Composite Material Samples Research Articles

PREPARATION AND THERMOELECTRIC PROPERTIES OF Cux/Bi2Te3 COMPOSITES

Thermoelectric materials are the use of solid internal carriers to realize mutual conversion between thermal energy to electrical energy. Bismuth telluride (Bi<sub>2</sub>Te<sub>3</sub>) based thermoelectric materials are relatively mature near low temperatures. Due to the excellent conductivity of copper, the method of combining copper with a thermoelectric matrix to produce thermoelectric composite materials with better thermoelectric properties has always been a research focus in thermoelectric composite materials. Bismuth telluride thermoelectric composite materials (Cu<sub>x</sub>/Bi<sub>2</sub>Te<sub>3</sub>) samples with different mass percentages of purity (Cu) powder were prepared by spark plasma sintering (SPS) method. The influences of the Cu with different incorporation ratios on the performance of Cu<sub>x</sub>/Bi<sub>2</sub>Te<sub>3</sub> thermoelectric composites were investigated, such as differential thermal conductivity, thermal conductivity, Seeback coefficient, and ZT values. The Cu<sub>x</sub>/Bi<sub>2</sub>Te<sub>3</sub> thermoelectric composites with Cu chemical composition of 0.005 exhibited excellent Seebeck coefficients and ZT value at the heat source temperature of 325 K. The values are -289.46 μV/K and 1.69, respectively. The value of ZT is improved by about 2 times, compared with Bismuth telluride Bi<sub>2</sub>Te<sub>3</sub> thermoelectric materials.

PLASMA DISCHARGE IN LIQUID MEDIA UNDER THE EFFECT OF ULTRASOUND FOR THE SYNTHESIS OF FILLERS FOR POLYMER COMPOSITES WITH ENHANCED MECHANICAL STRENGTH AND GAS PERMEABILITY

Zinc oxide nanoparticles were synthesized using a plasma discharge method under the effect of ultrasonic cavitation, and films of a polymer composite material were obtained and studied. Comparatively, the mixture of zinc oxide nanoparticles with planar graphene oxide nanostructures were also used as a filler. Using melt compounding technology, composite materials were obtained in the form of thin films consisting of the copolymer of ethylene and vinyl acetate and nanoparticles of zinc oxide and graphene oxide. The obtained samples of composite materials were examined by X-ray phase analysis, X-ray fluorescence analysis, and scanning electron microscopy. The physical, mechanical, and gas transport properties of composite films made of polymers filled with nanoparticles were studied: permeability measurements were carried out for carbon dioxide and helium gases.

ELASTIC AND STRENGTH PARAMETERS DETERMINATION OF POLYMER COMPOSITE MATERIALS AND CYLINDRICAL SHELLS

The article presents a method for layout optimization in polymer composite materials that allows to assess their strength. In order to assess the stress-strain state of each layer, an orthotropic elasticity model is used assuming that the fibers in the material are parallel. The behavior model of polymer composite materials is based on the Hashin criterion, which makes it possible to separate the destruction mechanisms of matrix and fiber. The strength assessment was carried out in accordance with the structural approach involving studying the strength of each layer separately. The parameters of the deformation model and the Hashin strength criterion were determined based on the results of testing. Tests were carried out on unidirectional polymer composite materials samples cut at angles of 0, 90 and 45° to the direction of reinforcement. The verification was based on the results of bending tests of polymer composite materials samples. Verification showed high proximity between the calculation results and the experimental data. A method for selecting the layout angles of each layer of polymer composite materials has been developed making it possible to calculate the greatest strength of the cylindrical shell under various external loads. The method involves determining the stresses in each of the polymer composite materials layers, as well as Hashin indicators corresponding to the destruction of the fiber or matrix under tension or compression. Based on the indicator values, the optimal angle and layout pattern can be selected, providing the greatest margin of safety for the shell. This method allows for a preliminary assessment of the safety factor of cylindrical shells made of polymer composite materials based on the experimentally determined elastic parameters of the material and the parameters of the Hashin strength criterion. The method takes into account the angle and layout of the prepreg under the influence of internal pressure, axial compressive force and torque.

