• Title/Summary/Keyword: Porous SiC

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Fabrication of SiC Fiber Reinforced Porous Reaction Bonded SiC Composite and Its Mechanical Properties (SiC Fiber 강화 다공질 반응 소결 탄화규소 Composite의 제조 및 기계적 특성)

  • Han, Jae-Ho;Park, Sang-Whan
    • 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.

Characteristics of porous 3C-SiC thins formed by anodization (양극 산화법으로 형성된 다공질 3C-SiC 막의 특성)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2009.11a
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    • pp.45-45
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    • 2009
  • This paper describes the formation of porous 3C-SiC by anodization. 3C-SiC thin films were deposited on p-type Si(100) substrates by APCVD using HMDS (Hexamethyildisilane: $Si_2(CH_3)_6$). UV-LED(380 nm) was used as a light source. The surface morphology was observed by SEM and the pore size was increased with increase of current density. Pore diameter of 70 ~ 90 nm was achieved at 7.1 $mA/cm^2$ current density and 90 sec anodization time. FT-IR was conducted for chemical bonding of thin film and porous 3C-SiC. The Si-H bonding was observed in porous 3C-SiC around wavenumber 2100 $cm^{-1}$. PL shows the band gap enegry of thin film (2.5 eV) and porous 3C-SiC (2.7 eV).

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Effects of In-situ doping Concentration on the Characteristics of Porous 3C-SiC Thin Films (In-situ 도핑량이 다공성 3C-SiC 박막의 특성에 미치는 영향)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.6
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    • pp.487-490
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    • 2010
  • This paper describes the elecrtical and optical characteristics of $N_2$ doped porous 3C-SiC films. Polycrystalline 3C-SiC thin films are anodized by $HF+C_2H_5OH$ solution with UV-LED exposure. The growth of in-situ doped 3C-SiC thin films on p-type Si (100) wafers is carried out by using APCVD (atmospheric pressure chemical vapor deposition) with a single-precursor of HMDS (hexamethyildisilane: $Si_2(CH_3)_6)$. 0 ~ 40 sccm $N_2$ was used for doping. After the growth of doped 3C-SiC, porous 3C-SiC is formed by anodization with $7.1\;mA/cm^2$ current density for anodization time of 60 sec. The average pore diameter is about 30 nm, and etched area is increased with $N_2$ doping rate. These results are attributed to the decrease of crystallinity by $N_2$ doping. Mobility is dramatically decreased in porous 3C-SiC. The band gaps of polycrystalline 3C-SiC films and doped porous 3C-SiC are 2.5 eV and 2.7 eV, respectively.

Formation of porous 3C-SiC thin film by anodization with UV-LED (양극산화법과 UV-LED를 이용한 다공성 3C-SiC 박막 형성)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Journal of Sensor Science and Technology
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    • v.18 no.4
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    • pp.307-310
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    • 2009
  • This paper describes the formation of porous 3C-SiC by anodization. 3C-SiC thin films were deposited on p-type Si(100) substrates by APCVD using HMDS(Hexamethyildisilane: $Si_2(CH_3)_6$). UV-LED(380 nm) was used as a light source. The surface morphology was observed by SEM and the pore size was increased with increase of current density. Pore diameter of 70 $\sim$ 90 nm was achieved at 7.1 mA/cm$^2$ current density and 90 sec anodization time. FT-IR was conducted for chemical bonding of thin film and porous 3C-SiC. The Si-H bonding was observed in porous 3C-SiC around wavenumber 2100 cm$^{-1}$. PL shows the band gap enegry of thin film(2.5 eV) and porous 3C-SiC(2.7 eV).

Electrical and optical characteristics of porous 3C-SiC thin films with dopants (도핑량에 따른 다공성 3C-SiC 박막의 전기 및 광학적 특성)

  • Kim, Kan-San;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2010.06a
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    • pp.27-27
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    • 2010
  • This paper describes the electrical and optical characteristics of $N_2$ doped porous 3C-SiC films. Average pore diameter is about 30 nm and etched area was increased with $N_2$ doping rate. The mobility was dramatically decreased in porous 3C-SiC. The band gaps of polycrystalline 3C-SiC films and doped porous 3C-SiC were 2.5 eV and 2.7 eV, respectively.

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Deposition and Photoluminescence Characteristics of Silicon Carbide Thin Films on Porous Silicon (다공성실리콘 위의 탄화규소 박막의 증착 및 발광특성)

  • 전희준;최두진;장수경;심은덕
    • Journal of the Korean Ceramic Society
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    • v.35 no.5
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    • pp.486-492
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    • 1998
  • Silicon carbide (SiC) thin films were deposited on the porous silicon substrates by chemical vapour de-position(CVD) using MTS as a source material. The deposited films were ${\beta}$-SiC with poor crystallity con-firmed by XRD measurement. It was considered that the films showed the mixed characteistics of cry-stalline and amorphous SiC where amorphous SiC where amorphous SiC played a role of buffer layer in interface between as-dep films and Si substrate. The buffer layer reduced lattice mismatch to some extent the generally occurs when SiC films are deposited on Si. The low temperature (10K) PL (phtoluminescence) studies showed two broad bands with peaks at 600 and 720 for the films deposited at 1100$^{\circ}C$ The maximum PL peak of the crystalline SiC was observed at 600 nm and the amrophous SiC of 720 nm was also confirmed. PL peak due the amorphous SiC was smaller than that of the crystalline SiC, PL of porous Si might be disapperared due to densification during heat treatment.

