• Title/Summary/Keyword: $Si_3N_4$ composites

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Mechanical Properties of Silicon Carbide-Silicon Nitride Composites Sintered with Yttrium Aluminum Garnet (YAG상 첨가 탄화규소-질화규소 복합재료의 기계적 특성)

  • 이영일;김영욱;최헌진;이준근
    • Journal of the Korean Ceramic Society
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    • v.36 no.8
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    • pp.799-804
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    • 1999
  • Composites of SiC-Si3N4 consisted of uniformly distributed elongated $\beta$-Si3N4 grains and equiaxed $\beta$-SiC grains were fabricated with $\beta$-SiC,. $\alpha$-Si3N4 Al2O3 and Y2O3 powders. By hot-pressing and subsequent annelaing elongated $\beta$-Si3N4 grains were grown via$\alpha$longrightarrow$\beta$ phase transformation and equiaxed $\beta$-Si3N4 composites increased with increasing the Si3N4 content owing to the reduced defect size and enhanced crack deflection by elongated $\beta$-Si3N4 grains and the grain boundary strengthening by nitrogen incorporation. Typical flexural strength and fracture toughness of SiC-40 wt% Si3N4 composites were 783 MPa and 4.2 MPa.m1/2 respectively.

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The Fabrication of $Si_3N_4/SiC$ Nano-Composite ($Si_3N_4/SiC$ Nano Composite의 제조)

  • Lee, Su-Yeong;Lee, Han-Seop
    • 연구논문집
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    • s.23
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    • pp.165-171
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    • 1993
  • $Si_3N_4/Sic$. nano-composites were fabricated by hot-pressing, gas pressure sintering. The composites contained up to 50 wt. % of SiC. The mechanical properties such as strength, toughness, and hardness of the composite are compared each other. The flexural strength of the composites was improved significantly by introducing fine SiC particles into $Si_3N_4$ matrix, while the fracture toughness was not improved. The increase in flexural strength is attributed to the formation of uniformly elongated $\beta -Si_3N_4$ grains as well as the reduction of grain size.

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Effects of Carbon-coated SiC Whiskers on the Mechanical Properties of SiC Whisker Reinforced Silicon Nitride Ceramic Composite (SiC 휘스커 강화 질화규소 복합재료의 기계작 성질에 미치는 카본 코팅 SiC 휘스커의 영향)

  • 배인경;이영규;조원승;최상욱;장병국;임실묵
    • Journal of the Korean Ceramic Society
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    • v.36 no.10
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    • pp.1007-1015
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    • 1999
  • The Si3N4 composites reinforced with carbon-coated SiC whiskers were fabricated by hot-pressing at 180$0^{\circ}C$ for 2 hours to examine the effects of carbon-coated whiskers on the mechanical properties of SiC whisker reinforced Si3N4 composites. The flexural strength of the Si3N4 composites and Si3N4 monolith respectively. The weak interfacial bond between carbon-coated SiC whiskers and Si3N4 matrix which enhances the crack deflection and whisker pull-out could contribute to the improvement of mechanical properties of the composites.

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Fabrication and characterization of Copper/Silicon Nitride composites

  • Ahmed, Mahmoud A.;Daoush, Walid M.;El-Nikhaily, Ahmed E.
    • Advances in materials Research
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    • v.5 no.3
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    • pp.131-140
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    • 2016
  • Copper/silicon nitride ($Cu/Si_3N_4$) composites are fabricated by powder technology process. Copper is used as metal matrix and very fine $Si_3N_4$ particles (less than 1 micron) as reinforcement material. The investigated powder were used to prepare homogenous ($Cu/Si_3N_4$) composite mixtures with different $Si_3N_4$ weight percentage (2, 4, 6, 8 and10). The produced mixtures were cold pressed and sintered at different temperatures (850, 950, 1000, $1050^{\circ}C$). The microstructure and the chemical composition of the produced $Cu/Si_3N_4$ composites were investigated by (SEM) and XRD. It was observed that the $Si_3N_4$ particles were homogeneously distributed in the Cu matrix. The density, electrical conductivity and coefficient of thermal expansion of the produced $Cu/Si_3N_4$ composites were measured. The relative green density, sintered density, electrical conductivity as well as coefficient of thermal expansion were decreased by increasing the reinforcement phase ($Si_3N_4$) content in the copper matrix. It is also founded that the sintered density and electrical conductivity of the $Cu/Si_3N_4$ composites were increased by increase the sintering temperature.

