• Journal of Ceramic Processing Research
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• v.22 no.1
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• pp.86-90
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• 2021

Fabrication of infrared (IR) transparent ZnS ceramics by spark plasma sintering (SPS) suffers from carbon contamination due to the graphite mold in the SPS system. In the present work, we consolidated transparent ZnS ceramics by SPS using Mo metal foil to prevent the generation of carbonate and/or carbon impurities in the sintered product. The effect of Mo foil on carbon contamination and IR transmittance was investigated. The Fourier transform infrared spectroscopy (FTIR) results revealed that the C-O absorption peak was significantly reduced, however, sulfur vacancies were generated, thus, deteriorating the overall transmittance. The sulfur vacancies were eliminated by post-annealing the specimen in a nitrogen atmosphere, whereby the overall IR transmittance was partially recovered. The results indicate that metal foil wrapping of green bodies could be potentially applicable for the fabrication of carbon contamination-free ZnS ceramics via SPS system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.2 s.245
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• pp.157-163
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• 2006

Our research dealt with micro fabrication using micro forming process. The goal of the research was to establish the limit of forming process concerning the size of forming material and formed shape. Flat-rolled ultra thin metallic foils of pure copper(3.0 and $1.0{\mu}m$ in thickness)and stainless steel($2.5{\mu}m$ in thickness) were used for forming material. We obtained the various shapes of micro channels as using designed forming process. $12-14{\mu}m$ wide and $9{\mu}m$ deep channels were made on $3.0{\mu}m$ thick foil and $6{\mu}m$ wide and $3{\mu}m$deep channels were made on $1.0{\mu}m$ thick foil. Si wafer die for forming was fabricated by using etching technique. And the relation of etching time and die dimension was investigated for fabricating precisely die groove. For the forming, die and metal foil were vacuum packed and the forming was conducted with a cold isostatic press. The formed channels were examined in terms of their dimension, surface qualities and potential for defects. Base on the examinations, formability of ultra thin metallic foil was also discussed. Finally, we compared the forming result with simulation. The result of research showed that metal forming technology is promising to produce micro parts.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.05a
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• pp.207-210
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• 2002

Metal matrix composites(MMCs) are increasingly attractive for high technology components such as aerospace applications and transportations due to their high strength, stiffness, and toughness. Many processes for fabricating MMCs have been developed, and relatively simple Foil-Fiber-Foil method is usually employed in solid state consolidation processes. During the consolidation processes at high temperature, densification occurs by the inelastic flow of the matrix materials, and the process is coupled with the conditions of pressure, temperature and volume fraction of fiber and matrix materials. This is particularly important in titanium matrix composites, and thus a generic model based on micro-mechanical approaches enabling the evolution of density over time to be predicted has been developed. The mode developed is then implemented into FEM so that practical process simulation has been carried out. Further the experimental investigation of the consolidation behavior of SiC/Ti-6Al-4V composites using vacuum hot pressing has been performed, and the results obtained are compared with the model predictions.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.27-30
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• 2007

We have been setting up experiments on propagation of shock waves generated by the pulsed laser ablation. One side of a thin metal foil is subjected to laser ablation as a shock wave is generated from a localized spot of high intensity energy source. The resulting reactive shock wave, which penetrates through the foil is reflected by an acoustic impedance which causes the metal foil to high-strain rate deform. This short time physics is captured on an ICCD camera. The focus of our research is generating reactive shock wave and high strain rate deforming of thin metal foil for accelerating micro-particles to a very high speed on the orders of several thousand meter per second. Somce innovative applications of this device will be discussed.

