Mechanical Characteristics Of Composites Research Articles

Effect of brass slag particles on the microstructure and hardness of Al-Si alloy matrix composites

The current study investigated the effects of brass slag particles on the microstructure and hardness of Al-Si alloy (LM30) matrix composite. Stir casting was used to fabricate a composite with brass slag particles of finesize (i.e. 100–215 μm), coarse size(i.e. 215–350 μm) and three different concentrations of 3 wt%, 6 wt%, and 9 wt%. The dynamic shear force generated by stirring prevents brass slag particles from sinking into the melt which result in uniform particle dispersion throughout the melt. Optical microscopy analysis reveals a uniform distribution of reinforcement particles in cast composites, accompanied by silicon refinement. The findings suggest that the incorporation of industrial waste (brass slag as a reinforcement) in the fabrication process enhances microstructure and mechanical characteristics of composites. 9 wt% concentration of brass slag reinforced of fine size composite demonstrated an impressive ∼60.7% improvement in hardness compared to base alloy (LM30). It was also observed that theoretical density (ρth) and experimental densities (ρex) approximately 25% and 18.4% greater than that of the base alloy (LM30).

Impact of proximity of hard and soft segment on IR frequency of carbamate links correlating the mechanical properties of surface-functionalized fly ash–reinforced polyurethane composites

Abstract Polyurethane composites synthesized by interaction of fly ash filler with polyether polyol, cross-linking agent, and curing agent in a certain ratio. The study’s findings show that the mechanical properties of polyurethane composite are lowered by the hydroxyl moieties of surface-functionalized fly ash that are chemically or physically linked. The study also reveals that prior subjecting the samples of surface-functionalized fly ash–reinforced polyurethane composite material for destructive analysis by UTM for evaluating mechanical properties. The in-depth study of the IR spectroscopy data of the composites is done focusing onto the stretching frequency of carbonyl group of carbamate links the trend in mechanical behavior of the samples, the number of fly ash–carbamate links, and proximity of HS–SS (hard segment–soft segment) of fly ash–reinforced polyurethane composites can be foretold. By a detailed analysis of the patterns of carbonyl stretching frequencies of carbamate links, one can gain insight into the microphasic level of the separation and proximity of hard and soft segments in composites, which govern their mechanical properties. The relationships between carbamate carbonyl stretching frequencies and mechanical characteristics of composites have been found to be inversely correlated. In order to offset the excess hydroxyl group contribution due to OH-loaded fly ash, as indicated by the isocyanate (NCO) peak intensity (2,240–2,280 cm−1) in the composite’s infrared spectra, the studies were conducted at a higher index ratio (1.64).

High Dk and ultra-high thermal conductivity ST/μBN/polyolefin composites for microwave applications

In this work, we examined the structure, microwave dielectric, thermal and mechanical characteristics of composites containing SrTiO3/xμBN/polyolefin (with x at 0, 6, 8, 10 and 12 weight percent). SrTiO3 (ST) and micro boron nitride (μBN) powders were fabricated with 1,2-PB/EPDM/SBS (1,2-PB, EPDM and SBS are abbreviations of 1,2-polybutadienes, ethylene-propylene-dicyclopentadiene and styrene-butadiene-styrene triblock copolymer, respectively) by hot-press process after modified by Vinyltrimethoxysilane (VTMS) and 3-aminopropyltriethoxysilane (KH550), respectively. The ball mill and surface modification procedure enhanced the dispersion of the boron nitride in the solution and promoted compatibility between ceramic particles and polyolefin matrix. The incorporation of BN created more effective boron transfer pathways with ST particles, significantly improving the thermal conductivity of the composite. However, as μBN content increased, more ceramic agglomerates and pores were introduced, deteriorating dielectric, thermal and mechanical properties of the samples. The particle size test and XPS were conducted to determine the effect of surface modification on the dispersion and surface properties of ceramics. Cross-plane thermal conductivity, TGA and stress-strain curves were used to evaluate the thermal and mechanical properties of the composites. In all, a composite with high-Dk and high thermal conductivity was obtained when x = 10 wt.%: Dk = 17.4, Df = 0.0071 and λ = 1.784 W/(m*k), which is promising for microwave applications.

