% to 20% and five percentage graphite. The metal matrix composites were fabricated using the stir casting technique at temperatures varying from 800 °C to 1000 °C. The Tribological characteristics were evaluated through pin-on-disk tests conducted under dry slipping conditions at room temperature and velocities of 0.979 m/s, using normal pressures ranging from 10 N to 50 N. The worn surfaces were investigated using scanning electron microscopy to elucidate the wear mechanism. Moreover, the study examined the impact of graphite volume fraction and the inclusion of graphite on the mechanical behavior, specifically hardness and tensile strength. The results indicated that the addition of graphite increased the metal matrix composites wear resistance. It was discovered that the wear rate of graphite-reinforced metal matrix composites was lower compared to silicon carbide particulates reinforced composites. Among the silicon carbide particulates reinforced composites, those with a 15% volume fraction demonstrated superior wear resistance, hardness, and tensile strength. The friction coefficients were also raised while the applied load was decreased by the addition of both 15% silicon carbide particulates and 5% graphite.

Development and mechanical characterization of cenosphere-reinforced CFRP and natural rubber core sandwich composite

Driven by the growing concern for environmental sustainability, there is an increasing need to explore innovative approaches for repurposing industrial waste materials. This study focuses on investigating the potential uses and challenges associated with cenosphere, a waste product derived from coal combustion in thermal power plants. Typically regarded as waste, cenosphere offers an opportunity to contribute to sustainability efforts. The objective of this research is to evaluate the influence of cenosphere, a ceramic-rich industrial waste, on the mechanical properties of woven CFRP-Rubber-CFRP (Carbon fibre-reinforced polymers) sandwich composites. The composite specimens were fabricated using the conventional hand lay-up technique, incorporating different weight percentages (5, 10, 15, and 20 wt.%) of cenosphere as a particulate filler. Tensile, flexural, and impact testing were conducted according to ASTM standards to assess the impact of the filler content on the mechanical properties. The results demonstrate that the inclusion of approximately 15% by weight of discarded cenosphere significantly enhances the tensile strength, flexural strength, interlaminar shear strength (ILSS), and impact strength of the sandwich composites, yielding improvements of approximately 1.6, 1.56, 2.06, and 1.85 times, respectively, compared to unfilled composites. Microscopic analysis of the composites reveals a well-dispersed cenosphere distribution within the matrix, contributing to the notable enhancement in overall strength characteristics.

Fabrication and Characterization of Tantalum-Iron Composites for Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen evolution represents a transformative avenue in addressing the challenges of fossil fuels, heralding a renewable and pristine alternative to conventional fossil fuel-driven energy paradigms. Yet, a formidable challenge is crafting a high-efficacy, stable photocatalyst that optimizes solar energy transduction and charge partitioning even under adversarial conditions. Within the scope of this investigation, tantalum-iron heterojunction composites characterized by intricate, discoidal nanostructured materials were meticulously synthesized using a solvothermal-augmented calcination protocol. The X-ray diffraction, coupled with Rietveld refinements delineated the nuanced alterations in phase constitution and structural intricacies engendered by disparate calcination thermal regimes. An exhaustive study encompassing nano-morphology, electronic band attributes, bandgap dynamics, and a rigorous appraisal of their photocatalytic prowess has been executed for the composite array. Intriguingly, the specimen denoted as 1000-1, a heterojunction composite of TaO2/Ta2O5/FeTaO4, manifested an exemplary photocatalytic hydrogen evolution capacity, registering at 51.24 µmol/g, which eclipses its counterpart, 1100-1 (Ta2O5/FeTaO4), by an impressive margin. Such revelations amplify the prospective utility of these tantalum iron matrices, endorsing their candidacy as potent agents for sustainable hydrogen production via photocatalysis.

