Volume Fraction Of Reinforcement Research Articles

Synthesis and characterization of in-situ (Al–Al3Ti–Al2O3)/Al dual matrix composite

Abstract Aluminum matrix composites (AMCs) with high volume fraction of reinforcement exhibit superior mechanical properties at the expense of ductility. To overcome this shortcoming, a dual matrix composite microstructural design has proven to be beneficial in increasing the ductility while maintaining the optimal strength. In the present investigation, an in-situ dual matrix composite from Al-TiO2 system was successfully fabricated by a mechanical and thermal synthesis process via powder metallurgy route. The in-situ dual matrix composite microstructure comprises of Al-Al2O3-Al3Ti composite regions separated by ductile unmilled outer Al matrix. The composite region provides strength to the dual matrix composite while the outer Al matrix provides plasticity during deformation. The differential scanning calorimetry (DSC) technique was used to analyze the chemical reactions occurring during the synthesis. A comparative study on the microstructure evolution of in-situ single and dual matrix composites was done using XRD, SEM, EDS and EBSD. The in-situ dual matrix composite shows lower microhardness and compressive strength with significant increase in ductility and wear resistance compared to the in-situ single matrix composite with the same amount of reinforcement.

Dry Sliding Wear Performance of Ni–SiC Composites Developed Through an In Situ Microwave Casting Process

Abstract Metal matrix composites of nickel-based powder reinforced with silicon carbide are processed through a domestic microwave applicator. In situ melting and casting of composites were carried out using microwave energy with average processing time of 25 min. Phase analysis of processed composites revealed the formation of some hard-intermetallic compounds such as nickel silicides (NiSi, Ni2Si, and Ni3Si2) and carbides (Cr3C2 and Cr7C3). Microstructure analysis confirms the favorable growth of equiaxed grains with uniform dispersion of reinforcement and low porosity defects (1.5–1.8%). The formation of hard-intermetallic compounds and the presence of SiC reinforcement led to the increased microhardness of composites. Sliding wear tests under dry sliding conditions with varying load and velocity conditions revealed the formation of stable oxide tribolayers at 1.0 m/s of sliding velocity and 15 N load. Fractography of worn-out samples revealed abrasion of surfaces at the lower load (10 N) condition. However, on increasing the load, the shearing of surfaces due to adhesion, plastic deformations, and surface pullout was observed. At higher loads (20 N) and higher sliding velocities (1.5 m/s), particle pullout and three-body abrasive wear mechanisms were observed. The overall weight loss study revealed that the addition of 5% and 10% volume fraction of SiC reinforcement reduced the wear-rate by 58.9% and 80.6% in comparison to the pure nickel casting at the sliding velocity of 1 m/s and under 15 N load.

Moisture absorption of composites with interfacial storage

Thermosetting polymer composites are often exposed to wet and humid environments, leading to a considerable reduction in their thermo-mechanical properties. Hence, accurate description of the moisture absorption dynamics, including anomalous effects such as molecular bonding and interfacial storage of moisture, is particularly important. In this study, the hindered diffusion model is extended to include the moisture storage at the interface of impermeable fibers or inclusions within the composite. The model is independent of the reinforcement geometry and can be used for fibrous and spherical reinforcements, or for nanoscale additives. The nondimensional formulation and the analytical solution of the model are shown to yield a nondimensional hindrance coefficient that governs the amount of interfacial moisture storage. This phenomenological parameter is expected to be dependent on the interfacial area available for moisture storage, hence should be correlated with the reinforcement volume fraction. To validate this model, available experimental moisture absorption data for epoxy composites containing APS- and nBS-treated glass spheres at different volume fractions are used. The absorption behaviors exhibited by these composites are shown to be successfully described by the hindered diffusion model for all sphere volume fractions. Moreover, the nondimensional hindrance coefficient and the amount of interfacial moisture storage for both composites are found to be linearly related to the volume fraction of the spheres. These results uncover the underlying relationship between the phenomenological model coefficients and the composite microstructure, further validating the theoretical approach to describe the interfacial moisture storage.

