bluuebunny/crossref_metadata_2025 huggingface dataset:
Worker, peasant, soldier … middle class? Class figures in Jia Zhangke’s 24 City
Authors: hultz Corey Kai Nelson
Published: August 2015

This article analyses the Maoist-class figures in Jia Zhangke’s 24 City (2008) and compares them with those found in Maoist-era visual culture. It examines how the films record the destruction and redevelopment of the social order, and the ways that the Maoist figures in the film have been made wretched or have disappeared. It argues, however, that the echo of their importance still remains, since the middleclass figures that appear in the film fuse previous Maoist elements with the contemporary success of economic reforms. They thus serve as a symbolic solution that combines the Maoist past with the Reform era present, therefore evoking the past to serve the present and the anticipated future.
TRAYECTORIA Y RESULTADOS DEL PROYECTO RISU EN EL CONTEXTO DE ARIUSA
Authors: Sáenz Orlando
Published: August 2015

Este artículo comienza por reseñar los esfuerzos que se realizaron durante los últimos años en algunas de las redes de la Alianza de Redes Iberoamericanas de Universidades por la Sustentabilidad y el Ambiente (ARIUSA) para definir un sistema de indicadores ambientales o de sostenibilidad en las instituciones de educación superior de América Latina y el Caribe. El proyecto más destacado ha sido la investigación colaborativa internacional adelantada por la Red de Indicadores de Sostenibilidad en las Universidades (RISU) con la participación de 65 universidades de 10 países de la región. En los apartados centrales de este artículo se presenta una reseña sobre la creación de la red RISU en el marco de ARIUSA, así como sobre el desarrollo y productos de su proyecto Definición de indicadores para la evaluación de las políticas de sustentabilidad en universidades latinoamericanas. Para complementar el primer reporte de resultados del proyecto RISU, se propone otra lectura de los datos básicos allí publicados, con base en una escala de medición de los niveles de compromiso ambiental alcanzados por las universidades y un reagrupamiento de los indicadores en solo cinco bloques o áreas de acción universitaria. Finalmente, se destacan las principales conclusiones sobre el proyecto de indicadores de sostenibilidad en las universidades latinoamericanas y se hacen algunas consideraciones sobre el estado actual y las futuras acciones de articulación entre RISU y ARIUSA.
ESTRATÉGIA PARA FIDELIZAÇÃO DO CLIENTE EM TURISMO: O CASO DE UMA OKTOBERFEST NO BRASIL
Authors: Moyano Carlos Alberto Mello , Lengler Jorge Francisco Bertinetti , Angnes Derli Luís , Sampaio Franco Vieira
Published: August 2015

A primeira edição da Oktoberfest de Santa Cruz do Sul/RS ocorreu no ano de 1984 e guarda as tradições dos imigrantes germânicos que se instalaram na Região Sul do Brasil. A festa chega a reunir 450 mil pessoas a cada ano, sendo a principal manifestação das tradições alemãs no Rio Grande do Sul. A importância do evento para a economia da região exige dos gestores uma procura permanente e um aprimoramento dos elementos para elevação da satisfação dos visitantes. Em virtude desta importância, o presente estudo tem como finalidade avaliar a satisfação dos visitantes da Oktoberfest de Santa Cruz do Sul, como instrumento para o desenvolvimento de estratégias de fidelização. O método utilizado apoiou-se na teoria do comportamento do consumidor e considera a adaptação do Escore Global de Satisfação do ASCI e do SCSB (FORNELL, 1992; FORNELL et al., 1996), assim como a aplicação da Matriz de Posição Competitiva (MELLO MOYANO, 1999) e das Estratégias de Fidelização (MELLO MOYANO; LENGLER, 2011). Os resultados sugerem que uma posição competitiva positiva com clientes leais representa menos gastos em estratégias mercadológicas para manutenção e fidelização dos clientes. Palavras-chave: Turismo. Comportamento do consumidor. Estratégia de marketing. Fidelização.
A SUSTENTABILIDADE E A CADEIA PRODUTIVA HOTELEIRA: UM ESTUDO DE CASO NO JW MARRIOTT, RIO DE JANEIRO
Authors: Dos Santos Rodrigo Amado , Matschuck Tamires Chagas
Published: August 2015

As fundamentações, os valores, os princípios e as condutas do desenvolvimento de uma prática turística mais sustentável se mostram como o objeto central da análise desse trabalho. Em específico, aqui os autores buscarão enfatizar de que forma propostas de sustentabilidade atreladas ao segmento turístico/hoteleiro devem assumir uma conotação estratégica, participativa e descentralizada que permita atender as necessidades atuais e futuras do trade turístico, de seus stakeholders, comunidades autóctones e turistas, sem deixar de lado as particularidades e as fragilidades a serem apreciadas e monitoradas nas relações de uso que serão constituídas junto às dimensões ambientais, sociais, econômicas, políticas, culturais e espaciais que sustentarão sua cadeia produtiva. Assim, reconhecendo a capacidade de intervenção temporal e territorial, positiva e/ou negativa, que os empreendimentos hoteleiros perpetram e difundem entre tais personagens e dimensões, o presente trabalho apresentará um estudo de caso pautado por pressupostos qualitativos, realizado no Hotel JW Marriott Rio de Janeiro, expondo uma mensuração, por meio da planilha SWOT, de suas práticas, condutas, valores e programas atrelados à sustentabilidade. Desse modo, por meio de entrevistas semiestruturadas e análises in loco, os autores identificaram ações que vão além dos preceitos do Triple Bottom Line e que acabam por legitimar o hotel como uma empresa sustentável. Palavras-chave: Desenvolvimento Sustentável. Hotel JW Marriott Rio de Janeiro. Gestão Hoteleira.
Effect of SDBS on the drag reduction characteristics of polyacrylamide in a rotating disk apparatus
Authors: Bari Hayder A. Abdul , Yousif Zainab , Yaacob Zulkefli Bin , Oluwasogaakindoyo Edward
Published: August 2015

