Showing papers on "Metal matrix composite published in 2013"

Evaluation of mechanical properties of aluminium alloy 2024 reinforced with silicon carbide and fly ash hybrid metal matrix composites

Abstract: Materials are frequently chosen for structural applications because they have desirable combinations of mechanical characteristics. Development of hybrid metal matrix composites has become an important area of research interest in Materials Science. In view of this, the present study focuses on the formation of aluminium-Sic-fly ash hybrid metal matrix composites. The present study was aimed at evaluating the physical properties of Aluminium 2024 in the presence of silicon carbide, fly ash and its combinations. Consequently aluminium metal matrix composite combines the strength of the reinforcement with the toughness of the matrix to achieve a combination of desirable properties not available in any single conventional material. The compositions were added up to the ultimate level and stir casting method was used for the fabrication of aluminium metal matrix composites. Structural characterization was carried out on metal matrix composites by x-ray diffraction studies and optical microscopy was used for the micro structural studies. The mechanical behaviors of metal matrix composites like density, tensile strength, yield strength, elongation and hardness tests were ascertained by performing carefully designed laboratory experiments that replicate as nearly as possible the service conditions. In the presence of silicon carbide and fly ash [SiC (5%) + fly ash (10%) and fly ash (10%) + SiC (10%)] with aluminium, it was fairly observed that the density of the composites was decreased and the hardness was increased. Correspondingly, the increase in tensile strength was also observed but elongation of the hybrid metal matrix composites in comparison with unreinforced aluminium was decreased. The aluminium-SiC-fly ash hybrid metal matrix composites significantly differed in all of the properties measured. Aluminium in the presence of SiC (10%)-fly ash (10%) was the hardest instead of aluminium-SiC and cluminium-fly ash composites. The study can be further extended by evaluating the wear and corrosion of the resultant material.

Fabrication and characterization of A359/Al2O3 metal matrix composite using electromagnetic stir casting method

Abstract: A composite material is a material consisting of two or more physically and chemically distinct phases. The composite has superior characteristics than those individual components. Usually the reinforcing component is distributed in the continuous or matrix component. When the matrix is a metal, the composite is termed a metal matrix composite (MMC). In MMCs, the reinforcement usually takes the form of particles, whiskers, short fibers, or continuous fibers. An MMC is a composite material with at least two constituent parts, one being a metal. The other material may be a different metal or another material, such as a ceramic or organic compound. Recently, aluminum and its alloy based cast MMCs have gained lot of popularity in all the emerging fields of engineering and technology owing to their superior strength, lower creep rate, better fatigue resistance, lower coefficients of thermal expansion as compared to monolithic materials. The desired properties of the cast MMCs are influenced by the solidification behavior of the cast MMCs. The present paper aimed to investigate the best possible predicted results and to carry out the experimental set up of electromagnetic stir casting process in composite materials. The present paper also shows significant effect of the mechanical properties such as hardness and tensile strength, and analyzes the microstructure of A359/Al2O3.

An Analysis of Mechanical Properties of the Developed Al/SiC-MMC's

Abstract: Metal Matrix Composites (MMC's) have evoked a keen interest in recent times for potential applications. Advance composite materials like Al/SiC metal matrix composite is gradually becoming very important materials in manufacturing industries e.g. aerospace, automotive and automobile industries due to their superior properties such as light weight, low density, high strength to weight ratio, high hardness, high temperature and thermal shock resistance, superior wear and corrosive resistance, high specific modulus, high fatigue strength etc. In this study aluminum (Al-6063)/SiC Silicon carbide reinforced particles metal-matrix composites (MMCs) are fabricated by melt-stirring technique. The MMCs bars and circular plates are prepared with varying the reinforced particles by weight fraction ranging from 5%, 10%, 15%, and 20%. The average reinforced particles size of SiC are 220 mesh, 300 mesh, 400 mesh respectively. The stirring process was carried out at 200 rev/min rotating speed by graphite impeller for 15 min. The microstructure and mechanical properties like Proportionality (MPa) limit, Tensile strength upper yield point (MPa), Tensile strength lower yield point (MPa), Ultimate tensile strength (MPa), Breaking strength(MPa), % Elongation, % Reduction in area, Hardness (HRB), Density (gm/cc), Impact Strength (N.m) are investigated on prepared specimens of MMCs. It was observed that the hardness of the composite is increased with increasing of reinforced particle weight fraction. The tensile strength and impact strength both are increased with rising of reinforced weight fraction. Different mechanical tests were conducted and presented by varying the particle size and weight fractions of SiC.