Investigating mechanical, thermal and rheological properties of polypropylene/carbon nanotubes composites

Multi-walled carbon nanotube-polypropylene nano-composite loaded at 0.01–5 wt% of CNTs has been prepared using twin-screw mixer. The rheological and thermo-mecanical properties have been studied using rheometer and tensile machine. The CNTs were well dispersed in PP with fairly good dispersion stability. The effect of the volume fraction of CNT reinforcements on the Young’s modulus of the nano-composites is investigated.

Effect of Material and Process Variables on Characteristics of Nitridation-Induced Self-Formed Aluminum Matrix Composites-Part 1: Effect of Reinforcement Volume Fraction, Size, and Processing Temperatures.

This paper investigates the effect of the size and volume fraction of SiC, along with that of the processing temperature, upon the nitridation behavior of aluminum powder during the nitridation-induced self-formed aluminum composite (NISFAC) process. In this new composite manufacturing process, aluminum powder and ceramic reinforcement mixtures are heated in nitrogen gas, thus allowing the exothermic nitridation reaction to partially melt the aluminum powder in order to assist the composite densification and improve the wetting between the aluminum and the ceramic. The formation of a sufficient amount of molten aluminum is key to producing sound, pore-free aluminum matrix composites (AMCs); hence, the degree of nitridation is a key factor. It was demonstrated that the degree of nitridation increases with decreasing SiC particle size and increasing SiC volume fraction, thus suggesting that the SiC surface may act as an effective pathway for nitrogen gas diffusion. Furthermore, it was found that effective nitridation occurs only at an optimal processing temperature. When the degree of nitridation is insufficient, molten Al is unable to fill the voids in the powder bed, leading to the formation of low-quality composites with high porosities. However, excessive nitridation is found to rapidly consume the nitrogen gas, leading to a rapid drop in the pressure in the crucible and exposing the remaining aluminum powder in the upper part of the powder bed. The nitridation behavior is not affected by these variables acting independently; therefore, a systematic study is needed in order to examine the concerted effect of these variables so as to determine the optimal conditions to produce AMCs with desirable properties for target applications.

Effect of Material and Process Variables on Characteristics of Nitridation-Induced Self-Formed Aluminum Matrix Composites-Part 2: Effect of Nitrogen Flow Rates and Processing Temperatures.

The nitridation-induced self-formed aluminum matrix composite (NISFAC) process is based on the nitridation reaction, which can be significantly influenced by the characteristics of the starting materials (e.g., the chemical composition of the aluminum powder and the type, size, and volume fraction of the ceramic reinforcement) and the processing variables (e.g., process temperature and time, and flow rate of nitrogen gas). Since these variables do not independently affect the nitridation behavior, a systematic study is necessary to examine the combined effect of these variables upon nitridation. In this second part of our two-part report, we examine the effect of nitrogen flow rates and processing temperatures upon the degree of nitridation which, in turn, determines the amount of exothermic reaction and the amount of molten Al in the nitridation-induced self-formed aluminum matrix composite (NISFAC) process. When either the nitrogen flow rate or the set temperature was too low, high-quality composites were not obtained because the level of nitridation was insufficient to fill the powder voids with molten Al. Hence, since the filling of the voids in the powder bed by molten Al is essential to the NISFAC process, the conditions should be optimized by manipulating the nitrogen flow rate and processing temperature.

FEM analysis of the elastic behavior of composites and nanocomposites with arbitrarily oriented reinforcements

This work is aimed at studying the effect of different morphological features on the stiffness of discontinuous fiber reinforced composites and nanocomposites by means of FEM analysis. The morphological features include not only volume fraction and aspect ratio of reinforcement, but also its orientation. The FEM approach, based on continuum mechanics, required the definition of a proper representative volume element, in which reinforcement is randomly dispersed in the simulation domain. The developed model has been used in order to calculate the stiffness matrix of unidirectional discontinuous glass fiber reinforced composite (DGFRC) as well as carbon nanotubes reinforced nanocomposites (CNTRNC). Comparison with closed form analytical models showed that the Halpin-Tsai (HT) model is able to predict the evolution of the elastic constants over a wide range of volume fractions and aspect ratio. The Tandon-Weng (TW) model, in contrast, shows a poor agreement with the simulation results.On the other hand, the developed FEM model also allowed accounting for reinforcement orientation. The calculated elastic properties are in excellent good agreement with the corresponding values calculated according to the classical lamination theory, indicating the accuracy of the developed FEM model for estimation of stiffness of composites and nanocomposites, also accounting for reinforcement orientation.