Magnetic Resonance Imaging Study of Water Absorption of Polymer Composite Materials Subjected to Mechanical and Temperature Impact

The results of a study of water absorption processes by samples of polymer composite materials(PCMs) based on fiberglass, subjected to low-speed impact with controlled impact energy and alternatingtemperature cycling are presented. Using magnetic resonance imaging (MRI), the distribution of absorbedwater in the fiberglass structure is visualized and the dynamics of its accumulation in various areas of the sampleare studied. It is found that mechanical impact leads to a nonuniform distribution of the absorbed waterin the samples and a significant accumulation of free water in the areas of destruction and adjacent layers inthe event of a violation of the integrity of the outer layer of the material. It is shown that cyclic alternatingtemperature effects do not lead to a noticeable change in the water absorption processes and are comparablein effect to mechanical nondestructive effects. The results obtained using MRI are in close agreement withthe data of traditional weight measurements, which shows the effectiveness of the method in diagnosingdefects and mechanical damage to PCMs exposed to the aquatic environment.

Prediction of mechanical properties of dental composite materials using machine learning algorithms

AbstractThe durability of dental materials, when used in the mouth, is determined by their mechanical qualities. Composite resins are frequently used in dental restorations. Flexural tests and Vickers micro‐hardness tests on selected dental composite materials were performed in a universal testing machine (ASTM D790‐10 standard) and Vickers micro‐hardness tester (ASTM E384‐11e1standard). In this study, four different dental composite material samples are employed. The samples are dipped in a chewing tobacco solution for a few days before being removed and put through the tests. Also in this work, four different machine learning models were tested to see how well they could analyze the mechanical characteristics of dental composite materials when submerged in a chewing tobacco solution. For predicting the mechanical properties of dental composite specimens, four distinct machine‐learning models (extreme gradient boosting (XGBoost), adaptive boosting (AdaBoost), random forest, and k‐nearest neighbors (KNN) have been selected. AdaBoost machine learning model yields a coefficient of regression value of 0.9903 in predicting the flexural strength, whereas the XGBoost model gives a coefficient of regression value of 0.9890 in predicting the Vickers hardness distinctly better than the other models.

Biocompatibility and antibacterial activity of MgO/Ca3(PO4)2 composite ceramic scaffold based on vat photopolymerization technology

Recent advancements in medical technology and increased interdisciplinary research have facilitated the development of the field of medical engineering. Specifically, in bone repair, researchers and potential users have placed greater demands on orthopedic implants regarding their biocompatibility, degradation rates, antibacterial properties, and other aspects. In response, our team developed composite ceramic samples using degradable materials calcium phosphate and magnesium oxide through the vat photopolymerization (VP) technique. The calcium phosphate content in each sample was, respectively, 80 %, 60 %, 40 %, and 20 %. To explore the relationship between the biocompatibility, antibacterial activity, and MgO content of the samples, we cultured them with osteoblasts (MC3T3-E1), Escherichia coli (a gram-negative bacterium), and Staphylococcus aureus (a gram-positive bacterium). Our results demonstrate that as the MgO content of the sample increases, its biocompatibility improves but its antibacterial activity decreases. Regarding the composite material samples, the 20 % calcium phosphate content group exhibited the best biocompatibility. However, after 0.5 h of co-cultivation, the antibacterial rates of all groups except the 20 % calcium phosphate content group co-cultured with S. aureus exceed 80 %. Furthermore, after 3 h, the antibacterial rates against E. coli exceed 95 % in all groups. This is because higher levels of MgO correspond to lower pH values and Mg2+ concentrations in the cell and bacterial culture solutions, which ultimately promote cell and bacterial proliferation. This elevates the biocompatibility of the samples, albeit at the expense of their antimicrobial efficacy. Thus, modulating the MgO content in the composite ceramic samples provides a strategy to develop gradient composite scaffolds for better control of their biocompatibility and antibacterial performance during different stages of bone regeneration.

Application of Organosilicon Modifier Based on Tetraethoxysilane for the Production of Heat-Resistant Chrysotile Fibers and Reinforced Cement Composites

This research is aimed at obtaining boron-containing nanotubular chrysotile fibers with increased neutron absorption capacity. The possibility of using an organosilicon modifier based on tetraethoxysilane to increase the hydrothermal stability of chrysotile, as well as the strength of nanoreinforced composites based on a cement binder is considered. The mechanisms for the synthesis of heat-resistant nanotubular fibers of the composition Mg6(OH)8SiB4O10, which have a chrysotile structure, have been established. To increase the hydrothermal stability of chrysotile, crystalline hydrate phases were localized inside nanotubes using amorphous silica formed as a result of hydrolysis of silicon alkoxide under hydrothermal conditions in an alkaline environment. The modification of chrysotile via amorphous silica increases its hydrothermal stability by 97 °C. It is shown that the introduction of an organosilicon modifier based on tetraethoxysilane into the composition of Portland cement composite material leads to an increase in the structural strength and density of the composite due to the activation of silicate formation processes in the cement matrix, especially under hydrothermal conditions. The experiments showed that the strength of silicon alkoxide-modified samples of composite material increased by 34%.

