Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
Search Results
Item Equal channel angular processing-a modern deforming technique for quality products(Elsevier, 2021) Bhat K, U.K.; Bhat Panemangalore, D.B.; Bhat, S.The grain size plays a significant role in determining the mechanical properties of the materials. Decreasing grain size increases strength, toughness, and ductility. Due to these, a lot of research has been executed to develop deforming techniques to produce ultrafine-grained materials. Among several plastic deformation techniques available, equal channel angular pressing or processing (ECAP) produces ultra-fine grained materials with substantial amount of high angle grain boundaries. ECAP produces ultra-fine grained material with typical substructural features, which are difficult to achieve using other severe deformation techniques. This chapter presents characteristics, variables, die design, and die materials employed in the process. The chapter also presents recent developments in the domain, such as, use of finite element techniques, etc. © 2021 Elsevier Inc. All rights reserved.Item Microstructural Aspects of Metal-Matrix Composites(Elsevier, 2021) Bhat Panemangalore, D.B.; Shabadi, R.Microstructures play a very important role in deciding the end properties of an alloy or a composite. Optimized microstructure could be obtained by a careful choice of processing technique and selection of materials. Metal-matrix composites (MMCs) that have been developed significantly over the last five decades possess valuable properties. MMCs can be tailored with myriad of variations to suit for a particular application and hence they belong to a unique class of materials. However, it is important to understand the microstructural aspects to understand the behavior of the component in different environmental and working conditions. This article presents an overview on different microstructural aspects of metal matrix composites. © 2021 Elsevier Ltd. All rights reserved.Item Ionic Liquid Electrolytes for Flexible Supercapacitors(wiley, 2021) Udaya Bhat, K.; Bhat Panemangalore, D.B.Compact, flexible, high energy and high density energy storage devices are required to power electronic skins, implantable devices and flexible sensors. Compact and flexible supercapacitors are the need of the hour. Research has been in progress to improve the performance of the electrodes and electrolyte with respect to the batteries and supercapacitors. A number of electrolytes have been designed and tested for the supercapacitor applications. Electrolytes based on ionic liquids are useful to improve the performance from the angle of widening operating voltage, improving energy density, charge-discharge cycling, etc. In this chapter, essential details of a supercapacitor, followed by different components of a supercapacitor, various types and features of electrolytes, developments in ionic liquid electrolytes, design aspects in ionic liquid electrolyte usage, concept of mechanical integrity in flexible supercapacitor design are explored. © 2021 Scrivener Publishing LLC.Item Review-energy storage through graphite intercalation compounds(IOP Publishing Ltd, 2021) Gopalakrishnan, V.; Sundararajan, A.; Omprakash, P.; Bhat Panemangalore, D.B.Research and development with regards to battery technologies have been evolving at a profitably good rate with an impressive amount of progress being made at different levels. Graphite has been continuously preferred as the anode material for lithium-ion batteries since its commercialization in 1991. The interlayer spacing of about 3.35 Å promotes the intercalation of guest ions, thereby resulting in what is called graphite intercalation compounds (GICs). Through such intercalation mechanisms, graphite can contribute to electrochemical charge transfer owing to its ionic and electronic conduction properties. The intercalation of alkali metal ions into graphite is considered the epitome of ion intercalation with regards to layered materials. Putting together various inferences made through the years, this review aims at establishing a foundational understanding of GICs and their applications in energy storage devices. A brief overview of graphite intercalation chemistry has been provided and discussions on the advancements in various GICs ranging from binary-GICs to ternary-GICs have been elaborated. Towards the end, this paper provides a comprehension of the specific strategies that might improve the performance of a GIC, following which the challenges and the future of GIC-based research have also been highlighted. © 2021 The Electrochemical Society.Item Coating technologies for copper based antimicrobial active surfaces: A perspective review(MDPI AG, 2021) Bharadishettar, N.; Bhat K, U.; Bhat Panemangalore, D.B.Microbial contamination of medical devices and treatment rooms leads to several detrimental hospital and device‐associated infections. Antimicrobial copper coatings are a new approach to control healthcare‐associated infections (HAI’s). This review paper focuses on the efficient methods for depositing highly adherent copper‐based antimicrobial coatings onto a variety of metal surfaces. Antimicrobial properties of the copper coatings produced by various deposition methods including thermal spray technique, electrodeposition, electroless plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), and sputtering techniques are compared. The coating produced using different processes did not produce similar properties. Also, process parameters often could be varied for any given coating process to impart a change in structure, topography, wettability, hardness, surface roughness, and adhesion strength. In turn, all of them affect antimicrobial activity. Fundamental concepts of the coating process are described in detail by highlighting the influence of process parameters to increase antimicrobial activity. The strategies for developing antimicrobial surfaces could help in understanding the mechanism of killing the microbes. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item Review - A Review of 2D Perovskites and Carbon-Based Nanomaterials for Applications in Solar Cells and Photodetectors(IOP Publishing Ltd, 2021) Omprakash, P.; Viswesh, P.; Bhat Panemangalore, D.B.Photonic devices such as solar cells and photodetectors that produce electricity play a vital role in our daily life for applications such as fibre optic communication systems, process control, and also in defence related applications. Today, two-dimensional perovskites that belong to the class of emerging materials show promising energy applications. 