• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.21-21
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• 2018

다양한 소재(금속, 세라믹, 고분자 소재 등)들이 3차원 형상기반 적층제조법에 적용되고 있는데, 금속 소재를 이용하여 3D 프린팅 법으로 치과용 수복물을 제조하는 연구가 많이 보고되고 있다. 하지만, 티타늄 또는 티타늄 합금 분말을 이용하여 3D 프린팅 법으로 제작한 치과용 보철물에 관한연구 보고는 많지 않다. Kanazawa 등 (2014)은 Ti-6Al-4V 합금분말을 이용하여 SLM법으로 총의치 용 framework를 제작하여 주조법으로 제작한 것과 비교 평가하였고, Mangano 등(2013)은 Ti-6Al-4V 합금분말로 지름이 작은 일체형 (1-piece narrow-diameter) 임플란트를 SLS법으로 제작하여 16명의 환자에게 식립한 다음, 2년간 관찰하였고, Mangano 등 (2014)은 cone-beam computed tomography (CBCT) data를 3D이미지로 변환시켜 DLMS법으로 치근 형상의 임플란트를 제작하여 15명의 환자에게 식립한 다음, 1년간 관찰하였다. 또한 서울대학교 및 연세대학교 치과생체재료과학교실 (2016)에서는 3D 프린팅 법으로 제작한 티타늄 시편과 기계 가공한 티타늄 시편의 물성을 비교하였다. 그러나 티타늄 합금 분말을 이용하여 3D 프린팅 법으로 제작한 치과용 보철물을 실제 임상에 적용하는 단계에서 기존 기계가공 방식으로 제작한 티타늄 보철물과 3D 프린팅 법으로 제작한 티타늄 보철물의 물성과 표면특성을 다양하게 비교 평가하는 것이 필요하여 본 연구에서는 3D 프린팅 법으로 제작한 티타늄 시편과 기계 가공한 티타늄 시편의 물성특성과 표면특성을 비교하여 조사하였다.

• Journal of Korea Foundry Society
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• v.43 no.3
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• pp.107-136
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• 2023

Natural silica sand was commonly used for sand casting of cast steel products, and chromites sand was used to suppress seizure defects due to the lack of thermal properties of silica sand. However there are disadvantages such as deterioration by repeated use, system sand mixing problem, difficulty separating and removing, increased during mold according to high density and to being waste containing chrome. Recently, industrial waste reduction and atmospheric environment improvement have been highlighted as important tasks in the casting industry. In order to solve the problems that occur when using foundry Sand and to improve the environment of casting factories, various artificial sands that can be applied instead of natural silica sand have been developed and introduced. Artificial sands can be classified into artificial sand manufactured by the electric arc atomization or gas flame atomization, artificial sand manufactured by the spray drying & sintering process, artificial sand manufactured by the sintering & crushing process and exhibit different physical properties depending on the type of raw-minerals and manufacturing method. In this study, comparative evaluation tests were conducted on the physical properties of various foundry sands, mold strength, physical durability, thermal durability, and casting test pieces. When comprehensively considering the actual amount of molding sand used according to density, the mold strength according to the shape of sand, the physical and thermal durability of foundry sand, and the heat resistance characteristics of foundry sand, 'Molten artificial sand A1' or 'Molten artificial sand B' is judged to be the most suitable spherical artificial sand for casting of heavy steel castings.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.25-32
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• 2022

Investment casting is a production method commonly used to manufacture precision equipment, medical fields, and accessories, and has continued to develop through the modernization of equipment and high quality of materials, and its scope of use has been expanded. The purpose of this study is to minimize the defect rate by deriving structural improvement and standardization of mold temperature, which are key elements of the investment casting process, to minimize the defect rate. The scope of the study is limited to jewelry manufacturing casting processes suitable for understanding the structure and principles of small gate, and an experimental research is to be conducted by using soft Wax, gypsum powder, and 14 K gold as research materials. According to the results, the most appropriate casting standard temperature for the casting pattern of Alloy 14 k was the lowest turbulence at 980℃ flask temperature of 550℃, so good products could be produced. As a future task of this study, detailed studies are needed to data the structure and system temperature of small gate, reduce production defects in the field, and provide data for excellent investment casting competitiveness.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.211-211
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• 2013

Ru-Cr은 차세대 반도체 메모리(RAM, MRAM, FeRAM), 헤드(MR, TMR), 캐피시터의 웨이퍼 등에 전극층이나 시드층 형성을 위해 스퍼터링 타겟으로 제조되며, IT산업이 발달함에 따라 수요가 증가하고 있다. 기존의 스퍼터링 타겟은 산처리와 주조와 같은 습식법이 주를 이루었으나, 긴 제조시간과 강산사용의 위험성화 강산폐유의 처리가 문제되고 있다. 최근에는 습식공정을 보완하기 위한 건식법의 연구가 진행 중이며, 합금소재에 대한 건식법의 연구가 필요하다. 본 연구에서는 폐 Ru-Cr 금속합금 스퍼터링 타겟을 Hammer-mill, jet-mill 등 건식으로 분쇄하고 RF-Plasma를 이용하여 소결에 용이한 구형, 고순도 Ru-Cr금속합금분말을 제조하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.205-205
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• 2003

