• Journal of the Korean Society for Precision Engineering
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• v.22 no.10 s.175
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• pp.129-136
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• 2005

The demand on thermos furnace of Al molten metal has recently been getting higher and higher according to the increase in use of Al and Al alloys. This study considers the estimation of the thermal and mechanical stability in the thermos furnace for Al casting. It is executed through the analysis of heat transfer on the refractory material and heat stress on each steel shell. Also, the estimation of structural stability was appraised through the strength analysis of the lower structure. In result, the temperature of steel shell rose to 320.15K and its elastic deformation was about 1.5mm. The elastic deformation of the lower structure was about 0.66mm. As a result of it, the data obtain from the analysis in this study are regarded as stable value on considering that the size of the furnace is 2500mm.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.265-275
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• 1999

Titanium nitride and related overlayers produced by arc ion plating (AIP) are applied as commercial coatings in world-wide scale since the middle of 80s. Due to the achievements of low temperature deposition (LTD), they begin now to be used as wear and corrosion-resistant coatings for machine parts, besides applications on cemented carbide and high speed steel cutting tools. On the other side, TiN can be now applied successfully to brass, Al-alloy, ZnAl alloy articles as decorative coating through LTD. Various nitrides, carbonitrides, borides and other refractory compounds, such as (Ti, Al)N, TiCN, CrN, are used as the coatings for special heavy-duty working conditions instead of TiN since 90s. More and more multilayer coatings are applied now substituting single layer ones. Duplex processes are under development.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.97-105
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• 1998

Antioxidation mechanism of Al metal powders on $Al_2O_3-C$ refractory was investigated in temperature range from 800 to $1400^{\circ}C$. The addition of 5 wt% Al metal powders suppressed the oxidation of carbon in $Al_2O_3$-C sample. The carbons were distributed uniformly on the surface and the interface of the $Al_2O_3$-C-Al. Reaction products of $Al_4C_3$ and AIN were found with a composition of Al-C at temperatures between 800 and $1200^{\circ}C$ and transformed to $Al_2O_3$ above $1400^{\circ}C$. Cavity structures related to the to the formation of $Al_4C_3$ were observed for the AI-C after heating at $1000^{\circ}C$ ofr 1 hour. Thermodynamic mechanism was considered to discuss the formation $Al_4C_3$, AlN and their transformation to $Al_2O_3$, which leads to the effect of oxidation resistance.

• Journal of the Korean Ceramic Society
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• v.36 no.6
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• pp.604-610
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• 1999

Silicide layer structures and morphology degradation of the surface and interface of the silicide layers for he Co/refractory metal bilayer sputter-deposited on the P-doped polycrystalline Si substrate and subjected to rapid thermal annealing were investigated and compared with those on the single Si substrate. The CoSi-CoSi2 phase transition temperature is lower an morphology degradation of the silcide layer occurs more severely for the Co/refractorymetal bilayer on the P-doped polycrystalline Si substrate than on the single Si substrate. Also the final layer structure and the morphology of the films after silicidation annealing was found to depend strongly upon the interlayer metal. The layer structure after silicidation annealing of Co/Hf/doped-poly Si is Co-Hf alloy/polycrystalline CoSi2/poly Si substrate while that of Co/Nb is polycrystalline CoSi2/NbSi2/polycrystalline CoSi2/poly Si.

• Journal of the Korean Ceramic Society
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• v.23 no.5
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• pp.86-92
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• 1986

As there is a growing trend to make high quality steel improving production efficiency and utilizing slag as resources the technologies of hot metal pretreatment have been progressed to meet these demands. Although mill scale $Na_2CO_3$ and CaO used as fluxes proved to be excellent agents then can severely corrode refractories such as chamotte and high alumina for torpedo or open ladle car. Thus it was considered necessary to develop new refractories which can endure suchy conditions. Desulfurization fluxes vastly used in POSCO are $CaCO_3$ and CaO Recent trials have been made by testing phenol resin bonded $Al_2O_3-SiC-C$ bricks in torpedo ladle car for hot metal pretreatment. The results showed that the life of this brick became about 1.2 times longer than that of foreign products. And the crushing strength M.O.R corrosion resistance and oxidation resistance were tested.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.2
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• pp.169-178
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• 2016

