Conference Papers
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Item Linear and NLO properties of an organic single crystal(2012) Rajesh Kumara, P.C.; Ravindrachary, V.; Janardhana, K.; Poojary, B.; Manjunath, K.B.; Umesh, G.Organic compound of 1-(4-methoxyphenyl)-3-(2-methoxy 5-bromophenyl)prop-2- en-1-one [MMBPP] with molecular formula C16H11BrO 3 was synthesized using Schmidt condensation method. A FT-IR spectrum was recorded to identify the various functional groups present in the compound. The single crystals were grown using slow evaporation solution growth technique. The high quality transparent crystals up to a size 10×7×5 mm3 are obtained with in fifteen days. UV-Visible spectrum reveals that the crystal is transparent in the entire visible region. The single crystal XRD study shows that the compound crystallizes in orthorhombic crystal system with a space group P212121 and the observed cell parameters are a =7.6095(13) Å, b =13.049(2) Å, c = 15.525(3) Å, Volume 1541.6(5) Å3. The third order Nonlinearity was confirmed by Z-scan technique and non-linear parameters were determined. © 2012 American Institute of Physics.Item Multilayer Zn-Ni-Al2O3 coatings for corrosion protection(Inderscience Publishers, 2014) Ullal, Y.; Hegde, A.C.The paper reports the development of composite coatings of Zn-Ni-Al2O3 by composition modulated multilayer (CMM) technique using m-aminophenol and gelatin as additives. The bath constituents and deposition parameters were optimised by conventional method. The role of gelatin and m-aminophenol in the bath was analysed by cyclic voltammetry (CV) study. Corrosion performance of the monolayer coatings was enhanced further by multilayer technique. The modulation in composition was effected by pulsing the DC in square-wave patterns. The coatings configurations were optimised for peak performance of the coatings against corrosion. It was found that corrosion resistance of CMM coatings increased with number of layers up to certain optimal numbers, and then decreased. Incorporation of Al2O3 particles into metal matrix was confirmed by EDAX. Formation of layered coating and their phase structures were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) study. Reasons responsible for better corrosion resistance of CMM composite coatings are analysed and results are discussed. Copyright © 2014 Inderscience Enterprises Ltd.Item Effect of substrate temperature on the structural and electrical properties of spray deposited lead sulfide thin films(Elsevier Ltd, 2016) Veena, E.; Bangera, K.V.; Shivakumar, G.K.Lead sulfide (PbS) thin films were prepared by chemical spray pyrolysis method using lead acetate and thiourea as precursors of Pb+2 and S-2 ions. X-ray diffraction (XRD) technique, scanning electron microscope (SEM) and EDAX analysis were used for structural, morphological and compositional characterization. XRD analysis shows that the films are cubic in nature with a preferred orientation along (2 0 0). EDAX analysis shows that films deposited at 150°C are sulfur rich. An increase in the substrate temperature results in a decrease in the sulfur content of the prepared film. It has been observed that thin films deposited at or above 225°C are smooth & uniform morphologically. Beyond a substrate temperature of 275°C, the films become discontinuous and non-uniform. However, the films are sulfur rich, even at 275°C. Electrical conductivity of prepared thin films have been measured using silver contacts in coplanar geometry. Films are n - type as confirmed by hot probe technique. The electrical conductivity at room temperature (25°C) was in the order of 10-4 Ω-1cm-1 and was found to increase with increase in temperature showing the semiconducting nature of the films with the band gap of 0.39 eV. © 2016 Elsevier Ltd.Item Durability of Bricks Coated with Red mud Based Geopolymer Paste(Institute of Physics Publishing michael.roberts@iop.org, 2016) Singh, S.; Basavanagowda, S.N.; Aswath, M.U.; Ranganath, R.V.The present study is undertaken to assess the durability of concrete blocks coated with red mud - fly ash based geopolymer paste. Concrete blocks of size 200 x 200 x 100mm were coated with geopolymer paste synthesized by varying the percentages of red mud and fly ash. Uncoated concrete blocks were also tested for the durability for comparison. In thermal resistance test, the blocks were subjected to 600°C for an hour whereas in acid