우리나라에서는 많은 양의 폐분진이 발생하며 경남지역에서는 연간 3만톤의 폐분진이 발생한다. 매년 폐기물의 발생량은 증가하고 있으며 폐분진류의 주성분은 실리카와 알루미나가 주성분을 이룬다. 특히 주조, 제강 등 금속공업에서 발생하는 분진은 입자가 미세한 다량의 실리카와 알루미나로 이루어져 있어 탄화규소(SiC) 및 알루미나-탄화규소-탄소(A1$_2$O$_3$-SiC-C)계 내화물 제조에 분쇄공정 없이 세라믹스의 원료로 활용할 수 있다. 현재 알루미나-탄화규소-탄소(Al$_2$O$_3$-SiC-C)계 내화물 제조를 위해 제조공정이 간단한 연소합성법을 이용하지만 분말제조 공정 중 분위기 조절에 많은 비용이 요구되고 있어 시급한 대안이 필요한 상태이다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.191-194
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• 1995

The business of manufacturing is increasingly becomeing time-compresssing, precise and long-life oiented, owing to various needs form the consumers and harsh global competition. with the emergence of the layer laminate maunfacturing methods, it is possible to prototypes directly from 3D CAD and additive process, the production time and cost have shortened dramatically. However there are some problems like surface-step, dimensional deviation and warp. A newly developed powder casting is suitable for rapid-manufacturing metallic tools. Powder casting can serve as a promising repid tooling method because of high density charateristics and low dimensional shrinkage below 0.1% during sintering and infiltration. By this process, we have realized significant time savings bypassing the wait for prototype tooling and cost savings eliminating the expense of conventional prototype tooling process.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.261-264
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• 2007

In this study, the consolidation and casting processes of fine Si powders, by-products of making high purity Poly-Si rods in the current method, were systematically investigated for use as economical solar-grade feedstock. Morphology, size, and contamination type of the poly-Si fine powders were inspected by combined analysis of SEM, particle size analyzer, and FT-IR. Poly-Si powder compacts were tried to fabricate by a consolidation process without a binding agent and then their density ratio and strength were evaluated. Finally, the electrical resistivity of the specimens prepared by an electromagnetic casting method was examined for purity assessment.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.58-60
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• 2005

기존의 금속조형물은 만드는 공정으로 주조-후처리 또는 정밀 기계가공방법은 많은 시간과 노력이 필요한 단점이 있었다. 최근에 귀금속 성형점토 (PMC)라는 마이크로 크기의 분말과 바인더가 혼합되어 마치 점토와 같이 직접 수공 또는 치공구를 이용하여 완성하고 $650-850^{\circ}C$ 정도의 저온에서 소결하여 단시간 안에 최종 조형물을 만들 수 있는 신공정이 개발된 바 있다. 본 연구에서는 선진사와 비슷한 $1{\~}3{\mu}$m급은 분말을 1:1로 혼합하고 고형 바인더를 첨부하여 기존 선진사와 동등하거나 우수한 미세조직과 표면경도를 확보하고 조형비가 있는 시작품을 만드는데 성공하였다.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.39-45
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• 1998

In the previous study. the powder casting was attempted as the rapid tooling. The powder casting was the process to cast dry powder into the casting mold transferred from R/P model and infiltrate the liquid binder to solidify the powder. And then, the melted copper was infiltrated to control the shrinkage rate of the final mold Conseqently, the shrinkage rate was under 0.1% through that process. The mechanical characteristic was also excellent. Generally, in the slurry casting, the alumina powder and the water soluble phenol were mainly used. However, the mechanical property of the phenol was not good enough to apply to molds directly. In this study, aluminium powder filled with epoxy is applicated to the slurry casting to solve these problems. The mechanical and thermal properties are better than phenol because the epoxy is the thermosetting resin. We achieved a successful result that the shrinkage rate is shortened about 0.047%. Futhermore, the manufacturing time and cost savings are significant. Finally, we assume that the developing possibility of this process is very optimistic.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.36-44
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• 1999

The rapid Tooling technique is classified into two methods: one to directly utilize the model which was made by rapid prototyping technologies for dies, and the other to make a transferred type using the model as a master model and create dies and molds using it. In this study, the Al powder filled resin was made several mixed ratios and meshes sizes, and applied to slurry casting. And, variation of mechanical characteristics such as the shrinkage rate, the tensile strength, the elongation, the hardness, and surface roughness, are measured to compare. Consequently, as higher is the powder mixed ration and as smaller is the grain size of the power, the mechanical characteristics of the final mold are improved. Finally, the metal short fiber which can be fabricated easily and cheaply, if the self-excited vibration of an elastic tool, was also applied to slurry casting. It has been found tat the hardness gets higher, while the shrinkage rate lower, if mixed with short fiber.