Fabrication and Characterization of A356-Basalt Ash-Fly Ash Composites Processed by Stir Casting Method

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1 Fabrication and Characterization of A356-Basalt Ash-Fly Ash Composites Processed by Stir Casting Method Fabrication and Characterization of A356-Basalt Ash-Fly Ash Composites Processed by Stir Casting Method Department of Mechanical Engineering, K. S. Rangasamy College of Technology, Tiruchengode, Summary This paper presents the characterization of A356 composite reinforced with fly ash and basalt ash produced by stir casting method. Aluminium metal matrix composites (AMC) are used in wide variety of applications such as structural, aerospace, marine, automotive etc. Stir casting is cost effective manufacturing process and it is useful to enhance the attractive properties of AMCs. Three sets of hybrid AMC are prepared by varying the weight fraction of the reinforcements (3% basalt + 7% fly ash, 5% basalt + 5% fly, 7% basalt + 3% fly ash). The effect of reinforcements on the mechanical properties of the hybrid composites such as hardness, tensile, compressive and impact strength were studied. The obtained results reveal that tensile, compressive and impact strength was increased when weight fraction of fly ash increased, whereas the hardness increases when weight fraction of the basalt ash increased. Microscopic study reveals the dispersion of the reinforcements in the matrix. Keywords: Aluminum, Fly ash, Basalt; Mechanical properties 1. Introduction Metal matrix composites (MMCs) are suitable for applications requiring combined strength, damping properties, low weight and low density. These properties of MMCs enhance their usage in many applications in automotive field such as pistons, cylinder block and brake drum because of better corrosion resistance and wear resistance. Aluminium fly ash composites metal matrix dispersion strengthening composite. Discontinuously reinforced aluminium (DRA) MMCs are of increasing interest because of high isotropic, high specific stiffness, strength, excellent wear resistance and cost effective manufacturing 1. It can be used in various automobile applications, electronic packaging and aerospace, as well as other structural applications. Fly ash particle s surface treatment is a prerequisite and getting an acceptable level of its dispersion in 356 alloy 2. Fly ash s damping capacity strengthened of Al-based composite increases with the increase in volume fraction of fly ash 3. Fly ash s twelve volume percent reinforced composites show lower wear rates while compared with unreinforced alloy and in its load range is N 4,5. The size of the impeller, stirring speed and holding temperature, as well as the position of the impeller in the melt these are processing variables 6,7,8. Production of cast metal matrix composites also considered that important factors. That cast metal matrix as these have a consequence on mechanical properties. That s distribution, the level of the intimate contact of the wetting with the matrix materials and also porosity content. The reinforcement of fly ah reduces the density as well as improved the mechanical behaviour of composites 9,10. Compressive strength, modulus of the composites and plateau stress increases with the increase in composites density. The hybrid composite s density decreases because of that, the hardness and porosity increases with the increase in % of the reinforcement 11,12. Composite material s tensile compared to the as cast A359 alloy is increased significantly by 60-70%. Hardness of hybrid composite is increases with increase in weight percentage of fly ash and Al2O3 up to 12 percent 13,14. In this work, an attempt is made to fabricate aluminium alloy A356 reinforced with basalt and fly ash by stir casting method. Properties such as microstructure, hardness, wear and tensile strength are investigated and also study the effects of fly ash and basalt content on microstructure and mechanical properties of A356-basaltfly ash aluminium metal composites. 2. Methodology The research methodology for A356 composition was shown in Figure 1. venkat6670@gmail.com, kumaraveliitm@yahoo.com Smithers Information Ltd., Material Selection A356 aluminium alloy (AA) is a casting alloy consisting of aluminium, Polymers & Polymer Composites, Vol. 25, No. 3,