This paper focuses on the determination of the interaction between polymer (Polyacrylamide (PAM)) and surfactant (Sodium dod benzene sulfonate (SDBS)) as a drag reducer using Rotating Disk apparatus (RDA) at various concentrations (500, 700, 1000, 1500 and 2000) ppm individually and in the combined form under turbulent conditions at different rotation speed up to 3000 rpm, as well as studying their mechanisms as a drag reducer. The results show that the maximum percent drag reduction increases to (40, 41, 43, 45 and 48)% by using the combined additives of surfactant and polymer at the above concentrations respectively, with slower degradation and display drag reduction for a larger range of Reynolds numbers. The nano and micro particles formed from the combined PAA and SDBSA was studied using cryo-transmission electron microscopy (cryo-TEM) techniques. The images show the surrounding of polymer chain to the surfactant micelle to form an aggregate structure. A hexagonal crystalline form was suggested to describe the shape of the aggregate structure.
Opinions of students participating in the pedagogical formation certificate program with regard to the profession and the program
Authors: Önder Emine , Tagay Özlem
Published: August 2015

In this research, the aim is to determine opinions of students participating in the pedagogical formation certificate program with regard to the teaching profession and the formation program. Study group of the research consists of 136 students who receive teaching formation education in the Faculty of Educational Sciences in Mehmet Akif Ersoy University as of fall term in the academic year of 2014-2015. In the research as a qualitative study, the phenomenological pattern is used. The data used in the study was collected by means of a question form developed by researchers and consisting of three parts. Research data was analyzed using the frequency analysis and the content analysis techniques. As a result of analyses, it was concluded that most of the participants considered teaching profession as a suitable profession for their personalities, and they thought that formation training was necessary for teaching profession and formation program brought teachers in the knowledge, skills and attitudes required for the teaching profession. In addition, it was also observed that the participants inserted their criticism of process and content of the program and gave different suggestions towards improving the quality of the program. 
Recovery Of Electrodic Powder From Spent Nickel-Metal Hydride Batteries (NiMH)
Authors: Shin S.M. , Shin D.J. , Jung G.J. , Kim Y.H. , Wang J.P.
Published: August 2015

This study was focused on recycling process newly proposed to recover electrodic powder enriched in nickel (Ni) and rare earth elements (La and Ce) from spent nickel-metal hydride batteries (NiMH). In addition, this new process was designed to prevent explosion of batteries during thermal treatment under inert atmosphere. Spent nickel metal hydride batteries were heated over range of 300°C to 600°C for 2 hours and each component was completely separated inside reactor after experiment. Electrodic powder was successfully recovered from bulk components containing several pieces of metals through sieving operation. The electrodic powder obtained was examined by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) and image of the powder was taken by scanning electron microscopy (SEM). It was finally found that nickel and rare earth elements were mainly recovered to about 45 wt.% and 12 wt.% in electrodic powder, respectively.
Manufacturing And High Temperature Oxidation Properties Of Electro-Sprayed Fe-24.5% Cr-5%Al Powder Porous Metal
Authors: Lee Kee-Ahn , Oh Jae-Sung , Kong Young-Min , Kim Byoung-Kee
Published: August 2015

Fe-Cr-Al based Powder porous metals were manufactured using a new electro-spray process, and the microstructures and high-temperature oxidation properties were examined. The porous materials were obtained at different sintering temperatures (1350°C, 1400°C, 1450°C, and 1500°)C and with different pore sizes (500 μm, 450 μm, and 200 μm). High-temperature oxidation experiments (TGA, Thermal Gravimetry Analysis) were conducted for 24 hours at 1000°C in a 79% N2+ 21% O2, 100 mL/min. atmosphere. The Fe-Cr-Al powder porous metals manufactured through the electro-spray process showed more-excellent oxidation resistance as sintering temperature and pore size increased. In addition, the fact that the densities and surface areas of the abovementioned powder porous metals had the largest effects on the metal’s oxidation properties could be identified.
Atomistic Analysis Of Radiation-Induced Segregation In Ion-Irradiated Stainless Steel 316
Authors: Lee G.-G. , Jin H.-H. , Chang K. , Lee B.H. , Kwon J.
Published: August 2015

