Eco-Materials Processing & Design VI

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Authors: Woo Teck Kwon, Seong Youl Bae
Abstract: The reutilization of waste plastics as a fuel in the cement kiln precalciner process was investigated. For uniform feeding into the fluidized bed calciner, waste plastics were prepared to form of pellet type by shredding, melting, pressing, cutting and screening. We examine the property of combustion for different pellet size using the Computational Fluid Dynamic analysis program to minimize a risk and to optimize condition of an actual proof plant. Based on the results from the computational fluid dynamic analysis, the waste plastic for the industrial scale experiment were used as 20mm, 50mm and 100mm in size. The experimental result of an actual proof plant showed comparatively good correlation with the computational fluid dynamic analysis.
399
Authors: Jung Whan Yoo, Jin Ho Jung, Hyung Tae Kim
Abstract: Utilizing coal waste byproducts formed during mine development or use is important in solving environmental problems and recycling of waste materials. In this study, specimens prepared by mixing coal waste of 10, 20, 30, 40, and 50 % into clay brick have been investigated in terms of water absorption and compressive strength according to coal waste amounts and calcination temperature. As coal waste content increased water absorption increased and compressive strength decreased. When up to 30% coal waste was mixed into clay at 1300 oC, specimens satisfied 1st-class brick of Korea Standard requirements (water absorption 10%>, compressive strength 210 kgf/cm2<).
403
Authors: Hoi Kwan Lee, Sheng Jian Hwang, Won Ho Kang
Abstract: For the application of environment conscious glass-fertilizer, K2O-CaO-P2O5 glasses were fabricated by melt-quenching process, and the dissolution properties of these glasses were investigated using pH meter and ICP analyzer. Additionally, the fertilizer effects on rice culture were evaluated. The pH values depended on the glass compositions, and the ICP analysis confirmed that the dissolution amount was inversely proportional to the change of the K2O/P2O5 ratio, which was a main factor in controlling chemical durability, and which could be controlled by mother glass composition. The results of their application to rice plants indicated that the growth and quantity were similar to those used in chemical fertilizer. Therefore, the phosphate glasses are expected to provide the slow-releasing nutrient fertilizers that are easy to produce, environmentally safe, and widely applicable.
407
Authors: Won Yong Kim, Jae Sung Park, Mok Soon Kim
Abstract: Mechanical properties of a nano-structured Al-8Fe-2Mo-2V-1Zr alloy produced by spray forming and subsequent hot-extrusion at 420°C were investigated in terms of tensile test as a function of temperature. Warm rolling was adapted as an additional process to expect further refinement in microstructure. Well-defined equiaxed grain structure and finely distributed dispersoids with nano-scale in particle size were observed in the spray formed and hot extruded sample (as-received sample). The average grain size and particle size were measured to 500 nm and 50 nm, respectively. While it was found that warm rolling gives rise to precipitate fine dispersoids less than 10 nm without influencing the grain size of matrix phase, in the temperature range of RT∼150°C, distinguishable changes in ultimate tensile strength were not found between the as-received and warm-rolled samples. At elevated temperatures ranging from 350 to 550°C, warm-rolled sample showed a higher value of elongation than as-received one although similar values of elongation were observed between two samples at temperatures lower than 350°C.
411
Authors: Si Joon Noh, Mok Soon Kim, D. Jung, Jeong Whan Han, Byung Don You
Abstract: Three layer clad brazing sheets composed of Al-7.5Si alloy (filler, thickness:10 ㎛ )/Al-1.2Mn-2Zn-(0.04-1.05)Si alloy (core, thickness:80 ㎛)/Al-7.5Si alloy (filler, thickness:10 ㎛), were produced by laboratory fabrication, through casting, hot rolling, cold rolling, intermediate annealing, and final cold rolling. The effects of Si content in the core(0.04-1.05wt.%) and reduction rate of the final cold rolling(10-45%) on microstructure and brazing behavior were investigated. The results revealed that the microstructure and brazeability of the brazing sheet are governed both by Si content in the core and by the reduction rate of the final cold rolling. The excellent brazeability was obtained when the core alloy has the Si content of/cold rolled to 0.04%/10-45%, 0.41%/20-45% and 0.64%/30-45%. In these cases, a coarse grain structure was developed in the core during the brazing process, which suppressed the penetration of melting filler into the core.