The properties of wastes for melting need to be considered to minimize the maintenance of refractory and to discharge the molten slags smoothly from a plasma torch melter. When the nonflammable wastes from nuclear facilities such as concrete debris, glass, sand, etc., are melted, they become acid slags with low basicity since the chemical composition has much more acid oxides than basic oxides. A molten slag does not have good characteristics of discharge and is mainly responsible for the refractory erosion due to its low liquidity. In case of a stationary plasma torch melter with a slant tapping port on the wall, a fixed amount of molten slags remains inside of tapping hole as well as the melter inside after tapping out. Nonmetallic slags keep the temperature higher than melting point of metal because metallic slags located on the bottom of melter by specific gravity difference are simultaneously melted when dual mode plasma torch operates in transferred mode. In order to minimize the refractory erosion, the compatible refractories are selected considering the temperature inside the melter and the melting behavior of slags whether to contact or noncontact with molten slags. An acidic refractory shall not be installed in adjacent to a basic refractory for the resistibility against corrosion.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.1-6
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• 2008

There are some methods that have been used to manage a degasing process in recent years, such as an injection method that uses aluminum molten metal powder and chemicals supplier and input method that supplies argon and nitrogen, or chlorine gas by using a gas blow-tube. However, these methods show some problems, and it shows that it is a difficult process to handle, pollution due to producing a lot of toxic gases like chlorine and fluoride gas, irregular effects, and lowering work efficiency due to the excessive processing time. The problems that are the most fatal are the producing a lot of sludge due to the reaction of aluminum molten metal with chemicals, loss of metals, and decreasing the life of refractory materials. In order to solve these problems, this paper develops a technology that is related to aluminum continuous casting molten metal and monolithic degasing apparatus. A degasing apparatus developed in this study improved the existing methods and prevented environmental pollution with smokeless, odorless, and harmlessness by using a new method that applies argon and nitrogen gas in which the methods used in the West and Japan are eliminated. The method developed in this study decreases the molten metal processing and settling time compared to the existing methods and improves the workers' health, safety, and environment because there is no pollution in processes.

• Journal of Korea Foundry Society
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• v.27 no.1
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• pp.42-47
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• 2007

Vacuum molding process(V-process) has several benefits such as a lower total production cost and a high quality casting comparing to the conventional sand molding. Influence of the gating design on the molten metal flow was investigated in this study. General criteria for the gating design of the castings and commercial codes for the flow and solidification analysis were used to attain the optimized gating design in V-process. Though mold cavity was filled smoothly under the low initial velocity of molten metal, molten metal dashed against the upper part of the mold before the completion of the mold filling with higher initial molten metal velocity and fell soon. This phenomenon may affect collapsing the mold shape, however it is thought that the possibility of burning out of the vinyl by the molten metal is not so high because vinyl is coated with refractory material.

• 전기의세계
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• v.34 no.11
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• pp.696-701
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• 1985

glow나 arc방전에 의해서 생기는 플라즈마는 고융점을 갖는 refractory금속이나 superalloy의 용해, 제조에 이용되며, 플라즈마를 이용한 repid solidification방법은 amorphous metal이나 suepralloy제조에 이용되는 최신의 방법이다. 또한 기상반응을 이용해서 신소재로써 관심이 증대되고 있는 fine ceramics나 polymer를 만들수 있고, 높은 강도와 내마모성이 요구되는 금형, 절삭공구, 베어링, 치차부품의 표면에 질화막이나 TiC, TiN의 박막을 입히는데 이용될 수 있다. 플라즈마를 이용한 방법의 피처리물이 저온으로 유지될 수 있고, 에너지소비가 적은 점등의 여러가지 장점이 있어서 앞으로 이용이 활발해지리라고 생각되며 플라즈마의 기본성질의 이해가 성공적인 이용의 첫걸임을 부언하고 싶다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.7
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• pp.823-828
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• 1992

A thermionic energy converter test station is constructed for the study of electromagnetic energy generation. Of particular interest is the frequency variations due to changes in the interelectrode gap, the electrode temperature, and the cesium vapor pressure. It is found experimentally that the most intense ratio-frequency(rf) oscillations occur at two non-overlapping regions.