Probabilistic homogenization of hyper-elastic particulate composites with random interface

A principal aim of this study is determination of deterministic and basic probabilistic characteristics of the effective material properties and stresses in hyper-elastic particulate composites with spherical reinforcement and uncertain volume fraction of the interface defects. This is done on the basis of laboratory tests of Laripur LPR 5020 High Density Polyurethane (HDPU) using the FEM homogenization method applied on the cubic multi-particle Representative Volume Element (RVE). This 3D homogenization scheme is based upon numerical determination of strain energy density in the RVE under uniaxial stretch. Each particle is spherical, linear elastic and embedded in the hyper-elastic matrix. The interphase is a thin layer around particle and contains all the particle-matrix interface defects; these defects are of the semi-spherical shape lying with the diameters on the interface. A constitutive relation of the matrix is experimentally recovered through the uniaxial stretch test and computationally approximated with three best fitting available hyper-elastic material potentials. The coincidence of these results serves for verification of the numerical results. Uncertainty of volume fraction of interface defects is assumed to be Gaussian, whose coefficient of variation does not excess 0.25. A relation of the effective stress to this uncertain parameter is recovered as some polynomial basis via the Least Squares Method (LSM) with two different approaches. The first one introduces a functional based directly on the potentials with parameters related to the strain level and to the volume fraction of interface defects, while the alternative approach is based upon a bivariate polynomial. This polynomial order is optimized via simultaneous maximization of correlation and minimization of LSM error and variance and its order is optimized for minimum LSM error. The RVE meshing is completed with the use of 20-noded brick or 10-noded tetrahedral elements. Probabilistic computations have been carried out with three independent approaches, namely the Stochastic Finite Element Method (SFEM), the crude Monte-Carlo simulation and probabilistic semi-analytical method. Probabilistic characteristics of the effective constitutive tensor include expected values, coefficients of variation, skewness and kurtosis of the effective stress. It is investigated numerically (1) if the resulting homogenized characteristics are also Gaussian, (2) how fluctuation of the interface defects volume fraction affects an effective stress in context of the deterministic and probabilistic analysis and (3) how these characteristics vary together with an increase of the applied strain.

Mechanical properties of poly–propylene reinforced with Argan nut shell aggregates: Computational strategy based microstructures

This paper aims at developing 3D numerical simulations of the mechanical properties of polymer composites based on the aggregates of argan shell. The microstructure is made up of two phases, corresponding to the Poly–Propylene PP matrix and the natural aggregates. Due to the grinding operation of agran shell during the manufacturing process, the aggregates shapes, crushed aggregates, greatly vary with their surfaces. The majority of published works used the spherical or ellipsoidal forms in order to study numerically the mechanical behavior of such composites, because of the inherent simplification in algorithm formulations. However, real microstructures of these composites based simple microscopic, show that the shape of aggregates does not takes a spherical form, but a polyhedral form. In this study, the microstructure is described and modeled as a combination of Poisson polyhedral and PP matrix. In the numerical model, the obtained aggregate morphology is similar to that of many argan shell powders often used as reinforcement of the PP matrix. This technique allows generating models with different reinforcement volume fractions up to 28%. The numerical homogenization technique is used to estimate the mechanical properties of these composites. The set obtained numerical results with 3D polyhedral model are compared with the pertinent experimental data and analytical models reported in the literature. The performance of the most used micromechanical schemes used in predicting the effective elastic properties of biocomposites was discussed.

Squeeze-winding: A new manufacturing route for biomimetic fiber-reinforced structures

Natural materials represent ideal biomimetic models for materials design. However, the sophisticated natural hierarchical architectures are rather difficult to be implemented in synthetic FRCs and components through classic manufacturing methods. We propose a new method, called squeeze-winding (SW), specifically designed for the fabrication of FRC-tubes with a bone-inspired internal structure. SW represents a modification to the classic filament winding (FW) and is aimed at implementing a bone-like structure characterized by axially-oriented cylindrical features and achieving a high reinforcement volume fraction (~60%). The outcome of compression testing shows: a high repeatability of the mechanical characteristics achieved by SW, a higher fiber volume fraction of SW tubes compared to the conventional FW tubes, and improved mechanical properties. Moreover, we demonstrate how SW can be used to manufacture a sophisticated bio-inspired design, which mimics the cortical bone microstructure, ensuring enhanced mechanical properties compared to laminated tubes obtained by FW.

