Faculty Publications

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Author: search.filters.author.Mukunda, P.G.Subject: search.filters.subject.Microstructure

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    Evolution of microstructure and hardness of AL-SI functionally graded material cast through centrifuge technique using hypereutectic and eutectic Al-SI
    (2011) Kiran Aithal, A.S.; Desai, V.; Narendranath; Mukunda, P.G.
    Functionally Graded Materials (FGMs) are a new class of inhomogeneous materials wherein the composition and the microstructure is varied to alter the material property within a component. The present study is to fabricate a Functionally Graded Al-Si in-situ material and to characterize. Al-Si alloys with 17wt%Si (hyper eutectic) and 11.7wt%Si (eutectic) have been used to fabricate Al- Si FGMsby centrifuge casting process. The microstructural characteristics and hardness profiles of these FGMs have been evaluated. The study shows the structure of Al-Si samples produced by this method show Hyper eutectic through Eutectic to Hypo eutectic structure along their depth. It also reveals that hardness of the sample and the silicon content decrease steeply along the depth of the sample.
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    Correlation of Tribological Properties with Microstructure and Mechanical Properties of Graphite Cast Irons Centrifugally Cast for Engine Liner
    (Springer India sanjiv.goswami@springer.co.in, 2014) Desai Gowda, H.S.; Mukunda, P.G.; Herbert, M.A.
    This is a study of the influence of centrifugal process on the graphite morphology, mechanical and wear properties on flake graphite iron (FGI), spheroidal graphite iron (SGI) and compacted graphite iron (CGI). Melts of hypereutectic and almost of identical composition with or without melt treatment were centrifugally cast. The microstructure, mechanical and wear properties of these specimens were studied. In the microstructure for FG iron it has been observed that the centrifugal process produces flake size range class 2–3 (range 160–320 ?m) and graphite of flake type A by about 67.9 % (field %) and combined flakes of type B, C, D and E will be of 32.1 % (field %). While SGI has been observed to have 96.1 % nodules and 330.0 nodules per square millimeter. Similarly CGI has been seen to produce 52.0 % nodules and 113 nodules per square millimeter. SGI possess the highest tensile strength, rupture strain and hardness of 604 N/mm2, 6.1 %, 233 BHN respectively. Whereas FGI possess the least tensile strength, rupture strain and hardness of 303 N/mm2, 0.65 %, 185 BHN respectively among the irons. CGI has a tensile strength, rupture strain and hardness of 369 N/mm2, 1.2 % and 200 BHN respectively which lies in between those of FGI and SGI. During the wear test similar materials for both disk and pin combination show higher co-efficient of friction and wear rate than those for dissimilar material combinations. SGI disk and FGI pin combination show least wear. This combination would be ideally suited for engine liner and piston rings. © 2014, Indian Institute of Metals.
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    The influence of the addition of 4.5 wt.% of copper on wear properties of Al-12Si eutectic alloy
    (Hashemite University huniv@hu.edu.jo, 2015) Channappagoudar, S.; Kiran Aithal, K.; Sannayallappa, N.; Desai, V.; Mukunda, P.G.
    The influence of 4.5 wt.% copper addition on wear behavior of as-cast Al-12Si alloy prepared by gravity casting is investigated in dry sliding against a steel counterface using a pin-on-disk apparatus. The microstructures of test alloys and worn surfaces were examined by scanning electron microscopy and energy dispersing X-ray spectroscopy. The addition of copper to the binary Al-12Si alloy led to the precipitation of CuAl2 phase. Copper addition resulted in a refinement of ?-Al and a minor modification of eutectic Si. The Al-12Si-4.5Cu alloy showed a higher wear resistance as compared to Al-12Si binary eutectic alloy. © 2015 Jordan Journal of Mechanical and Industrial Engineering. All rights reserved.
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    Effect of combined grain refinement and modification on microstructure and mechanical properties of hypoeutectic, eutectic and hypereutectic Al-Si alloys
    (Inderscience Publishers, 2015) Shivaprasad, C.G.; Kiran Aithal, K.; Narendranath, S.; Desai, V.; Mukunda, P.G.
    The effect of melt treatment owing to the combined addition of grain refiner and modifier on the microstructure and mechanical properties of Al-Si alloys having 7% (hypoeutectic), 12% (eutectic) and 15% silicon (hypereutectic) is studied. 1 wt. % of Al-1Ti-3B Master alloy was used as grain refiner. For modification of eutectic Si, 0.2 wt. % of Al-10Sr Master alloy was added to hypoeutectic alloy and 0.4 wt. % is added to eutectic alloy as well as hypereutectic alloy. Furthermore, refinement of primary Si in hypereutectic alloy was achieved by addition of 0.04 wt. % of phosphorus. The goal of this investigation is to determine the influence of combined addition of grain refiner and modifier on mechanical properties and qualitatively correlate with the microstructural changes. © 2015 Inderscience Enterprises Ltd.