Influence of thermomechanical treatment on the formation of the structure in dispersed-reinforced aluminum alloy-based metal composite materials

The study explored various facets of the structure of dispersed-reinforced aluminum alloy-based metal composite material (MCM) under different modes of thermomechanical treatment. Replacing traditional structural materials with MCM provides manufacturers with an opportunity to achieve higher levels of engineering superiority. The ability to choose composition, modify primary component ratios, and employ a range of MCM manufacturing techniques allows for precise tuning of the material's strength, rigidity, temperature range, and other physical and mechanical properties. Two prevalent technologies for crafting dispersed-reinforced aluminum alloy-based MCM exist: liquid-phase and powder technologies. Liquid-phase methodology entails merging the reinforcing component into the binder alloy's melt, followed by crystallization. This process guarantees the dispersion and fixation of reinforcing particles within the binder volume. In contrast, powder technology involves simultaneous processing of primary component powders in high-energy mills, with subsequent amalgamation of the resultant composite granules via pressure molding. The chief aim of thermomechanical treatment lies in yielding blanks that closely mimic the final product's geometry and reshaping the deformable material's structure to heighten its strength properties. Powder technology was employed to fabricate monolithic composite material samples. Their structures were analyzed, accompanied by tests to ascertain density and strength parameters of the MCM at room temperature. Consequently, dispersed-reinforced aluminum alloy-based MCM possessing a uniform structure, density exceeding 99.0 % of the theoretical value, and elevated mechanical attributes: σu = 300÷305 MPa and E = 87÷95 GPa, were successfully produced.

Color stability of composite materials to food colorants: A laboratory study

BACKGROUND: Maintaining the esthetic characteristics of direct composite restorations for a long time is relevant. The color stability of food colorants is an important esthetic characteristic of a composite material. Comparative information about the color stability of modern composite restorative materials and recommendations based on optimal clinical results for direct composite restoration are of interest.
 AIM: To compare the color stability of modern composite restorative materials with the most common food colorants in laboratory conditions.
 MATERIALS AND METHODS: The color stability of modern restorative materials, namely, Restavrin (Technodent, Russia), GrandioSO (VOCO, Germany), Harmonize (Kerr, USA), Charisma Classic (Kulzer, Germany), Filtek Z250 (3M, USA/Germany), and Estelite Asteria (Tokuyama, Japan), were assessed. Black coffee, black tea, carbonated soft drink cola, dry red wine, and cognac were used as coloring solutions. The samples were exposed for 14 days, and the temperature was 37 C. The control solution was distilled water. Vita Easyshade Advance 4.0 spectrophotometer was used. The average deviation of the color of the studied samples from the reference indicators (∆E), total color stability of the studied materials ( ∆Em), and coloring potential of different coloring solutions in relation to composite materials ( ∆Ec) were determined.
 RESULTS: The deviation of the color of the studied samples of composite materials from the reference indicators (∆Е) depending on the coloring solution was assessed. The total color stability of the studied materials in relation to food colorants ( ∆Em) as this characteristic deteriorates was as follows: Estelite Asteria, 8.640.08; Harmonize, 10.300.14; Restavrin, 12.300.12; GrandioSO, 12.960.10; Charisma Classic, 13.940.14; and Filtek Z250,15.820.15. The most aggressive food colorants with respect to composite restorative materials were black coffee ( ∆Ec=20.080.12), dry red wine ( ∆Ec=19.180.10), and black tea ( ∆Ec=18.54 0.15).
 CONCLUSION: Information about the color stability of composite materials in relation to food colorants allows planning the restoration of teeth located in an esthetically significant area, taking into account the eating habits of patients.

Problem of the Boundary Control of Oscillations of a Sample of a Layered Two-Phase Composite Material

Problem of the Boundary Control of Oscillations of a Sample of a Layered Two-Phase Composite Material

PROJECT MANAGEMENT APPLIED FOR COMPOSITE MATERIALS USED IN AERONAUTICS. CARBON FIBER AND NANO-ADDITIVES

This paper presents the results of theoretical and applied research related to composite materials, carbon fiber and nano-additives. The objective of this work is to investigate the properties and behavior of custom designed composite materials which are intended for applications in aerospace engineering. The holistic approach is expressed by the structure of this research project which consists of the technical part and the economic part, that is analyzed in terms of project management. The specificity of the work is given by the requirements of the European Project Semester EPS, where international teams of students actively experience a multidisciplinary and multicultural project for one semester in another university, which has developed research and industrial partnerships. For developing such project, the approach provided by INCAS as Research Partner is oriented towards Problem Based Learning and Project Organized Learning. The University as Organizer provides Project Related Courses and some complementary Project Organized Learning. The research was oriented towards the customized design and analyzing of composite materials samples for potential use in aerospace engineering, the development and validation of materials and methodologies. The benefits of the research project are related to the applications of composite materials and in the subsidiary to allow the students learn valuable professional lessons and experience from this research project.

