Increasing Volume Fraction Of Reinforcement Research Articles

Investigation on mechanical properties of hybrid graphene and beryl reinforced aluminum 7075 composites

The emerging technologies and trends of present generation requires downsizing the unwieldy structures to light weight structures on one hand and integration of varied properties on other hand to meet the application demands. In the present investigation an attempt is made to familiarize and best possibilities of reinforcing agent in aluminum 7075 matrix with naturally occurring beryl (Be) and graphene (Gr) to develop a new hybrid composite material. A stir casting process was used to fabricate with fixed volume fraction of 6wt% weight beryl and various volume fractions of 0.5wt%, 1wt%, 1.5wt% and 2wt% of graphene. The properties such as tensile strength, compression strength, and hardness of hybrid composites were examined. The crystallite size and morphology of the graphene and beryl particles were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. It was observed that ultimate tensile strength and compression strength of the hybrid composite increased with increasing reinforcement volume fraction as compared to specimen without reinforcement additions.

Investigations on mechanical properties of aluminum hybrid composites

A double stir casting process was used to fabricate aluminum composites reinforced with various volume fractions of 2, 4, 6, and 8wt% RHA and SiC particulates in equal proportions. Properties such as hardness, density, porosity and mechanical behavior of the unreinforced and Al/x%RHA/x%SiC (x=2, 4, 6, and 8wt%) reinforced hybrid composites were examined. Scanning electron microscope (model JSM-6610LV) was used to study the microstructural characterization of the composites. It was observed that the hardness and porosity of the hybrid composite increased with increasing reinforcement volume fraction and density decreased with increasing particle content. It was also observed that the UTS and yield strength increase with an increase in the percent weight fraction of the reinforcement particles, whereas elongation decreases with the increase in reinforcement. The increase in strength of the hybrid composites is probably due to the increase in dislocation density. A systematic study of the base alloy and composites was done using the Brinell hardness measurement and the corresponding age hardening curves were obtained. It was observed that in comparison to that of the base aluminum alloy, the precipitation kinetics of the composites were accelerated by adding the reinforcement. This effectively reduced the time for obtaining the maximum hardness by the aging heat treatment.

Effects of Reinforcement Geometry on Strength and Stiffness in Adhesively Bonded Steel-Timber Flexural Beams

A finite element model is developed to analyse, as a function of volume fraction, the effects of reinforcement geometry and arrangement within a timber beam. The model is directly validated against experimental equivalents and found to never be mismatched by more than 8% in respect to yield strength predictions. Yield strength increases linearly as a function of increasing reinforcement volume fraction, while the flexural modulus follows more closely a power law regression fit. Reinforcement geometry and location of reinforcement are found to impact both the flexural properties of timber-steel composite beams and the changes due to an increase in volume fraction.

Effects of Particle Volume Fraction on Dynamic Deformation Behaviors of B<sub>4</sub>C Reinforced Aluminum Matrix Composites

Particles size grading method was employed to fabricate aluminum matrix composites reinforced with 75% volume fraction B4C particles by squeeze casting. Dynamic behaviors of the composite was investigated and compared with 55 vol. % composite which were reinforced with particles of uniform size. The results showed that the flow stress increased but the fracture strain decreased with increasing reinforcement volume fraction. Furthermore, the dynamic behaviors of 55 vol. % composite were significantly affected by adiabatic heating softening which was demonstrated by the local melted matrix on the fracture surface and an increase-decrease tendency on flow stress and failure strain was obtained with increasing impact velocity. However, due to load redistribution caused by particles size grading, no melted region was found on the fracture surface and no increase-decrease tendency on flow stress and failure strain was observed for 75 vol. % composites under the same impact loading.