Microstructure, mechanical properties and corrosion performance of 7075 Al matrix ceramic particle reinforced composite coatings produced by the cold gas dynamic spraying process

Abstract: In this study, microstructural evolutions, mechanical properties and corrosion performance of coatings made of 7075 Al matrix with B4C or SiC reinforcement deposited on T6 6061 Al alloy using the cold gas dynamic spraying process were investigated. Microstructural surveys have shown that coatings with no discontinuity at the interface as well as with fine grains were obtained and the addition of ceramic particles enhanced the coating density for a prescribed set of spray parameters and nozzle configuration. The presence of ceramic particles in the 7075 Al matrix improved the coatings hardness and wear resistance when compared to unreinforced 7075 Al coatings. Although coatings hardness increased with increasing ceramic particle content, the effect on the coatings wear performance is not that significant. B4C reinforced composite coatings exhibited slightly better wear performance compared to SiC reinforced composite coatings. The cold sprayed coatings showed more noble corrosion potentials but higher corrosion current densities than those of the T6 6061 Al substrate. The addition of ceramic particles into 7075 Al matrix led to increased corrosion current densities when compared to that of unreinforced 7075 Al coating.

Development of WC-based metal matrix composite coatings using low-pressure cold gas dynamic spraying

Abstract: A low-cost, low-pressure cold spray unit was used to fabricate tungsten carbide (WC)-based metal matrix composite (MMC) coatings. A sintered and crushed WC-based powder was mixed with nickel powder, forming various compositions of mechanical blends. Scanning electron microscopy (SEM), coupled with image analysis, Vickers micro-hardness, and X-ray diffraction (XRD) was used to characterize the coatings. Image analysis was used to determine the WC content in the coating and the mean free path between the reinforcing particles. The WC content in the coating increased as the WC content in the powder blend increased. Each coating fabricated by the various mechanical blend compositions had a non-homogeneous distribution of the hard WC reinforcing particles embedded in the nickel matrix. However, as the WC content in the powder increased, the coating porosity decreased and the WC deposition efficiency increased. An inversely proportional relationship between hardness and mean free path between the reinforcing WC particles was observed, where a decrease in mean free path led to an increase in hardness. The hardness of each MMC coating was predicted using the rule of mixtures (ROM) method and compared to the experimental hardness values. However, the ROM method did not completely describe the strengthening mechanism of the MMC coatings because densification, plastic deformation, and adiabatic shear instability played a role, especially for the coatings with a lower WC content.

Influence of Reinforcement Type on Microstructure, Hardness, and Tensile Properties of an Aluminum Alloy Metal Matrix Composite

Abstract: This paper presents the results of the comparative study of as cast microstructures and mechanical properties viz yield strength, ultimate tensile strength, elastic modulus, percentage elongation, hardness, percentage porosity and fracture characteristic of 5 wt% SiC and Al2O3 particulate reinforced Al-4% Cu-2.5% Mg matrix composites. These composite materials were prepared through stir casting process. Quantitative metallographic techniques were utilized to determine the average grain size of particles. The microstructures and tensile fracture characteristic of the representative samples of the composites were examined using optical microscope (OM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray diffraction (XRD) techniques. The experimental results demonstrate a fairly uniform distribution of 50.8 μm Al2O3 and 49.2 μm SiC spherical particles with some clustering in few areas. At the interfaces of Al2O3 and the matrix, MgO and MgAl2O4 were observed. Similarly, Al4C3 was formed at the interfaces between SiC and the matrix. The mechanical property test results revealed that, for the same weight percentage of reinforcement, Al-4% Cu-2.5% Mg/5 wt% SiC composite exhibit a 15.8%, 16.4%, 4.97% and 10.8% higher yield strength, ultimate tensile strength, elastic modulus, and hardness, respectively. On the other hand, even if some porosity was observed in the Al2O3 reinforced composite, the percentage elongation (ductility) was 31% higher than that of SiC rein-forced composite. The tensile specimen of SiC reinforced composite failed in a brittle fashion without neck formation, whereas the Al2O3 reinforced composite failed in a ductile fashion with noticeable neck formation.