Problem of the Boundary Control of Oscillations of a Sample of a Layered Two-Phase Composite Material

We consider the problem of the boundary control of one-dimensional oscillations of an effective (averaged) medium corresponding to a two-phase medium consisting of periodically alternating layers of elastic and viscoelastic materials with long-term memory or various viscoelastic materials with Kelvin–Voigt friction and long-term memory. The averaged model is described by a boundary value problem for an integrodifferential equation. It is shown that for this model, it is impossible to bring oscillations to a state of rest in finite time (in contrast to the equation of string oscillations) by a force acting at one end of the band. A hypothesis is formulated on the possibility of bringing the specified object to a state of rest with the help of force effects distributed along the entire length of the object.

Получение полимерных композиционных материалов на основе наночастиц оксида цинка, синтезированных в плазменном разряде под действием ультразвука

Zinc oxide nanoparticles were synthesized and samples of films of polymer composite materials on their basis were obtained and studied. Zinc oxide nanoparticles were synthesized in a plasma discharge under the action of ultrasonic cavitation. To create composites with a homogeneous distribution of nanoparticles, solution technology was used, and then melt compounding technology. Composite materials based on a copolymer of polyethylene and vinyl acetate and zinc oxide nanoparticles were obtained, and not sonicated and sonicated nanoparticles were used. The obtained samples of composite materials were studied by X-ray phase analysis, X-ray fluorescence analysis and scanning electron microscopy. It was shown that there are differences between the samples: in the case of nanoparticles without ultrasonic treatment, the particles are more strongly aggregated inside the composite material and their average size is visually larger than in the case of a sample with nanoparticles subjected to ultrasonic treatment.

A micromechanical model of multi-scale nano-reinforced composites

Nano-reinforced composites have a wide range of useful applications thanks to their exceptional all-encompassing characteristics. Understanding the micromechanical model and the reinforcing process in nano-composites is crucial for a quantitative assessment of the reinforcement impact of nano-fillers and performance optimization. The original micromechanical model for common composite materials is no longer applicable since mechanical modeling of composite materials takes into consideration variables like multi-scale, multi-phase, and multi-morphology. The multi-scale parameter equivalent modeling theory of nano-reinforced composites is examined in this work. It is suggested to use a generalized modified Halpin-Tsai micromechanical model, which may accommodate any reinforcement form, size, or orientation, after theoretical and experimental comparison and verification. A tiny sample of the nano-reinforced composite material's mechanical tensile characteristics was examined, and its microscopic.

Processing composite materials with lasers

Composite materials, consisting of fibers and binders of natural and artificial origin, are increasingly used in various fields of industry. Processing of the obtained materials into finished forms is often difficult and expensive. Treatment of composite materials, such as milling, cutting, or grinding, is currently dominant.At present, lasers are increasingly used in production processes. It should be noted that modern industrial production is unthinkable without the use of laser equipment. However, when using lasers, initial adjustment of their laser parameters is required for optimal material processing. When considering different lasers and materials to be processed, the setting parameters are different and the obtained processing quality is varied.In the research, samples of composite materials have been made, consisting of epoxy resin as a binder and hemp, flax, and carbon fibers as reinforcing materials. The obtained composite materials have been studied with fiber laser for their processing quality.

Investigating the Microstructure, Tensile Strength, and Acidic Corrosion Behaviour of Liquid Metal Stir Casted Aluminium-Silicon Carbide Composite

The main objective of this investigation is to study the microstructural features and evaluate the tensile strength, hardness, and acidic corrosion resistance of liquid metal stir casted aluminium-silicon carbide (Al-SiC) composite. As reinforcement for the Al alloy matrix, SiC particles were added to the matrix in the percentages of 0%, 10%, and 20%. The microstructure of Al-SiC composite was studied using optical microscope. The effect of addition of SiC particles on tensile strength and hardness of Al-SiC composite was analyzed.. There were significant improvements in tensile strength and hardness for Al–SiC composite reinforced with 20% SiC particles compared to unreinforced Al–SiC composite, and those improvements were of 14.70% and 26.88%, respectively. The evolution of harder SiC islands in the ductile matrix of aluminium alloy reinforce the Al-SiC composite which enhances the strength and hardness of Al-SiC composite. A weight loss method was used to determine corrosion rate. The samples of Al-SiC composite material were immersed in HCl, HNO3, and H2SO4 solutions for immersion times of 30 hours, 56 hours, and 80 hours. It was found that the weight % of reinforcement had the largest contribution to corrosion rate with 49.86% to that of acidic solution with 29.88%, followed by immersion time with 8.85% and acidic solution with a contribution of 29.88% to the corrosion rate. The Al-SiC composite developed using 20 wt. % of SiC particles showed higher corrosion rate due to the interfacial region formed due to the addition of greater wt % SiC particles to the pure alloy.