Microstructure and abrasive wear behaviour of B4C particle reinforced 2014 Al matrix composites

In this study, the microstructure and abrasive wear properties of varying volume fraction of particles up to 12% B4C particle reinforced 2014 aluminium alloy metal matrix composites produced by stircasting method was investigated. The density, porosity and hardness of composites were also examined. Wear behaviour of B4C particle reinforced aluminium alloy composites was investigated by a block-on-disc abrasion test apparatus where the samples slid against the abrasive suspension mixture (contained 10 vol.% SiC particles and 90 vol.% oil) at room conditions. Wear tests performed under 92 N against the abrasive suspension mixture with a novel three body abrasive. For wear behaviour, the volume loss and specific rate of the samples have been measured and the effects of sliding time and the content of B4C particles on the abrasive wear properties of the composites have been evaluated. The dominant wear mechanisms were identified using SEM. Microscopic observation of the microstructures revealed that dispersion of B4C particles was generally uniform while increasing volume fraction led to agglomeration of the particles and porosity. The density of the composite decreased with increasing reinforcement volume fraction but the porosity and hardness increased with increasing particle content. Moreover, the specific wear rate of composite decreased with increasing particle volume fraction. The wear resistance of the composite was found to be considerably higher than that of the matrix alloy and increased with increasing particle content.

Changes in Fracture Micromechanism with Increasing Reinforcement Volume Fraction in Glass Matrix Composite

Fracture behaviour and mechanical properties are the key features when a material for given application is supposed to be selected. Advanced glass ceramics composites are perspective structural materials for many applications due to their low production expenses and satisfactory properties even at elevated temperatures. Borosilicate glass matrix composite reinforced by alumina platelets was investigated to describe toughening mechanisms and their changes in a wide range of temperatures (from room temperature up to glassy transition temperature Tg). The dissipation of energy by bridging and/or deflection of propagating crack by alumina platelets uniformly dispersed in the glass matrix were the main toughening mechanisms observed. The alumina platelets have a higher ability to deflect propagating crack in comparison with spherical or rectangular particles having the same volume. Three and four point bend test for Young’s modulus and flexural strength determination was used. Fracture toughness determination was conducted using chevron notch technique. More than 100% increase of fracture toughness was observed when 30% of alumina platelets were added in to borosilicate matrix.

Anisotropy of the residual strain in Mg–SiCp composites

Residual strains have been determined by neutron diffraction in pure magnesium matrix composites. In the reinforcing phase, they are hydrostatic, compressive and increase with increasing reinforcement volume fraction. Both the unreinforced alloy and the composites present anisotropic matrix residual strains. They are hydrostatic and compressive for grain with their basal pole almost perpendicular to the extrusion direction (“basal oriented grains”) and tensile and deviatoric for some other orientations (“non-basal grains”). This can be explained modeling the material as a three-phase composite, where both the “basal oriented grains” and the SiC particles are hard phases and the rest of the Mg grains are the soft phase.

Effect of particle orientation anisotropy on the tensile behavior of metal matrix composites: experiments and microstructure-based simulation

Abstract Deformation processing of particle reinforced metal matrix composites induces preferential orientation of the reinforcement particles. Thus, the orientation anisotropy of the reinforcement will strongly influence the mechanical behavior of the composite. In this study, the effect of reinforcement orientation anisotropy on the mechanical behavior of extruded 2080 Al matrix composite was examined. Microstructure characterization showed a preferred orientation of the reinforcement particles parallel to the extrusion axis, although the degree of orientation decreased with increasing reinforcement volume fraction. Young's modulus and tensile strength in the longitudinal orientation (parallel to the extrusion axis) were higher than that in the transverse orientation (perpendicular to the extrusion axis). The particle orientation-induced changes in stress–strain behavior were modeled using a microstructure-based finite element method approach, yielding good agreement with experimental results. The relationship between tensile behavior of the composites, especially elastic modulus, to the degree of anisotropy in orientation of the reinforcement particles is discussed.