Stainless steel (SS) is a well-known material for the internal parts of nuclear power plants. It is known that these alloys exhibit radiation-induced segregation (RIS) at point defect sinks at moderate temperature, while in service. The RIS behavior of SS can be a potential problem by increasing the susceptibility to irradiation-assisted stress corrosion cracking. In this work, the RIS behavior of solute atoms at sinks in SS 316 irradiated with Fe4+ ions were characterized by atom probe tomography (APT). There were torus-shaped defects along with a depletion of Cr and enrichment of Ni and Si. These clusters are believed to be dislocation loops resulting from irradiation. The segregation of solutes was also observed for various defect shapes. These observations are consistent with other APT results from the literature. The composition of the clusters was analyzed quantitatively almost at the atomic scale. Despite the limitations of the experiments, the APT analysis was well suited for discovering the structure of irradiation defects and performing a quantitative analysis of RIS in irradiated specimens.
Self-Consolidation Mechanism Of Porous Ti-6Al-4V Implant Prototypes Produced By Electro-Discharge-Sintering Of Spherical Ti-6Al-4V Powders
Authors: Lee W.H. , Jo Y.J. , Kim Y.H. , Jo Y.H. , Seong J.G. , Van Tyne C.J. , Chang S.Y.
Published: August 2015

Electro-Discharge-Sintering (EDS) was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 – 150 μm), that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in less than 86 – 155 μsec. It is known that EDS can simultaneously produce the pinch pressure to squeeze and deform powder particles and the heat to weld them together. The formation of a solid core in these prototypes depends on the amounts of both the pinch pressure and heat generated during a discharge. The size of the solid core and the thickness of the porous layer can be successfully controlled by manipulating the discharge conditions such as input energy and capacitance.
Synthesis And Electrochemical Characteristics Of Mechanically Alloyed Anode Materials SnS2 For Li/SnS2 Cells
Authors: Hong J.H. , Liu X.J. , Park D.K. , Kim K.W. , Ahn H.J. , Ahn I.S.
Published: August 2015

With the increasing demand for efficient and economic energy storage, tin disulfide (SnS2), as one of the most attractive anode candidates for the next generation high-energy rechargeable Li-ion battery, have been paid more and more attention because of its high theoretical energy density and cost effectiveness. In this study, a new, simple and effective process, mechanical alloying (MA), has been developed for preparing fine anode material tin disulfides, in which ammonium chloride (AC), referred to as process control agents (PCAs), were used to prevent excessive cold-welding and accelerate the synthesis rates to some extent. Meanwhile, in order to decrease the mean size of SnS2 powder particles and improve the contact areas between the active materials, wet milling process was also conducted with normal hexane (NH) as a solvent PCA. The prepared powders were both characterized by X-ray diffraction, Field emission-scanning electron microscopeand particle size analyzer. Finally, electrochemical measurements for Li/SnS2 cells were takenat room temperature, using a two-electrode cell assembled in an argon-filled glove box and the electrolyte of 1M LiPF6 in a mixture of ethylene carbonate(EC)/dimethylcarbonate (DMC)/ethylene methyl carbonate (EMC) (volume ratio of 1:1:1).
Joining Of Green Body And Dense Substrate For Indium Tin Oxide Under Uniaxial Pressure In An Open Condition
Authors: Moon G.-S. , Chung T.-J. , Yang S.-H. , Hong G.-S. , Oh K.-S.
Published: August 2015

The green body and dense substrate of indium tin oxide was joined by uniaxially pressing at 0.3 MPa at 1300°C to test the restoring of the eroded part of transparent conducting oxide target. The green body was sintered to 98% of theoretical density under the suppression of shrinkage along the boundary below 5%. The boundary between two parts was free of pore but could be recognized from the difference in grain sizes. The joined part had the virtually same density with the substrate, but the grain size was less than one fifth compared with that of substrate.
Co Oxidation Properties Of Selective Dissoluted Metallic Glass Composites
Authors: Kim S.-Y. , Lee M.-H. , Kim T.-S. , Kim B.-S.
Published: August 2015

Porous metallic materials have been widely used in many fields including aerospace, atomic energy, electro chemistry and environmental protection. Their unique structures make them very useful as lightweight structural materials, fluid filters, porous electrodes and catalyst supports. In this study, we fabricated Ni-based porous metallic glasses having uniformly dispersed micro meter pores by the sequential processes of ball-milling and chemical dissolution method. We investigated the application of our porous metal supported for Pt catalyst. The oxidation test was performed in an atmosphere of 1% CO and 3% O2. Microstructure observation was performed by using a scanning electron microscope. Oxidation properties and BET (Brunauer, Emmett, and Teller) were analyzed to understand porous structure developments. The results indicated that CO Oxidation reaction was dependent on the specific surface area.
Effect Of Different Mechanical Milling Processes On Morphology And Microstructural Changes Of Nano And Micron Al-Powders
Authors: Kim H.-S. , Madavali B. , Eom T.-J. , Kim C.-M. , Koo J.-M. , Lee T.-H. , Hong S.-J.
Published: August 2015

In this research, effect of the various mechanical milling process on morphology and microstructural changes of nano and micron Al-powders was studied. The milling of Al-powders was performed by both high energy and low energy ball milling process. The influence of milling (pulverizing) energy on the structural changes of Al-powders was studied. Al-nanoparticles were agglomerated during the MA and its size was increased with increasing milling while micron Al-powder gets flattened shape during high energy ball milling due to severe plastic deformation. Meanwhile, structural evolution during high energy ball milling of the nano powder occurred faster than that of the micron powder. A slight shift in the position of X-ray diffraction peaks was observed in nano Al-powders but it was un-altered in macro Al-powders. The variation in lattice parameters was observed only for nano Al powders during the high energy ball milling due to lattice distortion.
Improved Photovoltaic Properties Of Dye-Sensitized Solar Cells Using Laser Patterned F-Doped SnO2 Thin Films
Authors: An Ha-Rim , An Hyelan , Riu Doh-Hyung , Ahn Hyo-Jin
Published: August 2015

