Aluminium Silicon Carbide Metal Matrix Research Articles

The Development of Molecular-Based Materials for Electrical and Electronic Applications

Aluminum silicon carbide (AlSiC) metal matrix composite materials have a unique set of material properties that are ideally suited for electronics, hence the development of molecular-based materials (MBM) for the electrical and electronic industries. The low material density of AlSiC (3 g/cm3) makes it ideal for weight-sensitive applications such as portable devices over traditional thermal management materials like copper molybdenum (10 g/cm3) and copper tungsten (16 g/cm3). The aim of this work is to develop MBM for electrical and electronic industries. Aluminum (99.66% C.P.) and silicon carbide (SiC) particulates of 240 grit (45 µm), 320 grit (29 µm), 600 grit (9 µm) and 1200 grit (3 µm) at 2.5% weight fraction were used to achieve the objective. The aluminum was melted at 750°C for 25 min in a graphite crucible tilting furnace designed for this work using oil as a firing medium. After melting, a two-step mixing method of stir casting technique was adopted. The cast samples were further analyzed for mechanical and electrical properties. The electrical properties were carried out by using a 4-point probe machine. The result showed that hardness increases at lower grit level, while the electrical properties marginally increased at higher grit. It is therefore recommended that, to make AlSiC composite materials for electrical industries, the higher grit of SiC should be preferred.

EFFECT OF SILICON CARBIDE PERCENTAGE ON FRACTURE TOUGHNESS OF ALUMINIUM SILIOCN CARBIDE METAL MATRIX COMPOSITES

Metal matrix composites are composites in which one component will be a metal and other metal or non metal. It has wide applications in various fields like automobile, turbines blades etc which needs good mechanical properties. This thesis work studies about Aluminium Silicon Carbide metal matrix composites and their properties. Earlier studies revealed that as the percentage of Silicon Carbide is increased the properties get increased up to a limit and fracture toughness gets reduced beyond that. Here, in this work different percentage of SiC is added and fracture toughness is analyzed in terms of Stress intensity factor since fracture toughness cannot be calculated directly. Both software simulation and experimental methods has been done to find out the best percentage composition.

Experimental and Simulation Aspects Regarding LM6/Sicp Composite Plastic Deformation under Different Frictional Conditions

The deformation behaviour of solid aluminium alloy (LM6) and silicon carbide metal matrix composite cylinders under axi-symmetric compression over constant aspect ratios using different lubricants were examined. Dry condition and three different lubricants namely MoS2, graphite and white grease were prepared and cold upset forged. In the light of the previous studies, the calculations were made with the assumption that the curvatures of deformed specimens were in the form of a circular arc. The calculated radius of curvature of the bulge was found under different lubricating conditions. The flow curve of composite was determined by compression tests and data were used in simulation analysis. The FEA simulation was carried out using DEFORM software. Results gained by Finite Element Analysis and by experiment show high degree of similarity, so this way of modeling could be used for even more complex technology of plasticity.

An experimental investigation during finishing of particulate reinforced Al/10 wt% SiC<SUB align="right">p-MMC on developed AFF setup

This paper presents the improved results of an experimental investigation during abrasive flow finishing (AFF) of particulate reinforced aluminium silicon carbide metal matrix composite (Al/SiCp-MMC). The influence of AFF process parameters, e.g., abrasive mesh size, number of cycles, extrusion pressure, percentage of abrasive concentration and media viscosity grade on arithmetic mean value of surface roughness height (Ra, μm) and maximum peak-valley surface roughness height (Rt, μm) have been investigated. Experimental results show that the achieved Ra is as low as 0.005 µm and improvement in surface finish over conventional machining, i.e., reaming is 96.07%. Mathematical models for Ra and Rt are developed for proper selection of the to AFF process parameters. From the test results and SEM micrographs of the workpiece samples before and after AFF, suitable range of process parameters can be selected to achieve better surface finish. Taguchi method-based experimental design, L18 (61 × 37) mixed orthogonal array, S/N ratios are employed to identify the optimal parametric combinations for minimum Ra and Rt. This paper also attempts to explain the basic mechanism of material removal during AFF of Al/10 wt% SiCp-MMC.

Development, experimental investigation and neural network modelling of surface-electrical discharge diamond grinding of Al-SiC metal matrix composite

Grinding metal matrix composites (MMCs) has been proven to be extremely difficult to machine due to presence of hard ceramic reinforcement. Electro-discharge machining (EDM) of MMCs containing electrically non-conducting phases causes some problems in terms of hampering the process stability and impeding the material removal process. Use of combination of grinding and EDM has potential to overcome these problems. This article presents the machining characteristic of aluminium-silicon carbide (Al-SiC) composite using hybrid machining process comprising of diamond grinding (DG) and electro-discharge grinding (EDG) in surface grinding mode which is termed as surface-electro-discharge diamond grinding (S-EDDG). Experiments were carried out on newly self developed S-EDDG set up. The effect of current, pulse on-time, wheel speed, duty factor on removal rate (MRR) and average surface roughness (Ra) has been studied to elucidate the issue. Simultaneously a back propagation neural network is also developed to pred...