Production and properties of SiCp-reinforced aluminium alloy composites

A vacuum infiltration process was developed to produce aluminium alloy composites containing various volume fractions of ceramic particles. The matrix composites of aluminium with 9.42 wt%Si and 0.36 wt%Mg containing up to 55 vol% SiCp were successfully infiltrated and the effect of infiltration temperature and volume fraction of particle on infiltration behaviour was investigated. In addition to aluminium powder, magnesium was used to improve the wetting of SiC particles by the molten aluminium alloy. The infiltration rate increased with increasing infiltration time, temperature and volume fraction of particle, but full infiltration appeared at the optimum process parameters for the various volumes of fraction composite compacts. In addition, the microstructure, hardness, density, porosity and wear resistance of the composites were also examined. It is observed that the distribution of SiC particles was uniform. The hardness and density of the composite increased with increasing reinforcement volume fraction and porosity decreased with increasing particle content. Moreover, the wear rate of the composite increased with increasing load and decreased with increasing particle content.

Fracture Behavior of Particle Reinforced Metal Matrix Composites

The contributions of the reinforcement volume fraction and annealing temperatures to crack opening force and propagation energy are systematically studied by three point bending tests and by SEM investigations. The bending test data show that for the same reinforcement volume fraction, 2618 and 7075 Al composites require much higher force to open the cracks than 6061 matrix. This relates to the much higher levels of solute elements which causes matrix hardening. Studies reveal that the energy absorption level of the materials during crack propagation depends on both matrix strength and ductility which relates to the reinforcement volume fraction, composition and heat treatment conditions. Large deformation zones are found in front of the crack tip before crack propagation which indicate a ductile failure mode for the composites. Studies also reveal that cracks initiate generally at the particle/matrix interfaces for the low volume fraction reinforced composites. However, for the high volume fraction reinforced composites, crack initiation has been found from both reinforcement/matrix interfaces and broken particles. This indicates that increasing reinforcement volume fraction and matrix strengthening tend to change the fracture mode from interface debonding to particle cleavage cracking.

Hybrid and conventional particle reinforced metal matrix composites by squeeze infiltration casting

Particle reinforced metal matrix composites have received a significant amount of attention due to their high strength-to-weight ratio and relatively low cost [1–3]. In particular, the development of high volume fraction composites (>50%) has been driven by several structural and thermal applications, where high elastic modulus, high strength, and low thermal expansion are required. From a processing point of view, achieving homogeneous particle packing and distribution at these high reinforcement loadings is problematic. Furthermore, consolidation of the matrix, even using a liquid infiltration route, can be problematic with the high volume fraction of reinforcement because the matrix must infiltrate through a network of particles with a very small interparticle spacing. While the strength and stiffness of the composites generally increase with increasing reinforcement volume fraction, the ductility decreases significantly. This has been attributed to an increase in the severity of the triaxiality of stress in the matrix, which results in an earlier onset of void nucleation in the matrix and at the particle/matrix interface. In this note, we report the properties of a liquid infiltrated composite with a novel, hybrid reinforcement architecture. The hybrid reinforcement allows the incorporation of a high volume fraction of particulate reinforcement, without the detrimental effects of matrix porosity and lower ductility associated with their conventionally reinforced counterparts. The results are compared with the properties of a composite with a

Development and performance of new hard and wear-resistant engineering materials

Wear is a major problem in many industrial applications, and the development of wear-resistant materials is therefore both a technical and an economic advantage. Iron-base composites bring new possibilities into the production of wear-resistant materials because of their high hardness and sufficient fracture toughness. They are suitable replacements for the conventional WC/Co cermets owing to their lower fabrication cost, better machinability, weldability, and corrosion resistance. In this study, hot-work steel/Cr3C2 composites and reference wear-resistant materials were produced by hot isostatic pressing. It was found that the matrix powder size used during processing did not affect the resultant wear properties of the composite. On the other hand, the impact toughness increased when fine matrix powders were used. The increasing reinforcement volume fraction increased significantly the hardness and wear resistance of the composite; however, the impact resistance decreased. The newly proposed hot-work steel/30 vol% Cr3C2 composite demonstrated a better combination of properties than some of the most abrasion-resistant materials available today.