Abstract
The metal matrix composite (MMC), despite of its high stiffness, strength, corrosion resistance, wear resistance, non-react with chemicals and so many other tailored qualities which are never obtained in alloy of metals, has limited utilization due to the high cost of fabrication. In this study, a modest attempt has been made to find out the process parameters at which best mechanical properties of Al6061, 4% Cu and reinforced 5% SiCP ceramic MMC can be obtained. The addition of 4% Cu in Al6061 is more or less comparable to the composition duralumin, which are widely used in aerospace applications. SiCP is hard and has linear thermal expansion at high temperature. With reinforcement of SiCP in Al6061-Cu alloy, it can be postulated that hardness of MMC retains at high temperature applications. An analysis of Variance (ANOVA) and linear regression was used for analysis of data with the help of SPSS (Version-17.0). Independent parameters are five levels of pouring rates (1.5 cm/s, 2.0 cm/s, 2.5 cm/s, 3.0 cm/s and 3.5 cm/s), and material type (Al6061 + 4% Cu alloy and Al6061 + 4% Cu, reinforced 5% SiCp MMC processed using stir casting technique) and dependent parameters are hardness and impact strength material removal rates of workpiece. It is found that at different pouring rates material hardness and impact strength of workpiece are highly significant but the material removal rate of workpiece is having no significance value. At pouring rate of 2.5 cm/s and 700℃ ± 5℃ pouring temperature, optimum values of hardness and impact strength are observed as compared to other values of pouring rates (1.5 cm/s, 2.0 cm/s, 3.0 cm/s and 3.5 cm/s). Material Removal rate for work pieces of Al6061 + 4% Cu alloy is less as compared to MMC. So it can be concluded that MMC has better machining ability compared to Al6061 + 4% Cu alloy. Material removal rate of Al6061 + 4% Cu, reinforced 5% SiCP MMC has maximum values at 1.5 cm/s pouring rate compared to 2.0 cm/s, 2.5 cm/s, 3.0 cm/s and 3.5 cm/s pouring rates. With reinforcement of 5% SiC trend of mechanical properties is same, but the hardness and impact strength of MMCs are increased by 25% and 20% respectively. Also it is observed from scanning electron microscopy (SEM) that at pouring rate 2.5 cm/s a better homogeneity can be obtained.
Highlights
metal matrix composite (MMC) of aluminium are used for space shuttle, commercial airliners, electronic substrates, bicycles, automobiles, golf clubs and a variety of other applications due to its light weight [1]
The result of Multivariable Analysis of Variance (MANOVA) to see the effect of input variables such as pouring rate and material type on output properties such as hardness, impact strength and material removal rate. It is obtained from MANOVA (Table 2), the effect of pouring rate and material type are highly significant for the output variables but for output variable material removal is not found significant for pouring rate
2) Increased material removal rate due to addition of SiC particulates is concluded as better machinability of MMC as compared to base alloy
Summary
MMCs of aluminium are used for space shuttle, commercial airliners, electronic substrates, bicycles, automobiles, golf clubs and a variety of other applications due to its light weight [1]. [2,3,4,5], and these qualities make it appropriate for demanding application in aerospace and automobile industries. Reinforcement of ceramics (Al2O3 or SiC) in Al MMC, mechanical properties is improved. Mechanical properties and homogeneity depend on the reinforced particulate size, weight percentage and processing methods [5,6]. The major complication in processing MMCs is achieving a homogeneous distribution of reinforcement in the matrix as it has a strong impact on the properties and the quality of the material [7]. Christy et al studied the effect of particulate silicon carbide on the mechanical behavior of Al 6061 MMC [8]
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