Performance Evaluation of PCD 1300 and 1500 Grade Inserts on Turning A356 Alloy with 20% Reinforcement of SiC Particles

Aluminum silicon carbide Metal Matrix Composites (Al-MMC) are widely used in aeronautical and automobile industries due to their excellent mechanical and physical properties. However the harder reinforcement particles make machining difficult. Tool wear occurs more quickly and reduces the life of the tool. This paper presents the experimental investigation on turning A356 matrix metal reinforced with 20 % by weight of Silicon carbide (SiC) particles, fabricated in house by stir casting. Fabricated samples were turned on medium duty lathe with Poly crystalline Diamond (PCD) inserts of 1300 and 1500 grade exposed to various cutting conditions. Parameters such as power consumed by main spindle, machined surface roughness and tool wear are studied. Scanning Electron Microscope (SEM) images support the result. It is evident that, surface finish, and power consumed are good for 1500 grade when compared with 1300 grade at higher cutting speed and tool wear is strongly dependent on the abrasive hard reinforcement particles.

Modeling and analysis of roundness error in friction drilling of aluminum silicon carbide metal matrix composite

Friction drilling is a newer nontraditional hole-making chipless process, which is used to make holes in materials that are used in aerospace, automotive, commercial and industrial products, electronic packaging, and thermal management. In friction drilling, a rotating conical tool is applied to penetrate work-material and create a hole in single step. In this study, comprehensive analysis on friction drilling of Al/SiCp metal matrix composites is carried out. This article discusses the roundness (hole diameter accuracy) errors on dry friction-drilled holes. The parameters considered for the experiment are: the composition of workpiece, workpiece thickness, spindle speed, and feed rate. The effect of parameters on roundness errors is analyzed using experimental design matrix and empirical relation between the process parameters and roundness error is established using response surface methodology. Analysis of variance is used for analyzing the results. The influences of individual input process parameters on roundness error are analyzed and presented in this study.

Grinding of aluminium silicon carbide metal matrix composite materials by electrolytic in-process dressing grinding

The grinding cost of metal matrix composite materials is more due to low removal rates and high rates of wear of super abrasive wheels. This electrolytic in-process dressing (ELID) technique uses a metal-bonded grinding wheel that is electrolytically dressed during the grinding process for abrasives that protrude continuously from super abrasive wheels. This research carries out ELID grinding using various current duty ratios and conventional grinding of 10% SiCp reinforced 2,124 aluminium composite materials. Normal forces and tangential forces are monitored. Surface roughness of the ground surface, Vickers hardness numbers and metal removal rate (MRR) are measured. The results show that the cutting forces in the ELID grinding are unstable throughout the grinding process due to the breakage of an insulating layer formed on the surface of grinding wheel and are less than conventional grinding forces. A smoother surface can be obtained at high current duty ratio in ELID grinding. The micro-hardness is reduced at high current duty ratio. In ELID, the MRR increases at high current duty ratio. The results of this investigation are presented in this paper.

Characterization of centrifugal cast functionally graded aluminum-silicon carbide metal matrix composites

The present investigation is on characterization of functionally graded composites based on 356 cast and 2124 wrought aluminum alloys reinforced with SiC particles of 23 μm average particle size processed by liquid metal stir casting followed by horizontal centrifugal casting. A maximum of 45 and 40% SiC particles are obtained at the outer periphery of the Al(356)-SiC and Al(2124)-SiC FGMMC casting respectively. The maximum hardness obtained at the outer periphery after heat treatment for Al(356)-SiC and Al(2124)-SiC FGMMC are 155 BHN and 145 BHN respectively. The freezing range of the matrix alloy has been found to dictate the nature of transition from particle enriched to depleted zone. These composites are suitable for making engineering components, which require very high surface hardness and wear resistances with high specific strength.

Experimental Investigation on the Effect of Reinforcement Particles on the Forgeability and the Mechanical Properties of Aluminum Metal Matrix Composites

The wide choice of materials, today’s engineers are posed with a big challenge for the right selection of a material and as well as the right selection of a manufacturing process for an application. Aluminium Metal Matrix Composites is a relatively new material among all the engineering materials. It has proved its position in automobile, aerospace, and many other engineering applications due its wear resistance properties and due to its substantial hardness. One of the most important criteria is forgeability by which the workability of the material can be determined. The nature of distribution of reinforcing phase in the matrix greatly influenced the properties of Aluminum Metal Matrix Composites. The forgeability of Aluminum Metal Matrix Composites, which are produced by powder metallurgy method, are greatly depends on the size and percentage of reinforcement materials, compacting load, sintering temperature and soaking time etc. In this present work, the forgeability of Aluminum Metal Matrix Composites reinforced with silicon carbide (400 meshes) has investigated. A comparison have been made with different types of Aluminum Silicon Carbide Metal Matrix Composite materials contains 0%5%,10%,15%&20% by weight of silicon carbide. The mechanical properties like hardness of the different composites have also investigated. It is observed that the forgeabilty of the composites decreases with increasing the wt% of SiC but the mechanical properties like hardness enhanced on increasing the wt% of SiC.