Wear behavior of the friction stir alloyed AZ31 Mg at different volume fractions of Al particles reinforcement and its enhanced quality attributes

Wear behavior of friction stir alloyed (FSAed) AZ31-Mg with externally added Al has been investigated. The phase distribution pattern in the case of 6% Al alloying was best with honey-comb like structure with enhanced metallurgical properties. The major wear occurs due to abrasion, adhesion, delamination, plastic deformation and oxidation. The friction coefficient and wear characteristics at 6% Al alloyed sample is comparatively less than 3 and 9% alloying. With an increase in Al volume 3–6% the hardness increases 10%. The wear loss of the alloyed specimen at 6% Al are 16% and 11% less compared to the base metal and processed specimen respectively. In brief, 6% Al alloying sample gives the best tribological, metallurgical and mechanical properties.

Microstructure and mechanical properties of lightweight TiC-steel composite prepared by liquid pressing infiltration process

A TiC reinforced steel composite was fabricated by a liquid pressing infiltration (LPI) process. The TiC reinforced steel composites with density <6.0 g/cm3 were fabricated with a high volume fraction of TiC reinforcement. The results showed that the core-rim structure in the composite was formed by partial dissolution of the reinforcement during the LPI process. The effect of dissolution of TiC particles on the microstructure and mechanical properties of the composites was investigated. Enhanced mechanical properties are attributed to the effective load transfer from the matrix to the TiC because of the strong interfacial bonding. This interfacial stability results from chemical bonding from the partial dissolution and the precipitation of the TiC during the process. In order to establish the correlation between the core-rim structure and properties of the composite, the hardness (H) and Young's modulus (E) were examined by nano-indentation.

The effect of powder addition manner and volume fraction of reinforcement on tribological behavior of Al7075/B4C surface composite produced by friction stir processing

Al7075/B4C surface composites were fabricated by friction stir processing using four passes. The B4C powders were added into the prepared grooves with 1 and 2 mm width at the surface of Al7075 alloy in two different manners. In the first one, the B4C powders were added prior to the four consecutive passes in one stage. In the second manner, the powders were added in two stages, prior to the first pass and following the second one. The microstructural evaluations showed that the increase in the volume fraction of reinforcement significantly reduced the matrix grain size. Meanwhile, the reinforcement had a more homogeneous and uniform distribution in the samples processed through four consecutive passes. The maximum hardness and wear resistance was achieved in the one-stage powder-added samples, containing higher volume fraction of the reinforcement. A direct relationship was observed between the wear resistance and the composite layer hardness. The wear mechanism in the Al7075 substrate and the non-reinforced friction stir processed sample was the delamination of unstable aluminum oxide tribolayer. However, in the composite samples, a mechanically mixed layer, containing aluminum, chromium, and iron mixed oxides was formed along with B4C on the worn surface. In the two-stage powder-added samples, containing lower amounts of reinforcement, the detachment of mechanically mixed layer resulted in three-body abrasive wear condition and high friction coefficient. However, the most stable mechanically mixed layer was formed on the surface of the one-stage powder-added sample containing higher amounts of B4C.

