Study on Properties of Multi Walled Carbon Nanotube Reinforced Aluminum Matrix Composite through Casting Technique

Composite materials are defined as material systems consisting of mixture of or combination of two or more micro constituents insoluble in each other and differing in form and or material composition. In this study Metal Matrix Composite (MMCs) has been produced using stir casting method for performing the mechanical properties. Most of the engineering industries want light and better mechanical properties of components; this can be achieved by MMCs of Aluminium because of its excellent performance. In this research work we fabricate the Aluminium by liquid route. Here Al 7075 is used as a base metal and Multi Walled Carbon Nanotubes (MWCNT) used as sub metal with various percentages. Experiments were conducted to analyze microstructure, hardness & tensile strength. By using optical microscope and Scanning Electron Microscope (SEM) we analyze the sample specimens are well dispersion in MWCNT with AA 7075. Hardness and tensile strength increases with increasing of wt. %. Hardness of material increases with increase in percentages of MWCNT, whereas tensile strength of the material increases with increase in percentages of MWCNT and Elongation reduces. CONTACT Shuib Pasha S A shuaib8787@gmail.com Department of Mechanical Engineering, Brindavan College of Engineering, Bangalore-560063, VTU, Karnataka, India. © 2021 The Author(s). Published by Enviro Research Publishers. This is an Open Access article licensed under a Creative Commons license: Attribution 4.0 International (CC-BY). Doi: http://dx.doi.org/10.13005/msri/180111 Article History Received: 12 December 2020 Accepted: 07 April 2021


Introduction
MMC's are used to improve the mechanical properties. Omkar Aranke et al. 1 in this study stir casting method are used to produce composites of AL-7075 with MWCNTs. It is observed that microstructure study under SEM shows the uniform dispersion of MWCNTs. In this investigation hardness, tensile strength and impact strength of the material increases with various weight of MWCNT. Chaitanya Gandhi 2 in this investigation stir casting method is used to get al-MWCNT composites, here the wear rate gets reduced with increase of sub metal but severe condition 0.75% MWCNT shows the negative results compared with 0.5% of reinforcement. Ravi kumar M 3 in this experimental study the distribution of Al 2 O 3 and SIC by using stir casting method, the tensile strength increased with increase the weight % of SIC, the hardness value also increased and the wear rate decreased with increase the SIC weight %. R. Pérez-Bustamante 4 in this study, Al-MWCNT composite produced using by mechanical milling method. The mechanical properties increased from the nanocomposites. Kesavulu A 5 in this study by using stir casting method; Al with fly ash composite, here with the addition of fly ash, the density of Alfly ash is decreased. Again with the addition of fly ash the hardness and tensile strength of Al-fly ash is increased. Sedat Ozden 6 in this investigation we prepare Al reinforced with SIC by using stir casting method, here higher impact toughness was found in the varying weight % compare to pure aluminium. S. E Shin 7 in this investigation by using mechanical milling and the press-and-sinter process, Al2024 with MWCNT composite is produced. This study used get good tensile properties like better yield strength, young modulus and elongation to failure. These properties of materials are widely used in applications such as automobile parts.Sabitha Jannet 8 in this investigation by using stir casting method, AA-5083 with SiC & MWCNT composite is produced. Here Tensile strength of the composite increased as the wt. % of the MWCNTs increased. Mehrdad Shayan 9 in this study stir casting method is used to produce composites of AA2024−TiO 2 .
Here the microstructure changes due tothe presence of nanoparticles agglomerations, and the increased porosity and the mechanical properties of the products were improved by adding TiO 2 nanoparticles to the matrix alloy.B.N Yadav 10 in this investigation hybrid composites is produced, LM 13 Alloy with MWCNT &SiC through stir casting technique.Here The plateau stress and energy absorption increase with the individual addition of MWCNTs and SiC, but when both were added together the improvement is more than individual addition. Nekilesh 11 in this study AA5083 -MWCNT (1.5 wt %) was fabricated using compo-casting method to study the corrosion behavior. Here from the PDP and EIS experiments it is evident that the AA5083 -MWCNT have better corrosion resistance than the AA5083 matrix material. M Sanju 12 in this study by using stir casting method Al7075 with MWCNT & flyashhy brid composite is produced.
Here the percentage of reinforcement affects the hardness of the material and reduced the wear rate with the increase in the reinforcement.

Materials
Composition of Al7075 is shown in the table 1. Al-7075 is consists of good mechanical property like hardenability and finds its application in aircraft and automobiles. MWCNT's is considered as the reinforcement with 90% of purity because of high strength as well as low density. (Table 2). By using various weight % of MWCNT composites was prepared., and CNTs having a better lubricating properties.

Methodology Preparation of MWCNT
MWCNT and acetone solution stirring it in a magnetic stirrer for 30 to 40 minutes (quantity sufficient to stir). Now we get a mixture of MWCNT and acetone in a glass beaker, keep this aside by covering the top with aluminium foil. Now take a glass beaker of tween 80 liquid, sodium lauryl sulphate and acetone. Tween 80 is a non-ionic surfactant that is widely used as an emulsifier in cosmetics, pharmaceuticals and food products.
TWEEN 80 is a polyethylene sorbitol ester, with a calculated molecular weight of 1,310 daltons, First an emulsion of MWCNT was prepared, and then we will be having two glass beakers-Beaker 1 with solution MWCNT and acetone. Beaker 2 with solution of liquid tween 80, sodium lauryl sulphate and acetone then carry both the solutions carefully. Now Al7075 meltedin 850°C and then put simultaneously both the solutions from beaker 1 and 2 into the melt, stir and pour into the moulds.
Acetone was used as a dispersion medium, sodium lauryl sulphate was used to disperse Nanotubes and Tween 80 was used as an emulsifier.

Specimen preparation and Tests Microstructure
By using Optical Microscope microstructure characterization was studied, specimens are prepared according to the ASTM standards (ASTM E407). By using polishing machine the specimens are polished with different grades.

Micro Hardness
According to the ASTM norms (ASTM E10-18) the specimens are prepared. The specimens are tested under Vickers's hardness tester with varying load (gf) and dwell time (sec).
Four readings of each sample were taken ata distance of 1 mm and the mean value is taken as a result.

Tensile Strength
As per ASTM norms (ASTM D638) specimens were prepared. By using UTM the specimens were determined.

Microstructure
From the figure 2 clearly shows the both unreinforced and reinforced sample are micro tested with different % of MWCNT. Fig. 2. (B) to (D) shows the clearly distribution of MWCNT into Al7075.
The presence of MWCNT along the grain boundaries restricts the growth of grain size during solidification and also from Fig. 2. (c) to (d) some porosities shown in the microstructure because agglomeration of CNTs in some areas in the base matrix. This is due to the act that the excess amount of CNTs does not get any room to fill thevoids and hence start to agglomerate at one place.

Micro Hardness
The study of hardness test with different sample was shown in graph. From the result cleared that hardness increases with increase in the wt. % of reinforcement because MWCNT has high tensile strength and stiffness properties.

Tensile Strength
It is the ability of the material to with stand in tension or elongation, tensile strength of specimens was

Conclusion
Following conclusion were derived from the varying % of MWCNT with different samples • Microstructure shows the uniform distribution of MWCNT throughout the matrix alloy, and there is a presence of tiny holes (0.5% MWCNT) and cracks due to agglomeration of CNTs in some areas in the base matrix. Which has to be study in the future? • Hardness of the material was increased as weight fraction of MWCNT increased in the matrix alloy, maximum hardness of 148.35 HV achieved for 0.75wt% sample (Fig. 3).