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Preparation and Characterization of Porous Silicon and Carbon Composite as an Anode Material for Lithium Rechargeable Batteries

  • Park, Junsoo;Lee, Jae-Won
    • Journal of Powder Materials
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    • v.22 no.1
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    • pp.15-20
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    • 2015
  • The composite of porous silicon (Si) and amorphous carbon (C) is prepared by pyrolysis of a nano-porous Si + pitch mixture. The nano-porous Si is prepared by mechanical milling of magnesium powder with silicon monoxide (SiO) followed by removal of MgO with hydrochloric acid (etching process). The Brunauer-Emmett-Teller (BET) surface area of porous Si ($64.52m^2g^{-1}$) is much higher than that before etching Si/MgO ($4.28m^2g^{-1}$) which indicates pores are formed in Si after the etching process. Cycling stability is examined for the nano-porous Si + C composite and the result is compared with the composite of nonporous Si + C. The capacity retention of the former composite is 59.6% after 50 charge/discharge cycles while the latter shows only 28.0%. The pores of Si formed after the etching process is believed to accommodate large volumetric change of Si during charging and discharging process.

Thermal and Mechanical Properties of a N2 Doped Porous 3C-SiC Thin Film (질소가 도핑된 다공질 3C-SiC 박막의 열적, 기계적 특성)

  • Kim, Kang-San;Chung, Gwiy-Sang
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.8
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    • pp.651-654
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    • 2010
  • This paper describes the thermal and mechanical properties of doped thin film 3C-SiC and porous 3C-SiC. In this work, the in-situ doped thin film 3C-SiC was deposited by using atmospheric pressure chemical vapor deposition (APCVD) method at $120^{\circ}C$ using single-precursor hexamethyildisilane: $Si_2(CH_3)_6$ (HMDS) as Si and C precursors. 0~40 sccm $N_2$ gas was used as doping source. After growing of doped thin film 3C-SiC, porous structure was achieved by anodization process with 380 nm UV-LED. Anodization time and current density were fixed at 60 sec and 7.1 mA/$cm^2$, respectively. The thermal and mechanical properties of the $N_2$ doped porous 3C-SiC was measured by temperature coefficient of resistance (TCR) and nano-indentation, respectively. In the case of 0 sccm, the variations of TCR of thin film and porous 3C-SiC are similar, but TCR conversely changed with increase of $N_2$ flow rate. Maximum young's modulus and hardness of porous 3C-SiC films were measured to be 276 GPa and 32 Gpa at 0 sccm $N_2$, respectively.

Effect of Si Addition on Resistivity of Porous SiC-Si Composite for Heating Element Application (다공성 SiC-Si 복합체의 전기비저항에 미치는 Si 첨가량의 영향)

  • Jun, Shinhee;Lee, Wonjoo;Kong, Young-Min
    • Korean Journal of Materials Research
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    • v.25 no.5
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    • pp.258-263
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    • 2015
  • To fabricate porous SiC-Si composites for heating element applications, both SiC powders and Si powders were mixed and sintered together. The properties of the sintered SiC-Si body were investigated as a function of SiC particle size and/or Si particle contents from 10 wt% to 40 wt%, respectively. Porous SiC-Si composites were fabricated by Si bonded reaction at a sintering temperature of $1650^{\circ}C$ for 80 min. The microstructure and phase analysis of SiC-Si composites that depend on Si particle contents were characterized using scanning electron microscope and X-ray diffraction. The electrical resistivity of SiC-Si composites was also evaluated using a 4-point probe resistivity method. The electrical resistivity of the sintered SiC-Si body sharply decreased as the amount of Si addition increased. We found that the electrical resistivity of porous SiC-Si composites is closely related to the amount of Si added and at least 20 wt% Si are needed in order to apply the SiCSi composites to the heating element.

Mechanical Properties of Porous Reaction Bonded Silicon Carbide (반응소결 탄화규소 다공체의 기계적 특성)

  • Hwang, Sung-Sic;Park, Sang-Whan;Han, Jae-Ho;Han, Kyung-Sop;Kim, Chan-Mook
    • Journal of the Korean Ceramic Society
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    • v.39 no.10
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    • pp.948-954
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    • 2002
  • Porous reaction bonded SiC with high fracture strength was developed using Si melt infiltration method for use of the support layer in high temperature gas filter that is essential to develop the next generation power system such as integrated gasification combined cycle system. The porosity and pore size of porous RBSC developed in this study were in the range of 32∼36% and 37∼90 ${\mu}m$ respectively and the maximum fracture strength of porous RBSC fabricated was 120 MPa. The fracture strength and thermal shock resistance of porous RBSC fabricated by Si melt infiltration were much improved compared to those of commercially available porous clay bonded SiC due to the formation of the strong SiC/Si interface between SiC particles. The characteristics of pore structure of porous RBSC was varied depending on the amounts of residual Si as Well as the size of SiC particle used in green body.