ScienceDirect Wear Characteristics Comparison of Cast and Powder Metallurgy Based Al and Al-Si Alloy [LM6

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The dry sliding wear behaviour of Cast and Powder Metallurgy (PM) based Aluminium (Al) and Aluminium-Silicon alloy (LM6) were investigated by pin on disc as per ASTM G99 standard for varying load, speed and distance. Wear rate is decreased in LM6 for
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     Available online at www.sciencedirect.com  ScienceDirect Materials Today: Proceedings 5 (2018) 8138–8146 ww.materialstoday.com/proceedings 2214-7853 © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Emerging Trends in Materials and Manufacturing Engineering (IMME17). IMME17 Wear Characteristics Comparison of Cast and Powder Metallurgy Based Al and Al-Si Alloy [LM6] Shivaramu H.T a, *, Umashankar K.S a , Prashantha D.A  b   a  Dept. of Mechanical Engineering, K V G College of Engg., Sullia, D.K-574327, Affiliated to VTU Belagum, Karnataka, India b  Dept. of Mechanical Engineering, AJIET Mangalore, D.K-575006, Affiliated to VTU Belagum, Karnataka, India Abstract The dry sliding wear behaviour of Cast and Powder Metallurgy (PM) based Aluminium (Al) and Aluminium-Silicon alloy (LM6) were investigated by pin on disc as per ASTM G99 standard for varying load, speed and distance. Wear rate is decreased in LM6 for varying speed but increased for Al. Presence of Si particles in LM6 resists the deformation and avoids the loss of material  because of welding between the particles, but in Al, larger areas of welded particles slipped between the mating surfaces enhances the wear. The PM-LM6 has good density, low thermal expansion, better stiffness properties shown higher wear resistance. © 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Emerging Trends in Materials and Manufacturing Engineering (IMME17) .  Keywords:  Aluminium; Al -Si Alloy (LM6); Powder Metallurgy; Wear rate 1.   Introduction The increasing demand for comfortable life is directly relating to the growth of material science. The nature gift materials such as wood or stone is removed by copper, bronze, iron, composite and then by nonmaterial and nanocomposites. In engineering fields like mechanical, automobile, aircraft, electrical and electronics manufacturer * Corresponding author. Tel.: +0-996-414-4078; fax: +91 8257-232644.  E-mail address: shivaramkvgce@gmail.com   Shivaramu et al. / Materials Today: Proceedings 5 (2018) 8138–8146 8139   need a low mass, stronger, robust and reliable material to meet the requirements of the products in order to execute its proposed purpose smoothly. At this moment developing advanced materials with the tailored properties are very quick. The new promising production and processing techniques for metals, alloys, polymers, ceramics and composites are came rapidly. It is the responsibility of an engineer to see that today's material, because the currently using materials will be supersede by novel materials in a near future. The Aluminium (Al) is one such material has increased its usage, has its high strength to weight ratio, abundant availability, better ductility, malleability and machinability [1, 2]. Wear resistance is one of the significant factor during the selection of a structural parts having contacting surfaces met for relative movement. The reduction of friction and wear is crucial to the regular operation of modern apparatus [3]. The major problems are seizure, wear and tear in engineering production components; hence the investigation of wear behaviour is significant [4]. Since Al based alloys have high specific strength, stiffness and easy manufacturability so extensively used in aerospace and automotive components production [3]. The study of wear is also plays an important role on such materials. It is reviled from the literature survey that in Al–Si system wear resistance of eutectic alloys is better than other alloys and linearly wear rate increases with the load [5]. The PM  production technique overcomes the limitations and problems of foundry processing and produced materials with improved properties. The Al alloy property is improved by changing the production route from Casting to PM [6, 7 ]. The load applied is an important factor in determining rate of wear. Irrespective of the sliding condition wear rate increases proportionately with the load. In wet sliding condition, at higher load Al alloy shows minimum wear rate [5]. The present study highlights an experimental investigation of PM LM6 and compared with the Cast LM6 and Al components. The effect of Si in Al-Si alloys proven better wear resistance, lower density and co efficient of thermal expansion, improved specific strength and stiffness compared to base Al [8, 9]. Since the Al and LM6 material is  playing a vital role in the automobile, aircraft and other engineering sector. The current scenario is demanding wear resistance along with high specific strength and stiffness. 