Facture Prediction in SiC Fiber Reinforced $Si_3N_4$ Matrix Composites from Electrical Resistivity Measurements (전기저항측정에 의한 SiC섬유강화 $Si_3N_4$기 복합재료의 파괴예측)

  • Sin, Sun-Gi
    • Korean Journal of Materials Research
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    • v.10 no.5
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    • pp.364-368
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    • 2000
  • SiC fiber reinforced $Si_3N_4$ matrix composites combined with electrical conductive phases of carbon fiber and WC powder fabricated by hot pressing at 1773K. The ability to predict fracture in the ceramic matrix composites was evaluated by measuring simultaneous load-deflection and electrical resistanc difference-deflection curves in four point bending tests. The changes in electrical resistance differences closely corresponded to the fracture behavior of the composites. Different electrical conductive phases are suited to predicting different stages and rates of fracture. These obsevations how that it is possible to perform "in situ" fracture detection in ceramic composites.

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Effect of Sintering Time and Composition on Cutting Characteristics of $SiC-Si_3N_4$ Ceramic Tool ($SiC-Si_3N_4$ 세라믹공구의 소결시간과 조성변화가 절삭특성에 미치는 영향)

  • 박준석;김경재;이성구;권원태;김영욱
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.04a
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    • pp.321-326
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    • 2001
  • In the present study, $Si_3N_4-SiC$ ceramic composites that contained up to 20 wt% of dispersed SiC particles were fabricated via hot-pressing with an oxynitride glass. The microstructure, the mechanical properties, and the cutting performance of resulting ceramic composites were investigated. By fixing the composition as $Si_3N_4-20$ wt% SiC, the effect of sintering time on the microstructure, the mechanical properties, and the cutting performance were also investigated. For machining of gray cast i개n, the tool life increases with increasing the amount of SiC content in the composites; The tool life also increased with increasing the sintering time. The tool life of the home-made cutting tools was very close to that of commercial $Si_3N_4$ cutting tool. The superior cutting performance of $Si_3N_4-SiC$ ceramic cutting tools suggests the possibility to be a new ceramic tool material.

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Microstructures Of Continuously Porous SiC-Si3N4 Composites Fabricated Using Waste SiC Sludge (폐 SiC 슬러지를 이용하여 제조한 연속다공질 SiC-Si3N4 복합체의 미세조직)

  • Gain Asit Kumar;Lee Hee-Jung;Jang Hee-Dong;Lee Byong-Taek
    • Korean Journal of Materials Research
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    • v.15 no.3
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    • pp.177-182
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    • 2005
  • Large amounts of the waste SiC sludge containing small amounts of Si and organic lubricant were produced during the wire cutting process of the single silicon crystal ingots. The waste SiC sludge was purified by the washing process and the purified SiC powders were used to fabricate continuously porous $SiC-Si_3N_4$ composites using a fibrous monolithic process, in which carbon, $6wt\%\;Y_2O_3-2\;wt\%\;A1_2O_3$ and ethylene vinyl acetate were added as a pore-forming agent, sintering additives, and binder, respectively. In the burning-out process, carbon was fully removed and continuously porous $SiC-Si_3N_4$ composites were successfully fabricated. The green bodies containing SiC, Si particles and sintering additives were nitrided at $1410^{\circ}C$ in a flowing $N_2+10\%\;H_2$ gas mixture. Continuously porous composites were combined with SiC, ${\alpha}Si_3N_4,\;\beta-Si_3N_4$ and a few $\%$ of Fe phases. The pore size of the 2nd and the 3rd passed $SiC-Si_3N_4$ composites was $260\;{\mu}m$ and $35\;{\mu}m$ in diameter, respectively.