• The Journal of Korean Academy of Prosthodontics
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• v.24 no.1
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• pp.151-164
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• 1986

The purpose of this study was to evaluate the marginal fit of metal ceramic crowns made by different techniques. The techniques were metal butt margin technique, platinum foil technique, shoulder powder techniques and wax technique. The latter three techniques were for the fabrication of collarless metal ceramic crowns. Ten crowns were made of each techniques, and marginal fit was evaluated using scanning electron microscope under X200 magnification. The results were as follows. 1. The marginal fit in the descending order were wax technique shoulder powder technique, platinum foil technique and metal butt margin, before cementation, and wax technique, shoulder powder technique, metal butt margin, and platinum foil technique, after cementation. 2. The fit of collarless metal ceramic crowns was comparable to metal ceramic crowns with metal butt margins. 3. There were no statistically significant differences between marginal fit of metal ceramic crowns made by different techniques.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1916-1919
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• 2007

We have been setting up experiments on propagation of shock waves generated by the pulsed laser ablation. One side of a thin metal foil is subjected to laser ablation as a shock wave propagates through the foil. The shock wave, which penetrates through the foil is reflected by an acoustic impedance which causes the metal foil to high-strain rate deform. This short time physics is captured on an ICCD camera. The focus of our research is applying shock wave and deformation of the thin foil from the ablation to accelerating micro-particles to a very high speed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.353-357
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• 2007

We have been setting up experiments on propagation of shock waves generated by the pulsed laser ablation. One side of a thin metal foil is subjected to laser ablation as a shock wave propagates through the foil. The shock wave, which penetrates through the foil is reflected by an acoustic impedance which causes the metal foil to high-strain rate deform. This short time physics is captured on an ICCD camera. The focus of our research is applying shock wave and deformation of the thin foil from the ablation to accelerating micro-particles to a very high speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.31-32
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• 2010

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.09a
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• pp.49-53
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• 2005

The objective of this research was to establish the size limitation of micro metal forming and analyze the formability of foil. Flat-rolled ultra thin metallic copper foil($3{\mu}m$ in thickness) was used as a forming material and foil was annealed to improve the formability at the temperature of $385^{\circ}C$. Forming die was fabricated by using etching technique of DRIE(deep reactive ion etching) and HNA isotropic etching. For the forming die and coupe. foil were vacuum packed and the forming was conducted as applying hydrostatic pressure of 250MPa to the vacuum packed unit. We successfully obtained the micro channels of $12\~14{\mu}m$ width and $9{\mu}m$ depth from micro forming process we designed. We also investigated the thickness strain distribution of foil from experiment and FE simulation result. Micro channels had a good formability of smooth surface and size accuracy. We expect that micro metal forming technology will be applied to production of micro parts.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.287-293
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• 2017

PURPOSE. To compare the dimensional accuracy of three impression techniques- a separating foil impression, a custom tray impression, and a stock tray impression. MATERIALS AND METHODS. A machined mandibular complete-arch metal model with special modifications served as a master cast. Three different impression techniques (n = 6 in each group) were performed with addition-cured silicon materials: i) putty-wash technique with a prefabricated metal tray (MET) using putty and regular body, ii) single-phase impression with custom tray (CUS) using regular body material, and iii) two-stage technique with stock metal tray (SEP) using putty with a separating foil and regular body material. All impressions were poured with epoxy resin. Six different distances (four intra-abutment and two inter-abutment distances) were gauged on the metal master model and on the casts with a microscope in combination with calibrated measuring software. The differences of the evaluated distances between the reference and the three test groups were calculated and expressed as mean (${\pm}SD$). Additionally, the 95% confidence intervals were calculated and significant differences between the experimental groups were assumed when confidence intervals did not overlap. RESULTS. Dimensional changes compared to reference values varied between -74.01 and $32.57{\mu}m$ (MET), -78.86 and 30.84 (CUS), and between -92.20 and 30.98 (SEP). For the intra-abutment distances, no significant differences among the experimental groups were detected. CUS showed a significantly higher dimensional accuracy for the inter-abutment distances with -0.02 and -0.08 percentage deviation compared to MET and SEP. CONCLUSION. The separation foil technique is a simple alternative to the custom tray technique for single tooth restorations, while limitations may exist for extended restorations with multiple abutment teeth.