2D perovskites have been investigated for their exceptional properties such as high optical absorption coefficients, structural diversity and tuneable bandgaps which allow their application as active light absorbing materials to develop solar cells and photodetectors. Carbon-based nanomaterials have also found applications as transparent electrodes, charge acceptors and photosensitive layers in solar cells and photodetectors due to properties such as excellent electrical conductivity, high optical transparency, high surface area and remarkable mechanical strength. There has been growing interest in research on devices using these materials to improve their feasibility, ease of production and performance. With the growing urgency of switching to alternate sources of energy and increasing demands for highly accurate and fast sensors, the development and application of such novel materials are essential. Hence, the current state of understanding of these materials and their applications in the field of solar cells and photodetectors are summarized in this review article. © 2021 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.Item Corrosion behavior, microstructure and mechanical properties of novel mg-zn-ca-er alloy for bio-medical applications(MDPI AG, 2021) Bhat Panemangalore, D.B.; Shabadi, R.; Gupta, M.In this study, the effect of calcium (Ca) and erbium (Er) on the microstructure, mechanical properties, and corrosion behavior of magnesium-zinc alloys is reported. The alloys were prepared using disintegrated melt deposition (DMD) technique using the alloying additions as Zn, Ca, and Mg-Er master alloys and followed by hot extrusion. Results show that alloying addition of Er has significantly reduced the grain sizes of Mg-Zn alloys and also when compared to pure magnesium base material. It also has substantially enhanced both the tensile and the compressive properties by favoring the formation of MgZn2 type secondary phases that are uniformly distributed during hot-extrusion. The quaternary Mg-Zn-Ca-Er alloy exhibited the highest strength due to lower grain size and particle strengthening due to the influence of the rare earth addition Er. The observed elongation was a result of extensive twinning observed in the alloys. Also, the degradation rates have been substantially reduced as a result of alloying additions and it is attributed to the barrier effect caused by the secondary phases. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item Influence of different fumed silica as thixotropic additive on carbonyl particles magnetorheological fluids for sedimentation effects(Elsevier B.V., 2021) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.; Bhat Panemangalore, D.B.The present work reports the influence of different types of surface area, hydrophobic, and hydrophilic fumed silica mixed in silicone oil as a thixotropic additive on carbonyl particles based magnetorheological fluids (MRFs) were prepared. Scanning electron microscopy analysis confirms the fumed silica particles attached to the surfaces of CIPs. The vibrating sample magnetometer result shows the MRF4 and 5 have a better magnetic saturation value of 30.12 emu/gm and 40.12 emu/gm, respectively. The experimental rheological flow curve behaviours are investigated using the magnetorheometer. The Herschel–Bulkley rheological model is found to be in good agreement with the experimental curves and suggested shear thinning property is observed. The results showed that the hydrophilic silica with larger surface area type presented (i.e.MRF 4 and 5) better magnetorheological fluid characteristics in terms of shear stress, with a high value of dynamic yield stress, and have much-improved sedimentation ratio up to seven days. © 2021 Elsevier B.V.Item Microstructure and corrosion behavior of extruded mg?sn?y alloys(MDPI AG, 2021) Bhat Panemangalore, D.B.; Shabadi, R.; Gupta, M.; Lesven, L.Magnesium and its alloys, with their unique properties such as high strength/density ratio, good castability, and machinability, have found several applications in the aerospace and automotive industries. One of the reasons that restrict their widespread applicability is their poor corrosion resistance since Mg is readily oxidized in the presence of oxygen and humidity. The oxide layer is pseudo?passive and non?protective. The present effort tried to improve the passivity of this layer with the addition of alloying elements such as Tin (Sn) and Yttrium (Y) to create phases that interact differently with the oxidizing environment, thereby improving the corrosion resistance. In this work, the corrosion behavior of pure magnesium and Mg?5Sn?xY (x = 0.5, 1, 2 wt.%) were evaluated using immersion and potentiodynamic polarization tests. XRD, SEM?EDS, and EBSD have investigated the microstructure and elemental composition of the alloys. The present study is focused on elucidating the microstructure?corrosion relationship in Mg?Sn?Y alloys. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Item Graph representational learning for bandgap prediction in varied perovskite crystals(Elsevier B.V., 2021) Omprakash, P.; Manikandan, B.; Sandeep, A.; Shrivastava, R.; Viswesh, P.; Bhat Panemangalore, D.B.Perovskites are an important class of materials that are actively researched for applications in solar cells and other optoelectronic devices due to their ease of fabrication and tuneable bandgaps. High throughput computational techniques like Density Functional Theory (DFT) and Machine Learning (ML) are viable methods to accelerate discovery of new perovskite materials with favourable properties. ML specifically is faster and requires lesser computational power. We recognized the importance of having robust datasets for ML and hence collated a dataset of varied perovskite structures along with their indirect bandgaps. We employed a graph representational learning technique and trained a model that predicted bandgaps for all types of perovskites. The model has a mean absolute error of 0.28 eV and can predict bandgap in a few milliseconds. The metric of generalization gap is introduced to quantify the performance of ML models. This metric will help in building more generalized models that can predict properties for novel materials. Furthermore, we believe that these computational techniques should be user-friendly to those less experienced in the field. Hence, for researchers unacquainted with DFT or ML, we built a pipeline that abstracts the specific processes. This makes it easier for material scientists to quickly screen viable inorganic perovskite compounds allowing them to synthesize and experiment on the more promising compounds. © 2021 Elsevier B.V.