2 Figure 1. Research methodology for MMC investigation magnesium, manganese, copper, ferrous, zinc, nickel, titanium and silicon. It has good strength and ductility as well as first-rate casting features, high corrosion resistance, and good fluidity. The chemical composition of A356 alloy is shown in the Table 1. Table 1. Chemical compositions of A356 alloy Element Si 7.20 Cu 0.02 Mg 0.29 Mn 0.01 Fe 0.18 Zn 0.01 Ni 0.02 Ti 0.11 Al Balance The machinery, aircraft and defence industries have widely applied the alloy, and particularly in the automotive industry to replace the AA instead of steel alloy have been widely applied. The incorporation of fly ash into AA matrix can lead to low cost aluminium production composites with improved hardness and strength. In automotive components such as pistons, cylinder liners and connecting rods are manufactured from AA that is annealed at 700 o C to obtain uniform properties after heat treatment. The casting and forgings for pistons, cylinder liners and connecting rods are precision machined to high dimensional accuracy by computer numerical control generators. After the machining, heat treatment processes are most important. 2.2 Fly Ash as Reinforcement Fly ash are low-cost and low-density reinforcement available in large quantities as a waste by-product in thermal power plants, fly ash particles are potential discontinuous dispersions used in metal matrix composites. The chemical composition of fly ash is shown in the Table 2. Table 2. Chemical composition of fly ash Element SiO Al 2 O Fe 2 O CaO 8.70 MgO 1.80 SO Na Two types of fly ash are namely, cenosphere (hollow particle) and precipitator (solid particle). The main chemical constituents of fly ash are Al 2 O 3, Fe 2 O 3, SiO 2 and CaO. Minera-logically, the fly ash constitutes the alumino silicate glasses containing hematite, magnetite, ferrite, spinel, anhydride, quartz, mullite, and alumina. The wear resistance, damping properties, hardness and stiffness are improved and reduce the density of AA by incorporation of fly ash particles. Aluminum fly ash composites have potential applications as covers, casings, pans, pulleys, shrouds, manifolds, valve covers, brake rotors, as well as engine blocks in automotive, small engine and the electromechanical industry sections. The fly ash reinforced AMCs are also named as ash alloys. 2.3 Reinforcement of Basalt Basalt is a natural material which is found in volcanic rocks. The elements present in basalt are O, Na, Mg, Al, Si, K and Ca. The properties like hardness and tensile strength increased with increase in the weight fraction of basalt. The chemical composition of basalt is shown in the Table 3. Table 3. Chemical composition of basalt Elements % O 30.6 Na 2.54 Mg 3.59 Al 6.8 Si 26.9 K 0.51 Ca Specimen Preparation Fly ash and basalt reinforced aluminium alloy (A356) composites was produced by stir casting technique. Three composition were taken for the stir casting process such as 90% Al + 3% basalt + 7% fly ash (Sample 1), 90% Al + 5% basalt + 5% fly ash (Sample 2), 90% Al + 7% basalt fiber ash + 3% fly ash (Sample 3) were taken according to the weight ratio of the composition. Aluminium alloy was preheated at a temperature of 650 C for 1 hr and melting at the temperature of 900 C. The fly ash and basalt particles were preheated at a temperature of 300 C for 30 minutes and then added at a constant feed rate into the molten aluminium was stirred with the speed of 300 rpm for 30 seconds. During this process 210 Polymers & Polymer Composites, Vol. 25, No. 3, 2017

3 Fabrication and Characterization of A356-Basalt Ash-Fly Ash Composites Processed by Stir Casting Method degassing agent and the skum powder were added to the mixture to remove the excess gas formation and to avoid the slag from the mixture. Then the composition was poured into the die and it gets solidified. After 10 minutes the composite materials were removed from the die and cooled at room temperature. The similar approaches were followed to produce all three types of samples. Figure 2. Tensile specimens (a) before testing and (b) after testing 3. Result and discussions 3.1 Tensile Strength Computerized universal testing machine is used to perform the tensile tests at a strain rate of 1 mm/ min and the ultimate tensile strength obtained during tensile test. It is found that the addition of fly ash and basalt has significant effect on the tensile properties and also increase the ultimate tensile strength (UTS) of the material. In addition of fly ash and basalt particles increase strength mainly due to the load transfer from matrix to the reinforcement and show the differences in the elastic constants. Figure 2 shows the tensile specimen before testing (a) and the tensile specimen after the testing (b). The ultimate tensile strength and percentage of elongation are shown in the Figure 3 and Figure 4. Figure 3. Composites vs. ultimate tensile strength Figure 4. Composites vs. % elongation 3.2 Chemical Composition of (A356 + Basalt + Fly ash) The effect of reinforcement (basalt and fly ash) increases the percentage of silicon, copper, magnesium and zinc. The presence of silicon reduces thermal expansion coefficient, shrinkage and high fluidity. Copper increases the ultimate tensile strength while heating and the role of magnesium reduces the friction coefficient. The presence of zinc increases the ultimate tensile strength. Chemical composition before reinforcement and after reinforcement of aluminium composites was shown in the Table 4. Table 4. Chemical composition before reinforcement and after reinforcement Elements % Before Reinforcement After Reinforcement Si Cu Mg Mn Fe Zn Al Balance Balance Polymers & Polymer Composites, Vol. 25, No. 3,