Artificial neural network accomplished prediction on tribology – A promising procedure to facilitate the tribological characterization of polymer composites

The aim of our investigations was to develop an artificial neural network (ANN) to reliably describe the pv dependence of different hybrid materials with identical basic components but different quantity ratios, and ultimately to explore whether it is possible to predict the effect of different component ratios on the tribological behavior on the basis of a limited number of experiments. For this purpose, the pressure (p) and velocity (v) dependence for five PEEK-based compounds systematically modified in their composition was investigated at different load levels on a block-on-ring tribometer. In parallel, an ANN was designed and optimized using Bayesian optimization. The results of four out of this five materials was used to train a ANN, whereas the Levenberg-Marquardt training algorithm was used as a kernel. This allowed us to describe the pv dependence of friction and wear of these materials in a fine-grained manner and thus evaluate their suitability under different operating conditions. The procedure was performed twice with four different materials.The experimental results of the fifth material in each case, which was not used for training, show very good agreement with the friction and wear properties predicted by the artificial neural network. It is thus shown that the combination of comparatively few experiments and ANN simulations enables a reliable and fine-mesh prediction of the friction and wear behavior of materials in a wide pv load range. Ultimately, the proportions of material components for different pv load ranges can thus be optimized by simulation, which would not be possible in experiments due to time and cost constraints. The comparative evaluation of different materials can be illustrated clearly in so-called tribomaps.

Preparation and Characterization of Wood Composites for Wood Restoration

Given the widespread use of wood-based materials and that these materials are often damaged, an abundance of materials have been developed to repair and restore wood. Most of these materials treat the binder and filler as a single system; however, there is yet to be a system that has all the desired properties of an ideal wood-repair composite. Aiming for the goal of creating an ideal wood filler, this study proposed a wood-repair composite that combined epoxy resins, polyether amines, and poplar wood fibers. The materials were selected to mimic the hydrophobicity of lotus leaves and the strong adhesion of mussel proteins. The properties of the designed wood composites were characterized by various testing methods. The prepared fillers were then used to repair damaged poplar wood panels. The mechanical properties of the wood sample repaired with the optimal filler formulation reached 97% of those of the undamaged wood. In summary, the wood composites proposed in this study present a new means of repairing wooden relics, exposed outdoor wooden buildings, and household panels.

Nanoscale dynamic mechanical analysis on interfaces of biological composites

Biological composites incorporate structural arrays of rigid-elastic reinforcements made of minerals or crystalline biopolymers, which are connected by thin, compliant, and viscoelastic macromolecular matrix material. The near-interface regions of these biological composites grant them energy dissipation capabilities against dynamic mechanical loadings, which promote various biomechanical functions such as impact adsorption, fracture toughness, and mechanical signal filtering. Here, we employ theoretical modeling and finite-element simulations to analyze the mechanical response of the near-interface in biological composites to nanoscale dynamic mechanical analysis (DMA). We identified the dominating load-bearing mechanisms of the near-interface region and employed these insights to introduce simple semi-empirical formulations for approaching the mechanical properties (storage and loss moduli) of the biological composite from the nanoscale DMA results. Our analysis paves the way for the nanomechanical characterization of biological composites in diverse natural materials systems, which can also be employed for bioinspired and biomedical configurations.

Orthotropic viscoelastic characterization of thin woven composites by a combination of experimental and numerical methods

Electric mobility is the driving force for the development of power electronic devices embedded in printed circuit boards (PCBs). Fast charge of batteries generates large increase of temperature in PCBs. Therefore, the characterization of the thermo-viscoelastic behavior of laminates is a necessity. Tests have been conducted at elevated temperature, with a specific attention to minimize the oxidation of the material. To model precisely the viscoelastic response of the laminate, since pure resin samples are usually not available, an inverse method based on the comparison of experimental results and finite elements simulations is proposed. Periodic boundary conditions allowing to apply uniaxial tension with an arbitrary orientation are developed. In order to validate this method, resin samples are extracted from pre-impregnated material and tested under the same temperature conditions. In a last step, the cyclic response of a buried hole in a PCB is simulated by finite element calculations, using the identified material data. For large maximum temperature, substantial differences are highlighted between thermo-elastic and thermo-viscoelastic approaches in terms of accumulated plastic strain in the copper barrel. The present work opens new possibilities to model the lifetime of electronic devices facing temperature excursions ranging over the glass transition temperature.