415
Authors: Ji Hui Kim, Kwon Yeong Lee, Gyung Guk Kim, Seon Jin Kim
Abstract: Al alloys containing boron or its compound are attractive for neutron shielding materials since boron exhibits high thermal neutron absorbing capability. However, poor fracture toughness and low ductility of boron compounds restrict their usage as structural materials. By adding Ti as a third element, it is expected to improve the toughness of Al-B alloys. The present study investigates the effect of the Ti addition on fracture toughness of the (Al+Xat%Ti)2at%B (X = 0.5, 1, 1.5 at%) alloy fabricated by high energy ball milling and spark plasma sintering (SPS). The SPS method was used to consolidate (Al+Xat%Ti)2at%B (X = 0.5, 1, 1.5 at%) alloy with the pressure of 50 MPa. Charpy impact tests showed that the fracture toughness of the 1 at%Ti added-alloy was 4 MPam1/2 , and that it was three times higher than that of Al-B alloys. Further reduction of the Ti addition down to 0.5 at% at 1.9 MPam1/2 or up to 1.5 at% at 2 MPam1/2 slightly decreased the fracture toughness. The microstructures of the present specimens were investigated by FE-SEM and TEM to describe the relationship with fracture toughness.
420
Authors: Jeong Min Kim, Bong Koo Park, Joong Hwan Jun, Ki Tae Kim, Woon Jae Jung
Abstract: Various amounts of Ca were added to AZ91D magnesium alloy, and their effects on the die-casting abilities were investigated. It was observed that fluidity as die filling ability tends to decrease by Ca additions except for about 2%Ca. This reduction of fluidity by Ca was more significant at high superheats probably due to the high affinity between Ca and oxygen. Contrary to expectation, hot cracking resistance was found to increase by Ca additions. High Ca alloys showed some die-sticking tendency. However, the tendency was not observed below 2%Ca.
424
Authors: H.C. Kim, Je Hyun Lee, Y.G. Heon, Chang Yong Jo, Jae Won Kim, Sung Gab Kim
Abstract: Al addition is known to enhance corrosion resistance and high temperature properties in ferritic and austenitic stainless steels. Due to the addition of Al, formation and characteristic of nitride were studied in Al added 18Cr stainless steels. The phase diagram and segregation were estimated with addition of Al in 18Cr stainless steels by the Thermo-calc program. Formation behavior of the AlN phase was studied by observing the solid/liquid interface through directional solidification and the phase characterization was performed by XRD in the extracted precipitates from the matrix. It was confirmed that the AlN phase formed at the cell boundary from the liquid in 3 and 5 wt.% Al added 18Cr stainless steels.
428
Authors: Hoon Huh, Ji Won Rhim, Ji Soon Park, Sang Yong Nam
Abstract: Utilization of membrane offers the promise of huge energy savings if successfully applied to petroleum separations. Membranes are bound to enter into refining petroleum operations involving liquid separations once appropriate materials and modules are developed. Hybrid processes such as utilizing membrane modules to azeotropes formed during distillation are particularly attractive because they can offer less process complexity and reduced capital investment. A pervaporation performance was studied using pervaporation through the polymer blendmembranes for the separation of benzene and cyclohexane mixtures to investigate the relationship between pervaporation performance and polymer blend design. Solubility parameter calculation and thermodynamic calculation were used to predict the pervaporation performance for the benzene and cyclohexane mixture system using polymeric blend membrane composed of NBR, PVC and polar copolymers with various solubility parameters. The solubility parameter of the polymer blend membranes were controlled with different blend ratio. Screening of the membranes was accomplished by simple swelling experiments. Selectivity for the polar component increased with increasing NBR and PVC contents. Solubility parameter from polar and hydrogen bonding properties and activity calculated from thermodynamic model predicted the trend of swelling characteristics and pervaporation performance. Solubility parameter and thermodynamic calculation provide an a priori methodology for seeking the best blend formulations.
432
Authors: Dong Sik Bae, Eun Jung Kim, Sang Whan Park, Kyong Sop Han
Abstract: Nanosized ZnxMn1-xFe2O4 powders were prepared in ethylene glycol solution under mild temperature and pressure conditions by precipitation from metal nitrates. The average size and distribution of the synthesized ZnxMn1-xFe2O4 powders were 10- 20 ㎚ and narrow, respectively. The magnetic property of the synthesized ZnxMn1- xFe2O4 powder was of superparamagnetic character at room temperature.
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