4 Figure 5. Wear samples Figure 6. Hardness test specimen 3.3 Wear Test The sample for wear test was prepared with standard dimension of 9 mm diameter and 50 mm height was shown in the Figure 5. Wear test were conducted using pin on disc machine. The wear test was conducted at three different loads, with increments of 1 kg. After 5 minutes the specimen was removed, cleaned, dried and to calculate the weight loss. Speed and track radius was kept at constant. The friction coefficients and wear rate were recorded continuously as shown in the Table 5. Wear results shows that the sample 1 having lower wears compare to other two compositions. 3.4 Hardness Test Hardness test specimens were prepared with standard dimensions of ASTM E-384 were shown in Figure 6. Figure 7. Vickers hardness of aluminium MMCs The hardness of the testing samples is measured using Vickers micro hardness, applying a load of 500 gm and load is applied for 10 seconds. The possibilities of errors were minimized by taking four readings of hardness value for each sample. From the Figure 7 the composition of sample 2 having maximum hardness value. Table 5. Wear rate and coefficient of friction Sample details Wear rate (micrometer) Coefficient of friction Load (1 Kg) Load (2 Kg) Load (1 Kg) Load (2 Kg) Sample Sample Sample Microstructure Observation The modification is usually used for those Al alloys with 4% or more silicon. Figure 8 shows alloy A356 before and once modification with metallic element. Pseudo-modification, within which the fineness of the mixture however not the structure is affected, could also be achieved by management of natural action rates. There are high cooling rate, fine dendrites and network of inter dendritic mixture type. 4. Conclusions There are three compositions of A356 were taken for the tensile test, Vickers hardness and wear test. The following results were suggested that test results 212 Polymers & Polymer Composites, Vol. 25, No. 3, 2017

5 Fabrication and Characterization of A356-Basalt Ash-Fly Ash Composites Processed by Stir Casting Method Figure 8. A356 microstructures of (a) Matrix alloy composites (b) Sample 1, (c) Sample 2 (d) Sample 3 on the hybrid composite material. Stir casting is cost effective manufacturing process. Addition of fly ash and basalt into A356 alloy increases the tensile strength in the first composition (A % basalt + 5% fly ash). Addition of basalt into A356 alloy increases the hardness value in the second composition (A % basalt + 3% fly ash). Addition of both fly ash and basalt reduces wear rate in second and third composition. Microscopic image of the microstructure reveals the dispersion of the reinforcements in the matrix. References 1. J.D.R. Selvam, D.R. Smart and I. Dinaharan, Microstructure and some mechanical properties of fly ash particulate reinforced AA6061 aluminum alloy composites prepared by compocasting, Materials and Design, 49, (2013) J. Hashim, L. Looney and M.S.J. Hashmi, Metal matrix composites: production by the stir casting method, Journal of Materials Processing Technology, 92, (1999) M.K. Surappa, Synthesis of fly ash particle reinforced A356 Al composites and their characterization, Materials Science and Engineering A, 480(1), (2008) M.K. Surappa, Dry sliding wear of fly ash particle reinforced A356 Al composites, Wear, 265(3), (2008) M. Sivashanmugam, N. Manoharan, D. Ananthapadmanabhan and S. Ravi Kumar, Investigation of microstructure and mechanical properties of GTAW and GMAW joints of AA7075 aluminum alloy, International Journal on Design and Manufacturing Technologies, 3(2), 56-62, M.S.R. Patil and P.B. Motgi, A Study on Mechanical Properties of Fly Ash and Alumina Reinforced Aluminium Alloy (LM25) Composites, Journal of Mechanical and Civil Engineering, 7(6), (2013) C. Neelima Devi, N. Selvaraj, V. Mahesh, Micro structural aspects of aluminium silicon carbide metal matrix composites, Int. J. Appl. Sci. Eng. Res. 1 (2012) H.B. Bhaskar and Abdul Sharief, Tribological properties of Aluminium 2024 Alloy-Beryl Particulate MMC s, Bonfring International Journal of Industrial Engineering and Management Science, 4(4), , Vignesh V. Shanbagh, Nitin N. Yalamoori, S. Karthikeyan R., Ramanujam R and K. Venkatesan, Fabrication, Surface Morphology and corrosion investigation of Al7075-Al2O3 matrix composite in sea water and Industrial environment, Procedia Engineering (GCMM 2014), 97, , P.K. Rohatgi, J.K. Kim, N. Gupta, S. Alaraj and A. Daoud, Compressive characteristics of A356/fly ash cenosphere composites synthesized by pressure infiltration technique, Composites Part A: Applied Science and Manufacturing, 37(3), (2006) R. Dhanasekaran and K. Sathish Kumar, Microstructure, Mechanical Properties Of A356/Li Aluminum Alloy Fabrication By Stir Casting Method, International Journal of Applied Engineering Research, 10(50), (2015) N. Yazdian, F. Karimzadeh and M. Tavoosi, Fabrication and precipitation hardening characterization of nanostructure Al7075 alloy, Indian Journal of Engineering and Materials Science, 21, 30-34, S.G. Kulkarni, J.V. Meghnani and A. Lal, Effect of Fly Ash Hybrid Reinforcement on Mechanical Property and Density of Aluminium 356 Alloy, Procedia Materials Science, 5, (2014) S. Kumaravel and D. Mohanraj, Production and Mechanical Properties of Fly ash and Basalt ash reinforced Al 6061composites, Indian Journal of Science, 16(49), (2015) Polymers & Polymer Composites, Vol. 25, No. 3,

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