resistance test, they were kept in 5% sulphuric acid solution for 4 weeks. The specimens were thereafter studied for surface degradation, strength loss and weight loss. Pastes with red mud percentage greater than 50% developed lot of shrinkage cracks. The blocks coated with 30% and 50% red mud paste showed better durability than the other blocks. The use of blocks coated with red mud - fly ash geopolymer paste improves the aesthetics, eliminates the use of plaster and improves the durability of the structure. © Published under licence by IOP Publishing Ltd.Item Electrodeposited Ni-P alloy thin films for alkaline water splitting reaction(Institute of Physics Publishing michael.roberts@iop.org, 2016) Elias, L.; Damle, V.H.; Hegde, A.Ni-P alloy thin films was developed as a robust electrode material for alkaline water splitting for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), through electrodeposition technique. The influence of alloy composition, achieved through induced codeposition of the reluctant non-metal, i.e. phosphorous (P) on its electrocatalytic activity was studied, and arrived at the best composition of alloy for HER and OER. The water splitting efficacy of the alloy films was tested in 1.0 M KOH using electrochemical methods such as cyclic voltammetry and chronopotentiometry. The experimental observation shows that the alloy thin film with 9.0 wt.% of P and 4.2 wt.% of P are the best electrode materials for HER and OER, respectively. The electrocatalytic performance of alloy films towards HER and OER were related to its surface topography, composition and crystal structure through field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) analyses, respectively. © Published under licence by IOP Publishing Ltd.Item Effective role of P2O5 on in-vitro bioactivity of soda lime phosphosilicate glasses(Elsevier Ltd, 2017) Kiran, P.; Udayashankar, N.K.; Shashikala, H.D.In-vitro bio active properties have been studied on Sol-gel derived 58SiO2-33CaO-(5-X) Na2O-(4+X) P2O5 (where X=0, 5) bio glass samples soaked for seven days in a simulated body fluid (SBF) solution. X-ray diffraction studies indicated the presence of Hydroxyl Apatite (HA) crystalline phase in the synthesized samples. The spherical shaped hydroxyl carbonated apatite (HCA) nuclei were observed under scanning electron microscope. The Fourier transform infrared (FTIR) and Raman spectroscopic analysis confirmed the presence of carbonates in the glass matrix. In particular, larger concentration of P2O5 in the bioglass resulted in superior bioactivity compared to low concentration of P2O5. © 2017 Elsevier Ltd.Item Effect of Sigma (σ) phase on Mechanical and Dry sliding wear(Elsevier Ltd, 2017) Davanageri, M.; Narendranath, S.; Kadoli, R.In this paper, the wear behaviour of heat treated (oil and water quenched) super duplex stainless steel (SDSS) AISI 2507 was studied using dry sliding wear test rig. Initially as received materials was solution treated at 1050°C for duration of 2 h to achieve a balanced austenite (γ) and ferrite (δ) microstructure. The effect of different heat treatment techniques on microstructure and wear behaviour was studied by heat treating specimen at 850°C for duration of 1 h and was followed by oil and water quenching. The microstructure and crystal structure were studied through scanning electron microscope (SEM) and X-ray diffraction. The sliding wear test was employed with variation in load and speed at constant sliding distance. The results reveal that wear rate increased with increase in wear parameters. The oil quenched exhibited better wear resistance than water quenched and solution treated specimen. The worn surface morphology were analysed through SEM micrographs. © 2017 Elsevier Ltd.Item Solubility Limits of Ceria-Zirconia-Lanthana Solid-Solutions(Elsevier Ltd, 2017) Abbas, Z.; Surendran, M.; Anjana, P.A.; Jidev, P.K.; Harshini, H.; Sudhakar Naidu, N.; Anandhan, S.; Bhat, K.U.; Bhaskar Babu, G.U.; Prasad Dasari, H.P.We demonstrate, the solubility limits of Ceria-Zirconia-Lanthana (CZLa) solid-solutions with the increase in heat-treatment temperature from 600°C to 1300°C. CZLa nano-crystalline samples were successfully synthesized by EDTA-Citrate complex method and were characterized by Raman Spectroscopy (RS) and Transmission Electron Microscopy (TEM) analysis. With an increase in temperature, it is noticed that the solubility limit is decreased in CZLa