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Journal of Rare Earths 2015年第6期33卷 639-646页

作者： N.k.Mohanty A.k.Behera S.k.Satpathy Banarji Behera P.Nayak Materials Research Laboratory School of Physics Sambalpur University

0.5BiDyxFe1-xO3-0.5PbTiOa（0.5BDxF1-x-0.5PT）（x=0.00, 0.05, 0.10, 0.15, 0.20） multiferroic composites were pre- pared by conventional solid state reaction method. Structural characterization was performed by X-ray diffraction and the mate- rials showed tetragonal structure at room temperature. Surface morphology of the composites was studied by a scanning electron microscope （SEM）. Frequency and temperature dependence of dielectric constant （er） and dielectric loss （tan~） of 0.5BDxF1_x- 0.5PT were measured in a wide range of frequency （100 Hz to 1 MHz） and temperature （25 to 400 ~C）. The analysis of the study showed that the er and tang decreased with increasing frequency in the given range for all the samples which could be explained through the occurrence of dipole relaxation process. The effect of substitution of rare earth element dysprosium （Dy） showed increase in er in all the samples prepared for different concentrations from 0.00 to 0.20. An explanation for high value of er for Dy modified 0.5BiFeO3-0.5PbTiO3 （0.5BF-0.5PT） compared to Gd modified 0.5BF-0.5PT was provided. The variation of AC conductivity with inverse temperature found to obey the Arrhenius equation and the composites showed negative temperature coefficient of resistance （NTCR） behavior. The activation energy was found to be in the range from 0.25 to 0.40 eV for all the studied samples.

关键词： X-ray diffraction dielectric constant tangent loss activation energy rare earths

Formation of microstructural features in hot-dip aluminized AISI 321 stainless steel

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International Journal of Minerals,Metallurgy and Materials 2018年第2期25卷 190-198页

作者： Prashant Huilgol k.Rajendra Udupa k.Udaya Bhat Department of Metallurgical & Materials Engineering National Institute of Technology Karnataka

Hot-dip aluminizing（HDA） is a proven surface coating technique for improving the oxidation and corrosion resistance of ferrous substrates. Although extensive studies on the HDA of plain carbon steels have been reported, studies on the HDA of stainless steels are limited. Because of the technological importance of stainless steels in high-temperature applications, studies of their microstructural development during HDA are needed. In the present investigation, the HDA of AISI 321 stainless steel was carried out in a pure Al bath. The microstructural features of the coating were studied using scanning electron microscopy and transmission electron microscopy. These studies revealed that the coating consists of two regions： an Al top coat and an aluminide layer at the interface between the steel and Al. The Al top coat was found to consist of intermetallic phases such as Al_7Cr and Al_3Fe dispersed in an Al matrix. Twinning was observed in both the Al_7Cr and the Al_3Fe phases. Furthermore, the aluminide layer comprised a mixture of nanocrystalline Fe_2Al_5, Al_7Cr, and Al. Details of the microstructural features are presented, and their formation mechanisms are discussed.

关键词： hot-dip aluminizing aluminide layer intermetallic phases microstructural features stainless steel

FINITE ELEMENT ANALYSIS OF A VERTICAL RECTANGULAR PLATE COUPLED WITH AN UNBOUNDED FLUID DOMAIN ON ONE SIDE USING A TRUNCATED FAR BOUNDARY

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Journal of Hydrodynamics 2009年第2期21卷 190-200页

作者： PANI P. k. BHATTACHARYYA S. k. Civil Engineering Department IGIT Sarang Orissa 759146 India Civil Engineering Department IIT Kharagpur 721302 India

The dynamic pressure distribution on a rectangular plate attached to a rigid wall and supporting an infinitely large extent of fluid subjected to a harmonic ground excitation is evaluated in the time domain. Governing equations for the fluid domain are set considering the compressibility of the fluid with negligibly small change in density and a linearized free surface. A far boundary condition for the three-dimensional fluid domain is developed so that the far boundary is truncated at a closer proximity to the structure. The coupled problem is solved independently for the structure and the fluid domain by transferring the acceleration of the plate to the fluid and pressure of the fluid to the plate in sequence. Helmholtz equation for the three-dimensional fluid domain and Mindlin＇s theory for the two-dimensional plate are used for the solution of the interacting domains. Finite element technique is adopted for the solution of this problem with pressure as nodal variable for the fluid domain and displacement for the plate. The time dependent equations are solved in each of the interacting domain using Newmark-fl method. The effectiveness of the technique is demonstrated and the influences of surface wave, exciting frequency and flexibility of the plate on dynamic pressure are investigated.

