• 한국공작기계학회논문집
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• 제16권6호
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• pp.193-200
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• 2007

Micro forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Al5083 superplastic alloy with very small grains has a great advantage in achieving micro deformation under low stress due to its relatively low strength at a specific high temperature range. Micro forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, the micro formability of Al5083 superplastic alloy and bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$, was investigated with the specially designed micro vibration forming system using pyramid-shape, V-shape and U-shape micro die pattern. With these dies, micro vibration forming was conducted by varying the applied load, time. Micro formability was estimated by comparing the hight of formed shape using non-contact surface profiler system. The vibration load effect to metal flow in the micro die and improve the micro formability of Al5083 superplastic alloy and $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk Metallic glass(BMG).

• 한국세라믹학회지
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• 제24권2호
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• pp.117-122
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• 1987

Glass forming ranges in the AlF3-(Mg＋Sr＋Ba)F2-P2O5 system are studied and ultraviolet transmission, infrared transmission, coefficient of refractive index, thermal expansion coefficient, density and chemical durability of the glasses are determined. Glass forming range is restricted MgF2 0-10wt%, SrF2 10-50wt%, BaF2 10-40wt% in this system. While BaF2 is substituted by SrF2, density and refractive index are decreased, micro hardness and thermal expansion coefficient are increased according to the increasing of SrF2 at fixed MgF2 contents. These samples represent high transmittance(93%) from 400nm to 3800nm and chemical durability of these samples show less than 0.3mg/$\textrm{cm}^2$$.$hy by weightloss.

• 한국주조공학회지
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• 제26권2호
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• pp.77-84
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• 2006

The effect of alloy composition on the glass forming ability (GFA) of the Ca-rich Ca-Mg-Zn alloys has been investigated in $Ca_{65}Mg_{5+x}Zn_{30-x}$ and $Ca_{55+x}Mg_{15}Zn_{30-x}$ (x=0, 5, 10, 15, 20) alloys. In a wide composition range of 15-25% Zn and 10-20% Mg bulk metallic glass (BMG) samples with the diameter larger than 6 mm are fabricated by conventional copper mold casting method in air atmosphere. Among the alloys investigated, the $Ca_{65}Mg_{15}Zn_{20}$ alloy exhibits the highest GFA enabling to form BMG sample with the diameter of at least 15 mm. The crystalline phase formed during solidification of $Ca_{65}Mg_{15}Zn_{20}$ ($D_{max}=15\;mm$) could be identified as a mixture of $Ca_3Zn$ and $CaMg_2$ cause by the redistribution of the constituent elements on long-range scale. The compressive fracture strength and fracture elongation of the $Ca_{65}Mg_{15}Zn_{20}$ BMG are 602 MPa and 2.08% respectively. The ${\sigma}$ parameter which has been recently proposed for evaluating GFA exhibits better correlation with GFA of Ca-Mg-Zn alloys than other parameters suggested so far such as ${\Delta}T_x$, $T_{rg}$, K, ${\gamma}$, and ${\Delta}T^*$ parameters.

• 한국자기학회지
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• 제17권3호
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• pp.128-132
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• 2007

큰 비정질 형성능을 가지는 FeSiBNb 비정질 리본 합금의 열적 및 자기적 특성에 미치는 Co의 첨가 효과에 대하여 연구되었다. 두께 $40\;{\mu}m$의 비정질$(Fe_{1-X}Co_X)_{72}Si_4B_{20}Nb_4(x=0{\sim}0.5)$ 합금에 대한 열분석 결과, Fe에 대한 Co의 치환량이 증가할수록 과냉각 액상의 존재 온도 범위가 넓어져 비정질 형성능이 증가하는 것으로 평가되었다. 또 Co 농도의 증가에 따라 약간의 $B_8$(800A/m에서의 유도 자속밀도)의 감소가 얻어지나, 투자율이 현저하게 증가하고 철손이 크게 감소하는 경향을 나타내었다. 한편 두께가 두꺼운 상기 비정질 합금의 교류 투자율의 주파수 특성은 와전류에 의한 표피 효과의 증대 때문에 $20\;{\mu}m$ 정도의 두께를 가지는 통상의 비정질 리본 합금에 비해 열화되는 것으로 나타났다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.33-33
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• 2007

In PDP industry, the dielectrics and barrier ribs have been required with low dielectric constant, low melting point and Pb-free composition due to the low power consumption, low signal delay time and the environment restriction. We were studied with $B_2O_3-Al_2O_3$-SrO glass systems about optical, thermal and dielectric properties. The glass forming region of the $B_2O_3-Al_2O_3$-SrO glass systems was narrow due to the amount of the glass former $(B_2O_3)$. The glass transition temperature (Tg) of the glasses was at $550{\sim}590^{\circ}C$. The glasses have 6~8 for the dielectric constant. Furthermore, the transmittance of the glasses was over 80% on the range of the visible ray. From the results, the glasses of the $B_2O_3-Al_2O_3$-SrO glass systems should enable to be a good candidate of the PDP devices for information display with low dielectric constant. The aim of this study is to give a fundamental result of new glass system for low dielectric constant in the information display.