Effect of Glass Fiber Reinforcement on the Mechanical Properties of Polyester Composites

Introduction. Glass fibers significantly improve the quality of composite materials, make them lighter, stronger, more corrosion resistant and thermally stable. Strengths and weaknesses of specific composites are actively discussed in the scientific and applied literature. At the same time, the effect of the ratio of fibers and matrix material on the mechanical characteristics of composites has not been sufficiently investigated. The presented study is intended to fill this gap. The work is aimed at manufacturing a composite material on a polymer basis reinforced with glass fiber, and investigating the influence of weight ratios of elements on the mechanical characteristics of the composite. For the first time, a report on the comparison of the characteristics of composites (with different fiber content) to each other and to steel is published.Materials and Methods. Fiberglass and polyester were used as starting materials with the addition of a mediator to speed up the molding process. The samples were made manually and tested for tensile strength, hardness, and impact strength using standard equipment. The results were summarized in the form of tables, visualized in the form of graphs, and processed by comparative analysis.Results. The technique of creating samples and methods of their testing were described. The research showed that hardness, tensile strength and impact resistance increased with a growth in the percentage of randomly distributed fiberglass to 50% with 50% unsaturated polyester. In this case, the maximum values of tensile strength — 175.4 MPa, hardness — 38 HV and impact resistance — 1.56 J/mm2 were obtained. The inexpediency of exceeding the proportion of fiberglass by more than 50% was experimentally proven, since mechanical properties deteriorated. This was due, in particular, to the fragility of the glass, which, if the proportions were violated, was transmitted to the entire composite. In addition, with an excessively high volume of reinforcing fibers, the resin was not enough for high-quality bonding of the elements, which significantly reduced the strength of the material. Most of the mechanical characteristics of a composite made of 50% polyester and 50% fiberglass are better than those of steel.Discussion and Conclusion. It has been proved that the properties of the composite material depend significantly on the glass fiber content. The resulting composite was compared to steel. It turned out that it had better mechanical characteristics and less weight. This allows us to recommend the material for boat hulls.

Experimental investigations on mechanical properties of sisal and coir fiber reinforced hybrid bio composites

Nowadays, natural fibres have emerged as a new category of material, gradually displacing synthetic fibres in a variety of contexts. Synthetic fibres have the potential to lower the price of hybrid composites while enhancing their use with natural fibres. Coir and sisal fibres were used to create the hybrid composites in this investigation. Epoxy LY556 and Hardener HY951 were used in a hand lay-up process to create composites with alternating stacks of coir and sisal fibres. The produced composites were tested in accordance with the ASTM standards for tensile strength, flexural strength, impact strength, compression strength, water absorption, and biodegradability. The mechanical characteristics of composites were shown to be significantly influenced by the orientation of the fibres through experimentation. When compared to their angle-ply and cross-ply equivalents, unidirectional hybrid composites prove to be the superior material. Flexural and impact characteristics of hybrid composites are greatly affected by the hand lay-up method, whereas tensile strength and water absorption % are unaffected. These hybrid composites have shown promise as a lightweight load-bearing structural material, and this is something that should be noted.

Dynamic mechanical and thermal properties of Flax/bio-phenolic/epoxy reinforced hybrid composites

ObjectivesThe influence of flax fibre loading on the dynamic thermal and mechanical characteristics of composites was investigated in this work. MethodsFlax composites were fabricated at 30 (F-30), 40(F-40) and 50(F-50) wt% fibre loading. As a control, a bio-phenolic/epoxy polymer blend (P-20) containing 20% bio-phenolic was made. ResultsThe findings suggest that the incorporation of flax into the composites led to an enhancement in the dynamic mechanical properties of the experimental sample. The glass transition temperature (Tg) was identified via dynamic mechanical analysis to be between 60 °C and 85 °C. Aside from that, the cole–cole plot revealed a heterogeneous mixture of fabricated samples, with strong fibre-to-matrix adhesion. Thermogravimetric analysis (TGA) showed adding flax to the composite reduces thermal stability. ConclusionsWith the integration of flax as reinforcement, it could be asserted that the composites' dynamic mechanical properties improved while their thermal stability reduced.