MICROSTRUCTURAL ANALYSIS, MICROHARDNESS AND COMPRESSIVE BEHAVIOUR OF DUAL REINFORCED PARTICLES ADC-12 ALLOY COMPOSITE

The aim of this study was to determine the compressive properties of silicon carbide (SiC) and zircon sand (ZrSiO4) particulate reinforced with ADC-12 alloy, ADC-12 alloy composite. In this experimental study, SiC and ZrSiO4 particulates reinforced with ADC-12 alloy composite were manufactured by stir casting methods. Compressive properties of these composite materials were investigated by different weight percentages of dual reinforcement combinations (9+3) %, (6+6) %, (3+9) %wt. silicon carbide (SiC) and zircon sand (ZrSiO4)respectively, The compressive tests were conducted to determine compressive strength and young’s modulus to investigate the effects of reinforce materials on different combinations of weight percentages. The outcome of the investigations reveals that the tensile strength of composites reinforced by Zircon sand (ZrSiO4) and silicon carbide particles with a total reinforcement 12% wt, and in this hybrid reinforcement the variations (9+3) %, (6+6) %, (3+9) % were taken in to account for investigating the properties such as density, compressivestrength and hardness of the composites synthesized by Stir casting technique, also compared between each other’s. The mechanical properties evaluation reveals variations in hardness and the compressive strength values with the composite combinations. From the experimental studies, the optimum volume fraction of hybrid reinforcement in ADC-12 alloy on the basis of microstructure and mechanical properties it is found that the (6+6) wt.% combination.

PENGARUH FRAKSI VOLUME PENGUAT 2, 2,5 DAN 3% SERAT BAMBU HAUR DAN FIBERGLASS TERHADAP KEKUATAN TARIK MATRIKS POLIESTER

Against the backdrop of the increasing need for quality composite materials and the development of increasingly advanced composite manufacturing technology in the machinery industry. The aim of this research is to develop composite materials with bamboo fiber reinforcement and glass fiber as an alternative to automotive raw materials to replace plastic. Preparation of composite specimens with each reinforcement with volume fractions of 2%, 2.5%, and 3% and specimens without reinforcement or 0% volume fraction as a comparison.&#x0D; The polymer material used is Yukalac 157-EX BQTN polyester as its matrix. With haur bamboo fiber and fiberglass as a reinforcement. Making specimens using the hand lay up method. Tests carried out are composite specimen tensile tests. Tensile testing was carried out using the ASTM D 638M-84 M-1 standard.&#x0D; Based on the test results, it was concluded that the effect of fiber volume fraction on the characteristics of composite samples for tensile tests. Composite strengthened by haur bamboo and fiberglass powder at 3% heavy volume fraction has the most ideal characteristics that have a tensile strength of 53.581 MPa, modulus of elasticity of 87.452 MPa and polymer composite material with a strength of haur bamboo and fiberglass powder with a length of 5 mm at 3% reinforcing volume fraction can be used as an alternative to automotive raw materials, namely replacing polyoxymethylene plastic materials for the front bumper.

Influence of micro-structural parameters on fatigue life of discontinuous reinforced metal matrix composites

The micro-structural parameters such as reinforcement shape, size, distribution, volume fraction, property mismatch, aging condition, bonding strength, and whisker orientation can influence the fatigue life of discontinuous reinforced metal matrix composites (DRMMCs). The strengthening effect plays a vital role in predicting the fatigue behaviour of DRMMCs. The modified shear lag (MSL) and enhance dislocation density (EDD) are two main factors that describes the strength of DRMMCs. In the present work, fatigue crack growth life model based MSL and EDD strengthening mechanism has been developed by integrating fatigue damage deformation at the crack-tip under the total strain-controlled conditions. The closed form expression predicts the dependency of particle size, reinforcement volume fraction and reinforcement constraint of the matrix on the fatigue crack growth life. The model fitting with experimental data affirms the appropriateness of proposed fatigue crack growth life prediction model for DRMMCs.

A re-analysis of effect of various process parameters on the mechanical properties of Mg based MMCs fabricated by powder metallurgy technique

In the present study, a reanalysis of Magnesium based metal matrix composites made by powder metallurgy has been done. The Properties of the powder metallurgy products are highly influenced by some basic parameters like; type of reinforcement, weight or volume fraction of reinforcement, compaction pressure, sintering temperature and sintering time, etc. That is why the present study was focused to investigate the effect of these parameters on the mechanical properties of magnesium based Metal Matrix Composites (MMCs). It was observed that the hard ceramic particles like Al2O3, SiC, B4C, TiO2, TiC and etc. are reinforced in the magnesium matrix to enhance the strength, hardness and other properties. The strength and hardness increases on addition of these hard ceramic particles but ductility is reduced. It has been also observed that the metallic reinforcement like Titanium increases both the strength as well as the ductility of Magnesium based MMCs.

