Journal Articles

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    Phase transformation, structural evolution, and mechanical property of nanostructured feal as a result of mechanical alloying
    (Springer New York LLC barbara.b.bertram@gsk.com, 2009) Rajath Hegde, M.M.R.; Surendranathan, A.O.
    The objective of the work is to synthesize nanostructured FeAl alloy powder by mechanical alloying (MEA). The work concentrates on the synthesis, characterization, and structural and mechanical properties of the alloy. Nanostructured FeAl intermetallics are prepared directly by MEA in a high-energy ball mill. Milling is performed under toluene solution to avoid contamination from the milling media and atmosphere. Mixtures of elemental Fe and Al are progressively transformed into a partially disordered solid solution with an average composition of Fe-50 at.% Al. Phase transformation, structural changes, morphology, particle size measurement, and chemical composition during MEA are investigated by X ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS). Vickers microhardness (VMH) indentation tests are performed on the powders. The XRD and SEM studies reveal the alloying of elemental powders as well as transition to nanostructured alloy; crystallite size of 18 nm is obtained after 28 h of milling. Expansion/contraction in lattice parameter accompanied by reduction in crystallite size occurs during transition to nanostructured alloy. Longer milling introduces ordering in the alloyed powders as proved by the presence of superlattice reflection. Elemental and alloyed phases coexist while hardness increases during MEA. copy2009 Springer Science+Business Media, Inc.
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    Phase transformation, structural evolution and mechanical property of nanostructured FeAl as a result of mechanical alloying
    (2009) Rajath Hegde, M.M.R.; Surendranathan, A.O.
    Objective of the work was to synthesize nanostructured FeAl alloy powder by mechanical alloying (MEA). The work concentrated on synthesis, characterization, structural and mechanical properties of the alloy. Nanostructured FeAl intermetallics were prepared directly by MEA in a high energy rate ball mill. Milling was performed under toluene solution to avoid contamination from the milling media and atmosphere. Mixtures of elemental Fe and Al were progressively transformed into a partially disordered solid solution with an average composition of Fe-50 at % Al. Phase transformation, structural changes, morphology, particle size measurement and chemical composition during MEA were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS) respectively. Vickers micro hardness (VMH) indentation tests were performed on the powders. XRD and SEM studies revealed the alloying of elemental powders as well as transition to nanostructured alloy, crystallite size of 18 nm was obtained after 28 hours of milling. Expansion/contraction in lattice parameter accompanied by reduction in crystallite size occurs during transition to nanostructured alloy. Longer milling duration introduces ordering in the alloyed powders as proved by the presence of superlattice reflection. Elemental and alloyed phase coexist while hardness increased during MEA. © 2009 Allerton Press, Inc.
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    Interparticle interactions and lacunarity of mechano-chemically activated fly ash
    (Elsevier, 2015) Patil, A.G.; Shanmugharaj, A.M.; Anandhan, S.
    A class F fly ash was subjected to high-energy ball milling-induced mechano-chemical activation aided by a surfactant. The resultant nanostructured fly ash was characterized by various techniques. X-ray fluorescence results showed that the amount of iron oxide was reduced from 4.39% to 2.75% after pre-treatment of fly ash by magnetic separation. Ethyl acetate as the milling medium, a ball to powder ratio of 12:1 and 2wt% of surfactant reduced the average particle size of fly ash to 329nm and led to a specific surface area of 8.73m2/g. The decrease in crystallite size of mechano-chemically activated fly ash was confirmed from a reduction in peak intensity with a broadened amorphous phase by X-ray diffraction studies. X-ray photoelectron spectroscopic characterization illustrated that peak area of major elements (O, Si and Al) increased after milling. Morphological and FTIR studies revealed that the smooth and inert surface of the fly ash was converted to a rough and more reactive one after mechano-chemical activation. The surface modification of fly ash with the surfactant was determined from FTIR spectroscopy. Also, a fractal approach was used to characterize the lacunarity of the agglomerates in the nanostructured fly ash. © 2014 Elsevier B.V.
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    Influence of planetary ball milling parameters on the mechano-chemical activation of fly ash
    (Elsevier, 2015) Patil, A.G.; Anandhan, S.