Microstructure Control and Mechanical Properties of Continuously Porous SiC-Si3N4 Composites (연속다공질 SiC-Si3N4 복합체의 미세구조 및 기계적 특성)

  • Paul Rajat Kanti;Gain Asit Kumar;Lee Hee-Jung;Jang Hee-Dong;Lee Byong-Taek
    • Korean Journal of Materials Research
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    • v.16 no.3
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    • pp.188-192
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    • 2006
  • The microstructures and mechanical properties of continuously porous $SiC-Si_3N_4$composites fabricated by multi-pass extrusion were investigated at different Si levels added. Si-powder with different weight percentages (0%, 5%, 10%, 15%, 20%) was added to the SiC powder to make the raw mixture powders, with $6wt%Y_2O_3-2wt%Al_2O_3$ as sintering additives, carbon ($10-15{\mu}m$) as a pore-forming agent, ethylene vinyl acetate as a binder and stearic acid ($CH_3(CH_2)_{16}COOH$) as a lubricant. In the continuously porous $SiC-Si_3N_4$ composites, $Si_3N_4$ whiskers like the hairs of nostrils were frequently observed on the wall of the pores. In this study, the morphology of the $Si_3N_4$ whiskers was investigated with the silicon addition content. In the composites containing of 10 wt% Si, a large number of $Si_3N_4$ whiskers was found at the continuous pore regions. In the sample to which 15 wt% Si powder was added, maximum values of about 101 MPa bending strength and 57.5% relative density were obtained.

Cutting Characteristics of SiC-based Ceramic Cutting Tools Part 1: Microstructure and Mechanical Properties of SiC-based Ceramic Cutting Tools (SiC계 세라믹 절삭공구의 절삭특성 평가 Part 1: SiC계 절삭공구의 미세구조와 기계적 특성)

  • Park, June-Seuk;Kim, Kyeug-Jae;Shim, Wan-Hee;Kwon, Won-Tae;Kim, Young-Wook
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.9
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    • pp.82-88
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    • 2001
  • In order to fulfil the requirements of the various performance profiles of ceramic cutting tools, six different SiC-based ceramics have been fabricated by hot-pressing (SiC--${Si}_3 {N}_4$composites) or by hot-pressing and subsequent annealing (monolithic SiC and SiC-TiC composites). Correlation between the annealing time and the corresponding microstructure and the mechanical properties of resulting ceramics have been investigated. The grain size of both ${Si}_3 {N}_4$and SiC in SiC-${Si}_3 {N}_4$composites increased with the annealing time. Monolithic SiC has the highest hardness, SiC-TiC composite the highest toughness, and the SiC-${Si}_3 {N}_4$composite the highest strength among the ceramics investigated. The hardness of SiC-${Si}_3 {N}_4$composites was relatively independent of the grain size, but dependent on the sintered density. The cutting performance of the newly developed SiC-based ceramic cutting tools will be described in Part 2 of this paper.

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Phase Equilibria and Reaction Paths in the System Si3N4-SiC-TiCxN1-x-C-N

  • H.J.Seifert
    • Journal of Powder Materials
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    • v.6 no.1
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    • pp.18-35
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    • 1999
  • Phase equilibria in the system Si3N4-TiC-TiCxN1-x-C-N were determined by thermodynamic calculations (CALPHAD-method). The reaction peaction paths for Si3N4-TiC and SiC-TiC composites in the Ti-Si-C-n system were simulated at I bar N2-pressure and varying terpreatures. At a temperature of 1923 K two tie-triangles (TiC0.34N0.66+SiC+C and TiC0.13N0.87+SiC+Si3N4) and two 2-phase fieds (TiCxN1-x+SiC; 0.13