• 한국세라믹학회지
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• 제16권3호
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• pp.178-183
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• 1979

The carborundum abrasive specimens bonded with a soda-borosilicate glass were prepared. Samples fired at specified temperatures with various mixing ratio and forming pressure were examined in terms of the structure, bonding strength, and microscopic observations. Increasing the forming pressure up to 400kg/$\cm^2$, the structure became denser in proportion to the forming pressure. The bonding strength was generally increased with increasing the mixing ratio (Vb/Vg), but the bloating phenomena were observed when samples were fired above 95$0^{\circ}C$ with mixing ratio above 20%, consequently, the bonding strength was decreased. Samples fired at the temperature range 900~95$0^{\circ}C$ with mixing ratio 15~30% had the dense structure with various grades.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2015년도 춘계학술대회 논문집
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• pp.77-77
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• 2015

Metallic glass alloys having dense packing structure have short range ordered structure with long range homogeneity. Therefore, they can provide complete corrosion protection and unique electrical properties. Recently, metallic glass thin films have received much attention to extend its application fields combining with PVC coating technologies. The metallic glass thin films can change the surface properties of the conventional bulk materials which need anticorrosion properties. However, multi-component alloying targets are required to fabricate the metallic glass thin films because metallic glass alloys contain more than three elements. Recently, many researchers have been reported the properties of the metallic glass thin films synthesized with multi-cathode systems or amorphous target. But, it is difficult to fabricate the large sized sputtering targets for mass production equipment with high toughness and thermal stability. In this study, newly developed sputtering target with glass forming ability and the properties of the metallic glass thin films will be introduced with respect to the various application fields such as bipolar plate in PEM fuel cell and decorative coatings for electric device and construction fields.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.589-592
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• 2005

Micro-forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Micro-forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, micro-formability of a representative bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$, was investigated for micro-forging of U-shape pattern. Micro-formability was estimated by comparing $R_f$ values $(=A_f/A_g)$, where Ag is cross-sectional area of U groove, and $A_f$ the filled area by material. Microforging process was simulated and analyzed by applying finite element method. FEM simulation results should reasonable agreement with the experimental results when the material properties and simulation conditions such as top die speed, remeshing criteria and boundary conditions tightly controlled. The micro-formability of $Zr_{62}Cu_{17}Ni_{13}Al_8$ was increased with increasing load and time in the temperature range of the supercooled liquid state. Also, FEM Simulation using DEFORM was confirmed to be applicable for the micro-forming process simulation.

• 한국정밀공학회지
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• 제23권4호
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• pp.153-161
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• 2006

Micro-forming is a suited technology to manufacture very small metallic parts(several $mm{\sim}{\mu}m$). Micro-forming of $Zr_{62}Cu_{17}Ni_{13}Al_8$ bulk metallic glass(BMG) as a candidate material for this developing process are feasible at a relatively low stress in the supercooled liquid state without any crystallization during hot deformation. In this study, micro- formability of a representative bulk metallic glass, $Zr_{62}Cu_{17}Ni_{13}Al_8$. was investigated for micro-forging of U-shape pattern. Micro-formability was estimated by comparing $R_f$ values ($=A_f/A_g$), where $A_g$ is cross-sectional area of U groove, and $A_f$ the filled area by material. Micro-forging process was simulated and analyzed by applying finite element method. FEM simulation results showed reasonable agreement with the experimental results when the material properties and simulation conditions such as top die speed, remeshing criteria and boundary conditions were tightly controlled. The micro-formability of $Zr_{62}Cu_{17}Ni_{13}Al_8$ was increased with increasing load and time in the temperature range of the supercooled liquid state. Also, FEM simulation using a commercial software, DEFORM was confirmed to be applicable for the optimization of micro-forming process.

• 반도체디스플레이기술학회지
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• 제22권1호
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• pp.64-71
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• 2023

In this study, we investigated the effects of BiAlSiO glass composition on its glass forming range, thermal properties, and plasma resistance. The results showed that increasing the Al2O3 content suppressed the tendency for crystallization and hindered glass formation beyond a certain threshold. Bi2O3 was found to increase the content of non-bridging oxygen, resulting in a decrease in glass transition temperature and an increase in thermal expansion coefficient. Furthermore, the etching rate was found to improve with increasing Al2O3 content but decrease with increasing SiO2 content. It was concluded that the boiling point of fluorinated compounds should be considered to 900℃. Therefore, this study is expected to contribute to the understanding of the properties of BiAlSiO glass and its application to low temperature melting PRG compositions.