Structure and Mechanical Characteristics of Composites with High Damping Properties

Structure and Mechanical Characteristics of Composites with High Damping Properties

Effect of Boron Carbide Particles Addition on the Mechanical and Wear Behavior of Aluminium Alloy Composites

In this research, synthesis and assessment of the mechanical and wear possessions of Al7049-nano B4C composites are determined by experiments. Using the liquid metallurgy route, a stir casting technique was used to create composites with increasing concentrations of nano B4C from 3 to 9 weight %. Each composite’s reinforcement particles were heated to 400 degrees Celsius before being added to the molten Al7049 alloy in two separate steps, i.e., two-stage stir casting to optimise wettability and distribution. Scanning electron microscopy (SEM) was utilised to examine the microstructure, and energy dispersive spectroscopy (EDS) was utilised to determine the elemental make-up. Mechanical characteristics of composites were determined by subjecting them to tensile, compression, and hardness tests. Wear tests were conducted as per ASTM G99 standards with varying loads and speeds. Nanosized B4C particles were found to be dispersed throughout the sample space in a microstructural analysis. Hardness, ultimate strength, yield strength, and compression strength of Al7049 alloy composites were found to increase significantly as the weight percentage of nano B4C was increased. Additionally, compared to the unreinforced form, the ductility of the Al7049 alloy composites was slightly reduced. SEM micrographs of tensile-fractured specimens were used for research into the field of tensile fractography. Nano B4C reinforced composites exhibited superior wear resistance as compared to Al7049 alloy. These prepared composites can be used for wing root fitting of an aircraft.

Comparative analysis of methods for calculating the physico-mechanical characteristics of multi-layered composite materials

The paper presents a comparative analysis of methods and results of calculating the physical and mechanical characteristics of single-layered and multi-layered polymer composite materials (PCM). The object of the study is a polymer composite which consists of epoxy binder and carbon fiber reinforcements. The principle of multiscale modelling is applied to determine the physical and mechanical characteristics of the composite. Within the framework of this study, a representative volume element (RVE), the structure of which corresponds the characteristics of real materials, is used. The initial data for the calculation in this case are physical and mechanical characteristics of anisotropic fibers (carbon fabric) and an isotropic binder, as well as the geometric model of the RVE. As a result of the calculation, the effective characteristics of a quasi-homogeneous anisotropic material suitable for numerical analysis of the composite structures are determined. A comparison of the results of determining the physical and mechanical characteristics of the polymer composite using ANSYS Material Designer and MSC Digimat software packages for various size of RVE model is carried out and ANSYS Workbench software is also used to perform the stress-strain conditions of RVE model to determine the physico-mechanical characteristics of polymer composites.

Fabrication and properties valuation of Natural fiber and filler-based hybrid-polymer composites

Because of biodegradability, low weight, non-da000nger, instability, decreased condition, contamination, little effort, and simplicity of recyclability, natural fibre polymer composites are now being utilized in place of synthetic fibre reinforced polymer composites. By altering the fibre and epoxy percentages, to find the effect of sisal fibre content on mechanical characteristics of composites is the objective of research. Melt-mixing was used to make the composite, which was then laid out by hand layup method. The purpose of this research is to look at fibre oriented reinforced composite polymer nano composite materials that mix with hybrid composites such as JUTE, SISAL/EGG SHELL, and epoxy polymer in the ratio of sisal fibre 70% + jute 20% + Egg shell 10% and sisal fibre 60% + jute 20% + Egg shell 20% by volume. The mechanical characteristics were calculated by performing tests on the specimen’s tension, hardness, and flexural qualities in line with ASTM standards.

