• Title/Summary/Keyword: micro-powder

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Die Compaction and Sintering Behavior of Fe Micro-nano-powder Feedstock for Micro-PIM (마이크로 PIM용 Fe 마이크로-나노 혼합분말 피드스톡의 다이성형 및 소결거동)

  • You, Woo-Kyung;Choi, Joon-Phil;Lee, Jai-Sung
    • Korean Journal of Metals and Materials
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    • v.49 no.1
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    • pp.32-39
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    • 2011
  • The present investigation was performed on the die compaction and sintering behavior of Fe micro-nano mixed powder with a mixed binder for powder injection molding. Warm die compaction of the feedstock for simulation of the static injection molding process was conducted using a cylindrical mold of 10 mm diameter at $100^{\circ}C$ under 4MPa. The die compaction of the micro-nanopowder feedstock underwent a uniform molding behavior showing a homogeneous distribution of nanopowders among the micropowders without porosity and distortion. After debinding, the powder compact maintained a uniform structure without crack and distortion, leading to a high green density of 64.2% corresponding to the initial powder loading of 65%. The sintering experiment showed that the micro-nanopowder compact underwent a near full and isotropic densification process during sintering. It was observed that the nanopowders effectively suppressed the growth of micropowder grains during densification process. Conclusively, the use of nanopowder for PIM feedstock might provide a new concept for processing a full density PIM parts with fine microstructure.

Effect of the Number of Nozzle Scanning in Micro-Line Grooving of Glass by Powder Blasting (Powder Blasting을 이용한 유리의 미세 선형 홈 가공시 노즐 주사 횟수의 영향)

  • 박경호;김광현;최종순;박동삼
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.294-299
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    • 2001
  • The old technique of sandblasting which has been used for decoration of glass surface has recently been developed into a powder blasting technique for various materials, capable of producing micro structures larger than 100 m. This paper describes the performance of powder blasting technique in micro-line grooving of glass and the effect of the number of nozzle scanning on the depth and width of line groove. Experimental results showed that increasing the no. of nozzle scanning resulted in the increase of depth and width in grooves. Increase of width which may cause several problems in the precision machining results from wear of mask film.

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Technical and Economical Comparison of Micro Powder Injection Molding

  • Atre, Sundar V.;Wu, Carl L.;Hwang, Chul-Jin;Zauner, Rudolf;Park, Seong-Jin;German, Randall M.
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.45-46
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    • 2006
  • In recent years, micro powder injection molding $(\mu-PIM)$ is being explored as an economical fabrication method for microcomponents in microsystems technology (MST). Technical and economic comparison was performed for $\mu-PIM$ processes. Molding experiment and simulation during the filling process were performed to evaluate several different geometries and processing conditions. The influence of material parameters and process conditions on mold filling were examined as a function of features size using microchannels as an example. It was found that the heat conductivity and viscosity of feedstock, geometry and mold temperature were the most critical parameters for complete filling of micro features.

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Net-shape Manufacturing of Micro Porous Metal Components by Powder Injection Molding

  • Nishiyabu, Kazuaki;Matsuzaki, Satoru;Tanaka, Shigeo
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.93-94
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    • 2006
  • A novel production method for porous metal components has been developed by applying powder space holder (PSH) method to metal powder injection molding (MIM) process. The PSH-MIM method has an industrial competitive advantage that is capable of net-shape manufacturing the micro-sized porous metal products with complicated shapes and controlled porosity and pore size. In this study, the small impeller with homogeneous micro-porous structure was manufactured by the PSH-MIM method. The effects of combinations in size and fraction of PMMA particle on dimensional tolerance and variation of sintered porous specimens were investigated. It was concluded that the PSH-MIM method could manufacture commercially microporous metal components with high dimensional accuracy.

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Effects of Nanopowder Additives in Micro-electrical Discharge Machining

  • Tan, Peng-Cheong;Yeo, Swee-Hock;Tan, Yie-Voon
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.3
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    • pp.22-26
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    • 2008
  • The use of electrical discharge machining (EDM) for micro-machining applications requires particular attention to the machined surface roughness and discharge gap distance, as these factors affect the geometrical accuracy of micro-parts. Previous studies of conventional EDM have shown that selected types of semi-conductive and non-conductive powder suspended in the dielectric reduced the surface roughness while ensuring a limited increase in the gap distance. Based on this, an extension of the technique to micro-EDM was studied Such work is necessary since the introduction of nanopowders suspended in the dielectric is not well understood. The experimental results showed that a statistically significant reduction in the surface roughness value was achieved at particular concentrations of the powder additives, depending on the powder material and the machining input energy setting. The average reduction in surface roughness using a powder suspended dielectric was between 14-24% of the average surface roughness generated using a pure dielectric. Furthermore, when these additive concentrations were used for machining, no adverse increase in the gap distance was observed.

