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Journal of Materials Science & technology 2021年第23期82卷 214-226页

作者： G.Karthick Lavanya Raman B.S.Murty Department of Metallurgical and Materials Engineering Indian Institute of Technology MadrasChennai600036India indian institute of technology Hyderabad Kandi502285India

High entropy pyrochlores(HEP)are potential candidates as dispersoids in the oxide dispersed strengthened steels or alloys,which can be used in nuclear reactors and supercritical *** the first time,HEP oxides Y_(2)(TiZrHfMoV)_(2)O_(7) were synthesized with Y_(2)Ti_(2)O_(7) as a base structure with the B site(Ti)substituted with five cations through reverse co-precipitation technique in the nanocrystalline form at lowest synthesis *** synthesis parameters for Y_(2)(TiZrHfMoV)_(2)O_(7)(5C)and other derived compositions(five compositions of four cationic systems with each cation eliminated at B site from 5 C)are optimised to obtain lower crystallite and particle sizes.5C has a smaller crystallite size(27 nm)than other single-phase *** cation’s influence,oxidation state,and oxygen vacancy in the phase formation were analysed through *** single-phase HEPs are consolidated through spark plasma sintering.Y_(2)(TiZrHfMo)_(2)O_(7)(4 C-V)shows the highest hardness among the compositions reported so far due to its finer grain size,and Y_(2)(TiHfMoV)_(2)O_(7)(4 C-Zr)has a higher Young’s modulus compared to other single-phase composition due to its higher degree of order in the structure.

关键词： High entropy pyrochlores Reverse co-precipitation B site substitution Hardness Young’s modulus

Pre-treatment of rocks prior to comminution--A critical review of present practices

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International Journal of Mining Science and technology 2017年第2期27卷 339-348页

作者： Somani Aditya Nandi Tapas K. Pal Samir K. Majumder Arun K. Department of Mining Engineering Indian Institute of TechnologyKharagpur 721302India Cryogenic Engineering Centre Indian Institute of TechnologyKharagpur 721302India

It has been an established fact that comminution processes, crushing and grinding, are most energy intensive processes which account for more than half of the total energy consumed in mineral *** alternative pre-treatment methods have been tried by experts around the globe. Although these methods yielded positive results in terms of reduction in energy consumption in crushing and particularly, in grinding operations at laboratory scale, their industrial application still remains an unresolved issue and challenge. Present review paper describes each one of these methods along with outcome of earlier studies and issues that need to be addressed through further rigorous experimental *** also suggests the direction in which future studies can be carried out to meet the primary objective of making comminution processes more energy efficient than today they are.

关键词： Comminution Rock breakage Microwave Thermal shock

Solution and Thermodynamic Studies on Binary and Ternary Complexes of Lanthanides

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Journal of Rare Earths 2005年第4期23卷 389-396页

作者： Rajeev Kumar Udai P Singh Department of Chemistry Indian Institute of Technology Roorkee Roorkee-247667 IndiaDepartment of Chemistry Indian Institute of Technology Roorkee Roorkee-247667 India

The interactions of La（ Ⅲ ）, Pr（ Ⅲ ）, Nd（ Ⅲ ）, Sm（ Ⅲ ）, Eu（Ⅲ）, Gd（ Ⅲ ）, Dy（ Ⅲ ）, and Yb（ Ⅲ ） with cytosine, 5-bromocytosine, 5-azacytosine and 5-flurocytosine as primary ligands （L） and guanine （A） as secondary ligand for both binary （ 1 ： 1 ） as well as ternary （ 1 ： 1 ： 1 ） systems were investigated by potentiometric equilibrium measurements at 25, 35 and 45 ℃ in aqueous solution （ionic strength, μ = 0.1 mol·dm^-3 NaNO3）. The stability constants of the binary （ 1 ： 1 ） and ternary （ 1 ： 1 ： 1 ） metal-ligand complexes follow the following order La 〈 Pr 〈 Nd 〈 Sm 〈 Eu 〉 Gd 〈 Dy 〉 Yb. Results also indicate that the ternary lanthanide complexes of La（Ⅲ）, Pr（Ⅲ）, Nd（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, Gd（Ⅲ）, Dy（Ⅲ）, and Yb（ Ⅲ ） are more stable than corresponding binary lanthanide complexes. The enthalpy （△Hf^o） and entropy （△Sf^o） changes for the formation of binary and ternary complexes were calculated from temperature coefficient data. The △△Sf^o values are positive for all the metal ligand systems. The negative △△Hf^o values indicate the extra stability of the ternary complexes by the exothermic enthalpy changes （△△Sf^o = △TSf^o - △BSf^o and △△Hf^o = △THf^o - △BHf^o where △TSf^o, △THf^o and △BSf^o, △BHf^o are the entropy and enthalpy values associated with the ternary and binary complexes, respectively）. It was also proposed that the guanine is bonded to metal ions through N1/C6 = O and N7 whereas cytosine and its derivatives are bonded through N3 atoms in ternary complexes.

