Faculty Publications
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Item Corrosion resistance and in-vitro bioactivity of BaO containing Na2O-CaO-P2O5 phosphate glass-ceramic coating prepared on 316 L, duplex stainless steel 2205 and Ti6Al4V(Institute of Physics Publishing helen.craven@iop.org, 2018) Edathazhe, A.B.; Shashikala, H.D.The phosphate glass with composition 11Na2O-15BaO-29CaO-45P2O5 was coated on biomedical implant materials such as stainless steel 316 L, duplex stainless steel (DSS) 2205 and Ti6Al4V alloy by thermal enamelling method. The structural properties and composition of glass coated substrates were studied by x-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive x-ray spectroscopy (EDS) analysis. The coatings were partially crystalline in nature with porous structure and pore size varied from micro to nanometer range. The polarization curve was obtained for uncoated and coated substrates from electrochemical corrosion test which was conducted at 37 °C in Hank's balanced salt solution (HBSS). The corrosion resistance of 316 L substrate increased after coating, whereas it decreased in case of DSS 2205 and Ti6Al4V. The XRD and SEM/EDS studies indicated the bioactive hydroxyapatite (HAp) layer formation on all the coated surfaces after electrochemical corrosion test, which improved the corrosion resistance. The observed electrochemical corrosion behavior can be explained based on protective HAp layer formation, composition and diffusion of ions on glass coated surfaces. The in-vitro bioactivity test was carried out at 37 °C in HBS solution for 14 days under static conditions for uncoated and coated substrates. pH and ion release rate measurements from the coated samples were conducted to substantiate the electrochemical corrosion test. The lower ion release rates of Na+ and Ca2+ from coated 316 L supported its higher electrochemical corrosion resistance among coated samples. Among the uncoated substrates, DSS showed higher electrochemical corrosion resistance. Amorphous calcium-phosphate (ACP) layer formation on all the coated substrates after in-vitro bioactivity test was confirmed by XRD, SEM/EDS and ion release measurements. The present work is a comparative study of corrosion resistance and bioactivity of glass coated and uncoated biomedical implants such as 316 L, DSS and Ti6Al4V. © 2018 IOP Publishing Ltd.Item Optical and structural properties of BCBS glass system with and without alumina(Elsevier B.V., 2018) Bhattacharya, S.; Shashikala, H.D.BaO–CaO–Al2O3–SiO2 (BCAS) glass and their derivatives have gained extreme importance for their high endurance to elevated temperatures and being suitable for various electrochemical applications. Two glass systems, one being 50mol% [SiO2–B2O3]-xBaO-(45-x)CaO–5Al2O3 called as BCBSA and another without Al2O3 termed as BCBS were synthesized using melt quenching technique in the present work. Addition of ZnO and MgO as flux helped in melting them at 1300 °C which is much lower than the usual melting temperature of these glasses [1–4]. Density of the quenched glasses was measured by Archimedes method and structural bond vibrations were confirmed through FTIR. UV Visible spectroscopy was used to determine band gap energy and confirm the insulating nature of the synthesized glasses. The samples were isothermally heated at 700 °C, 800 °C for 50 h and at 900 °C for 50 and 100 h duration in air to allow the devitrification process to take place. The heat treated samples were analyzed by X-ray diffraction to identify the developed phases. Five Al2O3 free samples synthesized at 1300 °C by regular melt quenching technique were found to be devoid of the monocelsian phase. This is a detrimental phase for high temperature sealant applications as it has a very low coefficient of thermal expansion (CTE). Al2O3 free BCBS glasses, properties of which are being reported for the first time and glasses with low BaO concentrations are found to meet the requirements for high temperature applications as sealants in Solid Oxide Fuel Cell (SOFC). © 2018 Elsevier B.V.Item Compressive behavior of fly ash based 3D printed syntactic foam composite(Elsevier B.V., 2019) Patil, B.; Bharath Kumar, B.R.; Doddamani, M.Syntactic foams are widely used in damage tolerance and low-density applications. In present work compressive behavior of 3D