2.   Experimental details The specimens prepared by Cast and PM route to compare the results 2.1 Specimen preparation The specimens prepared through Casting are machined to obtain the necessary dimensions. For the PM specimens, the die setup is used according to ASTM B-925 standard [7, 10]. The compaction load of 120KN is applied and the compacted billet is sintered at temperature of 480 0 C for a 1 Hr in a vacuum furnace. The sintered specimen were then hot extruded to obtain the 10 mm diameter with hydraulic press of 20 Ton capacity and later the standard sample pins of 8mm (diameter) x 20mm (length) are obtained by machining process. 2.2 Wear test The wear test is conducted using computerized pin on disc tester as per ASTM G99 standard having specimen of circular cross section with 8 mm diameter and 20 mm long. The pin is placed against the rotating disc, made with EN 31 steel hardened to 60HRC, having diameter of 165 mm and roughness of 1.6 Ra. The experimentation was done at room temperature in the ambient condition. The dry sliding investigation has done for the load of 1, 1.5 and 2 Kg, disc speed of 250, 500 and 750 rpm and sliding distance of 500, 1000 and 1500 m. After each trial for the specified parameters, the pin was taken off from the holder and acetone is used to remove the debris present over the surfaces. The pin weight was noted before and after the end of the experiments using weighing apparatus, with the 0.0001g of accuracy. The friction force (N) and wear in micro meter length is measured by the instrument. The wear rate (mm 3 /m) is computed based on considering the ratio of volume loss to distance traversed.  8140  Shivaramu et al./ Materials Today: Proceedings 5 (2018) 8138–8146    3. Results and discussion The wear behaviour of PM LM6 was found by varying the parameters and compared with the Cast LM6, PM Al and Cast Al. The calculated wear rate is represented by varying sliding speed with constant load and sliding distance and for varying sliding distances with constant speed and load. Fig. 1, 2 and 3 shows the wear behaviour of varying sliding speed with constant traversing distance for PM LM6 and it is compared with Cast LM6, PM Al and Cast Al. Fig. 1. Wear rate of PM LM6, Cast LM6, Cast and PM Al for varying sliding speed at load of 1.0 kg. Fig. 2. Wear rate of PM LM6, Cast LM6, Cast and PM Al for varying sliding speed at load of 1.5 kg.   Shivaramu et al. / Materials Today: Proceedings 5 (2018) 8138–8146 8141   Fig. 3. Wear rate of PM LM6, Cast LM6, Cast and PM Al for varying sliding speed at load of 2.0 kg. It is noticed that, rate of wear in PM LM6 decreases with the increase in sliding speed. The same trend observed in case of Cast LM6 but in case of Cast and PM Al the wear is increased with the increasing sliding speed. The increasing wear rate for the increasing the sliding speed in PM and Cast Al is because of development of surface abrasion due to friction between pin and disc which causes decrease in the shear strength of the material [6, 8]. Fig. 4 (a) and (b) showing the SEM images representing the higher wear rate in Cast and PM Al and observed as the number of longitudinal continuous grooves and delamination [14, 15]. But in Cast LM6 the time taken to traverse the sliding distance is decreased with higher sliding speed and hence the formation of surface abrasion avoided due to the lesser heat generation results in decreased wear with the sliding speed increment [16, 17]. The same trend is observed in PM LM6 but the rate of wear rate is still lower compare to Cast LM6. The SEM images Fig. 4 (c) and (d) depicts the complete solid surface of casted and porosity in PM specimen respectively. This is observed because of the chance of increasing the rate of heat transfer in PM specimen and expansion of material is less with temperature [18]. It is also noted that the exposure of Si particles between the mating surfaces accounts for less removal of material due to higher hardness value [11, 12, 19, 20] and for the higher speed the asperities of Si atoms increase and it is shown in the SEM photograph in Fig. 4 (e) and (f). a b  8142  Shivaramu et al./ Materials Today: Proceedings 5 (2018) 8138–8146    Fig. 4. S E M Images (a) Cast Al; (b) PM Al; (c) Solid casted specimen; (d) Porosity in PM Specimen; (e) Al-Si Alloy at 500rpm and (f) Al-Si Alloy at 750rpm. Fig. 5, 6 and 7 shows the wear behaviour of increasing sliding distance with constant sliding speed and load for PM LM6 and it is compared with Cast LM6, PM Al and Cast Al. The PM LM6 shows that initially increasing the wear rate up to 1000m then decrease with the sliding distance increases but in Cast LM6 the wear is decreased with the increase of sliding distance at constant load and speed. Fig. 5. Wear rate of PM LM6, Cast LM6 , Cast and PM Al for increasing the sliding distance at constant sliding speed and load.   cd e f
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