Weight Fraction Of Reinforcement Research Articles

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF HYPEREUTECTIC Al-Si/AlNp COMPOSITE

Hypereutectic Al - Si alloys with fine and evenly distributed Si precipitates have superior mechanical properties In this study, hypereutectic Al - Si alloy powders which contained 15 and 20wt% Si were prepared by a gas atomization process. 1, 3 and 5wt% AlN particles were blended with the Al - Si alloy powders using turbular mixer. The mixture was consolidated by Hot Press at 550°C for 1h under 60MPa. Relative density of the sintered samples was about 98% of theoretical density. This study was investigated by two ways. One is the effect of reinforcement weight fraction and the other is the effect of Silicon contents on the mechanical properties of the composite. Microstructural characterization and phase evaluation were carried out using X-ray Diffraction, Scanning Electron Microscopy equipped with Energy Dispersive Spectrometer. The results showed that the smaller the reinforcement particle size was and the better its distribution was, the higher ultimate tensile strength and hardness were.

The effect of sintering temperature and the amount of reinforcement on the properties of Al–Al 2O 3 composite

The aim of this research is to investigate the effect of the amount of reinforcement on the properties of Al–Al 2O 3 composite. Alumina particles were mixed with Aluminum particles in the range of 0–20 wt.%. The average particle sizes for the matrix and reinforcement were 30 and 12 μm, respectively. The samples were prepared at two levels of sintering temperature for a constant sintering time of 45 min. It was illustrated that at high weight fractions of reinforcement, the relative density decreases while the hardness and wear resistance increases. Results show that by increasing the amount of Alumina from 0% to 10%, the hardness increased from 33 to 62 BHN, while the compressive strength was raised from 133 to 273 MPa. The addition of alumina decreased the wear rate from 0.0447 mm 3/m to 0.0262 mm 3/m.

A Taguchi Approach for Investigation of Erosion of Glass Fiber — Polyester Composites

Polyester composites reinforced with three different weight fractions of woven E-glass fiber reinforcement are developed. To study the effect of various operational and material parameters on erosive wear behavior of these composites in an interacting environment, erosion test are carried out. For this purpose, an air jet type erosion test rig and the design of experiments approach utilizing Taguchi's orthogonal arrays are used. The findings of the experiments indicate that erodent size, fiber loading, impingement angle and impact velocity are the significant factors in a declining sequence affecting the wear rate. Significance of erosion efficiency in identifying the wear mechanism is highlighted. It is confirmed that the glass-reinforced-polyester composites exhibit mostly semi-ductile erosion response. An optimal parameter combination is determined, which leads to minimization of erosion rate. Analysis of variance (ANOVA) is performed on the measured data and signal to noise (S/N) ratios. A correlation derived from the results of Taguchi experimental design is proposed as a predictive equation for estimation of erosion wear rate of these composites. It is demonstrated that the predicted results obtained using this equation are consistent with experimental observations. Finally, optimal factor settings for minimum wear rate are determined using genetic algorithm.

Taguchi method applied to parametric appraisal of erosion behavior of GF-reinforced polyester composites

Polyester composites reinforced with three different weight fractions of woven E-glass fiber reinforcement are developed. To study the effect of various operational and material parameters on erosive wear behavior of these composites in an interacting environment erosion tests are carried out. For this purpose, air jet type erosion test rig and the design of experiments approach utilizing Taguchi's orthogonal arrays are used. The findings of the experiments indicate that the rate of erosion of composites by impact of solid erodent is greatly influenced by the control factors. An optimal parameter combination is determined, which leads to minimization of erosion rate. Analysis of variance (ANOVA) is performed on the measured data and S/N (signal to noise) ratios. A correlation derived from the results of Taguchi experimental design is proposed as a predictive equation for estimation of erosion wear rate of these composites. It is demonstrated that the predicted results obtained using this equation are consistent with experimental observations. Finally, optimal factor settings for minimum wear rate are determined using genetic algorithm.