printed three-phase syntactic foams under quasi-static strain rates (0.001, 0.01 and 0.1 s?1) are investigated. Extruded filaments of High density polyethylene (HDPE) with environmentally pollutant fly ash cenospheres (0, 20, 40 and 60 vol%) are used for 3D printing. Micrography reveal that syntactic foam filament and 3D printed samples are three phase systems comprising matrix, cenosphere and porosity. Matrix porosity of about 7% makes these foams lightweight and suitable for buoyant applications. The compressive properties are extracted from the stress-strain plots. It is observed that modulus and specific modulus increases with strain rate and cenosphere content. Specific compressive strength increases with strain rate and decrease with cenosphere content. © 2019 Elsevier B.V.Item Synthesis and characterization of zinc oxide incorporated iron borate glass-ceramic(Elsevier Ltd, 2019) Ramteke, R.; Kumari, K.; Bhattacharya, S.; Rahman, M.R.Here, zinc oxide (ZnO) incorporated iron borate (Fe3BO6) glass-ceramics have been synthesized using the traditional melt-quenching technique, and the role of ZnO has been investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveals that the prepared samples have a single crystalline phase and crystalline nanostructures, respectively. The orthorhombic crystal structure has been retained without the formation of a new crystalline phase. The addition of ZnO is found to distort the Fe3BO6 lattice by substituting Zn2+ in the Fe3+ sites, with the formation of ZnO6 structural units as revealed by Fourier transform infrared spectroscopy (FTIR). FTIR and Raman spectroscopy conducted to study the structure of glass-ceramic, have also revealed the formation of other structural units like ZnO4, BO3, BO4, and FeO6 in the system. Surface analysis conducted by X-ray photoelectron spectroscopy (XPS) reveals that the addition of ZnO diminishes the formation of surface B2O3 layer which forms over the Fe3BO6 phase in the Fe3BO6 iron borate glass-ceramic system. ZnO addition has also shown a remarkable difference in the volume of the crystallization in the system, thereby paving the way for controlled crystallization in the iron borate glass-ceramic system. The controlled crystallization was achieved through additive content, retaining the iron borate (Fe3BO6) glass-ceramic system without the evolution of any secondary phases even with large additive concentrations up to 10 mol%. © 2019 Elsevier B.V.Item Improved electrochemical performance of graphene oxide supported vanadomanganate (IV) nanohybrid electrode material for supercapacitors(Elsevier Ltd, 2020) Kumari, S.; Maity, S.; Anandan Vannathan, A.A.; Shee, D.; Das, P.P.; Mal, S.S.Graphene oxide (GO)-supported polyoxometalates (POMs) have been considered as promising electrode materials for energy storage applications due to their ability to undergo fast and reversible redox reactions. Herein, vanadomanganate-GO composites (K7MnIVV13O38.18H2O-GO with 2:1 and 4:1 ratio) were investigated for use as potential electrode materials in supercapacitors (SCs). The K7MnIVV13O38.18H2O (MnV13) was synthesized and anchored on GO through electron transfer interaction and electrostatic interaction to make the composite electrodes for the present study. All synthesized electrode materials were fully characterized by various techniques, e.g., Fourier Transform Infrared (FTIR) Spectroscopy, Powder X-ray Diffraction (XRD), Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDS) and High Resolution-Transmission Electron Microscopy (HR-TEM). The electrochemical properties of MnV13/GO composites with different MnV13/GO ratios were investigated by two-electrode cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) in different electrolytes. The MnV13/GO composite of ratio 2:1 in 1 M LiCl electrolyte and that of ratio 4:1 in 1 M Na2SO4 electrolyte showed significant specific capacitance values of 269.15 F/g and 387.02 F/g, respectively and energy density of 37.38 Wh/kg and 53.75 Wh/kg, respectively for a scan rate of 5 mV/s. Interestingly, the 1:1 (MnV13/GO) composite in 1 M Na2SO4 and 1 M LiCl electrolytes showed very low specific capacitance values as the deposition of MnV13 on GO was not sufficient, as indicated by FTIR and SEM. Thus, it is evident that the specific capacitance value of these composite materials depends on