Advanced Materials Research Vols. 1025-1026

Abstract: In this paper the change of electrical resistivity of the amorphous alloy Fe₈₀Ni₁₀Si₅B₅ during heat treatment is investigated. Parallel studies by magnetometry technique, X-ray diffraction and calorimetric analysis were used to interpret the nature of the changes in the structure and properties of the alloy during annealing. These features are related with magnetic nature of the alloy and crystallization at a higher temperature.

Abstract: Comparison study of oxidation behavior of low carbon steel was conducted at the temperature range of 500°C to 700°C under a 0.2 atm oxygen pressure by continuous and discontinuous oxidation methods. Oxidation rate of both cases was found to be increased with increasing temperature from 500°C to 700°C and obeyed parabolic rate law. In addition, activation energy for the continuous oxidation of steel was found to be a 164.8 kJ/mole, which means that oxidation rate is proportionally dependant on temperature. In case of cyclic oxidation, the oxidation rate was shown to faster than continuous oxidation at all temperatures due to direction oxidation through spallation of the oxide layer.

Abstract: Vanadium metal powder was successfully synthesized by combination reduction process with hydrogen gas and liquid magnesium. V₂O₅ as a raw material was first reduced by hydrogen gas to produce V₂O₃ at 873K for 3 hours and then it was reduced by liquid magnesium at 1,073K for 48 hours to become final vanadium powder. The microstructure and chemical composition of pure vanadium powder fabricated were examined by SEM(Scanning Electron Microscopy) and EDX(energy dispersive spectroscopy), respectively. The oxygen content of vanadium powder was finally found to be 0.5 wt.% showing the structure loosely agglomerated with fine particles of about 1~2μm.

Abstract: Three kinds of porous materials were synthesized using calcined kaolin with small molecular amine templates by hydrothermal methods. Sodium silicate was chose as silicon sources and three different amines namely acetamide, ethylenediamine and hexamethylenetetramine were chose as the organic templates. The physicochemical properties of obtained samples were characterized by X-ray diffraction, infrared spectrum and scanning electron microscopy.Crystallinity and morphology of samples were investigated. The influence of small molecular amines templates was discussed.

Abstract: Ni recycling from Fe-Ni alloy scrap was successfully performed by Mg reaction and distilling process. Ni component in Fe-Ni alloy scraps dissolve selectively in molten magnesium metal and then vacuum distilling was applied to remove Mg from Mg-Ni liquid. Above 1,073K in dissolving stage, more than 99% Ni from scraps was recovered and under the distilling process at 1,273K, 10^-5 torr, the high quality Ni with 99.5% could be obtained. This study suggests the recycling process of Ni in Fe-Ni scrap with the combination of Mg reaction and distilling process.

Abstract: ZnO nanoparticles synthesized by precipitation method using zinc nitrate tetrahydrate and sodium hydroxide as starting materials. ZnO nanoparticles synthesized exhibited a crystalline structure with hexagonal structure. The average primary size of ZnO synthesized around 22.71 nm and the specific surface area around 28.17 m²/g. EPDM foam used oxy-bis benzene sulfonylhydrazide (OBSH) as blowing agent and ZnO nanoparticles synthesized as activator of sulphur vulcanization. The effect of ZnO nanoparticles synthesized compared with conventional ZnO on cure characteristics and morphology of EPDM foam were investigated. The result showed that the maximum torque (M_H) increased, optimum cure time (t₉₀) and scorch time (T5) decreased with increasing ZnO nanoparticles synthesized loading. The cell structure of EPDM foam was spherulite and smaller when increased ZnO nanoparticles synthesized loading. The compressive load value increased with increasing ZnO nanoparticles synthesized loading which may be attributed to thickness of the cell wall and hardness increased. ZnO nanoparticles synthesized could be reduced successfully from 5 to 3 phr (40%) for EPDM foam.

Abstract: Natural indigo dye, Indigofera tinctoria, was applied on poly (lactic acid) (PLA) fabrics by exhaust dyeing in the presence of 5 g/L sodium dithionite and 0.2 g/L NaOH. Three dyeing parameters e.g. dyeing temperature, dyeing time and dye concentration were studied. When 5%owf indigo dye was applied on PLA, the maximum color strength was obtained at 80°C and 60 minutes. The color strength also increased as the dye concentration increased in the range of 4–20%owf. Applying natural indigo dye to PLA fabrics is more attractive than the commercial one due to better energy savings and the process being environmentally friendly.

Abstract: The most basic way to keep comfortable indoor environments for a building’s occupants and save energy for space heating and cooling in residential buildings is to insulate the building envelope. Among the building materials to be used, thermal insulation materials primarily influence thermal performance. In particular, the type, thermal conductivity, density, and thickness of heat insulator, are important factors influencing thermal insulation performance. We investigate the design status of residential buildings which were designed in accordance with the building code of Korea and selected the type of thermal insulation materials applied to the walls of buildings. The present study aims at measuring the thermal conductivity of thermal insulation materials used for building walls of residential buildings. In this study, after collecting the design documents of 129 residential buildings, we investigated the type and thickness of insulation materials on the exterior wall specified in the design documents. As the thermal insulation materials, extruded polystyrene (XPS) board and expanded polystyrene(EPS) board are used the most widely in Korea when designing residential buildings. The thickness of thermal insulation materials applied to the exterior wall was 70mm, most frequently applied to the design. We measured the thermal conductivity and the density of XPS board and EPS board. When the density of XPS and EPS was 30~35 kg/㎥, the thermal conductivity of XPS was 0.0292 W/mK and it of EPS was 0.0316 W/mK.

Abstract: Researches on development of technology to reduce CO₂ emission while satisfying physical properties during production of precast concrete, which is mainly applied to building structures, are necessary. Accordingly, a high early strength type mixture for which removal of precast concrete form can be done by curing at room temperature instead of steam curing in the production process of precast concrete was developed. The developed high early strength type mixture was mixed with concrete to conduct coagulation, slump, and compressive strength property tests. In addition, CO₂ emission and reduction performance of non-steam curing precast concrete were assessed.

Abstract: The aim of this research was to produce three-layer Medium Density Particleboard (MDP), with the addition of impregnated paper, in the inner layer, in proportions of 1; 5 and 20%. In this study, MDP was composed with particles of small size in outer layers, and larger particles in internal layer. After panel manufacturing, physical and mechanical tests based on Brazilian Code ABNT NBR 14.810 were carried out to determine moisture content; density; thickness swelling; water absorption; modulus of rupture (MOR) and modulus of elasticity (MOE) in static bending and internal adhesion. Test results were compared to commercial panels, produced with 100% Eucalyptus, considering the requirements specified by Brazilian Code. Properties presented values close to normative specifications, indicating positively the possibility of production of MDP using addition of waste paper impregnated.