Applied Mechanics and Materials Vols. 465-466 (2014) pp 1003-1007 (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/amm.465-466.1003 Fabrication Of - Composites From Direct Recycling uminium loy 6061 N.A. Badarulzaman 1,2,a, S.R. Karim 1,b, and M.A Lajis 1,3,c 1 Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Johor, Malaysia 2 Engineering Materials liance (ENIGMA), Universiti Tun Hussein Onn Malaysia 3 Advanced Materials and Manufacturing Centre (AMMC), Universiti Tun Hussein Onn Malaysia a azam@uthm.edu.my, b hd120083@siswa.uthm.edu.my, c amri@uthm.edu.my Keywords: Direct recycling; cold forging; uminium; Tin (stannum); composites; Abstract. Solid-state direct conversion method of recycled aluminium 6061 alloy to produce metalmetal composites was studied by using collected recycle chip. Different volume percent of stannum () matrix was studied to attempt the tensile strength and surface integrity of the aluminium composites product. Constant pressure was used to implement the cold forging process with constant sintering temperature. Single size of chip had been used which 2 mm length as suggested. The optimum result of yield strength and ultimate tensile strength is 3 Pa and 8.3 Pa for 20 vol% of composition. Analysis shows that composites beyond 20 vol% resulted in the tensile strength decreased. Introduction uminium () has widespread usage including artistic and engineering product. Among metals, and its alloy are often used in industries such as transportation, structural building, food containers and aerospace. Its properties include of high corrosion resistance with good strength, and low density was courage the researcher to explore new application from it. Besides, also offers better in conductivity, ductility and malleability and recyclability. It recyclability, make it vital in many applications especially for aeroplane and automotives sector. Growing application in automotives industries is with respect in reducing fuel utilization according to light in weight and shielding the environment [1]. recycling has a good properties unlike other materials with maintaining their properties as primary metal [2]. The production processes of primary are consuming high energy with high operating cost. Hence, recycling of is proposed in order to reduce the energy consumption and other several beneficial factors. Martchek [3] stressed that, by recycling aluminium, the energy consumptions can be saved around 85% compared using primary aluminium. In fact, this secondary resources (recycled ) only used among 5% of the energy to produce the same amount primary resources [4]. Besides, the production cost of primary is five times higher than steel production [4].The other reason of recycling is to reduce the environmental problem and sustainability stand point. Cole [5] reports that, fabrication of will produce 43% emission of CO₂ compared to recycled which only contributes 2.7% of CO₂ emission. CO₂ emission will influence the increment of global warming by greenhouse gas (GHG) produced. This is the reason why recycling become very popular in manufacturing and given priority in developed countries especially. Initially, recycling process was done by using conventional recycling process (CRP). CRP is a process melting metal as fundamental stages before casting process. Even though this method is one of the best methods, it also has difficulties associated. As examples, numbers of step, high energy consumption, exposed to hazardous during handling molten metal and some waste metal produces. Under such conditions, CRP has some metal loses approximately 46% during remelting process [6-8]. Gronostajski, et al. [9] stated that, metal dross and new metal scrap will occur in each single level of CRP. Hence, all of these factors were influence to the researcher to find out another method with more effective and compatible with our nature nowadays. The new technique l rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 103.31.34.2-08/11/13,10:13:39)
1004 4th Mechanical and Manufacturing Engineering are aiming to reduce GHG contributor, reduce cost, simpler method and lowering waste product was suggested by Samuel [7]. Direct conversion method is a solid state method that eliminating powder metallurgy process (PM) with direct to forging process or extrusion. Figure 1 shows the differentiation of scrap produce in direct conversion method and conventional method as reported by [7]. Figure 1: Comparison between (a) conventional process and (b) direct conversion technique Composites materials that posses numerous advantages become high attention by researcher lately. Composite is materials that have two or more distinct constituent or phases and thus can be classified. However, this definition must be satisfied with three criteria where both constituent must have reasonable proportion (greater than 5%), both constituent has different properties and hence the composites properties must different from constituents properties [10]. Experimental procedure - composites were prepared by using direct conversion method which including cold forging process and sintering process. First stages of this process 6061 and pure chip (Figure 2 (a) and (b)) were collected from milling machine. Chipping process was done in phase milling process with 1100 rev/min cutting speed, 0.02 feed rates and 0.5 depth of cut by Mozek Nexus 410A-II high speed machining. Then the chips were ultrasonically clean using acetone solution. After that, batching process was done by using volume percent as suggested in rule of mixture of composites [11]. Mixing process was done by using ball mill and ready mixed chip was compacted with constant operation pressure 300 MPa with 6 minutes holding time. Standard shape as suggested in ASTM-E8M was prepared in determining yield strength (YS) and ultimate tensile strength (UTS) [12]. Sintering process was conducted at 300 ⁰C with 1hour soaking time in order to consolidate the green body sample as suggested by [13]. Then the strength of sintered samples was tested by using Shimadzu EHF-EM0100K1-020-0A. Microstructures of the specimens were characterized by optical microscope (Olympus BX60M). Samples were etched in Keller reagent solution in obtaining grain boundaries of the specimens as suggested in ASTM E-407 [14]. The results of - base composites obtained were compared with reference specimen (pure recycled ).