    This study illustrates the design of statistical analysis by Taguchi methodology to obtain nanostructured fly ash by planetary ball milling. An orthogonal array and analysis of variance were employed to analyze the effect of milling parameters. A class-F fly ash was subjected to planetary ball milling induced mechano-chemical activation aided by a surfactant. Ball milling parameters, such as ball-to-powder weight ratio, type and quantity of surfactant and type of medium were varied as guided by the Taguchi design. The nanostructured fly ash was characterized by dynamic light scattering, BET surface area analysis, X-ray diffraction, FTIR spectroscopy, scanning electron microscopy, field emission scanning electron microscopy and transmission electron microscopy. The ball-to-powder weight ratio and the surfactant type are the major influencing factors on lower crystallite size and average particle size and higher specific surface area. The surface modification of fly ash was confirmed by FTIR spectroscopy. The nano fly ash produced by this method has a wide application potential in polymer industries as reinforcement in composites. © 2015 Elsevier B.V.
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    Nanostructured Fly Ash as Reinforcement in a Plastomer-Based Composite: A New Strategy in Value Addition to Thermal Power Station Fly Ash
    (Springer Netherlands, 2016) Patil, A.G.; Mahendran, A.; Anandhan, S.
    Class-F fly ash (FA) from a coal-fired thermal power station was subjected to high energy ball milling-induced mechanochemical activation aided by a surfactant. Subsequently, ethylene-octene copolymer/mechanochemically activated FA (EOC/MCA-FA) composites were prepared by solution casting. The surface modification of FA was confirmed from contact angle measurements and FTIR spectroscopy, which accounts for a good interaction between MCA-FA and the polymer matrix. X-ray diffraction reveals that the crystallite size of quartz phase present in FA got reduced, while the relative lattice strain on it increased during milling. Morphological studies revealed that interfacial adhesion between the polymer and MCA-FA is good and this accounts for the improvement in mechanical properties of the composites even at the minimum filler loading. Flame retardance of the matrix polymer is improved by the addition of either fresh FA or MCA-FA. The results imply that FA is a valuable reinforcing filler for ethylene-octene copolymer and its mechanochemical activation is an effective strategy for its future use. © 2014, Springer Science+Business Media Dordrecht.
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    Characterization of composites based on biodegradable poly(vinyl alcohol) and nanostructured fly ash with an emphasis on polymer-filler interaction
    (SAGE Publications Ltd info@sagepub.co.uk, 2016) Patil, A.G.; SelvaKumar, M.; Anandhan, S.
    A thermal power station fly ash (FA) was mechanochemically activated by high-energy ball milling that yielded nanostructured FA. This nanostructured FA was incorporated into biodegradable poly(vinyl alcohol) (PVA) matrix by solution mixing and ultrasonication. Transmission electron micrographs revealed that the smooth spherical particles of FA were changed into irregular and rough ones; in addition, the particle size of FA was reduced to a few hundred nanometers, and its specific surface area value increased after the high-energy milling process. All these factors, in turn, led to a thermodynamically favorable interaction between the mechanochemically activated FA and PVA as evidenced by Fourier transform infrared spectroscopy. The incorporation of a very small amount of the nanostructured FA led to an increase in crystallinity of the polymer matrix. The glass transition temperature of the PVA matrix increased by about 18°C when 5 wt% of the nanostructured FA was used as the reinforcement. © The Author(s) 2014.
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    Prediction of Bond's work index from field measurable rock properties
    (Elsevier B.V., 2016) Ram Chandar, K.; Deo, S.N.; Baliga, A.J.
    In mineral beneficiation, grinding is the final stage in the process of size reduction. The power consumed in this stage is higher when compared to other stages, owing to increased size reduction ratio. The primary purpose of grinding is to reduce the particle size to optimum so that mineral particles can be extracted more economically. Decision making plays an important role here, as it involves determining and comparing the energy that is required to perform the grinding process and also determining the amount of minerals lost as the coarser size particles are arrived at in mineral beneficiation. In general, Bond's work index is used to determine the grinding efficiency and also to calculate the power requirement. The process is very time consuming and it requires skilled labor and specialized mill. A systematic investigation was carried out to predict Bond's work index using simple field measurable properties of rocks. Tests were conducted on Basalt, Slate and Granite using a laboratory scale ball mill and rock properties namely density, Protodyakonov's strength index and rebound hardness number were determined. The results were analyzed using artificial neural networks and regression analysis. Mathematical equations were developed to predict Bond's work index based on rock properties using regression analysis, which resulted a very good correlation co-efficient values. © 2016 Elsevier B.V.