HIGH TEMPERATURE DEFORMATION BEHAVIOR OF Al-SiCp METAL MATRIX COMPOSITES

Aluminum-silicon carbide (Al-SiCp) metal matrix composite (MMC) materials were fabricated using the powder metallurgy (PM) techniques of hot compaction followed by hot extrusion. Different reinforcement weight fractions were used, i.e. 0, 2.5, 5, and 10 wt% SiCp. Hot tensile deformation tests were used to characterize the ductility deformation and strength at different temperatures, i.e. T = 0.3 Tm, 0.4 Tm, 0.5 Tm, and 0.6 Tm (where Tm is the absolute melting point of the matrix material), and at different strain rates, i.e. e• = 2 x10-3 s-1, and 0.6 Tm 100x 10-3 s-1. Brief microscopic examination was used to support the analysis of results. It was found that the stress-strain behavior is dominated by work-hardening at the lower temperature range. The work-hardening exponent (n) decreased as T increased and as reinforcement weight fraction increased but increased as e• increased. As reinforcement weight fraction increased, considerable strengthening was achieved compared to the unreinforced matrix. The reinforcement particles dominated the plastic flow and reduced the effect of high temperature in reducing the flow stress. However, as reinforcement weight fraction increased, the tensile strength σu, as well as the yieled strength, σy were negatively affected specially at high deformation temperatures and at high strain rates. σu was found to be more negatively affected than σy. σy and σu of the unreinforced material increased as e• increased, for all tested temperatures. As reinforcement particles were introduced to the matrix, the two parameters increased with strain rate up to e• = 50 x 10-3 s-1, then decreased as e• = 100 x 10-3 S-1. Maximum reduction in σy was obtained at T = 0.4 Tm at e• = 100 x 10-3 s-1. Ductility expressed by the strain to facture, ef, decreased with the increase in e•, for all investigated materials. Minimum ef was obtained for Al-10 wt% SiCp as T = 0.4 tm and e• = 100 x 10-3 s-1 was applied.

Effects of Changing Environment and Loading Speed on Mechanical Behavior of FRP Composites

Durability of fiber reinforced polymer composites (FRP) are controlled by the durability of their constituents: reinforcement fibers, resin matrices, and the status of interfaces. A great deal of research has been focused on attempting to assess the relationship between interfacial structure and properties of fiber-matrix composites. It is at the interfacial area where stress concentration develops because of differences in the thermal expansion coefficients between the reinforcement and the matrix phase. A significant mismatch in the environmentally induced degradation of matrix and fiber leads to the evolution of localized stress and strain fields in the FRP composite. The present investigation aims to study the effects of changing hygrothermal conditioning cycles (either by changing relative humidity (RH) and keeping the temperature constant, or by changing the temperature while RH the same is maintained) on moisture gain/loss kinetics and on interlaminar shear strength (ILSS) of varied weight fraction glass fiber reinforced epoxy and polyester matrices composites. The mechanical assessment is extended to evaluate the loading rate sensitivity of hygrothermally shocked glass/epoxy and glass/polyester laminates at 2 and 50 mm/min crosshead speeds, respectively. Observations on absorption/desorption kinetics are noticed to be dependent on the nature of hygrothermal shock cycle and on the weight fraction of fiber reinforcement. The results of mechanical performance are statistically significant at different stages of conditioning. Shear values are found to be greater at higher crosshead speed for all undertaken situations. Mechanical responses are observed to be dependent on the matrix resin and the type of hygrothermal shock cycle. Very little and limited literature is open to address the important interactions of polymer composites with this kind of realistic environmental situation.

Influence of reinforcement weight fraction on microstructure and properties of submicron WC–Co p/Cu bulk MMCs prepared by direct laser sintering

Direct metal laser sintering (DMLS), due to its flexibility in materials and shapes, exhibits a great potential for fabricating complex shaped bulk metal matrix composites (MMCs). In the present work, the submicron WC–10% Co particulate reinforced Cu matrix composites were prepared using DMLS. The influence of reinforcement content on the sintered densification and the attendant microstructures, e.g. the dispersion homogeneity of the reinforcing particulates and the interfacial bonding ability, was investigated using scanning electron microscopy (SEM), energy disperse X-ray (EDX) spectroscopy, and atomic force microscope (AFM). It shows that using a low reinforcement content of 20 wt.% results in a poor densification with severe balling phenomena, due to a higher average composite coefficient of thermal expansion (CTE) and a superheating of the melt. A heterogeneous microstructure with a significant particulate aggregation is obtained at a high reinforcement content of 40 wt.%, because of a limited liquid formation and the resultant high liquid viscosity and reduced Marangoni effect. Using an optimal reinforcement content of 30 wt.% leads to a uniform distribution of the reinforcing particulates and a compatible interfacial microstructure, so as to obtain a favorable sintered density of 90.3% theoretical density.