Producing of AA5083/ZrO 2 Nanocomposite by Friction Stir Processing (FSP)

Abstract: In this study, friction stir processing (FSP) was used to produce AA5083/ZrO2 nanocomposite layer. Optical microscopy and SEM were used to probe the microstructures formed in the composite layer. In addition, the mechanical properties of each sample are characterized using both tensile and hardness tests. Results showed that FSP is an effective process to fabricate AA5083/ZrO2 nanocomposite layer with uniform distribution of ZrO2 particles, good interfacial integrity, and significant grain refinement. On processing, in the proper combination of process parameters, the metal matrix composite layer was observed to have increased tensile and hardness properties.

Prediction of cutting force, tool wear and surface roughness of Al6061/SiC composite for end milling operations using RSM

Abstract: The results of mathematical modeling and the experimental investigation on the machinability of aluminium (Al6061) silicon carbide particulate (SiCp) metal matrix composite (MMC) during end milling process is analyzed. The machining was difficult to cut the material because of its hardness and wear resistance due to its abrasive nature of reinforcement element. The influence of machining parameters such as spindle speed, feed rate, depth of cut and nose radius on the cutting force has been investigated. The influence of the length of machining on the tool wear and the machining parameters on the surface finish criteria have been determined through the response surface methodology (RSM) prediction model. The prediction model is also used to determine the combined effect of machining parameters on the cutting force, tool wear and surface roughness. The results of the model were compared with the experimental results and found to be good agreement with them. The results of prediction model help in the selection of process parameters to reduce the cutting force, tool wear and surface roughness, which ensures quality of milling processes.

Effect of ceramic nanoparticle reinforcements on the quasistatic and dynamic mechanical properties of magnesium-based metal matrix composites

Abstract: We have investigated the microstructure, the quasistatic and high-rate mechanical properties of magnesium (Mg)-based metal-matrix composites (MMCs) reinforced with nanoparticles, also termed as metal-matrix nanocomposites (MMNCs), in this case reinforced with nanoparticles of β-phase silicon carbide (β-SiC) the volume fraction ranging from 5 to 15 vol%. The yield and the ultimate strength increase with reinforcement volume fraction up to 10 vol% nanoparticles. MMCs with micrometer-sized SiC particles have higher yield strength than their MMNC counterparts, whereas the ultimate strength shows the opposing trend, suggesting greater strain hardening in the MMNCs. Transmission electron microscopy shows that the average interparticle distance decreases with increasing SiC vol%. Recrystallization was reported as completed during sintering at 575 °C [R.D. Doherty et al., Mater. Sei. Eng. A, 238, 219 (1997), but dislocations might be generated due to thermal expansion mismatch of Mg/SiC during cooling. The majority of Mg-grains below 20 nm remain around the nanoparticles. As such a reverse volume fraction effect takes place in 15 vol% nanoparticle-reinforced MMNCs, which off sets the strengthening advantage induced by the nanoparticles.

Experimental evaluation of laser-assisted machining of silicon carbide particle-reinforced aluminum matrix composites

Abstract: An experimental study on machining of a particle-reinforced metal matrix composite (MMC) subjected to laser-assisted machining (LAM) was conducted. The MMC studied is an A359 aluminum matrix composite reinforced with 20 % by volume fraction silicon carbide particles. LAM was evaluated experimentally for its potential to improve machinability while minimizing the subsurface damage. The effectiveness of LAM was studied by measuring the cutting forces, specific cutting energy, surface roughness, subsurface damage, and tool wear under various material removal temperatures (Tmr). The optimum Tmr is established as 300 °C, with LAM providing a 37 % reduction in the surface roughness, a 12 % reduction in the specific cutting energy, and 1.7–2.35 times improvement in tool life over conventional machining dependent on the cutting speed.

Silicon Carbide Reinforced Aluminium Metal Matrix Composites for Aerospace Applications: A Literature Review

Abstract: This paper considers the potential of use Al-SiC metal matrix composite (MMC) with particular reference to the aerospace industry. Initially, the required properties are identified, after which, the work explores pure aluminium and its importance in the industry along with its limitations. Using these limitations, MMC’s were recommended as a possible replacement for aluminium and it is seen that the exact set of properties depend on certain factors. Therefore these factors such as reactivity at the interface, volume fraction of the reinforcing material, type of the reinforcing material and distribution of the reinforcing material are reviewed using the existing literature. Using the information available, the paper advocates the use of Al-SiC MMC in the fuselage skins of high performance aircrafts. However, it must be noted that the recommendations are purely based on the data available and the author’s interpretation of it although every effort has been made to be as logical as possible