关键词： lanthanide solution studies cytosine thermodynamic properties rare earths

Mo^(6+)Modified(K_(0.5)Na_(0.5))NbO_3 Lead Free Ceramics:Structural,Electrical and Optical Properties

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Journal of Materials Science & technology 2014年第5期30卷 459-465页

作者： Jyoti Rani Piyush Kumar Patel Nidhi Adhlakha Hemant Singh K.L.Yadav Satya Prakash Smart Materials Research Laboratory Department of PhysicsIndian Institute of Technology Roorkee Metallurgical and Materials Engineering Department Indian Institute of Technology Roorkee

Lead free polycrystalline ceramics （K0.5Na0.5）Nb（1-x）MoxO3 （x = 0, 0.02, 0.04, 0.06 and 0.08） have been synthesized via solid state reaction method. The formation of single phase perovskite structure up to 6 mol% of Mo^6＋ has been confirmed by X-ray diffraction pattern. Impedance spectroscopy reveals that bulk resistance decreases with increasing temperature, which indicates negative temperature coefficient of resistance （NTCR） behaviour of the compounds. The diffuse reflectance spectroscopy results indicate a red shift of the band gap energy of K0.5Na0.5NbO3 （KNN, from 4.28 to 3.61 eV） with increasing Mo^6＋ concentration due to structural modification. The photoluminescence spectra of doped samples are composed of two emission bands at room temperature. One emission band is near band edge ultraviolet （UV） emission （354 nm） and other is visible emission band （-397 nm） which may explore the possibility of these ceramics to be used in optical device applications.

关键词： Ceramics Characterization Dielectric constant Impedance spectroscopy Optical band gap

In-plane and out-of-plane quasi-static compression performance enhancement of 3D printed re-entrant diamond auxetic metamaterial with geometrical tuning and fiber reinforcement

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Defence technology（防务技术） 2023年第7期25卷 1-17页

作者： Niranjan Chikkanna Shankar Krishnapillai Velmurugan Ramachandran Department of Mechanical Engineering Indian Institute of Technology Madras600036India Department of Aerospace Engineering Indian Institute of Technology Madras600036India

Auxetic materials are cellular materials with a unique property of negative Poisson’s *** auxeticity and performance of these metamaterials utterly depend on the geometrical parameters and loading *** the first time,the quasi-static uniaxial compression performance of fused filament fabricated re-entrant diamond auxetic metamaterial is evaluated in the x-direction(in-plane)and z-direction(out-of-plane).The most commonly used thermoplastic feedstock,Acrylonitrile butadiene styrene,is considered a material of *** effect of influential geometrical parameters of the re-entrant diamond structure and printing parameter is systematically studied using Taguchi’s design of ***-based multi-objective optimisation technique has been adopted to arrive at the optimal *** are made to improve the stiffness and strength of the structure with fibre *** glass fibre reinforcements have enhanced specific strength and stiffness in both in-plane and out-ofplane directions.A sevenfold and thirteen times increase in specific strength and energy absorption is evident for glass fibre-reinforced structures in out-of-plane directions compared to in-plane *** tuning of geometrical parameters of the re-entrant diamond structure can result in a Poisson’s ratio of up to-3.49 when tested in the *** parametric study has illustrated the tailorability of the structure according to the application *** statistical study has signified each considered parameter’s contribution to the compression performance characteristics of the 3D printed re-entrant diamond auxetic metamaterial.

关键词： Auxeticity Fibre reinforcement Tailorability Anisotropy Geometrical influence Property enhancement

SYNTHESIS AND CHARACTERIZATION OF HYBRID PROTON CONDUCTING MEMBRANES OF POLY(VINYL ALCOHOL) AND PHOSPHOMOLYBDIC ACID

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Chinese Journal of Polymer Science 2006年第5期24卷 449-456页

作者： Arfat Anis A.K. Banthia S. Mondal A.K. Thakur Materials Science Centre Indian Institute of TechnologyKharagpur 721302India Department of Physics & Meteorology Indian Institute of TechnologyKharagpur 721302India

Hybrid proton conducting membranes of poly（vinyl alcohol）（PVA） and phosphomolybdic acid （PMA） were prepared by solution casting method. The effect of PMA doping and PVA crosslinking density on the membrane properties and proton conductivity were investigated. The crosslinking reaction between the hydroxyl group of PVA and the aldehyde group of glutaraldehyde （GA） was characterized by IR spectroscopy. Proton conductivity of the membranes increases with an increase in concentration of the doped PMA and also with an increase in crosslinking density of the membranes. Proton conductivity results indicate that a significant amount of PMA was maintained in the membranes even after several hours of immersion in water. A maximum conductivity of 0.0101 S cm^-1 was obtained for the membrane with 33.3 wt% PMA and crosslinking density of 5.825 mol%. X-ray diffraction studies were carried out to investigate the influence of PMA doping and crosslinking density on the nature of the membranes. These properties make them very good candidates for polymer electrolyte membranes for direct methanol fuel cell application.