Applied Mechanics and Materials Vols. 465-466 1005 Results and Discussion (a) (b) (c) Figure 2: (a) uminium chip (b) Stannum chip (c) green body specimen Mechanical Properties: The effect of the matrix () amount added on the mechanical properties of the composites is given in Figure 3. The main purpose of this testing is to determine strength values, UTS and YS. The 0.002 strain offset line is constructed parallel to the stress strain line at the beginning curve in order obtaining the YS value. Its intersection occurred on the beginning the chart line to curve. From the plotted data, the trend line clearly shows the strength of the composite increasing by increasing volume percent of and -20vol% composites have optimum UTS (8.3 Pa) and YS (3.0 Pa). However, the results are decreasing for volume fraction over 20%. From the results also, the YS and UTS shows high value increment between 100% sample and - composites as calculated in Table 1. Figure 3: Tensile strength Vs Vol% of
1006 4th Mechanical and Manufacturing Engineering Table 1: Strength increment by percentage between composite and 100% samples. composites Yield strength Ultimate tensile strength -6% 512% 171% -20% 518% 228% -40% 450% 157% Factors that contribute significant effect to the bonding of composites are amount of composites, form and size of the reinforcing phase, the cold pressing parameter and the temperature [9, 15]. Matrix precipitation is normally act to distribute loaded given and hold reinforces to increase strength, hardness and the other mechanical properties [16]. On the other hand, composites specimens have better mechanical strength compared to reference specimens. It is believes that, due to own properties which is weaker than and has lower sintering temperature due to its melting point at 232 ⁰C. Microstructure: Figure 4 shows the optical micrograph of - composites after sintering process. Samples were polished with Cr₂O₃ polisher medium and etched in Keller s reagent. Microstructure of samples with 20 vol% of has less obtained compared to sample prepared with 6 vol% of. The grain boundaries clearly show between and. Even so, from the image, the interphase that possible to occur in composites materials cannot be seen in this sample. From the figure also, it clearly show Micro-s were obtained in parts. a b Micro Micro Grain Micro Grain Figure 4: Microstructure of (a) -6vol% (b) cross section -6vol% (c) -6vol% (d) cross section -20vol% at 100 magnification
Applied Mechanics and Materials Vols. 465-466 1007 Conclusion Composites - had been done using direct conversion method by cold forging process in this study. Referred to the research had been done, the following conclusion can be write that, the optimum amount of to produce better composites at 300 ⁰C sintering temperature is 20 vol%. It is support by the increment value of the strength of the composites that was calculated. It was observed that, at this amount, it has higher strength and amount of the obtained smaller than the other samples. Acknowledgement. This work is financially supported by UTHM Postgraduate Study Incentive Scheme (GIPS Vot 1247) and MTUN-CoE Grant (Vot C016). Reference [1] T. Rameshkumar, I. Rajendran, and A. Latha, "Investigation on the mechanical and tribological properties of aluminium-tin based plain bearing material," Tribology in Industry, vol. 32, pp. 3-10, 2010. [2] N. J. T. I. Wernick, "Recycling Metals for the Environment," Annual Review Energy and Environment, 1998. [3] K. J. Martchek, "The importance of recycling to the environmental profile of metal products," The Minerals, Metals & society, pp. 19-28, 2000. [4] M. E. Schlesinger, Ed., "uminum Recycling". United States of America: Taylor & Francis Group, 2007, p.^pp. Pages. [5] G. S. Cole, "Issues that influence magnesium's use in the automotive industry," in Materials Science Forum, 2003, pp. 43-50. [6] W. Chmura and J. Gronostajski, "Mechanical and tribological properties of aluminium-base composites produced by the recycling of chips," Journal of Materials Processing Technology, vol. 106, pp. 23-27, 2000. [7] M. Samuel, "A new technique for recycling aluminium scrap," Journal of Materials Processing Technology, vol. 135, pp. 117-124, 2003. [8] T. Pepelnjak, K. Kuzman, I. Kačmarčik, and M. Plančak, "Recycling of MgSi1 aluminium chips by cold compression," Metalurgija, vol. 51, pp. 509-512, 2012. [9] J. Gronostajski, H. Marciniak, and A. Matuszak, "New methods of aluminium and aluminium-alloy chips recycling," Journal of Materials Processing Technology, vol. 106, pp. 34-39, 2000. [10] F. L. Matthews and R. D. Rawlings, Composite materials: engineering and science: Woodhead Publishing, 1999. [11] S. Test, "Methods for Constituent Content of Composite Materials," ASTM D3171. [12] A. Standard, "E8-04,," Standard Test Methods for Tension Testing of Metallic Materials, Annual Book of ASTM Standards, vol. 3, 2004. [13] X. Liu, M. Zeng, Y. Ma, and M. Zhu, "Melting behavior and the correlation of distribution on hardness in a nanostructured alloy," Materials Science and Engineering: A, vol. 506, pp. 1-7, 2009. [14] A. Standard, "E407, 2007. Standard practice for microetching metals and alloys. ASTM International, West Conshohocken, PA, doi: 10.1520/E0407-07," ed. [15] J. Gronostajski and A. Matuszak, "The recycling of metals by plastic deformation: an example of recycling of aluminium and its alloys chips," Journal of Materials Processing Technology, vol. 92, pp. 35-41, 1999. [16] M. Rashid, "Mathematical modeling and optimization of precipitation hardening of extrudable aluminium alloys," King Fahd University of Petroleum and Minerals, 1997.