We modified the surfaces of F-doped SnO2 thin films using laser patterning to improve the photovoltaic properties of dye-sensitized solar cells. To do so, we varied the laser power density and the distance between laser-patterned lines. First, we investigated three power densities. Higher densities led to higher sheet resistances owing to increases in surface roughnesses. The lowest power density increased surface roughness without electrical degradation. Next, we explored three line spacings at a fixed power density. The films with the narrowest spacing exhibited the highest power conversion efficiency (~7.00%), the highest short-circuit photocurrent density (16.28 mA/cm2), and a good fill factor (58.82%).
Study On The Separation And Extraction Of Rare-Earth Elements From The Phosphor Recovered From End Of Life Fluorescent Lamps
Authors: Shin D.-W. , Kim J.G.
Published: August 2015

In this study, recovered phosphor from end of life three-wavelength fluorescent lamp was selected for reuse rare earth elements in the phosphor. The effect of a type of acid, concentration, and time was investigated as solubility of rare earth elements. In addition, precipitate heat-treated was investigated as possibility of reusable phosphor. The results showed that the amount of the rare earth elements was different values depending on the type of acid, and it was investigated with concentration of acid and reaction time. After precipitation reaction, the precipitate was sintered in electric furnace in order to reuse rare earth elements as phosphor. It was confirmed that yttrium, europium, oxygen, and carbon through X-ray diffraction and inductively coupled plasma analysis. Following the results, it can assume that rare earth oxide reuse the phosphor as three-wavelength fluorescent lamp.
Oxide Formation In Metal Injection Molding Of 316L Stainless Steel
Authors: Jang Jin Man , Lee Wonsik , Ko Se-Hyun , Han Chulwoong , Choi Hanshin
Published: August 2015

The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.
High Temperature Deformation Flow Of A ZK60A Magnesium Alloy After Extrusion
Authors: Kawasaki M. , Lee H.-J. , Oh M.C. , Ahn B.
Published: August 2015

Flow behavior of a ZK60A magnesium alloy after continuous casting and subsequent extrusion was examined in tension at a range of strain rates of 3.0×10−6− 1.0×10−2s−1at temperatures of 473-623K. The results demonstrated that the alloy exhibited a maximum elongation of ~250% at 523K when tested at an initial strain rate of 1.0×10−5s−1and strain rate sensitivity,m, of ~0.3-0.4 and the activation energy of ~94 kJ/mol were calculated under the testing conditions. The detailed investigation suggested that the high temperature flow of the ZK60A alloy having submicrometer grains demonstrates quasi-superplastic flow behavior controlled by a dislocation viscous glide process.
Microstructural Characterization Of Laser Heat Treated AISI 4140 Steel With Improved Fatigue Behavior
Authors: Oh M.C. , Yeom H. , Jeon Y. , Ahn B.
Published: August 2015

The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.
Effect Of Hot Pressing On The Electrochemical Properties Of Ti-Ni Alloy
Authors: Balcerzak M. , Jurczyk M.
Published: August 2015

Ti2Ni alloy pellets were produced by mechanical alloying and hot pressing at 750°C for 0.5 h in vacuum. X-ray diffraction analysis showed that, after 8 h of milling, a starting mixture of elements mostly decomposed into an amorphous phase. Obtained powders and flakes have cleavage fracture morphology with huge number of dimples with different sizes. Hot pressing of materials caused formation of Ti2Ni main phase. Porosity of pellets strongly depended on size of agglomerates and pressure of pressing. Ti2Ni pellets were used as negative electrodes for Ni-MHx batteries. Maximum measured discharge capacity of studied materials was 220 mAh/g. Electrochemical properties resulted from size of agglomerates, degree of oxidation and pressure of pressing.
Whisker Formation On Galvanic Tin Surface Layer
Authors: Radanyi A.L. , Sycheva A. , Gacsi Z.
Published: August 2015

The present work reports the effect of substrate composition, thickness of the tin electroplate and its morphology on pressure-induced tin whisker formation. Pure tin deposits of different thickness were obtained on a copper and brass substrates using methane sulfonic industrial bath. The deposits were compressed by a steel bearing ball forming imprint on the surface. The microstructure of tin whiskers obtained at the boundary of each imprint, their length and number were studied using both light and scanning electron microscopy. It was shown that the most intensive formation and growth of whiskers was observed in the first two hours. In general, brass substrate was shown to be more prone to whisker formation than copper independently of the tin coating thickness. The results have been compared with industrial bright tin finish on control unit socket leads and proposals have been made as to modification of the production process in order to minimize the risk of whiskering.
Effect Of SiC Particles On Sinterability Of Al-Zn-Mg-Cu P/M Alloy
Authors: Rudianto H. , Jang G.J. , Yang S.S. , Kim Y.J. , Dlouhy I.
Published: August 2015

Premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder was analyzed as matrix in this research. Gas atomized powder Al-9Si with 20% volume fraction of SiC particles was used as reinforcement and added into the alloy with varied concentration. Mix powders were compacted by dual action press with compaction pressure of 700 MPa. High volume fraction of SiC particles gave lower green density due to resistance of SiC particles to plastic deformation during compaction process and resulted voids between particles and this might reduce sinterability of this mix powder. Sintering was carried out under ultra high purity nitrogen gas from 565°-580°C for 1 hour. High content of premix Al-5.5Zn-2.5Mg-0.5Cu alloy powder gave better sintering density and reached up to 98% relative. Void between particles, oxide layer on aluminum powder and lower wettability between matrix and reinforcement particles lead to uncompleted liquid phase sintering, and resulted on lower sintering density and mechanical properties on powder with high content of SiC particles. Mix powder with wt90% of Alumix 431D and wt10% of Al-9Si-vf20SiC powder gave higher tensile strength compare to another mix powder for 270 MPa. From chemical compositions, sintering precipitates might form after sintering such as MgZn2, CuAl2 and Mg2Si. X-ray diffraction, DSC-TGA, and SEM were used to characterize these materials.
A Study Of The Die Roll Height Of SHP-1 And SCP-1 Materials In The Fine Blanking Process
Authors: Lee C.K. , Kim Y.C.
Published: August 2015

The height of the die roll, the distance of the V-ring, and the shear rate were varied with the aim of investigating the effects of the applied changes on the fine blanking line in a cold-rolled and a pickled steel sheet, referred to as SCP-1 and SHP-1, respectively. Both materials consisted primarily of a ferrite phase with small amounts of impurities including F, Mn, and Cr. The distance was found to be a very important factor in controlling the shear of the V-ring in the fine blanking process. When the position of the V-ring was set at distances of 1.5 mm and 2 mm, the die roll height increased with increasing shear speeds from 6.4 m/min to 10 and 16 m/min. Analysis of the influence of the shear rate revealed that low rates resulted in the lowest die roll heights since the flow of material was effectively inhibited.
The Determination Of Diffusive Tortuosity In Concrete Specimens Using X-Ray Microtomography
Authors: Ranachowski Z. , Jóźwiak-Niedźwiedzka D. , Ranachowski P. , Dąbrowski M. , Kudela S. , Dvorak T.
Published: August 2015

The paper presents a method of pore connectivity analysis applied to specimens of cement based composites differing in water to cement ratio. The method employed X-ray microtomography (micro-CT). Microtomography supplied digitized three-dimensional radiographs of small concrete specimens. The data derived from the radiographs were applied as an input into the application based on the algorithm called ‘random walk simulation’. As the result a parameter called diffusive tortuosity was established and compared with estimated porosity of examined specimens.
Effect Of DyMn Alloy-Powder Addition On Microstructure And Magnetic Properties Of NdFeB Sintered Magnets
Authors: Lee M.-W. , Dhakal D.R. , Kim T.H. , Lee S.R. , Kim H.J. , Jang T.S.
Published: August 2015

Micostructural change and corresponding effect on coercivity of a NdFeB sintered magnet mixed with small amount of DyMn powder was investigated. In the sintered magnet mixed with the DyMn alloy-powder Dy-rich shell was formed at outer layer of the main grains, while Mn was mostly concentrated at Nd-rich triple junction phase (TJP), lowering melting temperature of the Nd-rich phase that eventually improved the microstructural characteristics of the gain boundary phase. The coercivity of a magnet increased more than 3.5 kOe by the mixing of the DyMn alloy-powder.
Evolution Of Precipitate Morphology During Extrusion In Mg ZK60A Alloy
Authors: Park J. , Jung K.H. , Lee G.A. , Kawasaki M. , Ahn B.
Published: August 2015

In this study, a continuously casted ZK60A magnesium alloy (Mg-Zn-Zr) was extruded in two different extrusion ratios, 6:1 and 10:1. The evolution of precipitates was investigated on the two extruded materials and compared with that of as-casted material. The microstructural analysis was performed by electron backscatter diffraction and transmission electron microscopy, and the compositional information was obtained using energy-dispersive X-ray spectroscopy. Several distinct morphologies of precipitates were observed, such as dot, rod, and disk shaped. The formation mechanisms of those precipitates were discussed with respect to the heat and strain during the extrusion process.
De-Lubrication Behavior Of Novel EBS Based Admixed Lubricant In Aluminum P/M Alloy
Authors: Oh M.C. , Seok H. , Kim H.-J. , Ahn B.
Published: August 2015

The objective of the present research is to develop a novel lubricant for Al-Cu-Mg P/M alloy and to address the effects of the lubricant and compaction pressure on sintered properties. A lubricant mixture consisting of Ethylene Bis Stearamide, Zn-Stearate, and fatty acid was newly developed in this study, and the de-lubrication behavior was compared with that of other commercial lubricants, such as Ethylene Bis Stearamide, Zn-Stearate, and Al-Stearate. Density and transverse rupture strength of sintered materials with each lubricant were examined, respectively. The microstructural analysis was conducted using optical microscope.
Effect Of Ti Powder Addition On The Fabrication Of TiO2 Nanopowders
Authors: Raihanuzzaman R.M. , Park H.Y. , Ghomashchi R. , Kwon T.H. , Son H.-T. , Hong S.J.
Published: August 2015