INFLUENCE OF STIRRING PROCESS ON THE MECHANICAL PROPERTIES OF ENAC-46000 REINFOR

In this study, ENAC-46000 alloy was reinforced by nano-particles in order to improve itsmechanical properties. ENAC-46000 alloy-based composites were produced via the stir castingmethod. Three different reinforcement volume fractions, stirring speeds, and stirring temperatureswere determined to study their effects on the mechanical properties of ENAC-46000 alloy-basedcomposites. Brinell hardness test and three-point bending test were applied to determine thehardness and the flexural strength of ENAC-46000 alloy and composite samples. The resultsshowed that the mechanical properties of the particle reinforced composites were improved dueto nano-sized reinforcement particles. The hardness and the flexural strength of the compositesamples increased with the increase in the volume fraction of nano-sized reinforcement particles.The mechanical properties of ENAC-46000 alloy declined as the stirring speed was increased. Onthe other hand, the mechanical properties of the composites improved with the increase in stirringspeed due to uniform reinforcement particle distribution. As the stirring temperature was raised,the mechanical properties of the nano-particle reinforced composite samples improved becausethe fluidity of the molten alloy increases due to the increase in stirring temperature. However,when the highest values of volume fraction, stirring speed, and stirring temperature weresimultaneously applied for the production of composite materials, these highest values of theinvestigated parameters resulted in a significant deteriorating influence on the mechanicalproperties of ENAC-46000 alloy-based composites.

Fatigue Life of Hybrid Composites (DGEBA)

This study presents the experimental results of the influence of mechanical fatigue and tensile on hybrid composite materials. Epoxy with Novolac resin are used as matrix for the reinforced materials that consist of glass fiber type E. The slates made of hybrid composite materials for two proportions (80% epoxy, 20% Novolac) and (60% epoxy, 40% Novolac) were reinforced by three volume fractions (10%, 20% and 30%) of glass fiber type (E), where been manufacturing (6) panels of hybrid composite materials, all these panels cutting into two groups samples with dimension (70x 10) mm in order to execute the fatigue test and (150x20) mm for tensile test, according to the specifications of the device used.The process took place in two stages: The two stages include executing the fatigue and tensile test specimens with a ratio (80% epoxy, 20% Novolac) in the first stage and (60% epoxy, 40% Novolac) in the second stage for the volume fractions (10%, 20% and 30%) of glass fiber type (E) and comparison the results between them for each stage. The results obtained from fatigue test in the first stage showed that the number cycle for fatigue limit decreased when the load and the number of layers of reinforcing are increased. But in the tensile test for the samples the results showed that the value of the elongation increasing to the point of failure when the load increased for the same layers of reinforcement, as well as the value of elongation decreasing to a failure when increased the number of layers of reinforcing glass fibers type (E) for the same load. The results of tensile and fatigue test obtained from the second stage showed similar to the results in the first stage, but the cycle number of fatigue limit less value from the first stage and the stress was higher in the fatigue test. For tensile test the elongation values ​​less and the stress values higher for the same volume fraction of the reinforcement due to increase in the proportion of Novolac.

Improvement of Mechanical Properties of Magnesium (Mg) Matrix Composites Reinforced with Nano Alumina (Al2O3) Particles

Nano alumina particle-reinforced magnesium was fabricated by powder metallurgy technique. Powders were mixed by ball milling (without balls) for 6 hours at rotation speed 60 rpm. Then, the powder was compacted at 550 MPa and sintered at 530°C for 2 hours. The magnesium contained 0.25, 0.5, 1, 1.5, 3, and 5 vol. % nano alumina Al2O3. The physical, mechanical properties and microstructures, such as density, porosity, compressive strength, hardness, wear rate, SEM and EDX, were measured and compared with the values of unmodified pure magnesium samples. The results revealed an improvement with Al2O3 in Mg matrix composites. The greatest improvement in UCS and Hv values were about 197 MPa and 70 Hv at the volume fraction of 3 vol.% Al2O3 respectively. The wear tests showed that wear resistance was increased with the increasing of the reinforcement volume fraction of Al2O3.