Microstructure and corrosion evaluations for Al2O3 –leaded brass matrix nanocomposites in marine solution

Hancing the corrosion resistance of various composites is a challenge; however, the mechanical characteristics of composites are usually high without any risks. Thus, in this paper, Al2O3 nanoparticles with various percentages as reinforcements were added to the brass matrix to increase the corrosion resistance. Tafel polarization, electrochemical impedance spectroscopy (EIS), and weight loss measurements were performed to investigate the corrosion characteristics of manufactured nanocomposites. Moreover, field emission scanning electron microscopy (FESEM) was used to study the surface morphology of nanocomposites before and after exposure of specimens to 0.6 M NaCl solution. FESEM images and the related energy dispersive spectroscopy results showed that Al2O3 nanoparticles were distributed in the α-phase of the matrix homogeneously. Corrosion rates of nanocomposite decreased significantly by about 41–99% compared to the matrix without reinforcement. Weight loss measurements showed that the weight loss of nanocomposites at 95 °C was lower than that at 25 °C. This was attributed to the formation of copper/zinc chloride salts on corroded surfaces.

Mathematical model of selective infrared heating application in the manufacture of glass-plastic products

Today's information resources offer a variety of rational composite structures hardening methods and equipment design for these processes. In parallel, there is literature that offers the mathematical modeling of the hardening process of polymer composite materials. Due to the complexity and long duration of the structures polymerization process, there is a need to create a mathematical model for polymerization results predicting, using different temperatures and infrared radiation (including selective) time. Performed the comparative analysis of different mathematical models based on the Navier-Stokes equation. Owing to the development of numerical methods, such as the finite difference method and the finite element method (MCR and FEM), new opportunities have opened up for a more complete physical features calculations of the studied processes. The polymerization process of the composite in time can be represented by the state function s (t), which is equal to one at the beginning of the process at t = 0, and zero at the end. The hardening process is characterized by a certain polymerization rate v, which shows which part of the composite is synthesized per unit time. A mechanism explaining the kinetics of the reaction rate v1 was proposed by Arrhenius. Accordingly, for any chemical reaction or any change in the physical state of the body, the molecules must overcome the energy barrier, which is called the activation energy. After analyzing the classical equations, a mathematical model was proposed, which describes the process of hardening the composite material under the combined action of heat flux and infrared radiation. A method for determining the parameters of a mathematical model based on the results of experimental research is proposed. A method of accounting for the parameters of infrared radiation in the presented mathematical model, which can be used for the selected spectrum of the radiation and the filters was used. Based on the Arrhenius Equation, a mathematical model was developed that describes the process of changing the physical and mechanical characteristics of composites during hardening. Having determined the constants of the curing process a1, a2 and Ea - the activation energy of the polymerization reaction, it is possible to estimate the degree of hardening of the composite at any time.

Effect of layer architecture on the mechanical behavior of accumulative roll bonded interstitial free steel/aluminum composites

Multi-layered interstitial free (IF) steel/aluminum (Al) composites were fabricated by the accumulative roll bonding (ARB) method. Two types of IF steel/Al6061 dissimilar layered metal composites (LMC) with varied stacking of aluminum layers were processed to examine the effect of the layer architecture. Microhardness and uniaxial tensile experiments were applied to analyze the surface and bulk monotonic mechanical properties. Besides, the cyclic mechanical response of the processed materials was investigated via high cycle fatigue (HCF) tests with positive mean stress. Microstructure and mechanical characteristics of composites with various layer architectures were analyzed up to five ARB passes. It is revealed that the monotonic and cyclic performances of all LMCs are significantly enhanced as compared to the base alloy with an aluminum layered structure. Moreover, composites with aluminum as the outer layer exhibited the highest fatigue life, due to crack branching at the interface region during propagation from the softer to the harder layer. Fracture morphology analysis of composites demonstrated that in addition to the significant impact of surface cracks on the outer layers, propagation of cracks initiating from the interface layers led to failure under cyclic loading.