The prediction of wear resistance model for the metal matrix composites

The prediction of wear resistance model for the metal matrix composites was developed based on the Taguchi method. The two-body abrasive wear behaviour of the specimens was investigated using pin-on-disc method where the samples slid against various size of SiC grits under different conditions. The orthogonal array, signal-to-noise (S/N) ratio and analysis of variance were employed to find out the optimal testing parameters. The experimental results show that abrasive grain size was found to be the major parameter among the other control factors on abrasive wear, followed by weight fraction of reinforcement. However, the applied load had a much lower effect while sliding distance was not significant. Moreover, the optimal combination of the testing parameters could be determined and predicted. A good agreement between the predicted and actual wear resistance was observed within ±5% significance level.

Effect of Particle Cracking on the Strength and Ductility of Al-SiCp Powder Metallurgy Metal Matrix Composites

The effects of particle cracking on the strength and ductility of Al-SiCp metal matrix composite material (MMC) was investigated. The composite was manufactured using a simple powder metallurgy (PM) technique of hot pressing followed by hot extrusion. Also, the effects of reinforcement weight fraction and strain rate variations on the strength and ductility of the same composite were examined. It was found that particle cracking plays a significant role in controlling the mechanical properties of the composite. It was shown that particle cracking is possible in an MMC material made with a low strength matrix (commercially pure aluminum), and increases with the increase of reinforcement weight fraction, applied strain rate, and amount of plastic deformation. The yield strength increases as a function of reinforcement weight fraction and to a lesser extent as the strain rate increases. The tensile strength increases at low SiCp weight fractions, then remains constant or decreases as more particles are added to the matrix.

Application of a model for the work hardening behavior to Mg/SiC composites synthesized using a fluxless casting process

An understanding of the work hardening behavior of particulate reinforced metal-matrix composites is crucial in optimizing the parameters for deformation processing of these materials. In the present study, elemental magnesium and magnesium–silicon carbide composites were synthesized using the methodology of fluxless casting followed by hot extrusion. The microstructures of the composites were characterized and the mechanical properties were determined. The results of ambient temperature tensile testing on the extruded Mg and Mg/SiC samples revealed that an increase in the weight percentage of SiC particulates in pure magnesium increases the elastic modulus, did not affect the 0.2% yield strength, and reduced the ultimate tensile strength and ductility. A modified continuum model was applied to relate the work hardening behavior of the composites to microstructural parameters and to predict the fracture strain of the composites. The model is shown to predict the fracture strain of the composites quite accurately for all the three weight fractions of reinforcements evaluated in this study.

Application of model for work hardening behaviour of SiC reinforced magnesium based metal matrix composites

An understanding of the work hardening behaviour of particulate reinforced metal matrix composites is crucial in optimising the parameters for deformation processing of these materials. In the present study, SiC reinforced magnesium metal matrix composites were produced using a liquid phase process. The microstructure of the composite was characterised and the mechanical properties were determined. The results of the ambient temperature tensile testing on the extruded Mg and Mg/SiC specimens revealed that an increase in the weight percentage of SiC particulates in pure magnesium increases the elastic modulus, does not affect the 0·2% yield strength, and reduces the ultimate tensile strength and ductility. A modified continuum model was applied to relate the work hardening behaviour of the composites to microstructural parameters and to predict the fracture strain of the composites. The model is shown to predict the fracture strain of the composites quite accurately for all the three weight fractions of reinforcements evaluated in the present study.

