Faculty Publications
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Item Effect of L/D ratio on Al-Si functionally graded material cast through centrifuge technique(2011) Kiran Aithal, A.S.; Narendranath; Desai, V.; Mukunda, P.G.Functionally Graded Material (FGM) is a class of material wherein the properties and structure are varied intentionally from one side to the other side of the specimen. This paper describes the effect of L/D (Length to Diameter) ratio of the cast on cast Al-Si FGM. The present study uses Al-17%wt Si to cast FGM's. The cast is evaluated for Microstructure and Hardness all along the length of the specimen. Three L/D ratios: 0.5, 1.0, 1.5 were cast using the Centrifuge Technique. The microstructures showed that enrichment of primary Si was largest in 1.5 ratio compared to other two. Hardness value of the cast at the upper and lower region were examined and found that gradient of hardness was more in 1.5 case. High volume percentage of primary Si was nearly 26% in the upper region and a hypoeutectic structure in the lower region. © (2011) Trans Tech Publications.Item Inference of optimal speed for sound centrifugal casting of Al-12Si alloys(2011) Rao, S.; Mukunda, P.G.; Rao, S.S.; Sudhakar, K.G.True centrifugal casting is a standard casting technique for the manufacture of hollow, intricate and sound castings without the use of cores. The molten metal or alloy poured into the rotating mold forms a hollow casting as the centrifugal forces lift the liquid along the mold inner surface. When a mold is rotated at low and very high speeds defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guess or based on experience. The defects in the casting are mainly due to the behavior of the molten metal during the teeming and solidification process. Motion of molten metal at various speeds and its effect during casting are addressed in this paper. Eutectic Al-12Si alloy is taken as an experiment fluid and its performance during various rotational speeds is discussed.Item Effect of process parameters on centrifugally cast Al-Si FGM(Minerals, Metals and Materials Society 184 Thorn Hill Road Warrendale PA 15086, 2013) Kiran Aithal, K.; Desai, V.; Narendranath, S.; Mukunda, P.G.Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation.Item Effect of centrifugal and gravity casting technique over metallographic and mechanical properties of spheroidal graphite iron(2013) Desai Gowda, H.S.; Mukunda, P.G.; Herbert, M.A.The mechanical properties of cast iron depend on the graphite morphology and characteristics of metallic matrix. In spheroidal graphite iron these properties are affected by the nodule count, nodule percentage, nodularity, nodules per square mm, nodule types and size distribution. In this work an attempt is made to study of the effect of centrifugal and gravity casting process on the morphology and mechanical properties. A comparison of microstructure and mechanical properties of specimens of the cast are studied. It has been observed that the centrifugal effect produces an increase in rupture strain but hardness is unaffected. In microstructure it has been observed that the centrifugal effect produces an increase in the number of bigger nodules and decrease in the number of smaller nodules and an increase of nodules per square mm. It has no effect on nodularity percentage. The centrifugal casting process produces better mechanical properties.Item Effect of process parameters on centrifugally cast Al-Si FGM(Springer International Publishing, 2016) Kiran Aithal, A.S.; Desai, V.; Narendranath, S.; Mukunda, P.G.Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation. © The Minerals, Metals & Materials Society 2016.Item Effect of low temperature annealing on the wear properties of NITINOL(Institute of Physics Publishing michael.roberts@iop.org, 2016) Mukunda, S.; Naths, N.; Herbert, M.; Mukunda, P.G.NiTi shape memory alloy is a wonder material that is a solution looking for problems. The material finds wide biomedical applications like endodontic files for root canal treatment and cardiovascular stents. This material has rendered the surgical procedure simple compared to that with the existing Stainless Steel (SS) or titanium ones. NiTi as an endodontic file would cause less discomfort to the patients in comparison to that with far stiffer SS or titanium ones. Here nearly equi-atomic 50:50 commercial NiTi rods were subjected to low temperature aging at 300 to 450°C. The wear resistance of the as-received and the heat-treated samples was studied using