关键词： fluid-structure interaction compressible fluid linear surface wave truncation boundary dynamic pressure

Thermal and Oxygen Barrier Properties of Chitosan Bionanocomposites by Reinforcement of Calcium Carbonate Nanopowder

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Journal of Materials Science & Technology 2014年第8期30卷 791-795页

作者： Sarat k. Swain Satyabrata Dash Sudhir k. kisku Rajesh k. Singh Department of Chemistry Veer Surendra Sai University of TechnologyBurlaSambalpur 768018India Department of Chemistry North Orissa UniversityTakatpurBaripada 757003India

Chitosan and calcium carbonate nanopowder（chitosan/CaCO3） bionanocomposites were prepared by solution *** between chitosan and CaCO3 was studied by Fourier transform infrared spectroscopy（FTIR）.Structure and surface morphology of chitosan/CaCO3 bionanocomposites were investigated by X-ray diffraction（XRD） and field emission scanning electron microscopy（FESEM）,*** energy dispersive X-ray spectroscopy（EDS） of chitosan/CaCO3 bionanocomposites was studied in order to establish the elements of *** stability of prepared bionanocomposites was studied by thermogravimetric analysis（TGA） and a substantial increase of thermal stability of virgin chitosan was noticed due to incorporation of CaCO3 *** oxygen permeability was reduced by three times as compared to the raw chitosan due to the dispersion of nano CaCO3 *** and resistance towards dilute acid and alkali of the prepared bionanocomposite were *** bionanocomposite having gas barrier and thermal stable property may be suitable for packaging and biomedical applications.

关键词： Chitosan Nanocomposites Thermal properties Oxygen permeability

Direct joining of oxygen-free copper and carbon-fiber-reinforced plastic by friction lap joining

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Journal of Materials Science & Technology 2018年第1期34卷 192-197页

作者： L.H. Wu k. Nagatsuka k. Nakata Joining and Welding Research Institute Osaka University 11-1 Mihogaoka Ibaraki Osaka 567-0047 Japan

Oxygen-flee copper （Cu） was successfully joined to carbon-fiber-reinforced thermoplastic （CFRTP, polyamide 6 with 20wt% carbon fiber addition） by friction lap joining （FLJ） at joining speeds of 200-1600 mm/min with a constant rotation rate of 1500 rpm and a nominal plunge depth of 0.9 ram. It is the first time to report the joining of CFRTP to Cu by FLJ. As the joining speed increased, the tensile shear force （TSF） of joints increased first, and decreased thereafter. The maximum TSF could reach 2.3 kN （ 15 mm in width）. Hydrogen bonding formed between the amide group of CFRTP and the thin Cu20 layer on the Cu surface, which mainly contributed to the joint bonding. The influence factors of the TSF of the joints at different joining speeds were discussed. The TSF was mainly affected by the joining area, the degradation of the plastic matrix and the number and the size of bubbles. As the joining speed increased, the influence factors varied as follows： the joining area increased first and then decreased; the degra- dation of the plastic matrix and the number and the size of bubbles decreased. The maximum TSF was the comprehensive result of the relatively large joining area, small degradation of the plastic matrix and small number and sizes of bubbles.

关键词： Friction lap joining Metal Plastic Carbon-fiber reinforced thermoplastic Dissimilar materials joining

Performance behaviour of elliptical-bore journal bearings lubricated with solid granular particulates

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Particuology 2016年第4期14卷 51-60页

作者： Faisal Rahmani Jayanta k. Dutt Raj k. Pandey Department of Mechanical Engineering Indian Institute of Technology Delhi New Delhi 110016 India

Journal bearings operating in hot environments and at high temperatures experience accelerated degra- dation of lubricating oils. In such situations, dry granular particulates have emerged as potential media for providing lubrication in journal bearings in place of lubricating oils. Granular particulates do not degrade thermally, even at considerably high temperatures. This work explores the static and dynamic perfor- mance characteristics of elliptical-bore journal bearings lubricated with granular particulates. It is found that a bearing lubricated with a larger size （2 μm） particles offers better performance compared with that using smaller size （1μm） particles. Bore ellipticity reduces the load-carrying capacity and increases side leakage and the coefficient of friction; however, rotor stability is marginally improved at low eccentricity ratios （〈0.6）, followed by significant improvement at high eccentricity ratios （〉0.6）.

关键词： Particulate Journal bearing Grain size Rigid rotor stability Hydrodynamic lubrication

ELECTRICAL TRANSPORT PROPERTIES OF PRISTINE AND IODINE DOPED POLYETHERIMIDES

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Chinese Journal of Polymer Science 2011年第5期29卷 586-596页

作者： J.k.Quamara Randhir Singh B.k.kaushik Physics Department National Institute of TechnologyKurukshetra 136119India

