Faculty Publications

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Now showing 1 - 8 of 8
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    Plasma nitriding of AISI 2205 steel: Effects of surface mechanical attrition treatment and chemical etching
    (Maney Publishing michael.wagreich@univie.ac.at, 2016) Gatey, A.M.; Hosmani, S.S.; Arya, S.B.; Figueroa, C.A.; Singh, R.P.
    In the present study, surface mechanical attrition treatment (SMAT) and plasma nitriding were conducted on AISI 2205 steel. SMAT was effective in enhancing the surface hardness of the steel by about 80%. The influence of SMAT on the corrosion behaviour of the steel was studied in a 3.5 wt-% NaCl solution. Due to the stable and thicker passive layer, improved corrosion resistance was observed for the SMATed steel. However, nitrogen diffusion during plasma nitriding was impeded by the improved passivation, especially for the lower duration (30 min) of chemical etching/cleaning (i.e. sputter cleaning in hydrogen plasma) of the specimen's surface. Furthermore, high chemical etching duration (120 min) resulted in improved surface hardness and nitriding kinetics. © 2016 Institute of Materials, Minerals and Mining.
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    Role of surface mechanical attrition treatment and chemical etching on plasma nitriding behavior of AISI 304L steel
    (Elsevier B.V., 2016) Gatey, A.M.; Hosmani, S.S.; Figueroa, C.A.; Arya, S.B.; Singh, R.P.
    In the present study, the effect of surface mechanical attrition treatment (SMAT) on corrosion resistance and plasma nitriding behavior of AISI 304L stainless steel (SS) was investigated. Mechanical twins and deformation induced martensite phase were observed in the SMAT affected region. SMAT improved the corrosion resistance and nitriding kinetics of AISI 304L SS. Effective nitriding time and hence, the thickness of the nitrided layer were increased with increase in the duration of chemical etching and a decrease in the stability of passive layer on the SMATed specimens. Surface hardness of the nitrided specimens was dependent on the formation of expanded austenite (?N) and its decomposition (especially, at higher effective nitriding time). © 2016 Elsevier B.V.
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    Dual-band dual-polarized leaky-wave structure with forward and backward beam scanning for circular polarization-flexible antenna application
    (John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2020) Rudramuni, K.; Majumder, B.; Kandasamy, K.
    In this paper, a novel dual-band dual-polarized leaky-wave antenna (LWA) with polarization diversity is proposed using half mode substrate-integrated waveguide (HMSIW)-based technology. HMSIW LWAs are generally single band. In this work, by etching simple spiral type slots on the HMSIW cavity, a novel dual-band dual-polarized LWA is designed. The proposed antenna resonates at 5.6 and 8.5 GHz. Moreover, the antenna radiates the linearly polarized wave in the lower band and circularly polarized (CP) wave in the higher operating band. Also, in the higher operating band between 8.7 and 9.3 GHz, the proposed overall antenna exhibits both right-hand circular polarization as well as the left-hand circular polarization in the near main beam direction. The ?10 dB impedance bandwidth of the proposed antenna at the lower and the higher operating bands are 27% (4.86-6.4 GHz) and 25% (7.4-9.6 GHz), respectively. In the higher band, the 3-dB axial ratio bandwidth of 6.6% (8.7-9.3 GHz) is achieved. The main beam of the antenna can be steered from 19° to 69° in the forward direction in the lower operating band. In the higher operating band, the antenna can steer the CP beam between ?17° and ?32°. In both the lower bands, the realized peak gain is observed around 13.3 dBi, whereas in the higher band, the realized peak gain is observed around 14 dBi. © 2020 Wiley Periodicals, Inc.
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    Beneficial Effect of Manganese(II) Ions on the Morphology of Polyol Synthesised Silver Nanowires
    (Korean Institute of Metals and Materials, 2020) Prabukumar, C.; Bhat, K.U.
    Abstract: Silver nanowires (Ag NWs) is a potential material to be used as the transparent conductive electrode (TCE) material, in the flexible electronic applications. The polyol method is the commonly used technique to synthesis the silver nanowires. The growth of the silver nanowires is facilitated by the oxidative etching of the silver seed particles. The present work investigates the influence of the manganese(II) ions to promote the growth of silver nanowires. The manganese(II) ions, due to its multiple oxidation states, play an essential role in removing the dissolved atomic oxygen, which prevent the growth of longer nanowires. Its effect on the length and diameter of the silver nanowires is studied in detail with different concentration levels. Characterization tools, such as X-ray diffractometry, electron microscopy (FESEM and TEM) and UV–VIS spectroscopy are used to characterise the synthesised silver nanowires. The addition of manganese(II) ions alters the aspect ratio of the silver nanowires that in turn, affects the optoelectrical properties of the TCE films. By using the synthesised silver nanowires, transparent heaters are successfully fabricated and their performances under different conditions are evaluated. Graphic Abstract: [Figure not available: see fulltext.]. © 2020, The Korean Institute of Metals and Materials.