ZnO Micro/Nanocrystals Synthesized by Thermal Evaporation Method using Mn Powder as the Reducing Agent (Mn 분말을 환원제로 사용하여 열증발법에 의해 생성된 ZnO 마이크로/나노결정)

  • So, Ho-Jin;Lee, Geun-Hyoung
    • Korean Journal of Materials Research
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    • v.29 no.7
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    • pp.432-436
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    • 2019
  • Zinc oxide(ZnO) micro/nanocrystals are grown via thermal evaporation of ZnO powder mixed with Mn powder, which is used as a reducing agent. The ZnO/Mn powder mixture produces ZnO micro/nanocrystals with diverse morphologies such as rods, wires, belts, and spherical shapes. Rod-shaped ZnO micro/nanocrystals, which have an average diameter of 360 nm and an average length of about $12{\mu}m$, are fabricated at a temperature as low as $800^{\circ}C$ due to the reducibility of Mn. Wire-and belt-like ZnO micro/nanocrystals with length of $3{\mu}m$ are formed at $900^{\circ}C$ and $1,000^{\circ}C$. When the growth temperature is $1,100^{\circ}C$, spherical shaped ZnO crystals having a diameter of 150 nm are synthesized. X-ray diffraction patterns reveal that ZnO had hexagonal wurtzite crystal structure. A strong ultraviolet emission peak and a weak visible emission band are observed in the cathodoluminescence spectra of the rod- and wire-shaped ZnO crystals, while visible emission is detected for the spherical shaped ZnO crystals.

Carbon Black Containing Micro-Grid Patterned Piezocapacitive Pressure Sensor (탄소분말이 함유된 마이크로 그리드패턴 전기용량형 압력센서)

  • Ma, Sung-Young;Chang, Seung-Hwan
    • Composites Research
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    • v.32 no.5
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    • pp.237-242
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    • 2019
  • In this research, a capacitive pressure sensor (Piezocapacitive Sensor) was fabricated using carbon black powder containing poly-dimethylsiloxane (PDMS) with micro-grid patterned surface. To investigate the effect of carbon black powder and micro-grid pattern on the sensor's performance, various sensors were fabricated with different carbon black powder concentration and grid pattern density. The performances of the developed sensors were compared in terms of operating range and sensitivity.

Micro Metal Injection Molding Using Hybrid Micro/Nano Powders

  • Nishiyabu, Kazuaki;Kakishita, Kenichi;Osada, Toshiko;Tanaka, Shigeo
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09a
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    • pp.36-37
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    • 2006
  • This study aims to investigate the usage of nano-scale particles in a micro metal injection molding ($\mu$-MIM) process. Nanoscale particle is effective to improve transcription and surface roughness in small structure. Moreover, the effects of hybrid micro/nano particles, Cu/Cu and SUS/Cu were investigated. Small dumbbell specimens were produced using various feedstocks prepared by changing binder content and fraction of nano-scale Cu particle (0.3 and $0.13{\mu}m$ in particle size). The effects of adding the fraction of nano-scale Cu powder on the melt viscosity of the feedstock, microstructure, density and tensile strength of sintered parts were discussed.

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Mechanical Etching of Micro Pocket by Powder Blasting (Powder Blasting에 의한 미세 포켓의 기계적 에칭)

  • Park, Kyoung-Ho;Oh, Young-Tak;Park, Dong-Sam
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.1
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    • pp.219-226
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    • 2002
  • The mechanical etching technique has recently been developed to a powder blasting technique for various materials, capable of producing micro structures larger than 100$\mu$ m. This paper describes the performance of powder blasting technique in micro-pocketing of stainless steel and the effect of the number of nozzle scanning and the nozzle height on the depth and width of pockets. Experimental results showed that increasing the no. of nozzle scanning and decreasing the nozzle height resulted in the increase of depth and width in pockets. Increase of width results from wear of mask film.