Influence of processing parameters during disintegrated melt deposition processing on near net shape synthesis of aluminium based metal matrix composites

This paper addresses the influence of processing parameters on the near net shape synthesis of Al–SiC particle reinforced metal matrix composites by the disintegrated melt deposition technique. The processing parameters that were investigated include stirring speed during reinforcement addition, holding and stirring times following reinforcement addition, and total flight distance. The effect of the weight fraction of SiC incorporated was also studied. Maximum incorporation of the reinforcement was achieved by dispersing SiC particles in liquid aluminium with an impeller at a stirring speed of 500 rev min-1. Composite porosity levels were minimised for holding and stirring times following SiC addition of 15 and 5 min, respectively, and for a total flight distance of 450 mm. Composite porosity levels were increased with increasing weight fractions of SiC incorporated. The results obtained clearly demonstrate the dependence of composite porosity levels on weight fraction of reinforcement incorporated, total flight distance, and holding and stirring times following addition of SiC particles, and reinforcement incorporation on stirring speed.

Effect of Deformation Temperature on the Mechanical Behavior and Deformation Mechanisms of Al-Al2O3 Metal Matrix Composites

Aluminum-alumina (Al-Al2O3) metal matrix composite (MMC) materials were fabricated using the powder metallurgy (PM) techniques of hot pressing followed by hot extrusion. Different reinforcement weight fractions were used, that is, 0, 2.5, 5, and 10 wt% Al2O3. The effect of deformation temperature was investigated through hot tensile deformation conducted at different temperatures. The microstructures of the tested specimens were also investigated to characterize the operative softening mechanisms.

Mechanism of material removal during three-body abrasion of FRP composite

The low-stress abrasive wear behaviour of chopped-glass-fibre-reinforced polyester composites has been studied by using a rubber wheel abrasion test (RWAT) apparatus. Silica sand particles of two different size ranges were used in the current study as dry and loose abrasives. Weight loss of the composites during three-body abrasion has been examined as a function of the sliding distance. Abrasive wear of the composites shows dependence both on abrasive particle sizes and applied load, as well as the weight fraction of glass fibre reinforcement. It has also been observed that the wear rate becomes constant with the increasing sliding distance. Scanning electron microscopy was used to observe the worn surfaces and to understand the mechanism involved in material removal.

Fracture toughness of short glass fibre and glass particulate hybrid composites

Abstract Toughness of particulate and fibrous composites has shown a tendency to increase with the increase in weight fractions of reinforcement; in the case of hybrids of particulates and fibres, however, it decreases with the increase in reinforcement. The mechanical interaction and internal friction between two types of reinforcements have contributed to the instability of macroscopic cracks and enhance their growth, thereby decreasing the fracture resistance. At lower weight fractions of reinforcement, the toughness appears to be a weighted sum of individual toughnesses of particulate and fibres, but at higher interdispersion of weight fractions of reinforcement, a negative synergistic effect is observed.

Strength and stiffness of short glass fibre/glass particulate hybrid composites

At high strains, randomly dispersed short glass fibre and glass particulate compounded in polypropylene, have shown higher flexure modulus than that of composites reinforced with either short glass fibre or glass particulate alone. The constant flexure stress independent of weight fractions of reinforcements due to the ‘hybrid effect’ has been observed in the present investigation.

The thermal expansion of reinforced nylon‐6 composites through the matrix glass transition temperature

AbstractThe coefficient of thermal expansion (CTE) of nylon‐6 reinforced with particulate filler, short glass fibers, and long‐to‐continuous glass fibers was measured between −30 and 170°C. As the reinforcement level, the reinforcement aspect ratio, or degree of orientation increases, the linear CTE decreases. The Tg range for the composite system is equal to the Tg for the pure nylon‐6 matrix. An unexpected result is observed when the nylon‐6 is reinforced with long or continuous glass fibers in random planar orientation and the weight fraction of reinforcement exceeds 10 percent. In this case, the longitudinal linear CTE (parallel to the plane of the fibers) above the Tg is lower than the longitudinal linear CTE below the Tg. Analysis of the mathematical descriptions of composite thermal behavior indicates that an extremely low composite modulus in the transverse direction above the Tg may be a cause for this low CTE. The differences in CTE between short fiber and long fiber reinforced compositions indicate that the critical fiber length for thermal stress transfer may be higher than the critical fiber length for mechanical stress transfer.