Sintered samples of Ti added TiO2 nanopowders were fabricated by combined application of magnetic pulsed compaction (MPC) and sintering. The effect of Ti nano powder on density, shrinkage and hardness of the samples were investigated as part of the study. The optimum processing conditions were found to be around 0.5 GPa MPC pressure and 1450°C sintering temperature, illustrating maximum density, hardness and minimum shrinkage. High pressure compaction using MPC was found to enhance density with increasing MPC pressure up to 0.9 GPa, and significantly reduce the total shrinkage (about 16% in this case) in the sintered bulks compared to other general processes (about 18%). While sintered samples blended with micro Ti showed presence of microstructural cracks, the samples with 1-2% nano Ti had less or no cracks on them. Overall, the inclusion of nano Ti indicated improvement in mechanical properties of TiO2 nanopowders sintered preforms as opposed to micro Ti-added TiO2.
Effect Of Compaction Pressure And Sintering Temperature On The Liquid Phase Sintering Behavior Of Al-Cu-Zn Alloy
Authors: Lee S.H. , Ahn B.
Published: August 2015

The liquid phase sintering characteristics of Al-Cu-Zn alloy were investigated with respect to various powder metallurgy processing conditions. Powders of each alloying elements were blended to form Al-6Cu-5Zn composition and compacted with pressures of 200, 400, and 600 MPa. The sintering process was performed at various temperatures of 410, 560, and 615°C in N2 gas atmosphere. Density and micro-Vickers hardness measurements were conducted at different processing stages, and transverse rupture strength of sintered materials was examined for each condition, respectively. The microstructure was characterized using optical microscope and scanning electron microscopy. The effect of Zn addition on the liquid phase sintering behavior during P/M process of the Al-Cu-Zn alloy was also discussed in detail.
High Purity Tungsten Spherical Particle Preparation From WC-Co Spent Hard Scrap
Authors: Han Chulwoong , Na Hyunwoong , Choi Hanshin , Kim Yonghwan
Published: August 2015

Tungsten carbide-cobalt hard metal scrap was recycled to obtain high purity spherical tungsten powder by a combined hydrometallurgy and physical metallurgy pathway. Selective leaching of tungsten element from hard metal scrap occurs at solid / liquid interface and therefore enlargement of effective surface area is advantageous. Linear oxidation behavior of Tungsten carbide-cobalt and the oxidized scrap is friable to be pulverized by milling process. In this regard, isothermally oxidized Tungsten carbide-cobalt hard metal scrap was mechanically broken into particles and then tungsten trioxide particle was recovered by hydrometallurgical method. Recovered tungsten trioxide was reduced to tungsten particle in a hydrogen environment. After that, tungsten particle was melted and solidified to make a spherical one by RF (Ratio Frequency) thermal plasma process. Well spherical tungsten micro-particle was successfully obtained from spent scrap. In addition to the morphological change, thermal plasma process showed an advantage for the purification of feedstock particle.
An Experimental Study Of Aluminum Alloy Matrix Composite Reinforced SiC Made By Hot Pressing Method
Authors: Suśniak M. , Karwan-Baczewska J. , Dutkiewicz J. , Grande M. Actis , Rosso M.
Published: August 2015

The present work investigates the possibility of using powder metallurgy processing for producing a metal matrix composite. Materials were prepared from AlSi5Cu2 chips with reinforcement of 10, 15, 20 wt. % silicon carbide. Aluminum alloy chips were milled with SiC powder in a high-energy ball mill by 40 hours. Mechanical alloying process lead to obtain an uniform distribution of hard SiC particles in the metallic matrix and refine the grain size. The consolidation of composite powders was performed by vacuum hot pressing at 450°C, under pressure of 600 MPa by 10 min. The results shows that the addition of SiC particles has a substantial influence on the microstructure and mechanical properties of composite powder as well as consolidated material. Hot pressing is an effective consolidation method which leads to obtain dense AlSi5Cu2/SiC composite with homogeneous structure and advanced mechanical properties.
Preparation Of Fine Grained SiC At Reduced Temperature By Two-Step Sintering
Authors: Kim K.-W. , Oh K.-S. , Lee H. , Kim B.-S. , Chung T.-J.
Published: August 2015

Two-step sintering route was applied for the densification SiC by promoting the role of liquid phase. The specimen contained 8 vol% of liquid phase composed of Al2O3and Y2O3. The heating schedule consisted with initial rapid heating to 2000°C and immediate quenching to 1700 or 1750°C. By heating at elevated temperature, even distribution of the liquid phase was intended. The heat treatment at reduced temperature was to suppress the evaporative loss of the liquid and to secure the time for densification. The two-step sintering effectively suppressed loss of mass and coarsening. The resultant SiC was thus dense and was composed of fine grains exhibiting hardness of 2321 kgf/mm2.
A Study On The Fabrication Of Iron Powder From Forging Scale Using Hydrogen
Authors: Shin S.M. , Lee D.-W. , Yun J.-Y. , Kang CH.-Y. , Wang J.-P.
Published: August 2015

This study was conducted to investigate the effect of hydrogen content, temperature, reaction time for the reduction of forging scale which is mainly composed of hematite (Fe2O3). All reductive reactions were performed over the temperature range of 700 to 1200°C as well as 0.1 to 1 atm of hydrogen partial pressures. The results showed that the mechanism for the reduction of iron oxides using hydrogen gas was not a simple process, but proceeded in multiple reduction stages thermodynamically. The iron oxide was almost completely reduced to metallic iron powder with 91 wt.% of iron content in the forging scale at 0.1 atm of hydrogen partial pressure. The content of iron was however found to be increased with increasing hydrogen partial pressure from 0.1 to 1 atm with regardless of temperatures. The metallic iron powder was obtained with the mean size of 100 μm and more porous structure was observed.
Aluminum Nitride Formation From Aluminum Oxide/Phenol Resin Solid-Gel Mixture By Carbothermal Reduction Nitridation Method
Authors: Mylinh Dang Thy , Yoon Dae-Ho , Kim Chang-Yeoul
Published: August 2015

