• 한국분말재료학회지
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• 제18권4호
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• pp.327-331
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• 2011

In order to fabricate the porous metal with controlled pore characteristics, unique processing by using metal oxide powder as the source and camphene as the sublimable material is introduced. CuO powder was selected as the source for the formation of Cu metal via hydrogen reduction. Camphene-based CuO slurry, prepared by milling at $47^{\circ}C$ with a small amount of dispersant, was frozen at $-25^{\circ}C$. Pores were generated subsequently by sublimation of the camphene. The green body was hydrogen-reduced at $200^{\circ}C$ for 30 min, and sintered at $500-700^{\circ}C$ for 1 h. Microstructural analysis revealed that the sintered Cu showed aligned large pore channels parallel to the camphene growth direction, and fine pores are formed around the large pore. Also, it showed that the pore size was controllable by the slurry concentration.

• 한국주조공학회지
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• 제33권2호
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• pp.69-74
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• 2013

Silicon (Si) wafer was grown by using direct growth from Si melt and contaminations of wafer during the process were investigated. In our process, BN was coated inside of all graphite parts including crucible in system to prevent carbon contamination. In addition, coated BN layer enhance the wettability, which ensures the favorable shape of grown wafer by proper flow of Si melt in casting mold. As a result, polycrystalline silicon wafer with dimension of $156{\times}156$ mm and thickness of $300{\pm}20$ um was successively obtained. There were, however, severe contaminations such as BN and SiC on surface of the as-grown wafer. While BN powders were easily removed by brushing surface, SiC could not be eliminated. As a result of BN analysis, C source for SiC was from binder contained in BN slurry. Therefore, to eliminate those C sources, additional flushing process was carried out before Si was melted. By adding 3-times flushing processes, SiC was not detected on the surface of as-grown Si wafer. Polycrystalline Si wafer directly grown from Si melt in this study can be applied for the cost-effective Si solar cells.

• 한국항행학회논문지
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• 제14권3호
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• pp.426-431
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• 2010

태양전지용 웨이퍼 제조공정에 있어 Slurry의 가격 비중은 약 68% 정도로 매우 큰 비중을 차지하고 있기 때문에, 제조비용 절감측면과 Wafering 원가혁신 및 산업폐기물 처리비용 절감효과, 환경오염 방지를 위해 Slurry의 순환 사용은 필수적이다. 기존 Slurry를 재생하는 방식은 물리적인 원심분리(데칸터) 방식을 이용한 방법을 사용하고 있으나 미분(微粉)이 남아 있어 재생품질에 한계가 있고, 대부분 액체, 100% 오일과 분리되지 않은 상태로 재생된다. 이 상태를 건조시키는 경우도 순도가 많이 떨어진다. 본 논문에서는 원심분리(데칸터) 방식과 케미컬 방식을 함께 사용하여, 태양전지 Wafering 공정에서 필수적인 Slurry를 재생함에 있어, 원심분리에 의한 재생품질의 한계를 극복할 수 있는 재생기술을 개발하였고, Slurry 재생에 대한 Total Solution을 제공하여 성능을 향상시키고 재생 회수율을 높였다.

• Bulletin of the Korean Chemical Society
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• 제30권3호
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• pp.683-686
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• 2009

Slurry phase reaction of elemental silicon with methanol has been studied in the presence of copper using a small amount of cuprous chloride as an activator in DBT (dibenzyltoluene) at various temperatures from 200 ${^{\circ}C}$ to 320 ${^{\circ}C}$. Trimethoxysilane (1a) with a Si-H unit was obtained as the major product and tetramethoxysilane (1b) as the minor product. The reaction worked well using a 0.5 wt % CuCl as an activator. The optimum temperature for this direct synthesis of 1a was 240 ${^{\circ}C}$. Methoxysilanes were obtained in 95% yield with 81% selectivity to 1a from 85% conversion of elemental silicon.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.193-194
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• 2005

By the high-temperature pad conditioning process: The slurry residues in pores and grooves of the polishing pad were clearly removed. These clear pores and enlarged grooves made the slurry attack the oxide surface. The changed slurry properties by high-temperature pad conditioning process made the oxide surface hydro-carbonate to be removed easily.

