• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.4
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• pp.626-631
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• 1997

AlSiCa powders were prepared from the domestic Hadong Kaolin ($Al_2O_3{\cdot}2SiO_2{\cdot}2H_2O$). As a result of the reaction of Hadong Kaolin and carbon powder at reducing atmosphere, $Al_2O_3{\cdot}SiC$ composite started to form at $1300^{\circ}C$ and completed at $1400^{\circ}C$. The optimum amount of carbon was 1:4 in mole ratio. It was found that only bright-green $\beta-SiC$ phase forms when the mixture was packed without carbon powder in alumina crucible.

• Resources Recycling
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• v.23 no.1
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• pp.33-39
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• 2014

In this study, the solubility of Cu, which is a main metal component of wasted PCB, in $CaO-SiO_2-Al_2O_3-MgO$ slag system was investigated. Each 20 grams of Cu chips and the quaternary slag manufactured was placed in an carbon crucible and melted for 10 hours in the temperature between 1673 K and 1825 K to confirm the equilibrium state. The oxygen partial pressure was controlled by the ratio of CO and Ar gas in the range of $10^{-17.23}$ to $10^{-15.83}$ atm. The concentration of Cu in the slag increased with increasing oxygen partial pressure, slag basicity, and MgO content in the slag. The concentration of Cu in the slag decreased with increasing temperature. The Cu dissolution reaction in the slag is an exothermic reaction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1204-1207
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• 2003

BiSrCaCuO superconducting thin films have been fabricated by co-deposition using IBS(ion Beam Sputtering) method. Despite setting the composition of thin film Bi2212 or Bi2223, in both cases, Bi2201, Bi2212 and Bi2223 phase were appeared. It was confirmed the obtained field of stabilizing phase was represented in the diagonal direction of the right below end in the Arrhenius plot of temperature of the substrate and $PO_3$, and it was distributed in the rezone.

• Conservation Science in Museum
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• v.4
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• pp.23-32
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• 2003

As the kettle excavated from a site in Hwangnam-dong, Gyeongju was presumed to have been used as a melting crucible in a glass production workplace, we decided to prove its usage by scientific analysis. First, we performed conservation treatment to find the original status of the kettle, and then SEM-EDS and XRD analysis of the five corrosions created on the surface of the kettle. The fragment of the spout, which played a crucial role for the kettle to be considered as a melting crucible, was discovered during the conservation treatment. So the mouth rim of the kettle was restored to perfection. When we observed the microstructure of the metal sample, it was proved to be cast iron gradually cooled without heat treatment. In the corrosion products, the main components were Fe and O and other components such as P, Si, Ca, and S were found. The main compounds were quartz, vivianite, goetheite, akaganite, lepidocrocite, hematite, etc. Although these components were used as raw materials for making glass, these were found not in the melting status but mere raw materials. This can be an evidence to show these site where the kettle was excavated had been a glass production workplace. However, it is not sure that the kettle was used as a melting crucible. Moreover, if we consider the organic mold and sand clay accumulated in the well site when the kettle was excavated at first, we can see this as a formative factor of the corrosions of the kettle. Therefore, we concluded that the kettle is a typical cast iron and was not used as a melting crucible of glass.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.1
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• pp.9-22
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• 2023

Spin-off pyroprocessing technology and inert anode materials to replace the conventional carbon-based smelting process for critical materials were introduced. Efforts to select inert anode materials through numerical analysis and selected experimental results were devised for the high-throughput reduction of oxide feedstocks. The electrochemical properties of the inert anode material were evaluated, and stable electrolysis behavior and CaCu generation were observed during molten salt recycling. Thereafter, CuTi was prepared by reacting rutile (TiO₂) with CaCu in a Ti crucible. The formation of CuTi was confirmed when the concentration of CaO in the molten salt was controlled at 7.5mol%. A laboratory-scale electrorefining study was conducted using CuTi(Zr, Hf) alloys as the anodes, with a Ti electrodeposit conforming to the ASTM B299 standard recovered using a pilot-scale electrorefining device.

• Journal of Conservation Science
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• v.36 no.3
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• pp.162-177
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• 2020

Research was conducted to characterize the copper production and smelting process with 11 copper smelting by-products (copper slag and copper crucible) excavated from the NA and LA areas at the Gwanbuk-ri archeological site in Buyeo. Scanning electron microscopy-energy dispersive spectroscopy, wavelength dispersive X-ray fluorescence, X-ray diffraction, and Raman microspectroscopy were employed in the analysis. The research results reveal that the copper slag from Gwanbuk-ri contained silicate oxide, magnetite, fayalite, and delafossite, which are typical characteristics of crucible slag and refined slag. The outward appearance and microstructure of the slag were grouped as follows: 1. glassy matrix + Cu prill, 2. glassy matrix + Cu prill + magnetite, 3. silicate mineral matrix + Cu prill, 4. crystalline (delafossite and magnetite) + amorphous (Cu prill), 5. magnetite + fayalite, and 6. slag from slag. The copper slags from Guanbuk-ri were found to contain residues of impurities such as SiO₂, Al₂O₃, CaO, SO₄, P₂O₅, Ag₂O, and Sb₂O₃ in their microstructure, and, in some cases, it was confirmed that copper, tin and lead are alloys. These results indicate that refining of intermediate copper(including impurities) and refining of alloys of copper(including impurities) - tin and refining of copper(including impurities) - tin - lead took place during the copper production process at Gwanbuk-ri, Buyeo.