Hexagonal and cubic crystalline aluminum nitride (AlN) particles were successfully synthesized using phenol resin and alpha aluminum oxide (α-Al2O3) as precursors through new solid-gel mixture and carbothermal reduction nitridaton (CRN) process with molar ratio of C/Al2O3 = 3. The effect of reaction temperature on the decomposition of phenol resin and synthesis of hexagonal and cubic AlN were investigated and the reaction mechanism was also discussed. The results showed that α-Al2O3 powder in homogeneous solid-gel precursor was easily nitrided to yield AlN powder during the carbothermal reduction nitridation process. The reaction temperature needed for a complete conversion for the precursor was about 1700°C, which much lower than that when using α-Al2O3 and carbon black as starting materials. To our knowledge, phenol resin is the first time to be used for synthesizing AlN powder via carbothermal reduction and nitridation method, which would be an efficient, economical, cheap assistant reagent for large scale synthesis of AlN powder.
Thermodynamic Assessment Of The Bi-In-Zn System
Authors: Onderka B. , Dębski A. , Gąsior W.
Published: August 2015

A thermodynamic description of the entire ternary Bi-In-Zn system was obtained by the CALPHAD modelling of the Gibbs energy of the liquid phase. The experimental data on the phase equilibria and the thermodynamic properties published and complemented by the authors’ own experiments were taken into account. In order to verify the phase equilibria in the Bi-In-Zn system, 15 different samples were studied in the temperature range of 300-900 K by the DTA technique during heating and cooling cycles. Coexisting phases and their composition were analyzed by the SEM and EDX techniques for 9 distinct samples after their thermal equilibration at 373 K and 473 K.

Assessment and selected phase equilibrium calculations were performed with ThermoCalc and Pandat softwares, and compared with experimental data. The obtained results reproduce well the experimental data on both the phase equilibria and the thermodynamic properties in the optimized system.
Mathematical Models For Calculating The Value Of Dynamic Viscosity Of A Liquid
Authors: Ślęzak M.
Published: August 2015

The objective of this article is to review models for calculating the value of liquid dynamic viscosity. Issues of viscosity and rheological properties of liquid ferrous solutions are important from the perspective of modelling, along with the control of actual production processes related to the manufacturing of metals, including iron and steel. Conducted analysis within literature indicates that there are many theoretical considerations concerning the effect of viscosity of liquid metals solutions. The vast majority of models constitute a group of theoretical or semi-empirical equations, where thermodynamic parameters of solutions, or some parameters determined by experimental methods, are used for calculations of the dynamic viscosity coefficient.

This article presents equations belonging to four groups of models for calculating the value of the dynamic viscosity coefficient: rheological models, non-rheological models, non-rheological and rheological models for calculating viscosity of metals. The last group of equations is developed by own experiments – high temperature rheological liquid steel measurements.
Electrowinning Of Tellurium From Acidic Solutions
Authors: Kowalik R. , Kutyła D. , Mech K. , Tokarski T. , Żabiński P.
Published: August 2015

The process of electrochemical deposition of tellurium was studied. Preliminary researches embrace the voltammetry and microgravimetric measurements. According to the results the electrolysis of tellurium was conducted under potentiostatic conditions. There was no deposition of tellurium above potential −0.1 vs. Ag/AgCl electrode in 25°C. The process of deposition is observed in the range of potentials −0.1 to −0.3 V vs. Ag/AgCl. The presence of tellurium was confirmed by XRF and XRD. The obtained deposits were homogenous and compact. Below potential −0.3 V vs. Ag/AgCl the Faradaic efficiency of the tellurium deposition decreased due to reduction of Te to H2Te and hydrogen evolution.
Use Of Pulsed IR Thermography For Determination Of Size And Depth Of Subsurface Defect Taking Into Account The Shape Of Its Cross-Section Area
Authors: Wysocka-Fotek O. , Maj M. , Oliferuk W.
Published: August 2015

The paper is devoted to reconstruction of size and depth (distance from the tested surface) of artificial defects with square and rectangular cross-section areas using the pulsed IR thermography. Defects in form of flat-bottom holes were made in austenitic steel plate. The defect size was estimated on the basis of surface distribution of the time derivative of the temperature. In order to asses the depth of defects with considered geometries on the basis of calibration relations (i.e. dependence of time of contrast maximum vs. defect depth for given defect diameter) obtained for circular defects, the ‘equivalent diameter’ describing not only the defect cross-section area but also its shape was assigned. It has been shown that presented approach gives satisfactory results.
Pt-Rh Alloys: Investigation Of Tensile Strength And Elongation At High Temperatures
Authors: Trumić B. , Gomidželović L. , Marjanović S. , Krstić V. , Ivanović A. , Dimitrijević S.
Published: August 2015