An investigation on the machinability of Al-SiC metal matrix composites using pcd inserts

The paper attempts to study the machinability issues of aluminium-silicon carbide (Al-SiC) metal matrix composites (MMC) in turning using different grades of poly crystalline diamond (PCD) inserts. Al-SiC composite containing 15%wt of SiC was used as work material for turning and PCD inserts of three different grades were used as cutting tools. Experiments were conducted at various cutting speeds, feeds and depth of cuts and parameters, such as surface roughness, specific power consumed, and material removal rate were measured. The worn surface of the insert was examined by scanning electron microscope (SEM). The surface finish observed was found to be much lower than the theoretical surface roughness. The influence of cut was examined for the different grades of PCD inserts. It was observed that the 1600 grade PCD inserts performed well from the surface finish and specific power consumption points of view closely followed by the 1500 grade.

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.

Thermal characterization of a liquid cooled AlSiC base plate with integral pin fins

In this study, we present the thermal analysis and experimental performance assessment of an aluminum silicon carbide (AlSiC) metal matrix composite (MMC) base plate with integral cooling fins. By attaching a pin-finned base plate to an open-chambered flow-through heat sink, the mechanical interface between the base plate and cooling medium is eliminated. This reduces the overall thermal resistance and improves module reliability as compared with traditional base plate cooling schemes. Computational fluid dynamics and heat transfer techniques were employed to model the thermal and hydrodynamic resistance characteristics through the pin fin structure of a prototype base plate design. A unit-cell approach was employed to avoid the computational expense of modeling the entire pin array. Performance was verified experimentally in a closed loop test facility using water as the cooling fluid. It was found that the unit-cell approach produced good agreement with experimental pressure drop and heat transfer results.

Optimum conditions for pressureless infiltration of SiC p preforms by aluminum alloys

The optimum parameters for processing aluminum silicon carbide metal matrix composites via pressureless infiltration of porous SiC p preforms are described. These optimum parameters were obtained by using a carefully designed experiment in which the effect of critical processing parameters on pressureless infiltration was investigated quantitatively. The parameters examined included: SiC particle size, infiltration time, preform height, % SiC in the preform, and Si coating on the SiC particles. The contribution of each of these parameters and their interactions to variation in density, modulus of elasticity, and modulus of rupture of the composites were determined and used to project the optimum processing parameters. Al/SiC p composites were produced using the conditions that were projected to produce optimum modulus of elasticity and their modulus of elasticity was measured. The results show excellent agreement between the projected and measured values.

Deformation behavior of an aluminum-silicon carbide metal matrix composite in plane stress/plane strain

The deformation behavior of Al/SiC metal matrix composites (MMCs) has been studied quite extensively. The high increased strength observed in short fiber reinforced Al/SiC MMCs is attributed to a high dislocation density in the ductile aluminum matrix. The deformation behavior of an Al-20 vol.%(SiC){sub p} composite was studied under plane stress/plane strain conditions and is well defined by a simple power law type of equation. Longitudinal microcracks form at low strains in the direction of the loading axis as a result of the lateral constraint developed because of the geometry of the Clausing specimen. Microcracks perpendicular to the loading direction are formed at larger strains. Final fracture is caused by the perpendicular cracks.

The effect of volume fraction of reinforcement on the elastic-viscoplastic response of metal-matrix composites

Analysis of the elastic—viscoplastic response of a particulate-reinforced Aluminium Silicon Carbide Metal—Matrix Composite material has been carried out, using the finite element “unit-cell” approach. The analysis has revealed that the various material dependent parameters in the elastic—viscoplastic constitutive equations are strongly affected by the volume fraction of reinforcement. Relationships are proposed to determine the values of the various material parameters for the composite material at low and medium volume fractions of reinforcement (up to about 20%), when the corresponding parameters for the unreinforced matrix material are known. Investigation of the kinematic hardening characteristics of the composite material showed that the strengthening offered by the particulate reinforcement only occurs over a small range of plastic strain from the onset of composite yielding. For higher volume fractions of reinforcement (> 30%), the hardening rate eventually drops below that of the unreinforced matrix material at higher levels of plastic strain. Detailed investigation of the hardening and the dynamic recovery components of the kinematic hardening has revealed that the drop in the composite's kinematic hardening relative to that of the unreinforced matrix material, is due to the rapidly increasing recovery component, the rate of which surpasses that of the hardening component at plastic strain levels coinciding with the commencement of the drop in the kinematic hardening observed. Both the hardening and the dynamic recovery components show a non-linear relationship with the volume fraction of reinforcement for the range of volume fraction considered.