• Title, Summary, Keyword: $Si_3N_4$/SiC

Search Result 961, Processing Time 0.049 seconds

Fabrication and Properties of $SiC/Si_3N_4$ Hybrid Composite Materials ($SiC/Si_3N_4$ 하이브리드 복합체이 제조 및 특성)

  • Gang, Jong-Bong;Jo, Beom-Rae;Lee, Su-Yeong
    • Korean Journal of Materials Research
    • /
    • v.6 no.4
    • /
    • pp.428-435
    • /
    • 1996
  • 초미립 SiC분말과 SiC platelet을 2차성으로 Si3N4에 첨가하여 SiC/Si3N4 하이브리드 복합체를 가압소결로 제조한 후 2차상의 영향을 조사한 결과핫프레스법을 이용한 경우 SiC platelet은 Si3N4 기지 복합채의 치밀화를 저해하지 않고 초미립의 SiC 첨가는 Si3N4의 입성장을 효과적으로 억제하여 미세한 $\beta$-Si3N4의 grain을 형성함을 관찰하였다. 초미립 SiC첨가를 통한 복합체의 강도 증진은 상대적으로 $\beta$-Si3N4입자의 미세화에 의한 인성의 저하를 유도하나 SiC platelet을 첨가하여 급격한 강도 저하 없이 높은 인성을 갖는 하이브리드 복합체를 제조할 수 있었으며 SiC/Si3N4 하이브리드 복합체의 인성증진은 elongated $\beta$-Si3N4와 platelet SiC의 debonding에 의한 grain pull-out 영향임을 알 수 있었다.

  • PDF

Effect of SiC Particle Size on Microstructure of $Si_3N_4/SiC$ Nanocomposites ($Si_3N_4/SiC$ 초미립복합체의 미세조직에 미치는 SiC 입자크기의 영향)

  • 이창주;김득중
    • Journal of the Korean Ceramic Society
    • /
    • v.37 no.2
    • /
    • pp.152-157
    • /
    • 2000
  • Si3N4/SiC nanocomposite ceramics containing 5 wt%dispersed SiC particles were prepared by gas-pressure-sintering at 200$0^{\circ}C$ under nitrogen atmosphere. SiC particles with average sizes of 0.2 and 0.5${\mu}{\textrm}{m}$ were used, and the effect of the SiC particle size on the microstructure was investigated. The addition of SiC particles effectively suppressed the growth of the Si3N4 matrix grains. The effect of grain growth inhibition was higher in the nanocomposites dispersed with fine SiC. SiC particles were dispersed uniformly inside Si3N4 matrix grains and on grain boundaries. When the fine SiC particles were added, large fraction of the SiC particles was trapped inside the grains. On the other hand, when the large SiC particles were added, most of the SiC particles were located on grain boundaries. Typically, the fraction of SiC particles located at grain boundaries was higher in the specimen prepared from $\beta$-Si3N4 than in the specimen prepared from $\alpha$-Si3N4.

  • PDF

Effect of SiC volume fraction on mechanical properties and microstructure of $Si_{3}N_{4}/SiC$ nanocomposites (SiC 부피분율이 $Si_{3}N_{4}/SiC$ 초미립복합재료의 기계적 특성과 미세구조에 미치는 영향)

  • 황광택;김창삼;오근호
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.6 no.3
    • /
    • pp.386-391
    • /
    • 1996
  • SiC particles (average size is 270 nm) of 0, 10, 20, 30, 40 vol% were dispersed in $Si_{3}N_{4}$, and $Si_{3}N_{4}/SiC$ nanocomposites were fabricated by hot press. After sintering, matrix phase, ${\alpha}-Si_{3}N_{4}$ was transformed to ${\beta}-Si_{3}N_{4}$, and second phase, ${\beta}-SiC$ was not changed. No grain boundary crystalline phase by adding of sintering additives was detected. Grain growth of $Si_{3}N_{4}$ was supressed with increasing of SiC contents, and then fine grain was occurred. The highest fracture strength was obtained at 10 vol% SiC, and fracture toughness was decreased, but hardness was linearly increased with SiC content.

