• Title/Summary/Keyword: whisker

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Microstructure and Mechanical Properties of Ni3Al Matrix Composites with Fine Aluminum Oxide by PM Method

  • Han, Chang-Suk;Choi, Dong-Nyeok
    • Korean Journal of Materials Research
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    • v.28 no.9
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    • pp.495-498
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    • 2018
  • Intermetallic compound matrix composites have been expected to be established as high temperature structural components. $Ni_3Al$ is a representative intermetallic alloy, which has excellent ductility even at room temperature by adding certain alloying elements. $Ni_3Al$ matrix composites with aluminum oxide particles, which are formed by the in-situ reaction between the alloy and aluminum borate whiskers, are fabricated by a powder metallurgical method. The addition of aluminum borate whiskers disperses the synthetic aluminum oxide particles during sintering and dramatically increases the strength of the composite. The uniform dispersion of reaction synthesized aluminum oxide particles and the uniform solution of boron in the matrix seem to play an important role in the improvement in strength. There is a dramatic increase in strength with the addition of the whisker, and the maximum value is obtained at a 10 vol% addition of whisker. The $Ni_3Al$ composite with 10 vol% aluminum oxide particles $0.3{\mu}m$ in size and with 0.1 wt% boron powder fabricated by the conventional powder metallurgical process does not have such high strength because of inhomogeneous distribution of aluminum oxide particles and of boron. The tensile strength of the $Ni_3Al$ with a 10 vol% aluminum borate whisker reaches more than twice the value, 930 MPa, of the parent alloy. No third phase is observed between the aluminum oxide and the matrix.

Mechanical Properties of Si3N4 Ceramic Composites with Aligned Whisker Seeds (배향된 휘스커 종자에 의해 제조된 질화규소 세라믹 복합체의 기계적 특성)

  • Kim, Han-Gil;Bang, Kook-Soo;Jung, Sang-Jin;Park, Chan
    • Journal of Ocean Engineering and Technology
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    • v.27 no.2
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    • pp.8-12
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    • 2013
  • Four kinds of silicon nitride composites with tri-laminate structure were prepared by stacking tapes with aligned ${\beta}-Si_3N_4$ whisker seeds. The composites were fabricated using a modified tape casting method for enhanced alignment of the whisker seeds. The relative densities of all four samples reached 99% at room temperature. The three-point flexural strengths of the samples according to the stacking sequences were measured at both room temperature and 1723 K. The high temperature strength of sample WWW was $457{\pm}14$ MPa. The fracture of sample WWW occurred mainly along the grain boundary. The room temperature strengths of samples OOO, OWO, WOW, and WWW were $430{\pm}32$ MPa, $470{\pm}19$ MPa, $700{\pm}14$MPa, and $940{\pm}14$ MPa, respectively.

Fracture Behaviors and Mechanical Properties of SiCf/SiC Composites Prepared by the Whisker Growing Assisted CVI Process (Whisker Growing Assisted 화학침착 공정으로 제조된 SiCf/SiC 복합체의 파괴거동과 기계강도 평가)

  • Kang, Seok-Min;Kim, Weon-Ju;Yoon, Soon-Gil;Park, Ji-Yeon
    • Journal of the Korean Ceramic Society
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    • v.46 no.5
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    • pp.484-487
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    • 2009
  • $SiC_f$/SiC composites with whiskers and pyrolytic carbon (PyC) coated whiskers in the matrix were fabricated for enhancement of the fracture behaviors by the whisker growing assisted chemical vapor infiltration (WA-CVI) process, respectively. $SiC_f$/SiC composites were also prepared by the conventional CVI process as reference material. The mechanical properties and fracture behaviors were analyzed by comparison of the two types of composites prepared by WA-CVI and conventional CVI. The densities of $SiC_f$/SiC composites were in the range of $2.6{\sim}2.65g/cm^3$. The flexural strengths of composite with whiskers and with those coated by PyC were 650 MPa and 600 MPa, respectively. The tensile strength of composites with whiskers was ${\sim}285$ MPa.

Material Properties of Squeeze Infiltrated Al Borate Whisker Reinforced Mg-3A1-2Ag-1Zn Matrix Composites (용탕가압침투법에 의한 알루미늄 보레이트 강화 Mg-3Al-2Ag-1Zn 금속복합재료의 물성)

  • Kang Hojune;Bae Gunhee;Park Yongha;Han Sangho;Park Yongho;Cho Kyungmox;Park Ikmin
    • Korean Journal of Materials Research
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    • v.15 no.12
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    • pp.791-795
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    • 2005
  • In this study, aluminum borate whisker reinforced Mg-3Al-2Ag-1Zn matrix composites were fabricated by the squeeze infiltration technique. The purpose is to develop materials for elevated temperature applications. Microstructure observation revealed successful fabrication of the metal matrix composites, namely no cast defects such as porosity and matrix/reinforcement interface delamination etc. High temperature hardness and creep rupture properties were improved significantly with addition of Ag to the Al borate whisker reinforced Mg alloy composite. $Mg_3Ag$ phase formed during aging heat treatment could improve creep properties of the Mg matrix composites.