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    Microstructure and Adhesion Strength of Ni3Ti Coating Prepared by Mechanical Alloying and HVOF
    (Pleiades Publishing compmg@maik.ru, 2018) Reddy, N.C.; Ajay Kumar, B.S.; Ramesh, M.R.; Koppad, P.G.
    In the present work we report the development of Ni3Ti intermetallic compound by high energy ball milling of Ni and Ti powders. The ball milled powders were taken at various intervals (4, 6, 8, 10, and 11 h) to analyze the formation of NixTix intermetallic compounds. The ball milled powders were analyzed using scanning electron microscopy and X-ray diffraction. The layered shaped powder particles of Ni3Ti phase were formed after 11 h of ball milling, which was confirmed by X-ray peaks. Further High-Velocity Oxy-Fuel (HVOF) process was used to coat Ni3Ti and Ni3Ti + (Cr3C2 + 20NiCr) on MDN 420 steel. Both the coated materials displayed excellent cohesion with minimal porosity less than 2%. The tensile adhesion strength test was carried out on these coatings to check the bond strength. Out of the two the Ni3Ti coating showed excellent bond strength of 41.04 MPa compared to that of Ni3Ti + (Cr3C2 + 20NiCr) coating. © 2018, Pleiades Publishing, Ltd.
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    Influence of microwave hybrid heating on the sliding wear behaviour of HVOF sprayed CoMoCrSi coating
    (Institute of Physics Publishing helen.craven@iop.org, 2018) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.
    CoMoCrSi superalloy powder (Tribaloy-T400) consists of intermetallic laves phase and primary eutectic phase of Co-rich solid solution. Processing of Tribaloy-T400 powder is carried out through high-energy ball milling (HEBM) technique to obtain a higher volume fraction of intermetallic laves phases. The feedstock is sprayed using high-velocity-oxy-fuel (HVOF) process on titanium grade-15 substrate. The coating microstructure is homogenized by microwave hybrid heating technique. Characterization of feedstock, as-sprayed and microwave fused coatings is done by using Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and x-ray Diffraction (XRD). Porosity, surface roughness, microhardness, and bond strength are measured. Adhesive wear behavior of the coatings under the dry sliding condition is evaluated at an applied load of l0 and 20 N and temperature of 200, 400 and 600 °C Fused coating exhibit higher wear resistance than the as-sprayed coatings and substrate. The hard intermetallic laves phases which are amorphous (bulk metallic glass) in nature strengthen the coating at high temperatures. © 2018 IOP Publishing Ltd.
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    Microstructure and tribological behavior of flame sprayed and microwave fused CoMoCrSi/CoMoCrSi-Cr3C2 coatings
    (Institute of Physics Publishing helen.craven@iop.org, 2019) Prasad, C.D.; Joladarashi, S.; Ramesh, M.R.; Srinath, M.S.; Channabasappa, B.H.
    This present work deals with the investigation of dry sliding wear behavior of CoMoCrSi and CoMoCrSi-Cr3C2 depositing on titanium substrate through Flame spray process, subsequently fused by the microwave hybrid heating process. Prior to the deposition of the coating, CoMoCrSi powder is milled by using high energy ball milling (HEBM) process and later 30% of Cr3C2 powder is added. Microstructural features and phase analysis of milled powders, as-coated and microwave fused coatings are inspected by using SEM with EDS and XRD process respectively. The coatings before and after fusing are tested for microhardness and bond strength by using a Vickers microhardness and universal tensile machines respectively. Dry sliding wear behavior of coatings before and after fusing is conducted against alumina counter face at ambient and elevated temperatures, also normal load is varied. The wear mechanism of both coatings is examined by employing XRD, SEM-EDS techniques. The fused coatings exhibit lower friction and better wear resistance compared with as-deposited coatings. The detailed results of each test of their coatings are discussed in this paper. © 2018 IOP Publishing Ltd.