adhesive wear tests on hardened steel counter face. Abrasive wear tests were run against Alumina disc to simulate the working of endodontic drills and files against dental hard and soft tissues. The abrasive wear resistance is expected to be proportional to the Vickers Hardness of the material and is high for the 450°C heat-treated sample. A correlation between the mechanical properties and microstructures of this material is attempted. © Published under licence by IOP Publishing Ltd.Item Experimental studies of flow patterns of different fluids in a partially filled rotating cylinder(Isfahan University of Technology, 2009) Mukunda, P.G.; Rao, S.; Kiran Aithal, A.S.; Shrikantha, S.R.An attempt has been made to investigate the various parameters affecting the fluid behaviour, partially filled in a rotating cylinder. When the cylinder is rotating at 'high' speed, a liquid forms a hollow cylinder. Different patterns are observed in the fluids for the rotatioal speeds below a critical speed. This study should give us some insight into molten metal behaviour during centrifugal casting. An extensive experimental investigation is required to obtain an appropriate functional relationship by knowing and understanding some dimensionless parameters. Here the effect of dimensionless parameters ? (which is 2 g/?2d, where g, ? and d denotes gravitational acceleration, container rotation rate and inner diameter of liquid cylinder) and G (number of times the gravity) was studied as variation of rotation speed, viscosity and aspect ratio of the mould.Item Inference of optimal speed for sound centrifugal casting of tin(Metallurgical Society of CIM, 2009) Mukunda, P.G.; Rao, S.; Rao, S.S.During centrifugal casting when a mould is rotated at low and very high speeds, defects are found in the final castings. Obtaining the critical speed for sound castings should not be a matter of guessing but based on experience. The defects in the casting are mainly due to the behaviour of the molten metal during the teeming and solidification process. The motion of molten metal at various speeds and its effect during casting are addressed in this paper. Tin is taken as an experiment fluid and its performance during various rotational speeds is discussed. The microstructures and hardness of all the castings are also investigated. © Canadian Institute of Mining, Metallurgy and Petroleum.Item Influence of rotational speed during centrifugal casting on sliding wear behaviour of the Al-2Si alloy(2009) Mukunda, P.G.; Rao, S.; Rao, S.S.The microstructures and dry sliding wear behaviour of an Al-2Si alloy cast centrifugally are studied. Results indicate that at optimum speed the cast has a microstructure consisting of uniformly distributed ?-Al grains and fine eutectic silicon grains. The cast exhibited better wear resistance compared to the same cast prepared at different rpms. This paper attempts to investigate the influence of the microstructural changes in the Al-2Si alloy by varying the rotational speed of the mould and its combined action on the dry sliding wear behaviour. © Higher Education Press and Springer-Verlag 2009.Item Wear and machinability study of SiCp reinforced and Al2O3p reinforced Al-Si alloy composites(Praise Worthy Prize, 2010) Sudheer Reddy, S.; Mukunda, P.G.; Suresh Hebbar, H.Keeping in mind a range of industrial applications, the performance of Al-Si alloy reinforced with ceramics as a metal matrix composites manufactured using Stir casting technique have been investigated. Aluminum-Silicon alloys of near eutectic composition (12% Silicon by weight) and Hypereutectic (17% Silicon by weight) were the matrix materials used. The two matrix materials were processed under identical conditions using two different reinforcements Silicon Carbide (SiCP) and Aluminium Oxide (Al2O3p) in particulate form with 0, 5, 7.5 & 10 Vol%. Wear and friction coefficients were determined from dry sliding wear tests of cast Particle Reinforced Metal Matrix Composites(PMMC's) at 20, 40, 60 N test loads and at 1.42 & 2.22m/s sliding velocities. Cutting forces exerted and Surface Roughness (Ra) produced during machining of cast PMMC's with Polycrystalline Diamond (PCD) and K10 cutting inserts at 75 m/min & 118 m/min cutting speed were studied. Wear of Al2O3P reinforced alloys was around 20% higher than SiCP reinforced alloys. PCD cutting insert seems appropriate in machining Al-Si alloy composites needing lesser cutting force and producing better surface finish. © 2010 Praise Worthy Prize S.r.l.- All right reserved.