Characteristics and Microstructure of Matrix Retaining Electrolyte in Phosphoric Acid Fuel Cell Prepared by Tape Casting (Tape Casting법으로 제조한 인산형 연료전지 전해질 매트릭스의 미세구조 및 특성)

  • 윤기현;허재호;장재혁;김창수
    • Journal of the Korean Ceramic Society
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    • v.31 no.4
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    • pp.375-380
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    • 1994
  • Matrices retaining electrolyte in phosphoric acid fuel cell were prepared with SiC to SiC whisker mixing ratios of 1:0.5, 1:1, 1:1.5, 1:2, 1:3 by tape casting method. When viscosity of the slurry was 5.9 poise and the SiC to SiC whisker mixing ratios were 1:1, 1:1.5, 1:2, the ranges of porosity, acid absorbency and bubble pressure were 80~90%, 2.5~6 and 700~2200 mmH2O, respectively. Those ranges are acceptable for a practical electrolyte-retaining matrix. With increasing the mixing ratio of SiC whisker to SiC, the porosity and the vol.% of large pores in the main pore size distribution which is between 1 and 10 ${\mu}{\textrm}{m}$, increased rapidly. Impedance spectroscopy was measured to know characteristics of matrix inside and contact region of matrix to catalyst layer. When the SiC to SiC whisker mixing ratio was 1:2, hydrogen ions were transported in the matrix most effectively because of high ionic conductivity and low activation energy due to high acid absorbency in spite of high interfacial resistance. The cell current density of the cell made using the matrix was 220 mA/$\textrm{cm}^2$ at 0.7 V.

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Impact behavior of including the boundary between A356/SiCw and Al alloy (Al alloy와의 경계면을 포함한 A356/SiCw의 충격거동)

  • 조종인;남현욱;한경섭
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.05a
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    • pp.97-100
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    • 2002
  • In this research, the impact behavior of the boundary between MMC-reinforced SiC whisker and Al alloy were studied. It is known that the resultant of the interfacial reaction between SiC whisker and Al alloy has brittle and low toughness property. In this paper, impact behavior of graded MMC & Al alloy shows the interfacial opening at the boundary. Generally this phenomenon is generated by thermal residual stress, brittle interfacial reaction resultant and difference of the deflection. So, these results may be interpreted as a macroscopic method of measuring the interfacial strength between matrix and reinforcement

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Effect of Al2O3 and SiC Whisker on Sintering and Mechanical Properties of Si3N3 Bonded SiC (첨가제 $Al_2O_3$ 및 SiC Whisker가 $Si_3N_3$ 결합 SiC 소결체 특성에 미치는 영향)

  • 백용혁;신종윤;정종인;권양호
    • Journal of the Korean Ceramic Society
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    • v.29 no.11
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    • pp.837-842
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    • 1992
  • SiC and Si mixtures dispersed by 0.5~10.0 wt% of Al2O3 and reinforced by SiC whisker were sintered to Si3N4 bonded SiC bodies at 140$0^{\circ}C$ in a N2 gas atmosphere, and the nitridation and mechanical properties of sintered bodies were investigated. From these observation, it is concluded that relative density and bending strength increased with the rising of nitridation and the highest nitridation ratio was obtained for a specimen having 1.5 wt% Al2O3. On the other hand, the amount of $\beta$-Si3N4 in the specimens containing Al2O3 more than 5.0 wt% was increased abruptly and the best in fracture toughness was sintered for a composits having 30 wt% SiC whiskers.

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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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Manufacture and Mechanical Properties of $ABO_w/AC4CH$ Composite Material ($ABO_w/AC4CH$복합재료의 제조 및 기계적 특성)

  • 허선철;박원조;허정원
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.5
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    • pp.188-194
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    • 2001
  • Metal matrix composites with whisker reinforcements have significant potential for demanding mechanical applications including defense, aerospace, and automotive industries. Especially, metal matrix composites, which are reinforced with aluminum borate whisker, have been used for the part of piston head in automobile because of good specific strength and wear resistance. Aluminum alloy-based metal matrix composites with whisker reinforcements have been produced using squeeze casting method, which is kind of an infiltration method. In this study, AC4CH-based metal matrix composites with $Al_{18}B$_4$O_{33}$ reinforcement have been produced using squeeze casting method, after T6 heat treatment, we evaluated mechanical properties of matrix and MMC composite were evaluated.

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Thermo-mechanical Properties and Microstructures of $ZTA-Al_2O_3$ Whisker Composites ($ZTA-Al_2O_3$ Whisker계 복합재료의 미세구조 변화에 따른 열적, 기계적 특성에 관한 연구)

  • 이문환;최성철;이응상
    • Journal of the Korean Ceramic Society
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    • v.30 no.6
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    • pp.457-468
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    • 1993
  • In oxide matrix-SiC(W) composites, instability and glassy phase formation due to oxidation at the high temperature and the diffusion of Si, respectively, cause brittle fracture and low reliability for ceramic materials. The mode of contribution in each mechanisms induced by matrix-whisker debonding, varies with the morphology of matrix-whisker interfaces. This work has described the dispersion behaviours and stabilization mechanisms in slip systems, and multiple toughening mechanisms by dint of two second phase different from each other when spherical ZrO2 and chemically stable Al2O3(W) is respectively added in Al2O3 matrix. To obtain complexshaped components, slip casted bodies were sintered at 1$600^{\circ}C$, 2hrs up to 98~99% R.D.. Multiple toughening mechanisms in comparison with theories reported until now will be discussed as a result of the phase analysis of ZrO2 by athermal behaviours and microstructural characterizations as well as measured mechanical properties.

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