• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.242-248
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• 1997

Porous silicons were prepared by dry etching as well as by chemical etching. The latter is a conventional method used by many researchers. Meanwhile, the former is a new method we developed. Also the porous silicon structure was made by E-beam lithography technique. However, due to the limit of this technique, minimum size we could produce was about 0.3 $\mu\textrm{m}$ in diameter on silicon wafer. In a new method, the porous silicon microstructure was fabricated by using Reactive Ion Etching method after covering with diamond powder on 4 inch wafer by using spin coater. In this method, diamond powder acted as a mask. The morphology of samples prepared under many different conditions were analysed be SEM and AFM. And we measured PL spectra for the samples. Based on these results, we observed the structure of a few hundreds $\AA$ in size from porous silicon which was made by dry etching with diamond powder. Also the PL peak for these samples lied around 590 nm compared to 760 nm for chemically etched porous silicon.

• Journal of Powder Materials
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• v.22 no.2
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• pp.87-92
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• 2015

Metallic porous materials have many interesting combinations of physical and geometrical properties with very low specific weight or high gas permeability. In this study, highly porous Cu foam is successfully fabricated by a slurry coating process. The Cu foam is fabricated specifically by changing the coating amount and the type of polyurethane foam used as a template. The processing parameters and pore characteristics are observed to identify the key parameters of the slurry coating process and the optimized morphological properties of the Cu foam. The pore characteristics of Cu foam are investigated by scanning electron micrographs and micro-CT analyzer, and air permeability of the Cu foam is measured by capillary flow porometer. We confirmed that the characteristics of Cu foam can be easily controlled in the slurry coating process by changing the microstructure, porosity, pore size, strut thickness, and the cell size. It can be considered that the fabricated Cu foams show tremendous promise for industrial application.

• Journal of Powder Materials
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• v.18 no.2
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• pp.172-175
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• 2011

We developed a 3D simulation model of microstructure evolution of vertically aligned porous structure due to phase separation during film growth. The model proves its validity by reproducing the results of previous researches which are topological features of the microstructures and effects of varied processing parameters. The model will be extended by including bulk diffusion effect and elastic effect.

• 연구논문집
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• s.34
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• pp.131-138
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• 2004

Porous silicon nitride ceramics were prepared by Self-propagating High Temperature Synthesis from silicon powder, silicon nitride powder and the pore-forming precursor. The microstructure, porosity and the flexural strength of the porous silicon nitride ceramics were varied according to the Si/$Si_3N_4$ ratio, size and amount of the pore-forming precursors. Some samples exhibited as high flexural strength as $162\pm24$ MPa. The high strength is considered to result from the fine pore size and the strong bonding among the silicon nitrid particles.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1009-1010
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• 2006

In this study, we attempt to synthesize the cordierite from the reaction of fly-ash, alumina, silicon dioxide, and magnesia powders. For the purpose of air purification, the honeycomb filter with porous cordierite was fabricated from the combination of synthetic cordierite and pore forming agent. Fabricated porous cordierite honeycomb was prepared with high porosity (58%), and good compressive strength (69MPa).

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.608-609
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• 2006

The deformation behavior under three-point bend test was found to depend on the loading uniformity and the macrostructure for SiC reticulated porous ceramics (RPCs). However, this dependence of loading uniformity is alleviated by improved macrostructure with fewer flaws and clogged pores. Even, this dependence becomes less important as the struts become thicker and stronger. The bend result of RPCs with highly uniform macrostructure is in excellent agreement with the GA (Gibson and Ashby) model, but the one with un-uniform macrostructure deviates from the GA model, suggesting that the macrostructure plays an important role in deformation behavior of RPCs under bend.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.606-607
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• 2006

A porous material with a surface layer was fabricated using glass abrasive sludge and expanding agents. The glass abrasive sludges were mixed with expanding agents and compacted into pellets. These pellets were sintered in the range of $700-900^{\circ}C$ for 20min. The sintered porous materials had a surface layer with smaller pores and inner parts with larger pores. The surface layer and pores controlled the absorption ratio and physical properties.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.62-67
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• 1999

The RP&M(Rapid Prototyping and Manufacturing) is the most appropriate technology for the small-lot production system, in which the production cycle is getting shorter owing to various needs from consumers. Recently RP products which are made of plastics, wax, and paper are used to verify the design of samples. But these products cannot be applied to the real mold because the strength enough to be a mold cannot be given by soft materials such as plastics. So RP products are copied to AFR(Al powder Filled Resin) molds or metal molds, which is called the RP&M. In this paper, RP&M is applied to a casting process. A porous casting mold, which is made from ceramic powder and binder, is used for rapid tooling of aluminum shoes molds.

• Journal of the Korean Ceramic Society
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• v.43 no.8 s.291
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• pp.509-514
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• 2006

In this study, chopped Hi-Nicalon SiC fiber Reinforced Porous Reaction Bonded SiC (RBSC) composites and it fabrication process were developed by using Si melt infiltration process. The porosity and average pore size in fabricated chopped SiC fiber reinforced porous RBSC composites were in the range of $30{\sim}40%$ and $40-90{\mu}m$, which mainly determined by the SiC powder size used as starting material and amount of residual Si in porous composites. The maximum flexural strength of chopped SiC fiber reinforced porous RBSC composite was as high as 80 MPa. The delayed fracture behavior was observed in chopped SiC fiber reinforced porous RBSC composites upon 3-point bending strength test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.523-524
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• 2012