STUDY OF STRENGTH CHARACTERISTICS AND RADIATION-PROTECTIVE PROPERTIES OF POLYSTYRENE TUNGSTEN COMPOSITE MATERIALS

Samples of composite materials are made of polystyrene, which is reinforced with dispersed aluminum. The radiation protective additive was powdered tungsten or powdered steel. The tensile strength, for these samples of composites, was investigated. The tensile strength value was obtained at various temperatures. It has been found that the ultimate strength of composites increases with an increase in the metal component. Composites with different component compositions were studied. The relative attenuation of the absorbed dose of gamma radiation by these composite materials has been calculated. Composites were with different mass composition. The code of Geant4 v 4.9.6p03 applied for calculations. It is got, that experimental results coincide with calculation results.

Structure Formation Processes During Explosive Welding of Copper and Molybdenum: A Research Study

The present study investigates samples of Cu-Mo composite material produced through explosive welding. The microhardness of these samples is measured and their structures are analyzed using optical and electron microscopy methods. Copper and molybdenum regions are mapped at the Cu-Mo boundary. The analysis reveals a complex fractal line and dark areas at this boundary, indicating the formation of a new phase.
 Microhardness measurements indicate that the hardness of both copper and molybdenum increases in comparison to standard values for annealed samples of copper and molybdenum, respectively. Furthermore, the hardness of molybdenum increases at the interface with copper, which may also suggest the formation of a new phase.
 The electron microscopy analysis and mapping of copper and molybdenum regions at the Cu-Mo interface confirm the presence of a new phase, which is referred to as "forced eutectic." This is because copper and molybdenum do not typically form solid solutions, eutectics, or intermetallic compounds under equilibrium conditions. The new phase exists only under nonequilibrium conditions.

Development of nano titania/polyvinylidene fluoride composite from new titanium(IV) derivative and its investigation on antibacterial, BSA interaction and cytotoxicity

A new heteroleptic complex of titanium(IV) has been synthesised and characterized by physico-chemical techniques. Complex [(C36H30N4O4)Ti] 2a, was obtained by treating Ti(OPri)4 with a new modifier bidentate ligand 1a (C24H20N2O2) as well as with 8-hydroxy quinoline in 1:1:2 stoichiometry in anhydrous benzene. The 2a was employed as a precursor for the synthesis of active rutile phase nano titania by sol-gel method. Nano TiO2 was embedded with PVDF to obtain a set of three TiO2/PVDF samples of composite materials in diverse compositions (30 wt%, 40 wt% and 50 wt%). Ligand 1a, titanium(IV) derivative 2a, nano titania and trio samples of TiO2/PVDF composites were subjected for antibacterial studies against four infective microbial strains such as Bacillus cereus, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa by well diffusion technique. The 50 wt%-TiO2/PVDF composite material exhibited efficient antibacterial activity against all four pathogens. Protein binding interaction of Bovine Serum Albumin (BSA) with the third sample of composite material was performed and the cytotoxicity of the same composite was also tested against HeLa and HT- 29 tumor cell lines and was evaluated by MTT assay. The IC50 values of 50 wt%-TiO2/PVDF were observed as 35.72 µg/ml and 39.42 µg/ml on HeLa and HT-29 cell lines, respectively.

Prediction of wear of dental composite materials using machine learning algorithms

Since dental materials are worn down over time and eventually need to be replaced. Resin composites are frequently employed as dental restorative materials. By employing the in-vitro test findings of the pin-on-disc tribometer [ASTM G99-04], the goal of this study is to evaluate the capability of three different machine learning (ML) models in analyzing the wear of dental composite materials when immersed in chewable tobacco solution. Four distinct dental composite material samples are used in this investigation, and after being dipped in a chewing tobacco solution for a few days, the samples are taken out and subjected to a wear test. Three different ML models (MLP, KNN, XGBoost) have been chosen for predicting the wear of dental composite specimens. XGBoost ML model yields an R 2 value of 0.9996 and it performs noticeably better than the other approaches.