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    New preparation methods for pore formation on polysulfone membranes
    (MDPI AG, 2021) Vainrot, N.; Li, M.; Isloor, A.M.; Eisen, M.S.
    This work described the preparation of membranes based on aromatic polysulfones through the phase-inversion method induced by a nonsolvent, generating the phase separation (NIPS) process. Three new techniques, including the nano iron acid etching method, base hydrolysis method of crosslinked polymers, and base hydrolysis method of a reactive component in a binary polymer blend, were developed for pore creation on membranes. The modified polymers and obtained membranes were carefully characterized. The uniform pores were successfully created by base hydrolysis of the crosslinked polymers and obtained at the size of the crosslinker. Moreover, homogeneous pores were created after base hydrolysis of the membranes prepared from binary polymer blends due to the internal changes in the polymer structure. The separation performance of membranes was tested with different inorganic salt solutions and compared with commercially known membranes. These new membranes exhibited high water flux (up to 3000 L/m?2·h?1 at 10 bar and at 25?C) and reasonable rejections for monovalent (21–44%) and multivalent ions (18–60%), depending on the different etching of the hydrolysis times. The comparison of these membranes with commercial ones confirmed their good separation performance and high potential application for water treatment applications. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.
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    High performance 2D molybdenum MXene polyphenylsulfone membranes for boosting water flux and efficient removal of humic acid, antibiotic and dyes from wastewater
    (Elsevier B.V., 2025) Satishkumar, P.; Isloor, A.M.; Farnood, R.
    MXene, a leading two-dimensional material, is attracting scientists due to its rich polar surface termination and compatibility. Through the etching of an aluminum layer from Mo3AlC2, we have effectively produced molybdenum MXene Mo3C2Tx (where T stands for polar moieties like –OH and ?F) and used it to fabricate a new Mo3C2Tx embedded mixed matrix membrane. By the incorporation of highly hydrophilic Mo3C2Tx MXene into polyphenylsulfone (PPSU) membrane, its water flux tremendously increased to a peak value of 290 L m-2h?1 and is higher than 300 % compared to pristine polyphenylsulfone membrane without Mo3C2Tx MXene. Water contact angle study of Mo3C2Tx MXene embedded membranes showed improvement in hydrophilicity with an increase in its loading. Mo3C2Tx-PPSU membrane demonstrated appreciable antifouling nature and pollutant separation efficacy. The optimal membrane revealed 98.68 %, 96.7 %, 84.72 %, and 80.2 % removal of toxic contaminants like humic acid, RB 5 dye, RO 16 dye, and tetracycline antibiotic, respectively. This study offers a novel Mo3C2Tx embedded polyphenylsulfone membrane for wastewater treatment that eliminates potentially harmful humic acid, antibiotics, and dyes. © 2025
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    Deep-eutectic solvent-assisted green synthesis of MAX-phase Cr2AlC and its 2D-MXene derivative Cr2CTxtowards room-temperature detection of ammonia gas
    (Elsevier Ltd, 2025) Lokeshwar, H.; Lakshmi Praveen, L.; Mandal, S.; Shakti, N.
    This study explores the novel and eco-friendly chemical etching of bulk Cr2AlC MAX phases using a deep eutectic solvent (DES) mixture of choline chloride (ChCl) and anhydrous ferric chloride (FeCl3) to synthesize chromium carbide (Cr2CTx) MXene nanolayers. ChCl-FeCl3enables a fluoride-free transformation approach to synthesize Cr2CTxMXene via selective etching of aluminium interlayers, resulting in mixed surface terminations (-O, -OH, -Cl) confirmed from bond vibrations observed in FTIR transmittance spectra. Also, the FESEM micrographs confirm the formation of Cr2CTxnanolayers with successful cleavage of Cr2AlC MAX phase nanolaminates identified from a distinct red shift of D-band with the highest ID/IGratio peak intensity ratio, confirming the presence of high defect concentration in Cr2CTxMXene. The hydrothermally synthesized SnO2powders exhibiting a rutile tetragonal phase average particle size of 35.8 ± 0.8 nm were mixed with Cr2CTxto formulate screen-printable inks for the fabrication of Cr2CTx, SnO2, and their composite Cr2CTx-SnO2gas sensors. The addition of Cr2CTxdemonstrated a detrimental effect on the gas-sensing performance of the SnO2sensor, which was further supported from XPS analysis. However, the SnO2sensor recorded the highest gas-response of ?452 towards 100 ppm of ammonia gas among all sensors, highlighting the role of oxygen defects confirmed from photoluminescence spectra. This work paves the way for a novel and eco-friendly etching approach of MAX-phases and helps in their research towards the development of ultra-sensitive gas sensors. © 2025 Elsevier Ltd and Techna Group S.r.l. All rights are reserved, including those for text and data mining, AI training, and similar technologies.