Mechanical characteristics of composites based on oil palm empty fruit bunch, modified oca starch and polyvinyl alcohol

Tensile behavior of empty fruit bunch (EFB) reinforced modified-starch/polyvinyl alcohol (PVA) composites was studied. Initially, oca starch was chemically modified and characterized by nitrogen content. Afterward, a modified-starch/PVA blend was prepared. Spectrophotometric assessment of blend was carried out by Fourier transform infrared spectroscopy (FTIR). Besides, blend and EFB were evaluated through thermogravimetric analysis (TGA). Composite formulation was performed considering EFB loading (10 and 20 wt. %), EFB particle size (0.425 and 0.600 mm), and processing temperature (80 and 100 °C). FTIR and nitrogen content results confirmed the presence of starch carbamates as a product of chemical modification. TGA evidenced three and four decomposition stages for EFB and blend, respectively. On the other hand, the statistical evaluation showed that EFB content and particle size-processing temperature correlation were the main influence on tensile characteristics. Overall, tensile modulus raised as EFB loading increased, whereas tensile strength decreased slightly with EFB increment. Elongation at break fell by the addition of EFB. Notwithstanding the wide dispersion of tensile properties, results showed similarities to other analogous studies. Therefore, green composites based on oca starch carbamates and EFB have the potential to be duly enhanced by the optimization of fiber-matrix interaction.

Destruction of Silicon-Organic Composites Irradiated by High-Energy Electrons

The destruction of silicone composites irradiated by accelerated electrons is investigated. Experimental results showed that, at irradiation doses of the order of 103 Gy, the mechanical strength of silicon—organic composites is significantly reduced, and doses of the order of 106–107 Gy, their total destruction occurs. This phenomenon was investigated theoretically using a mathematical model for calculating the mechanical characteristics of composites that is based on the idea that their destruction is caused by a gradual accumulation and merging of local defects into large clusters of critical sizes in the bulk of the material. The radiation defects formed by the flow of electrons were calculated by methods developed in the radiation physics of solids. From the concentration and distribution of the defects, the average mechanical characteristics of the composites were determined.

Developing physical-chemical principles to manufacture effective heating systems when using mica

The organization of effective heating systems in non-industrial, industrial and livestock buildings is an urgent problem. The developing of heating is especially relevant for utilizing in agricultural industry. Energy prices are steadily rising, and as a result, the efficient utilization of energy resources is of great significance for this industry. One of the most prospective lines of development in this area can be the trend to utilize resistive heaters where mica is used as a basic material. The research aim. Developing physical-chemical principles to manufacture effective heating systems when using mica for the construction industry. The possibility of employing composite materials to produce an economically sound, reliable, electro-permissible and stable heater is considered. Finding physical and chemical laws of interaction of mica with the binder element in the technology of micaceous composites. Research methods. The methods of thermodynamic quantum chemical calculations, as well as kinetic studies that involve a number of advanced techniques of physical and chemical studies (x-ray phase analysis, thermal analysis, and IR spectroscopy). Electro physical and mechanical characteristics of composites and starting materials were determined by the standardized methods to comply with the All Union State Standard. Research results. The foundations of effective heating systems when utilizing micalex have been worked out by means of scientific generalizations and experimental studies. The developed technology of electric heating elements (mica ceramic electric heating) is employed in various fields of construction industry.

Antibacterial properties of films of cellulose composites with silver nanoparticles and antibiotics

