• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.759-760
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• 2006

Ti-6Al-4V has low specific gravity, high corrosion resistance and superior mechanical properties but it is very difficult to control oxygen content in MIM process. It is necessary to use powders with coarse particle size to decrease oxygen content of powders, so feedstocks with poor fluidity and sintered bodies with lower density are obtained in such cases. Fine titanium hydride-dehydride powders were blended with atomized powders to accomplish higher fluidity and sintered density. Sintered bodies had higher sintered density and mechanical properties equivalent to those of wrought materials by controlling oxygen content less than 0.35mass%.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.13-14
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• 2009

• 한국표면공학회지
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• 제50권2호
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• pp.98-107
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• 2017

Pd-based membranes have been widely used in hydrogen purification and separation due to their high hydrogen diffusivity and infinite selectivity. However, it has been difficult to fabricate thin and dense Pd-based membranes on a porous stainless steel(PSS) support. In case of a conventional PSS support having the large size of surface pores, it was required to use complex surface treatment and thick Pd coating more than $6{\mu}m$ on the PSS was required in order to form pore free surface. In this study, we could fabricate thin and dense Pd membrane with only $3{\mu}m$ Pd layer on a new PSS support manufactured by metal injection molding(MIM). The PSS support had low surface roughness and mean pore size of $5{\mu}m$. Pd membrane were prepared by advanced Pd sputter deposition on the modified PSS support using fine polishing and YSZ vacuum filling surface treatment. At temperature $400^{\circ}C$ and transmembrane pressure difference of 1 bar, hydrogen flux and selectivity of $H_2/N_2$ were $11.22ml\;cm^{-2}min^{-1}$ and infinity, respectively. Comparing with $6{\mu}m$ Pd membrane, $3{\mu}m$ Pd membrane showed 2.5 times higher hydrogen flux which could be due to the decreased Pd layer thickness from $6{\mu}m$ to $3{\mu}m$ and an increased porosity. It was also found that pressure exponent was changed from 0.5 on $6{\mu}m$ Pd membrane to 0.8 on $3{\mu}m$ Pd membrane.

• 한국분말재료학회지
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• 제30권1호
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• pp.1-6
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• 2023

High-entropy alloys (HEAs) are attracting attention because of their excellent properties and functions; however, they are relatively expensive compared with commercial alloys. Therefore, various efforts have been made to reduce the cost of raw materials. In this study, MIM is attempted using coarse equiatomic CoCrFeMnNi HEA powders. The mixing ratio (powder:binder) for HEA feedstock preparation is explored using torque rheometer. The block-shaped green parts are fabricated through a metal injection molding process using feedstock. The thermal debinding conditions are explored by thermogravimetric analysis, and solvent and thermal debinding are performed. It is densified under various sintering conditions considering the melting point of the HEA. The final product, which contains a small amount of non-FCC phase, is manufactured at a sintering temperature of 1250℃.

• 한국생산제조학회지
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• 제22권2호
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• pp.248-255
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• 2013

The objective of this study is to optimize the Metal Injection Molding(MIM) process with design of experiments(DOE) and numerical analysis. To derive the optimal process condition, experiment or numerical analysis was performed under various process conditions. To analyze the interaction among influential factors contributing to the temperature at flow front and response surface in MIM, both central point and axial point were added to the full factorial design with 2 levels and 5 factors and then their impacts on response variable in 43 experimental conditions were analyzed and the significance was evaluated. As a result, sprue, runner, and gate were completely filled in about 0.247 seconds after injection, the front part of the green body was filled in about 0.3344 seconds, the green body except gate, etc changed to almost solid state in about 3.29 seconds, the Packinging pressure was completed in about 6.29 seconds, and the green body inside and outside and sprue, etc became solid in 13.2 seconds. The impact of individual or reciprocal action of factors on the temperature at flow front was analyzed through regular probability, test statistics, main effect, and interaction effect. As a result, of a total of 31 combinations of factors, 9 unit factors and reciprocal actions were significant, and the screening was also possible. A proper regression equation was drawn with regression analysis and response surface design on the response variable of temperature at flow front, and the applicability could be verified.

• 한국산학기술학회논문지
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• 제21권6호
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• pp.1-9
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• 2020

국내 유도무기 분야의 비약적 발전에도 불구하고, 유도무기 내 정밀 기계 부품의 제조 방식은 80년대의 기계 절삭가공 및 정밀주조 방식에서 눈에 띄는 발전이 없는 상황이다. 생산 수량이 많지 않고 높은 신뢰도를 요구하는 만큼 기계 절삭가공이나 정밀주조 방식이 유리한 측면이 있는 것은 분명하다. 하지만 광범위 지역 제압용 유도무기(천무, 해룡 등)의 경우 유도탄 1기당 수백 개 이상의 자탄이 소요되어 대량 생산성을 요구하고 있으며, 각각의 부품 중 가공 난이도가 높은 경우는 기존의 기계 절삭가공 및 정밀주조 방식으로는 생산성과 품질을 동시에 충족시키기 어려운 실정이다. 특히 최근에 대두되고 있는 국내 방산제품들의 해외 시장 수출 경쟁력 강화를 위해서는, 생산성의 개선을 통한 원가 절감이 필수적이라고 할 수 있다. 본 연구에서는 상기에 언급된 문제의 해결을 위해 유도무기 소형 정밀부품의 MIM(Metal Injection Moulding) 공법 적용 가능성에 대해 연구한다. MIM 공법의 기초연구를 수행하여 공정 설계 간 최적의 공정 조건을 도출하였으며, 이를 적용하여 제작된 자탄신관 소형 정밀부품과 기존 방식으로 제작된 제품의 품질 검사 결과 비교 및 해당 부품이 적용되어 제작된 신관의 기능시험 수행 결과를 통해 MIM 공법의 적용 가능성을 소개한다.

• 한국표면공학회지
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• 제51권5호
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• pp.277-290
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• 2018

In this study, Pd-Ni-Ag alloy hydrogen separation membranes were fabricated by Pd/Ag/Pd/Ni/Pd multi-layer sputter deposition on the modified MIM(Metal Injection Molding)-PSS(Porous Stainless Steel) support and followed heat treatment. Nickel, used as an alloying element in Pd alloy membranes, is inexpensive and stable material in a hydrogen isotope environment at high temperature up to 1123 K. Hydrogen perm-selectivity of Pd-Ni-Ag alloy membranes is affected not only by composition of membrane films but also by other factors such as surface properties of PSS support, microstructure of membrane films and inter-diffused impurities from PSS support. In order to clarify the effect of surface Ni composition on hydrogen perm-selectivity of Pd-Ni-Ag alloy membranes, the other effects were significantly minimized by the formation of dense and homogeneous Pd-Ni-Ag alloy membranes. Hydrogen permeation test showed that hydrogen permeability decreased from $7.6{\times}10^{-09}$ to $1.02{\times}10^{-09}mol/m{\cdot}s{\cdot}Pa^{0.5}$ as Ni composition increased from 0 to 16 wt% and the selectivity for $H_2/N_2$ was infinite.