• Journal of the Mineralogical Society of Korea
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• v.14 no.2
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• pp.99-110
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• 2001

A gem-quality yttria-stabilized zirconium oxide crystals were synthesized by the skull-melting method, using the RF electrical apparatus. Principal raw materials used were $ZrO_2$and 25 wt.% $Y_2O_3$as stabilizer and 0.03~0.05 wt.% $Nd_2O_3$decolorizing agent were added to it. The single crystals were approximately 20$\times$63 mm in size with chemical composition $Zr_{0.73}$ $Y_{0.27}$ $O_{1.87}$ . The crystals are isotropic with no appreciable anisotropism under a polarizing microscope. Their refractive indices are in the range of 2.15~2.18, specific gravity 5.85, Mohs' hardness 8~8.5, and reflectivity 13.47%. The zirconia crystals were confirmed to have cubic structure with Face-centered lattice(Z=4), space group Fm3m ($CaF_2$-type structure) and unit cell parameters are a=5.157 $\AA$. The optimal growing conditions for yttria-stabilized zirconia are 50 kW, 2.94 MHz in power and to use a crucible with 105 mm $\times$ 135 mm in size. When the lowering speed of the crucible was set 16mm/hr gave the best yield, 42%. Since the refractive index(2.15~2.18) of cubic zirconia is smaller than that of diamond, the angle between crown and pavilion should be fashioned to make it smaller than $40.5^{\circ}$ to show the maximum brilliancy and fire.

• Journal of the Korean Ceramic Society
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• v.34 no.5
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• pp.483-490
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• 1997

Al2O3/metal composites were fabricated by oxidation and reaction of molten Al-alloy into two types of commercial Al2O3-SiO2 fibrous insulation board. The growth rate, composition and microstructure of these materials were described. An AlZnMg(7075) alloy was selected as a parent alloy. Mixed polycrystalline fiber and glass phase fiber were used as a filler. The growth surface of an alloy was covered with and without SiO2. SiO2 powder was employed as a surface dopant to aid initial oxidation of Al-alloy. Al-alloy, SiO2, fiber block and growth inhibitor CaSiO3 were packed sequentially in a alumina crucible and oxidized in air at temperature range 90$0^{\circ}C$ to 120$0^{\circ}C$. The growth rate of composite layer was calculated by measuring the mass increasement(g) per unit surface($\textrm{cm}^2$). XRD and optical microscope were used to investigate the composition and phase of composites. The composite grown at 120$0^{\circ}C$ and with SiO2 dopant showed rapid growth rate. The growth behavior differed a little depending on the types of fiber used. The composites consist of $\alpha$-Al2O3, Al, Si and pore. The composite grown at 100$0^{\circ}C$ exhibited better microstructure compared to that grown at 120$0^{\circ}C$.

• Korean Journal of Crystallography
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• v.12 no.1
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• pp.5-9
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• 2001

Nd/sub 0.05/Y/sub 0.95/Ca₄O(BO₃)₃(Nd:YCOB) single crystals were grown by the Czochralski method using a iridium crucible under N₂ atmosphere. Optimum growth parameters to get high quality of single crystals were 1.5∼2 mm/hr of growth rate and 10∼20 rpm of rotation rate. The grown crystals were transparent with light purple color and well-developed in cleavage planes. The crystal structure of Nd;YCOB were identified to monoclinic by XRD method. Crystal defects acting as light scattering centers, such as micro-pores, secondary phases, inclusions and cracks were not observed under the He-Ne laser illuminations. Three red, green, blue laser devices for the RGB laser oscillations were designed and then fabricated from the grown Nd:YCOB crystals according to the phase-matching angles of negative type-I which were φ=16.40°, 33.95° and θ=22.59° with the flatness of λ/6 at least, respectively.

• Korean Journal of Materials Research
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• v.32 no.12
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• pp.560-564
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• 2022

In this study, lanthanum boron silicate glasses were prepared with a composition of x Li₂O-(60-x)B₂O₃-5CaO-5BaO-7ZnO-10SiO₂-10La₂O₃-3Y₂O₃ where x = 1,3,5,7, and 9 mol%. Each composition was melted in a platinum crucible under atmospheric conditions at 1,400 ℃ for 2 h. Clear glasses with a transmittance exceeding 85 % were fabricated. Their optical, thermal, and physical properties, such as refractive index, Abbe number, density, glass transition (T_g) and Knoop hardness were studied. The results demonstrated that refractive index was between 1.6859 and 1.6953 at 589.3 nm. The Abbe number was calculated using an equation for 589.3 nm (nd), 656.3 nm (nf) and 486.1 nm (nc) and was observed to be in the range from 57.5 to 62.6. As the Li₂O content increased, the glass transition temperature of the optical glass decreased from 608 ℃ to 564 ℃. If glass mold pressing is performed using a material with a low transition temperature and high mechanical strength, then the optical glasses developed in this study can be completely commercialized.