The present study describes production of bacterial cellulose composites with silver nanoparticles and antibiotics and compares their properties. Bacterial cellulose (BC) composites synthesized in the culture of the strain of acetic acid bacterium Komagataeibacter xylinus VKPM B-12068 with silver nanoparticles, BC/AgNps, were produced hydrothermally, under different AgNO3 concentrations (0.0001, 0.001, and 0.01 M) in the reaction medium. The presence of silver in the BC/AgNp composites was confirmed by elemental analysis conducted using scanning electron microscopy with a system of X-ray spectral analysis. Analysis showed that the average atomic number of silver particles in composite samples depended on the concentration of AgNO3: as AgNO3 concentration in the reaction solution was increased, silver content in the composites increased from 0.044 to 0.37 mg/cm2. BC composites with amikacin and ceftriaxone were prepared by immersing dry BC films in solutions containing different concentrations of the antibiotics. The surface structure and properties and physicochemical and mechanical characteristics of composites were investigated using SEM, DSC, X-ray analysis, the system for measuring water contact angles, and electromechanical tensile testing machine. The disk-diffusion method and the shake-flask culture method used in this study showed that all experimental composites had pronounced antibacterial activity against E. coli, Ps. eruginosa, K. pneumoniae, and St. aureus, and the BC/antibiotic composites were more active than BC/AgNp ones; S. aureus was the most susceptible to the effect of BC composites. No potential cytotoxicity was detected in any of the BC/AgNp composites in the NIH 3T3 mouse fibroblast cell culture, in contrast to the BC/antibiotic composites. These results suggest that BC composites constructed in the present study hold promise as dressings for managing wounds, including contaminated ones.

Modification of the surface of carbon fibers with multi-walled carbon nanotubes and its effect on mechanical characteristics of composites with epoxy resin

Effect of the catalyst composition on the structure of nanotubes layers obtained on the surface of carbon nanofibers was studied. We found the preliminary functionalization of the surface of carbon fibers to affect the coating uniformity and the thickness of synthesized nanotube layer. We determined the optimal surface concentration of the catalyst (Fe–Co) which provides uniform layer of nanotubes on the surface of carbon fibers. The effect of modification of the surface of carbon fibers with multi-walled carbon nanotubes on the mechanical properties of carbon fiber–epoxy resin composites was examined. The modification of the carbon fibers with multi-walled carbon nanotubes were shown to increase the flexural modulus and the flexural strength.

The Metal Oxides Fillers Properties Impact on the Dynamic Mechanical Characteristics of Composites, Cured in Constant Physical Fields

The Metal Oxides Fillers Properties Impact on the Dynamic Mechanical Characteristics of Composites, Cured in Constant Physical Fields

Tribological properties of A356 Al-Si alloy composites under dry sliding conditions

Purpose – Aluminium alloys are frequently applied in automotive and other industries, since they provide mass reduction. Besides positive effects, aluminium alloys have their shortcomings reflected, first of all, in inappropriate tribological properties of these materials. The aim of this research was to enable the production of cheap aluminium alloy matrix composite with favourable combination of structural, mechanical and tribological properties, focusing on the tribological behaviour. Design/methodology/approach – The A356 Al-Si alloy was used as a matrix for producing metal matrix composites in compocasting process. Three different materials, in form of particles, were added to the matrix (Al2O3, SiC and graphite). Hardness and tribological properties (wear, friction and wear mechanism) of heat-treated (T6) samples were examined and compared. Tribological tests were carried out on ball-on-block tribometer under dry sliding conditions. Sliding was linear (reciprocating). Counter body was alumina ball. Average velocity was 0.038 m/s (max. 0.06 m/s), sliding distance was 500 m and normal load was 1 N. Findings – The effect of two different ceramic particles and graphite particles on tribological properties of obtained composites was evaluated. Wear resistance of composites reinforced with SiC particles was higher and coefficient of friction was lower compared to the composite reinforced with Al2O3 particles. A dual hybrid composite (with SiC and graphite particles) showed the lowest value of wear rate and friction coefficient. Dominant wear mechanism for all tested material was adhesion. Research limitations/implications – It seems useful to continue the work on developing hybrid composites containing soft graphite particles with A356 Al-Si alloy as matrix. The major task should be to improve particles distribution (especially with higher graphite content) and to explore tribological behaviour in diverse working conditions. Originality/value – Particulate composites with A356 aluminium alloy as a matrix produced in compocasting process using ceramic particles (Al2O3, SiC) were investigated in many researches, but there are only few detailed analyses of dual composites (with the addition of ceramic and graphite particles). In some previous studies, it was shown that compocasting process, as relatively cheap technology, can obtain good structural and mechanical characteristics of composites. In this study, it was shown that even a low graphite content, under specified conditions, can improve tribological properties.