Eco-Materials Processing and Design IX

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Authors: Young Seok Kim, Kyu Ho Lee, Tae Ho Kim, Young Joon Jung, S. H. Yim, Bong Ki Ryu
Abstract: The nucleation and crystallization kinetics of P2O5-B2O3-ZnO-BaO-Al2O3-TiO2 crystals in bulk glass in which this crystals were found to crystallize in the heating process of the glass, were studied by non-isothermal measurements using differential thermal analysis (DTA). A nucleation rate-temperature was determined by plotting either the reciprocal of the temperature corresponding to the crystallization peak maximum, 1/Tp, or the height of the crystallization peak, (*T)p, as a function of nucleation temperature, Tn. The temperature where nucleation can occur for this glass ranges from 700°C to 890°C and the temperature for maximum nucleation is 760±5°C. The correct activation energy for crystallization, Ec, for this glass is the same for surface and/or bulk crystallization, and is 533±15°CkJ/mol. The analysis of the crystallization data with the Kissinger equation and the Marotta equation yields the correct value for Ec only crystal growth occurs on a fixed number of nuclei. The crystallization process of a sample heat treated at the temperature of the maximum nucleation rate was fitted to kinetic equations with an Avrami constant, n ≈2 and a dimensionality of crystal growth, m ≈2.
Authors: Kyu Ho Lee, Young Seok Kim, Tae Ho Kim, Young Joon Jung, H. J. Chin, Bong Ki Ryu
Abstract: This paper presents results and observations obtained from a study of crystallization effect on optical property by doping Sm2O3 in amorphous material. The heat treatments, according to Differential Thermal Analyzer (DTA) results, have been performed in order to generate crystallization of amorphous material. The crystalline phase has been analyzed by X-Ray Diffractor (XRD). In this work, we have observed the emission intensity changes by increasing the concentration of Sm3+ ions up to 1.0mol%. As a result, we have confirmed the solubility of RE dopant in this composition glass by comparing the emission intensity at three strong emission bands [4G5/2-6H5/2 (564 nm), 4G5/2-6H7/2 (602 nm) and 4G5/2-6H9/2 (647 nm)]. Beside, the up-conversion of photoluminescence by the optimum crystalline size of host matrix has been shown by Fluorimeter data. In conclusion, we have estimated the effect of crystalline on optical property in amorphous matrix from this research.
Authors: Youn Gyu Han, Takafumi Kusunose, Tohru Sekino
Abstract: The polyaniline (PANI) coated titania (TiO2) has been prepared with ammonium persulfate (APS) as an oxidant in sodium dodecylsulfate(SDS) micellar aqueous solution. These nanosized powders could transfer into the organic phase. With increase in the amount of SDS, the dispersibility into the organic solvent was increased. Consequently, the electrical conductivity of the product was also decreased. The obtained composites showed 14.16 S/cm of conductivity at maximum while the value was almost independent on the polyaniline coating ratio in range of 100~20wt%. The conductivity value of composite with 20wt% polyaniline was 70000 times higher than that of raw titania. Modified titania had properties of polyaniline and titania together. In addition these composite showed the photoconductive response against the UV irradiation, which might show the existence of P-N junction between titania and polyaniline. The detailed structure and property analyses with X-ray, UV-spectroscopy, electron microscopy and so on will be discussed in relation to the synthetic conditions
Authors: Chan Joo Lee, Jung Min Lee, Byung Min Kim
Abstract: The deposition of thin hard coating onto tool steel is done to improve the surface properties such as wear, corrosion. The adhesion strength between substrate and coating is one of important parameters in practical applications since coating failure affects the lifetime of tool directly. Scratch test with acoustic emission(AE) technique was performed to evaluate the adhesion strength qualitative by observing the friction load vs. the normal load curves, the acoustic emission signal generated by the damage of coatings and the scratch track using an optical microscope. In this study, the effect of substrate hardness on the adhesion strength was investigated by evaluating critical load and work of adhesion and observing AE signal and failure mode in scratch track using optical microscope. Coatings were individually deposited on six substrates by means of physical or chemical vapor deposition(PVD, CVD) process and TD process. The critical load of the substrates with nitride layer is higher than without nitride. Although high load causes higher stresses which make flaking occur in the coating-substrate interface, the work of adhesion of harder substrates is also high. Because harder substrates have small contact area causing lower the plastic deformation around stylus.