  • PDF

The Development of Microstructure in $Si_3N_4$-Bonded SiC Refractory ($Si_3N_4$ 결합 SiC 내화재료에 있어서 생성된 $Si_3N_4$의 미구조 변화)

  • 최덕균;이준근
    • Journal of the Korean Ceramic Society
    • /
    • v.19 no.2
    • /
    • pp.121-126
    • /
    • 1982
  • This paper deals with the $Si_3N_4$-bonded SiC refractory in terms of its microstructure development during nitridation. When mixture of SiC grains and fine Si power is fired under nitrogen atmosphere, an interlocking network of $Si_3N_4$ whiskers is formed by nitridation of Si. It is found that the strength of $Si_3N_4$-bonded SiC refractory is soley due to the physical nature of this interlocking whiskers. At the initial stage of nitridation, $Si_3N_4$ whisker forms in very thin and long shape and, with further nitridation, it becomes thicker with diameters up to 0.35$\mu\textrm{m}$. It is found that the mechanical strength of $Si_3N_4$-bonded SiC refractory depends on the degree of nitridation and the development of microstructure.

  • PDF

Syntheses of SiC and $SiC-Si_3N_4$ Powder from Jecheon Quartz (제천규석으로부터 SiC 및 $SiC-Si_3N_4$계 분말 합성)

  • 이홍림;배철훈;문준화
    • Journal of the Korean Ceramic Society
    • /
    • v.23 no.1
    • /
    • pp.67-73
    • /
    • 1986
  • SiC and $SiC-Si_3N_4$ powder were synthesized via the carbiding and carbiding-nitriding reaction of Jecheon quartz respectively using graphite as a reducing agent. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbiding-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $H_2$ atmosphere. $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ composite was obtained by the carbidint-nitriding reaction of Jecheon quartz-graphite mixture at 1, 35$0^{\circ}C$ in $N_2-H_2$ atmosphere. The ratio of $\beta$-SiC+($\alpha$+$\beta$)-$Si_3N_4$ content in a produced composite could be controlled by adjusting the reaction time and gaseous mixture.

  • PDF

Mechanical Properties of SiC-$Si_3$$N_4$Composites Containing $\beta$-$Si_3$$N_4$Seeds ($\beta$-$Si_3$$N_4$종자입자 첨가 SiC-$Si_3$$N_4$복합재료의 기계적 특성)

  • 이영일;김영욱;최헌진;이준근
    • Journal of the Korean Ceramic Society
    • /
    • v.38 no.1
    • /
    • pp.22-27
    • /
    • 2001
  • $\beta$-Si$_3$N$_4$종자입자 첨가가 소결조제로 Y-Mg-Si-Al-O-N계 oxynitride glass를 사용하여 일축가압 소결을 행한 SiC-Si$_3$N$_4$복합재료의 미세구조와 기계적 특성에 미치는 영향을 고찰하였다. 길게 자란 $\beta$-Si$_3$N$_4$입자들과 등방성의 $\beta$-SiC 입자들이 균일하게 분포된 미세구조를 얻었다. $\beta$-Si$_3$N$_4$종자입자 함량이 증가함에 따라 SiC-Si$_3$N$_4$복합재료의 강도와 파괴인성이 증가하였고, 이는 복합화에 기인하는 결함크기의 감소와 길게 자란 $\beta$-Si$_3$N$_4$입자에 의한 균열가교 및 균열회절 등에 기인하였다. SiC-70 wt% Si$_3$N$_4$복합재료의 대표적인 강도와 파괴인성은 각각 770 MPa과 6.2 MPa.m$^{1}$2/ 이었다.

  • PDF

Decomposition Behavior of Ferro-Si3N4 for High Temperature Refractory Application (고온 내화물 응용을 위한 질화규소철 (Ferro-Si3N4)의 분해거동)

  • Choi, Do-Mun;Lee, Jin-Seok;Choi, Sung-Churl
    • Journal of the Korean Ceramic Society
    • /
    • v.43 no.9
    • /
    • pp.582-587
    • /
    • 2006
  • Decomposition behavior of $ferro-Si_3N_4$was investigated with varying temperature and holding time in mud components for high temperature refractory applications. Porosities gradually increased with increasing temperature and holding time due to the carbothermal reduction of $Si_3N_4\;and\;SiO_2$. Silicon monoxide (SiO) as a intermediate resulted from evaporation of $Si_3N_4\;and\;SiO_2$ reacted with C sources to generate needle-like ${\beta}-SiC$ and Fe in $Si_3N_4$ acted as a catalyst in order to enhance growth of SiC grain with the preferred orientation. SiC generation yield increased with increasing holding time, all of the $Si_3N_4\;and\;SiO_2$ affected on SiC formation up to 2h. However, SiC generation was only dependent on residual $SiO_2$ over 2h, because the carbothermal reduction reaction of $Si_3N_4$ was no longer possible at that time.