关键词： Polymer electrolyte membranes Proton conductor Phosphomolybdic acid Crosslinked PVA membranes.

Optimization of thermoacoustic refrigerator using response surface methodology

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Journal of Hydrodynamics 2013年第1期25卷 72-82页

作者： HARIHARAN N. M. SIVASHANMUGAM P. KASTHURIRENGAN S. Department of Chemical Engineering National Institute of Technology Centre for Cryogenic technology Indian Institute of Science

Thermoacoustic refrigerator （TAR） converts acoustic waves into heat without any moving parts. The study presented here aims to optimize the parameters like frequency, stack position, stack length, and plate spacing involving in designing TAR using the Response Surface Methodology （RSM）. A mathematical model is developed using the RSM based on the results obtained from DeltaEC software. For desired temperature difference of 40 K, optimized parameters suggested by the RSM are the frequency 254 Hz, stack position 0.108 m, stack length 0.08 m, and plate spacing 0.0005 m. The experiments were conducted with optimized parameters and simulations were performed using the Design Environment for Low-amplitude ThermoAcoustic Energy Conversion （DeltaEC） which showed similar results.

关键词： Design Environment for Low-amplitude ThermoAcoustic Energy Conversion (DeltaEC) optimization Response Surface Methodology (RSM) temperature difference thermoacoustic refrigerator (TAR)

Response Analysis of Tension-Based Tension Leg Platform Under Irregular Waves

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China Ocean Engineering 2016年第4期30卷 603-614页

作者： D.S.Bhaskara Rao R.Panneer Selvam Department of Ocean Engineering Indian Institute of Technology Madras

Tension Leg Platform（TLP） is a hybrid structure used as oil drilling and production facility within water depths of 1200 m. The extension of this TLP concept to deeper waters is a challenge and warrants for some innovative design concepts. In this paper, a relatively new concept of TLP which is christened as Tension-Based Tension Leg Platform（TBTLP） and patented by Srinivasan（1998） has been chosen for study. Response analysis of TLP with one tension base under irregular waves for three different sea states has been performed using hydrodynamic tool ANSYS？ AQWA？. Results are reported in terms of RAOs, response spectrums for surge, heave and pitch degrees of freedom from which spectral statistics have been obtained. The statistics of TBTLP have been compared with TLPs（without tension base） for two different water depths to highlight the features of the new concept. The effect of viscous damping and loading effects on the RAOs are also investigated.

关键词： Tension-Based Tension Leg Platform irregular waves time domain response response amplitudeoperators spectrum statistics coupled analysis

Relationship between the microstructure and properties of thermomechanically processed Fe-17Mn and Fe-17Mn-3Al steels

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International Journal of Minerals,Metallurgy and Materials 2019年第1期26卷 64-75页

作者： Renuprava Dalai Siddhartha Das Karabi Das Department of Metallurgical and Materials Engineering Indian Institute of Technology

Two austenitic Mn steels(Fe-17 Mn and Fe-17 Mn-3 Al(wt%, so as the follows)) were subjected to thermomechanical processing(TMP) consisting of forging followed by solutionization and hot rolling. The rolled samples were annealed at 650 and 800°C to relieve the internal stress and to induce recrystallization. The application of TMP and heat treatment to the Fe-17 Mn/Fe-17 Mn-3 Al steels refined the austenite grain size from 169 μm in the as-solutionized state to 9–13 μm, resulting in a substantial increase in hardness from HV 213 to HV 410 for the Fe-17 Mn steel and from HV 210 to HV 387 for the Fe-17 Mn-3 Al steel. The elastic modulus values, as evaluated by the nanoindentation technique, increased from(175 ± 11) to(220 ± 12) GPa and from(163 ± 15) to(205 ± 13) GPa for the Fe-17 Mn and Fe-17 Mn-3 Al steels, respectively. The impact energy of the thermomechanically processed austenitic Mn steels was lower than that of the steels in their as-solutionized state. The addition of Al to the Fe-17 Mn steel decreased the hardness and elastic modulus but increased the impact energy.

关键词： austenitic manganese steel(AMS) thermomechanical processing(TMP) microstructure property hardness elastic modulus

Some hydrodynamic aspects of 3-phase inverse fluidized bed

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China Particuology 2007年第5期5卷 351-356页

作者： Krishna S.V.S.R. Bandaru D.V.S. Murthy K. Krishnaiah Department of Chemical Engineering Indian Institute of Technology Madras

Hydrodynamics of 3-phase inverse fluidized bed is studied experimentally using low density particles for different liquid and gas velocities. The hydrodynamic characteristics studied include pressure drop, minimum liquid and gas fluidization velocities and phase holdups. The minimum liquid fluidization velocity determined using the bed pressure gradient, decreases with increase in gas velocity. The axial profiles of phase holdups shows that the liquid holdup increases along the bed height, whereas the solid holdup decreases down the bed. However, the gas holdup is almost uniform in the bed.

关键词： Inverse fluidization Inverse fluidized bed Hydrodynamics Phase holdup Axial holdup