system. At 600°C, a very good solubility is observed in CZLa system and is confirmed from RS analysis. At higher heat-treatment temperatures (1000 and 1300°C), with an increase in La content, Zr precipitated in the CZLa system and is confirmed from RS analysis. The reason for such kind of behavior in this CZLa system is clearly explained in this work. © 2017 Elsevier Ltd.Item Influence of Fineness of Mineral Admixtures on the Degree of Atmospheric Mineral Carbonation(Springer Science and Business Media Deutschland GmbH info@springer-sbm.com, 2021) Farsana, C.; Das, B.B.; Snehal, K.Global carbon dioxide concentration is rising at the rate of 2 ppm every year, which had led to the demand of sustainable development. In construction industry, manufacturing of cement is the main source of global anthropogenic carbon dioxide emissions. Carbon capture and storage is a recent technology which had helped to sequester carbon dioxide from atmosphere and thus helps in reducing the greenhouse effect to a certain extent. This study mainly focuses on the atmospheric mineral carbonation of mineral admixtures like fly ash (FA), ground granulated blast furnace slag (GGBS), and silica fume (SF), which are the industrial by-products and are being treated as waste. This study also focuses on the effect of fineness of different mineral admixtures on the degree of atmospheric mineral carbonation. Fly ash with three different levels of fineness (FA, FA I, and FA II), GGBS with three different levels of fineness (GGBS, GGBS I, and GGBS II), and silica fume were mixed with activators like lime and gypsum and were left for atmospheric mineral carbonation. Mineralogical characterisations were done using X-ray diffraction (XRD), thermo gravimetric analysis (TGA), and scanning electron microscopy (SEM). Degree of carbonation of the samples was analyzed and calculated using the TGA results. From the comparative analysis of all the samples, it was found that GGBS II had highest degree of carbonation. It was also observed that calcium-based compounds like calcite, aragonite, vaterite, calcite magnesium syn, gismondine, waikarite, calcium silicate hydrate, diopside, calcium sulfate, and portlandite were formed in the samples after 45 and 90 days of atmospheric mineral carbonation. However, it was observed that with increasing levels of fineness of mineral admixtures, there was no significant change in the degree of atmospheric mineral carbonation. © 2021, Springer Nature Singapore Pte Ltd.Item Synthesis and characterization of nano-alumina powder by milling of Al and MnO2powder mixture(Elsevier Ltd, 2021) Ravikumar, K.S.; Ghanaraja, S.; Ramesh, M.R.There are extensive study on nano composites because of its outstanding mechanical properties when compared with the monolithic materials. The manufacturing of nano particles presents an increasing interest. There are two basic strategy for the synthesis of nano particles, they are bottom up and top down approach. Nano particles are built atom by atom in the bottom up approach. In the synthesis of nano particles, top down approach is most applied one. In this approach, bulk materials are broken down gradually into smaller sizes until they reach nano size. Ball milling is most widely used method for the top down approch. Ball milling process involves milling of constituent powders in a vial where mechanical deformation and chemical reactions takes place between the powders to form new phase. In the present study, constituent powder mixture of Al (1.845 μm) and MnO2(0.75 μm) are subjected to high energy planetary ball milling to form new phase which is of nano alumina (Al2O3). Initially, Al and MnO2powder mixture are taken in the ratio of 1:2.416 by weight for different milling duration of 120 min, 240 min and 360 min. The constant speed of the mill was maintained at 300 rpm. The powder mixture inside the mill subjected to impact force between ball to ball and between ball to wall of the container undergo cyclic deformation, cold welding and fracture ensures the generation of nano alumina particles in the range of 50 nm to 560 nm. The effect of mechanical alloying on the microstructure of the powder mixture have been studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and EDS. Toluene was used during milling appears effective process control agent to avoid severe agglomeration and to enhance milling effect. © 2021 Elsevier Ltd. All rights reserved.