Microstructure and Mechanical Properties of Ti-Si-C-N Coatings Synthesized by Plasma-Enhanced Chemical Vapor Deposition (PECVD 로 합성된 Ti-Si-C-N 코팅막의 미세구조 및 기계적 성질)

  • Hong, Yeong-Su;Kim, Gwang-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
    • /
    • /
    • pp.83-85
    • /
    • 2008
  • 4성분계 Ti-Si-C-N 코팅막은 $TiCl_4$, $SiH_4$, $CH_4$, Ar, 그리고 $N_2$ 가스 혼합체를 이용하여 RF-PECVD 기법에 의해 Si 와 AISI 304 기판위에 합성하였다. Ti-C-(0.6)-N(0.4) 조성의 코팅막에 Si를 첨가함으로 Ti(C,N) 결정질은 줄어들고, Si3N4 및 SiC 비정질상이 나타났다. Ti-Si(9.2 at.%)-C-N의 조성에서 나노 크기의 nc-Ti(C,N) 결정질을 비정질 a-Si3N4/SiC가 둘러싸고 있는 형태의 나노 복합체를 나타내었다. 경도 24 Gpa의 Ti-C-N 코팅막은 Si를 첨가함으로 Ti-Si(9.2 at.%)-C-N 조성에서 46 Gpa의 최고 경도를 나타내었으며, 마찰계수의 경우에도 Ti-C-N 코팅막에 Si를 첨가함으로 크게 낮아졌다.

  • PDF

Fabrication of $Si_3N_4-SiC$ Nanocomposites by Hot Pressing (Hot Pressing에 의한 $Si_3N_4-SiC$ 나노복합체의 제조)

  • 김성현;김인술;박홍채;오기동
    • Journal of the Korean Ceramic Society
    • /
    • v.31 no.9
    • /
    • pp.1021-1029
    • /
    • 1994
  • SiC ultrafine particles of 1, 10, 20 and 30 vol% were dispersed in $\alpha$-Si3N4 matrix and hot-pressed under the condition of 30 MPa at 1800 and 190$0^{\circ}C$ respectively. Physical, mechanical properties and microstructures of sintered Si3N4-SiC nanocomposites were investigated. Flexural strength and density of Si3N4-10 vol% SiC nanocomposites hot-pressed at 190$0^{\circ}C$ represented the 1002 MPa and 97.9%T.D respectively, and it was confirmed as a remarkable improvement of 67% compared to Si3N4 monolith. Fracture toughness was shown as 7.2 MPa.m1/2 when the same composition was hot pressed at 180$0^{\circ}C$. This effect was supposed to be due to the improvement of microstructure by the adequate suppression of the excessive growth of Si3N4 grain with SiC nano-particles.

  • PDF

Microstructure and Cutting Characteristics of SiC-$Si_3N_4$ Ceramic Cutting Tool (SiC-$Si_3N_4$ 세라믹 절삭공구의 미세구조 및 절삭특성)

  • Gwon, Won-Tae;Kim, Yeong-Uk
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.25 no.12
    • /
    • pp.1944-1949
    • /
    • 2001
  • Four SiC-Si$_3$N$_4$ceramic cutting tools with different composition have been fabricated by hot-pressing. Correlations among the annealing time, the corresponding microstructure and the mechanical properties of resulting ceramics have been investigated. The fracture toughness and the grain size of both SiC and Si$_3$N$_4$in SiC-Si$_3$N$_4$composites increased with the annealing time. 1\`he hardness of SiC-Si$_3$N$_4$composites was relatively independent of the grain size and the sintered density. These ceramic cutting tools were tested under various cutting conditions and compared with the commercial Si$_3$N$_4$ceramic cutting tools. The experimental results were compared in terms of tool life and cutting force. The performance of SiC-Si$_3$N$_4$ceramic cutting tool shows the possibility to be a new ceramic tool.