Faculty Publications
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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 Investigation of sedimentation, rheological, and damping force characteristics of carbonyl iron magnetorheological fluid with/without additives(Springer, 2020) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumar, H.In the present study, the magnetorheological fluid (MRF) samples are prepared using pure carbonyl iron particles (CIPs), CIPs/Claytone APA/Molyvan 855 additive, and friction reducer dispersed in poly-alpha-olefin oil. The scanning electron microscopy reveals that the Claytone additive morphology looks like a surface abundant in small folds, which connect the gaps between the spherical pure CIPs and prevent sedimentation in the MRF. The magnetic saturation properties are investigated through the vibrating sample magnetometer. The pure CIPs MRF shows (Ms) value as 146.12 emu/g, and the CIPs/Claytone APA/Molyvan indicates (Ms) as 55.12 emu/g. The magnetorheological flow curves, such as shear stress and viscosity as a function of shear rate, are investigated for the MRF samples through the magnetorheometer. The sedimentation analysis of the MRF is observed by visual inspection and shows that the CIPs/Claytone APA/Molyvan improved the sedimentation rate than the pure CIPs MRF. Finally, the experimental characterization of the prototype monotube MR damper is carried out using the hydraulic dynamic testing machine at 1.5 Hz frequency for damper peak–peak displacement length of ± 5 mm at three intervals of 0 h, 24 h, and 72 h in damper to know the effect on damping force for the prepared MRF samples against the sedimentation rate. © 2020, The Brazilian Society of Mechanical Sciences and Engineering.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 Characterization study and recovery of copper from low grade copper ore through hydrometallurgical route(Elsevier B.V., 2022) Mohanraj, G.T.; Rahman, M.R.; Arya, S.B.; Barman, R.; Krishnendu, P.; Meena, S.Characterization studies were conducted on low grade copper ore with the aid of standard approaches. The Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS) study specifies the semi-quantitative data of qualitatively analyzed chemical elements present in the ore sample. Optical Microscopy (OM) and X-Ray Diffraction (XRD) endorse the presence of chalcopyrite (CuFeS2) and pyrites along with other different mineral phases in the ore sample. Thermo Gravimetric Analysis (TGA) and Mossbauer spectroscopy studies confirm the formation of CuO and Fe2O3 after roasting at 700 °C. The better copper recovery from low grade copper ore was achieved through optimized leaching parameters. It was found that the particle size of −63+53 µm can be leached up to 94.96 % of copper using a lixiviant reagent mixture (30 vol. % hydrogen peroxide and 0.5 M sulfuric acid) under magnetic stirring for 30 min at a constant speed of 300 rpm, by keeping the liquid/solid (L/S) ratio at 20/2 ml/g. Moreover, the solvent extraction process works well with the pregnant leach solution, whereby, 98.9 % of copper extraction is possible, and the loading time is less than a minute. Meanwhile, 93.91 % of overall copper extraction efficiency was achieved through optimized leaching parameters and solvent extraction method. © 2021Item Flexible Electromagnetic Shielding Material Using Multi-Walled Carbon Nanotube Coated Cotton Fabric(Institute of Electrical and Electronics Engineers Inc., 2022) Arun Kumar, D.S.; Tharehalli Rajanna, T.R.; Kandasamy, K.; Bhat Panemangalore, P.; Rahman, M.R.The present work focuses on the development of cotton fabric with multi-walled carbon nanotube coating (CMC) through a dip and dry process. The influence of multi-walled carbon nanotubes (MWCNTs) concentration on transmission, reflection, and absorption properties, which leads to an estimation of electromagnetic interference (EMI) shielding, was also studied. The merits of MWCNTs coating on the cotton fabric were evaluated using field-emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and surface resistivity. The Fourier transform infrared (FTIR) spectroscopy result supports the bonding between MWCNTs and cotton fabric. The significant increase of 98.9% of EMI shielding for the highest MWCNTs weight percentage (22.23 wt%) was attributed due to the well-interconnected network of MWCNTs. The shielding mechanism in the high wt% MWCNTs samples is dominated by both reflection and absorption properties. © 2011-2012 IEEE.Item A study on magnetorheological and sedimentation properties of soft magnetic Fe58Ni42 particles(Elsevier B.V., 2022) Aruna, M.N.; Rahman, M.R.; Joladarashi, S.; Kumara, H.; Meena, S.S.; Sarkar, D.; Umesh, C.K.In this study, the samples with two volume fractions (ϕ) of Fe58Ni42 (permalloy) i.e. (ϕ1 = 25 and ϕ2 = 30 %) were used as magnetic particles, silicone oil as a carrier fluid, and aluminium disterate as an additive. As received Fe58Ni42 particles surface morphology and composition of the Fe58Ni42 were investigated using field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS), respectively. The X-ray Diffraction (XRD) structural information analysis confirmed Fe58Ni42 particles have a face-centered cubic phase, corresponding with the result of the high resolution transmission electron microscopy (HRTEM) characterization technique. The magnetorheological properties were tested via rotational rheometer at four different magnetic field strengths. The results show that sample PMRF-30 has a maximum shear stress, shear viscosity, and dynamic modulus greater than the PMRF-25 sample. In addition, experimental shear stress flow curves are well fitted with Herschel-Bulkley rather than Bingham and Casson rheological models. The permalloy based magnetorheological fluid (PMRF) samples were prepared with a 25 % volume fraction and a 30 % volume fraction of permalloy particles with a sample abbreviation of PMRF-25 and PMRF-30, respectively. Furthermore, the sedimentation stability of suspensions of both the samples was observed using visual inspection. This method result shows the sedimentation ratio with respect to time of 72 h was 31 % and 29 %, respectively. © 2022 Elsevier B.V.Item Flexible and cost effective CNT coated cotton fabric for CO gas sensing application(Elsevier B.V., 2023) D.s, A.K.; Chauhan, S.S.; Krishnamoorthy, K.; P, D.B.; Bharathi, K.D.; Ravikumar, A.; Rahman, M.R.In this paper, a low-cost and room temperature flexible carbon monoxide (CO) gas sensor is presented using multi-walled carbon nanotubes coated cotton fabric. A dip and drying method is used to fabricate a lightweight, and high-performance fabric based CO gas sensor using different concentrations of multi-walled carbon nanotubes (MWCNTs). Transmission electron microscopy (TEM) is utilized for examining the deagglomeration of MWCNTs in the presence of a sufficient amount of surfactant. The field-emission scanning electron microscopy (FESEM) is used to evaluate the formation of a uniform network of MWCNTs on the cotton fabric. Fourier transform infrared (FTIR) spectroscopy is used to confirm the presence of functional groups which plays an important role in CO gas sensing. The fabricated cotton fabric coated with MWCNTs (CCM) sensors are tested with different concentrations of CO gas ranging from 25 ppm to 100 ppm at room temperature. It is found that in comparison to all other sensors, the CCM sensor coated with the higher concentration of MWCNTs (0.5 mg/ml) shows a maximum response of 9.11 % at 25 ppm and 15.2 % at 100 ppm concentration of CO gas respectively. The CCM 4 sensor shows the fastest response and recovery within 49s for 25–100 ppm of CO gas. Moreover, the fabricated CCM sensor exhibited good repeatability, reproducibility, and selectivity. These sensors are suitable for low-cost smart textile applications. © 2023 Elsevier B.V.