Authors: Won Hyo Cha, Ji Eon Yoon, Dong Hyun Hwang, Chul Su Lee, In Seok Lee, Young Gook Son
Abstract: Lanthanum modified lead zirconate titanate (Pb1.1La0.08Zr0.65Ti0.35O3) thin films were fabricated on indium-doped tin oxide (ITO)-coated glass substrate by r.f magnetron sputtering method. The thin films were deposited at 500°C and annealed at various temperature (550~600°C) by rapid thermal processing. The structure and morphology of the films were characterized with X-ray diffraction and atomic force microscopy. The hysteresis loops and fatigue properties of thin films were measured by precision material analyzer. As the annealing temperature increased, the remnant polarization value increased from 10.58 DC/cm2 to 31.35 DC/cm2, coercive field was reduced from 79.906 kV/cm to 60.937 kV/cm. For the switching polarization endurance analysis, the remnant polarization of PLZT thin films annealed at 700°C was decreased 15% after 109 switching cycles using 1MHz square wave form at 5V.
Authors: Gwon Seung Yang, Jong Kook Lee, Woo Yang Jang
Abstract: A small amount of misch metal was added to CuZnAl alloy in order to study the effect of grain refinement and mechanical properties, phase transformation behavior and stabilization of martensite. It was found that the addition of misch metal was very effective for reducing the grain size. The coarse grains over 1000 μm have been refined to the size of 30 μm by the addition of 0.43wt% misch metal. The grain size of thermo-mechanically treated alloys was barely affected by cold working. The fracture strength and ductility have been significantly increased with the increase of misch metal content when tensile test is carried out below Mf temperature. Also, the fracture strength has been more increased in the case of post-quench ageing treatment than the direct quench ageing treatment. The fracture mode has been changed from transgranular brittle fracture to ductile fracture with void formation and coalescence by the addition of misch metal.
Authors: N. R. Ha, Z. X. Yang, Kyu Hong Hwang, J. K. Lee
Abstract: Pure Titanium alloys are superiorities of biocompatibility, mechanical properties and chemical stability. The biocompatibility of Ti alloy is related to the surface effect. In this study, Ti Alloys were treated by alkali and acid activation process. And through the sol coating layer, biocompatibility were investigated. Consequently, it appeared that the porous layer was generated on the surface of alloy by surface treatment and sol coating process. It was found that with surface treatment on Ti alloy, the formation speed of porous was much quicker compared with those ones without treatment. Therefore, the biocompatibility was improved.
Authors: Jung Rak Lee, Dong Yeop Lee, Do Geun Kim, Gun Hwan Lee, Pung Keun Song
Abstract: The electrical, optical and mechanical properties were investigated for the In-Sn-Zn-O films deposited using ITO and ZnO targets, without substrate heating. Three types of ITO target, which are 90wt.% In2O3 : 10wt.% SnO2, 93wt.% In2O3 : 7wt.% SnO2, and 95wt.% In2O3 : 5wt.% SnO2, were used. The power of DC cathode equipped ITO target was fixed at 70W and the power of RF cathode equipped ZnO target was changed from 20W to 60W. The lowest resistivity (2.95x10-4 2cm) was obtained for the In-Sn-Zn-O films deposited under DC power of 70W of ITO (93wt.% In2O3 : SnO2 7wt.%) and RF power of 40W of ZnO target. It is confirmed that surface uniformity, electrical property, and mechanical durability were improved by introduction of Zn atom for all the ITO targets.
Authors: Dong Yeop Lee, Jung Rak Lee, Do Geun Kim, Gun Hwan Lee, Young Seok Kim, Pung Keun Song
Abstract: Ga-doped ZnO films were deposited on polyethylene terephthalate (PET) substrate by dc magnetron sputtering using a high density GZO target (doped with 6.65 wt% Ga2O3) without substrate heating. We investigated electrical, structural, and mechanical properties of GZO films deposited under various total gas pressures (Ptot). GZO films deposited at Ptot of 2.0 Pa showed the lowest resistivity (2.91 x 10-2 7cm), which could be attributed to higher crystallinity of the film. Also, this GZO film showed the lowest change in resistance (8 R/R0 = 0.3) for the dynamic bending test.
Authors: Ke Zheng Sang, Chun Feng Wan
Abstract: SiC/Al composites with high volume fraction of SiC were prepared at 1150°C by pressureless infiltration. The volume fraction of SiC was increased by decreasing the amount of starch in the green body. Both the microstructure and the strength of the composites were investigated. The results showed that the strength decreased with the increasing of the particle size and volume fraction of SiC. It was suggested that the interface between the SiC particles, which were not sintered, make of the defects in the composites. The defects led to the decreasing of the strength with increasing of the volume fraction of SiC.

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