It is very difficult to detect irradiated South Sea cultured pearls (SSCPs) at a low dose by gemological methods (e.g. optical transmission method, microscopic examination, UV fluorescence reaction, and so on). In this study, however, it was possible to distinguish between irradiated SSCPs from un-irradiated SSCPs by ESR analysis. We have analyzed the pearl nacre and nucleus by separating them for the purposed of providing information about the change of CO2− radical as growing absorbed doses. And it was found out that the signal of CO2− radical of the nacre is more distinct than the nucleus.
Amethyst gems represents thermal effects of far-infrared emission, promotes the body’s metabolism, and attracts attention as an eco-friendly interior material. In this paper, amethyst increase the value of jeweling by applying the characteristic purple motif, furthermore, I will intend to develop of design model. Metal crafting of brooch & necklace in the works performed based on the organic three-dimensional shape of the Rhino CAD Data. It was made possible through the precise laminated wax processing and then combining the amethyst. I researched the ornament modeling by applying the ‘Golden Ratio’, and suggesting utilizing method for interior jewel modeling, and also, is expected that this paper on the amethyst modeling design can contribute to the manufacturers’ productivity
The grain growth is very important because of its great influence on the various materials properties. Therefore,in this study, the effects of anisotropic grain boundary energy on grain growth in 2-D have been investigated with a large scale phase field simulation model on PC. A 2000 × 2000 grid system and the initial number of grains of about 73,000were used in the computer simulation. The anisotropic ratio of grain boundary energy, σmax/σmin, has been varied from 1 to 3. As the anisotropy increased, the grain growth exponent, n, increased from 2.05 to 2.37. The grain size distribution showed a central plateau in the isotropic case, and was changed into no central plateau and the increasing population of very small grains in the anisotropic case, resulting from slowly disappearing grains. Finally, simulated microstructures were compared according to anisotropy.
Surface treatments and their effects on high temperature properties for the Hastelloy X, which is a promising candidate alloy for high temperature heat-transport system, have been evaluated. For TiAlN and Al2O3 overlay coatings, the two different PVD (physical vapor deposition) methods using an arc discharge and a sputtering, were applied, respectively.
In addition, a different surface treatment method of the diffusion coating by a pack cementation of Al (aluminiding) was also adopted in this study. To achieve enhanced thermal oxidation resistance at 1000oC by suppressing the inhomogeneous formation of thick Cr2O3 crust at the surface region, a study for the surface modification methods on the morphological and structural properties of Hastelloy X substrates has been conducted. The structural and compositional properties of each sample were characterized before and after heat-treatment at 1000oC under air and He environment. The results showed that the Al diffusion coating showed the more enhanced high temperature properties than the overlay coatings such as the suppressed thick Cr2O3 crust formation and lower wear loss.
Transparent diamond-like carbon (DLC) films were synthesized on glass using radio frequency plasma enhanced chemical vapor deposition method from the gas mixture of CH4, SiH4 and Ar. The pressure, the rf-power, CH4/SiH4/Ar ratio, and the deposition time were 0.1Torr, 100W, 20 : 1 : 1, and 20 min, respectively. The optical transmittances of DLCdeposited glass and uncoated glass were compared with each other in the visible light regions. The DLC-deposited glass showed transmittance of approximately 83 % and 95 % as compared to the uncoated glass for the wavelength of 380 nm and 500 nm, respectively. The hardness and roughness of DLC-coated glass have been measured by nanoindentation and AFM, respectively. The DLC-coated glass showed a little less or similar optical transmittance compared to the uncoated glass, while the hardness of DLC-coated glass was 2.5 times higher than that of the uncoated glass. The deposited DLC film had the very smooth surface and was thicker than 150 nm after deposition for 20 min.
The LiMn1.5Ni0.5O4, substituting a part of Mn with Ni in the LiMn2O4, the spinel structure has good chargedischarge cycle stability and high discharge capacity at 4.7 V. In this study LiMn1.5Ni0.5O4 powders were synthesized by polymerization complex method. The effect on the characteristics of synthesized LiMn1.5Ni0.5O4 powders was studied with citric acid (CA) : metal ion (ME) molar ratio (5 : 1, 10 : 1, 15 : 1, 30 : 1) and calcination temperature (500~900oC). Single phase of LiMn1.5Ni0.5O4 was observed from XRD analysis on the powders calcined at low (500oC) and high temperatures (900oC). The crystalline size and crystallinity increased with calcination temperature. At low calcination temperature the particle size decreased and specific surface area increased as the CA molar ratio increased. On the other hand, high particle growth rate at high calcination temperature interfered the particle size reduction and specific surface area increase induced by the increase of CA molar ratio.
The artificial aggregate composing of coal bottom ash and waste catalyst slag (7 : 3, wt%) were fabricated using direct sintering method and, the bloating properties of aggregates were investigated as a function of raw material particle size and sintering temperature. Most of the artificial aggregates sintered at over 1150oC showed the bloating phenomenon regardless of particle size of the raw materials. Consequently, the specific gravity of the aggregates was drastically decreased to below 1.4. The aggregates containing waste catalyst slag of 90 μm under among the W-series specimens,however, did not show the noticeable bloating phenomenon. For the aggregates sintered at lower temperature as 1050~1150oC, the specific gravity increased with particle size of raw materials. Also, the water absorption of all aggregates decreased with the sintering temperature. The aggregates fabricated in this study met the lightweight aggregate standard showing the specific gravity 1.7~1.4 and water absorption 8~19 % and, therefore, can be applicable for the various fields.
A single phase Mg3Sb2 alloy was synthesized by melting the mixture of Mg and Sb metal powders at 1173 K.
The figure of merit of the Mg3Sb2 prepared by melting method increased with temperature and showed a value of 2.39 × 10−2 at 593 K. When the Mg3Sb2 powders were milled at high speed in a planetary ball mill for 12~48 h, Zintle phase (Mg3Sb2) was maintained as a main phase, but its crystallinity became deteriorated and elemental Sb phase appeared.
Sb phase free Mg3Sb2 could be obtained by the mechanical alloying of high speed ball milling for 24 h using elemental Mg and Sb powder mixtures.