• 한국세라믹학회지
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• 제53권6호
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• pp.622-627
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• 2016

The effects of the debinding atmosphere on the properties of sintered reaction-bonded $Si_3N_4$ (SRBSN) ceramics prepared by tape casting method were investigated. Si green tape was produced from Si slurry of Si powder, using 11.5 wt% polyvinyl butyral as the organic binder and 35 wt% dioctyl phthalate as the plasticizer. The debinding process was conducted in air and $N_2$ atmospheres at $400^{\circ}C$ for 4 h. The nitridation process of the debinded Si specimens was performed at $1450^{\circ}C$, followed by sintering at $1850^{\circ}C$ and 20 MPa. The results revealed that the debinding atmosphere had a significant effect on $Si_3N_4$ densification and thermal conductivity. Owing to the higher sintered density and larger grain size, the thermal conductivity of $Si_3N_4$ specimens debinded in air was higher than that of the samples debinded in $N_2$. Thus, debinding in air could be suitable for the manufacture of high-performance SRBSN substrates by tape casting.

• 한국세라믹학회지
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• 제33권5호
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• pp.479-484
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• 1996

The tribological properties of ceramics are very important in the application to engineering ceramic parts such as mechanical seal slurry valve disc and so on. In this study the effect of graphite addition on the mechanical and tribological properties of RBSC/graphite composites were investigated. The composites were prepared by adding graphite powder to the mixture of SiC powder metallic siliconcarbon black and alumina. Bending strength water absorption friction coefficient the amount of worn out material at a certain time and maximum surface roughness(Rmax) of the prepared composites were measured and crystalline phases were examined with XRD. The composite containing 5 vol% graphite powder showed improved bending strength due to high green density and decreased friction coefficient and wear resistance. The friction coefficient and the wear resistance of the composite were increased by adding graphite powder up to 10 vol% They decreased however as increasing the amount of graphite powder more that 10vol% There was no linear relationship between the tribological properties and bending strength of the composites.

• 한국기계가공학회지
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• 제2권1호
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• pp.32-38
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• 2003

Engineering ceramics have many unique characteristics both in mechanical and physical properties such as high temperature hardness, high thermal, chemical and electrical resistance. However, its machinability is very poor in conventional machining due to its high hardness and severe tool wear. In the current experimental study alumina($Al_2O_3$) was ultrasonically machined using SiC abrasives under various machining conditions to investigate the material removal rate and surface quality of the machined samples. Under the applied amplitude of 0.02mm, 27kHz frequency, three slurry ratios (abrasives water by weight) of 11, 13 and 15 with different tool shapes and applied pressure levels, the machining was conducted. Using the mesh number of 240 abrasive, slurry ratio of 11 and static pressure of $25kg/cm^2$, maximum material removal rate of $18.97mm^3/mm$ was achieved with mesh number of 600 SiC abrasives and static pressure of $30kg/cm^2$, best surface roughness of $0.76{\mu}m$ Ra was obtained.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.341-345
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• 2001

In this study, nano-sized powders of $Si0_2-0^{\sim}15mol%B_2O_3$ composition were prepared by sol-gel processing method using TEOS(Tetra ethyl ortho silicate) and $H_3BO_3$ solution. The powders were tape-cast on High silicate glass sheet(HSG) substrate and sintered to form a layer of undercladding for the planar light wave module, During the sol-gel processing, $H_2O/Si$ mole ratio were varied to modify the size of the powders in a range from 600 to 75nm. The dispersion of the powder was modified by changing the pH of the slurry. Sintering temperature of the tape was observed to decrease with the size of the powder and the $B_2O_3$ content in the powder. When the silica powders of 75-125nm in diameter containing 15mol% $B_2O_3$ were used, 98 TD% was obtained at $1250^{\circ}C$, which is approximately $300^{\circ}C$ reduction in sintering temperature compared with micrometer-sized powders.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.341-345
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• 2001

In this study, nano-sized powders of SiO$_2$-0∼15mo1%B$_2$O$_3$ composition were prepared by sol-gel processing method using TEOS(Tetra ethyl ortho silicate) and H$_3$BO$_3$ solution. The powders were tape-cast on High silicate glass sheet(HSG) substrate and sintered to form a layer of undercladding for the planar light wave module. During the sol-gel processing, H$_2$O/Si mole ratio were varied to modify the size of the powders in a range from 600 to 75nm. The dispersion of the powder was modified by changing the pH of the slurry. Sintering temperature of the tape was observed to decrease with the size of the powder and the B$_2$O$_3$ content in the powder. When the silica powders of 75∼125nm in diameter containing 15mo1% B$_2$O$_3$ were used, 98 TD% was obtained at 1250$^{\circ}C$, which is approximately 300$^{\circ}C$ reduction in sintering temperature compared with micrometer-sized powders.