In this paper are presented investigation results of tensile strength and elongation of selected alloys from Pt-Rh system. Samples with the content of rhodium in a concentration range of 7-40% (wt.) were studied. Studies were performed in the temperature range 1100-1500°C at a stress of 2-20 MPa. A universal device for measuring hardness was used to measure the Vickers hardness. For investigation of time strength and elongation at high temperatures, the device Mayes MK2 TC/10 was used. It was found that the value of tensile strength increases with increasing rhodium content, and decreases with increasing temperature. Elongation decreases to 7% Rh, then increases with increasing rhodium content to 15% and then slowly decreases again. With increasing temperature there is a slight increase in elongation.
Thermodynamics And Concentration Fluctuations Of Liquid Al-Cu And Al-Zn Alloys
Authors: Trybuła M. , Jakse N. , Gąsior W. , Pasturel A.
Published: August 2015

Thermodynamic properties of liquid Al-Cu and Al-Zn alloys are investigated using the free volume model. We also analyse local atomic arrangements and concentration fluctuations in both liquid binary alloys from the determination of the Warren-Cowley short-range order. For liquid Al-Cu alloys, our findings indicate a strong preference for heteroatomic nearest-neighbors bonds on the Cu-rich side and weaker ones in the Al-rich part while for the liquid Al-Zn alloy, a tendency to the phase separation is observed. Basing on Darken’s thermodynamic relationship, diffusivity has been examined for both liquid alloys.
Continuous Cooling Transformation (CCT) Diagrams Of Carbidic Nodular Cast Iron
Authors: Gumienny G. , Giętka T.
Published: August 2015

This work presents continuous cooling transformation diagrams for different kinds of carbidic nodular cast iron. We investigated the cast iron, chemical composition of which in nodular cast iron allows the obtainment of a metal matrix which consists of: pearlite, upper bainite and its mixture with lower bainite, ausferrite and martensite when the casts were cooled in the mold. The influence of the rate of cooling on the obtained microstructure and hardness of the casts was shown. The work describes the influence of the alloy additives on the curves of austenite decomposition in the carbidic nodular cast iron. Diagrams were plotted which enable an understanding of the kinetics of the transformations of austenite in carbidic nodular cast iron. The diagrams also indicate the possibility of obtaining pearlite, bainite, martensite and ausferrite with the established chemical composition and the wall thickness of the cast.
Exergo-Ecological Assessment Of Auxiliary Fuel Injection Into Blast-Furnace
Authors: Stanek W. , Szega M. , Blacha L. , Niesler M. , Gawron M.
Published: August 2015

Metallurgy represents complex technological chain supplied with different kinds of primary resources. Iron metallurgy based on blast-furnace process, dominates in world steel production. Metallurgical coke is the basic fuel in this case. Its production is connected with several environmental disadvantageous impacts. One of them is the extended production chain from primary energy to final energy. The reduction of coke consumption in the process can be achieved e.g. by injection of auxiliary fuels or increasing the thermal parameters in the process. In present injection of pulverised coal dominates while recirculation of top-gas seems to be future technology. However, the latter one requires the CO2 removal that additionally extended the production chain. The evaluation of resources management in complex energy-technological systems required application of advanced method based on thermodynamics. In the paper the system exergo-ecological assessment of pulverised coal injection into blast-furnace and top-gas recirculation has been applied. As a comparative criterion the thermo-ecological cost has been proposed.
Numerical And Experimental Study On Producing Aluminum Alloy 6061 Shafts By Cross Wedge Rolling Using A Universal Rolling Mill
Authors: Tofil A. , Tomczak J. , Bulzak T.
Published: August 2015

The paper presents a selection of numerical and theoretical results of the cross wedge rolling process for producing stepped shafts made of aluminum alloy 6061. The numerical modeling was performed using the FEM-based Simufact Forming simulation software. In the simulations, we examined the kinematics of metal flow and determined the distribution patterns of effective strains, temperatures, axial stresses and the Cockroft-Latham damage criterion. Variations in the rolling forces were determined, too. The numerical results were verified experimentally using a universal rolling mill designed and constructed by the present authors. This machine can be used to perform such processes as cross wedge rolling, longitudinal rolling and round bar cropping. During the experiments, we examined process stability and finished product geometry and recorded the torques. The experimental results confirm that axisymmetric aluminum alloy shafts can be produced by cross wedge rolling with two rolls. Last but not least, the experiments served to evaluate the technological potential of the rolling mill used.
Microstructure And Mechanical Properties Of An Al-Zn-Mg-Cu Alloy Produced By Gravity Casting Process
Authors: Saikawa S. , Aoshima G. , Ikeno S. , Morita K. , Sunayama N. , Komai K.
Published: August 2015

High-strength aluminum alloy are widely used for structural components in aerospace, transportation and racing car applications. The objective of this study is to enhance the strength of the Al-Zn-Mg-Cu alloy used for gravity casting process. All alloys cast into stepped-form sand mold (Sand-mold Casting; SC) and Y-block shaped metal mold(Permanent mold Casting; PC) C and then two –step aged at 398-423 K after solution treated at 743 K for 36 ks. The tensile strength and total elongation of the two-step aged SC alloys were 353-387 MPa and about 0.4% respectively. This low tensile properties of the SC alloys might be caused by remaining of undissolved crystallized phase such as Al2CuM, MgZn2 and Al-Fe-Cu system compounds. However, good tensile properties were obtained from PC alloys, tensile strength and 0.2% proof stress and elongation were 503-537 MPa, 474-519 MPa and 1.3-3.3%.

The reason of the good properties in PM alloys, is the lowed amount of undissolved crystallized phase than that of SC ones and primary crystallized alpha-Al phase was finer due to high cooling rate at solidification in casting.