the amount of MnV13 deposited on GO and these composite materials exhibit the potential to improve the performance of GO-based SCs. © 2019Item Impedance spectroscopy study of zinc oxide incorporated iron borate glass-ceramic(Elsevier B.V., 2021) Ramteke, R.; Kumari, K.; Bhattacharya, S.; Sharma, S.K.; Rahman, M.R.Here, the effects of zinc oxide (ZnO) on impedance and dielectric properties of the ZnO incorporated iron borate (Fe3BO6) glass-ceramics were studied using impedance spectroscopy in a wide range of frequency (1 Hz – 1 MHz) and temperature (25 °C–250 °C). With ZnO addition, the ?? and tan? values were reduced significantly, the strength of the relaxation process also decreased, along with a decrease in conductivity. Activation energies associated with modulus and conductivity plots suggest that similar type of charge carriers was responsible for the relaxation and conduction processes. The analysis of both complex impedance and conductivity show the negative temperature coefficient of resistance (NTCR) behavior of the samples. The thermistor constant B-values of 5ZnO and 10ZnO were found to be 7223 and 7088 respectively. The study of the NTCR properties suggests a potential candidate for thermistor applications. © 2021 Korean Physical SocietyItem Quasi-static compressive behavior of bioactive glass reinforced high density polyethylene composites(Elsevier B.V., 2022) Jeyachandran, P.; Bontha, S.; Bodhak, S.; Krishna Balla, V.; Doddamani, M.Compressive behavior of additively manufactured bioactive glass (BAG) reinforced high density polyethylene (HDPE) composites under quasi static conditions (0.001, 0.01 and 0.1 s−1 strain rates) is investigated in this work. HDPE feedstock filaments with 5, 10 and 20 wt% of bioactive glass are extruded for fused filament fabrication (FFF) based 3D printing (3DP). Compressive properties are extracted from the stress–strain plots. Elastic modulus and yield strength of the samples increase with filler addition and strain rate. Energy absorption increases with increase in strain rate and BAG content. All the samples exhibit homogeneous ductile deformation with distinct barrelling effect without any visible cracks. Deformation and energy absorption behavior of the tested samples are investigated using micrography. © 2021 Elsevier B.V.Item Effect of BTO piezoceramic on the mechanical and dielectric properties of 3D-printed PLA.BTO functional polymer composite(Springer Nature, 2025) Senthil Murugan, S.; Kattimani, S.; Saminathan, R.The development of polymer composite materials for additive manufacturing is critical for advancing industrial applications. This study enhances the functional performance of poly-lactic acid (PLA) by incorporating barium titanate (BTO/BaTiO?) particles. Uniform dispersion of BTO within the PLA matrix was achieved, and filaments were fabricated using fused deposition modelling (FDM) with a 60% infill rate, adhering to ASTM standards. The influence of BTO fillers on the mechanical and dielectric properties of PLA.BTO composites were analysed and compared to pure PLA. FESEM microstructural analysis confirmed distinct layering, defect-free deposition, and uniform BTO distribution. Mechanical testing revealed notable improvements, including increases in tensile strength (16.4%), flexural strength (17.1%), shore hardness (4.7%), impact strength (17.7%), and drop-weight energy absorption for a 5 mm plate (26%), attributed to enhanced interfacial bonding and reduced void formation. The dielectric properties exhibited significant enhancements, with a 12.9% increase in dielectric strength, a 15% higher dielectric constant, an 8% greater breakdown strength, and a 21.74% rise in electrical susceptibility. Furthermore, reductions in loss tangent (19.1%), AC conductivity (7.8%), and dielectric loss (6.8%) demonstrated the material’s ability to store and withstand electric fields efficiently. Ferroelectric analysis revealed improved remanence, coercivity, and polarization, underscoring the composite’s potential as a piezoelectric material. These findings highlight the suitability of PLA.BTO composites for energy storage devices, sensors, and biodegradable functional applications, offering a promising balance of mechanical durability and superior dielectric performance. © Qatar University and Springer Nature Switzerland AG 2025.