Electrical conduction behavior of pristine and iodine doped polyetherimides （PEI） has been investigated under both transient and steady state conditions in the operating temperature range 50-200℃ at various electric fields of 12-60 kV/cm. The transient currents show the hyperbolic decay character, and the decay exponent p （a measure of current decay rate） decreases with temperature （T） and doping concentration. The origin of transient currents has been attributed to the dipolar nature of carbonyl （〉C：O） groups and the ether linkages present in the main chain of PEI. The low field steady state conduction is ohmic in nature. The magnitudes of ionic jump distance （a） values do not favor an ionic type of conduction as a possible conduction mechanism in pristine as well as iodine doped PEI. The Schottky coefficients estimations do not show the possibility of Schottky type or Poole-Frenkel type conduction mechanisms in the low temperature region （〈 120℃）, however, in the high temperature region （〉 120℃） there is a certain possibility of Poole- Frenkel type conduction mechanism in both pristine and iodine doped samples. The dual slope in the lg/versus 1/T curves for iodine doped samples indicates the presence of more than one type of trapping levels.

关键词： Transient currents Electrical conduction Polyetherimide.

Structural, electronic, and mechanical properties of cubic TiO_2:A first-principles study

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Chinese Physics B 2018年第1期27卷 492-500页

作者： Debashish Dash Chandan k Pandey Saurabh Chaudhury Susanta k Tripathy Department of Electrical Engineering National Institute of TechnologySilchar Assam Department of Electronics and Communication Engineering National Institute of TechnologySilchar Assam

We present an analysis of structural, electronic, and mechanical properties of cubic titanium dioxide （TiO2） using an all electron orthogonalzed linear combinations of atomic orbitals （OLCAO） basis set under the framework of density functional theory （DFT）. The structural property, especially the lattice constant a, and the electronic properties such as the band diagram and density of states （DOS） are studied and analyzed. The mechanical properties such as bulk moduli, shear moduli, Young＇s Moduli, and Poison＇s ratio are also investigated thoroughly. The calculations are carried out on shear moduli and anisotropy factor for cubic TiO2. The Vickers hardness is also tested for fluorite and pyrite cubic-structured TiO2. Furthermore, the results are compared with the previous theoretical and experimental results. It is found that DFT- based simulation produces results which are approximation to experimental results, whereas the calculated elastic constants are better than the previous theoretical and experimental values.

关键词： density functional theory cubic TiO2 structural electronic and mechanical properties

Large nonlinear deflection behavior of IPMC actuators analyzed with an electromechanical model

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Acta Mechanica Sinica 2019年第5期35卷 992-1000页

作者： H.G.Liu k.Bian k.Xiong Faculty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang 212013China State key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006China

This study presents an electromechanical engineering model for the analysis of the large deflection curves of ionic polymer-metal composite(IPMC)cantilever actuators under direct current(DC)*** this paper,the longitudinal normal strain performance of the material was investigated using digital image correlation on a *** deflection of the actuator is analytically obtained with the application of an elliptic integration method based on the relationship between strain gradient and excitation voltage,and the minimum excitation voltage is derived based on the assumption that the actuators have small *** validity of the electromechanical model is then justified with the experimental results obtained from Pt-and Ag-IPMC actuators at various excitation *** findings of this study confirm that the introduced electromechanical model can accurately describe the large nonlinear deflection behavior of IPMC actuators.

关键词： Actuator Ionic polymer metal composite Large deflection Electromechanical model

Preparation of sulfur hydrophobized plasmonic photocatalyst towards durable superhydrophobic coating material

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Journal of Materials Science & Technology 2020年第6期41卷 159-167页

作者： Emese Lantos LászlóMérai ágota Deák Juan Gómez-Pérez Dániel Sebo?k Imre Dékány Zoltán kónya LászlóJanovák University of Szeged Interdisciplinary Excellence CentreDepartment of Physical Chemistry and Materials ScienceH-6720Rerrich Béla tér 1SzegedHungary University of Szeged Interdisciplinary Excellence CentreDepartment of Applied and Environmental ChemistryH-6720Rerrich Béla tér 1SzegedHungary

The widely used photocatalytic self-cleaning coating materials are often made of polymers and polymer based composites,where the photocatalyst immobilization occurs with ***,these organic polymers are often unstable under exposure to UV irradiation and easily degraded by reactive radicals produced in the photocatalytic *** order to solve this problem,in this paper,we present the facile preparation of a multifunctional coating with dual superhydrophobic and photocatalytic properties,where the fixation and the hydrophobization of the plasmonic Ag-TiO2 photocatalyst particles with visible light activity was performed with non-water soluble sulfur,which is a cheap and easily available *** resulted novel nanocomposite with rough and nano-tructured surface roughness(1.25–2.45 nm determined by small-angle X-ray scattering)has sufficient low surface energy(3.3 mJ/m2)for superhydrophobic(θ=151.1°v)***,in contrast of the organic and expensive fluoropolymer based composites,this non-wetting nature was durable,because the measured was higher than 150°during the long-term LED(λmax=405 nm)light irradiation.

关键词： Nanocomposite Coating materials Wetting Lotus-type structure Visible light photocatalyst