• Title/Summary/Keyword: Al matrix composite

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Mechanical Properties and Wear Behaviour of $Al/SiC/Al_{2}O_{3}$ Composite Materials ($Al/SiC/Al_{2}O_{3}$복합재료의 기계적 성질 및 마멸특성)

  • 임흥준;김영한;한경섭
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.10
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    • pp.2498-2508
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    • 1993
  • $Al/SiC/Al_{2}O_{3}$ hybrid composites are fabricated by squeeze infiltration method. From the misconstructive of $Al/SiC/Al_{2}O_{3}$ hybrid composites fabricated by squeeze infiltration method, uniform distribution of reinforcements and good bondings are found. Hardness value of $Al/SiC/Al_{2}O_{3}$ hybrid composites increases linearly with the volume fraction of reinforcement because SiC whisker and $Al_{2}$O$_{3}$ fiber have an outstanding hardness. Optimal aging conditions are obtained by examining the hardness of $Al/SiC/Al_{2}O_{3}$ hybrid composites with different aging time. Tensile properties such as Young's modulus and ultimate tensile strength are improved up to 30% and 40% by the addition of reinforcements, respectively. Failure mode of $Al/SiC/Al_{2}O_{3}$ hybrid composites is ductile on microstructural level. Through the abrasive wear test and wear surface analysis, wear behaviour and mechanism of 6061 aluminum and $Al/SiC/Al_{2}O_{3}$ hybrid composites are characterized under various testing conditions. The addition of SiC whisker to $Al/SiC/Al_{2}O_{3}$ composites gives rise to improvement of the wear resistance. The wear resistance of $Al/SiC/Al_{2}O_{3}$ hybrid composites is superior to that of Al/SiC composites. The wear mechanism of aluminum alloy is mainly abrasive wear at low speed range and adhesive and melt wear at high speed range. In contrast, that of $Al/SiC/Al_{2}O_{3}$ hybrid composites is abrasive wear at all speed range, but severe wear when counter material is stainless steel. As the testing temperature increases, wear loss of aluminum alloy decreases because the matrix is getting more ductile, but that of $Al/SiC/Al_{2}O_{3}$ hybrid composites is hardly varied. Oil lubricant is more effective to reduce the wear loss of aluminum alloy and $Al/SiC/Al_{2}O_{3}$ hybrid composites at high speed range.

Formation of SiC Particle Reinforced Al Metal Matrix Composites by Spray Forming Process(I. Microstructure) (분사성형법에 의한 SiC입자강화 알루미늄 복합재료의 제조 I. 미세조직에 대한 고찰)

  • Park, Jong-Sung;Kim, Myung-Ho;Bae, Cha-Hurn
    • Journal of Korea Foundry Society
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    • v.13 no.4
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    • pp.369-381
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    • 1993
  • Aluminum alloy(AC8A) matrix composites reinforced with SiC particles(10% in vol.) were fabricated by Centrifugal Spray Deposition(CSD) process. The microstructures were investigated in order to evaluate both the mixing mode between aluminum matrix and SiC particles, and the effect of SiC particles on the cooling behaviours of droplets during flight and preforms deposited. A non-continuum mathematical calculation was performed to explain and to quantify the evolution of microstructures in the droplets and preforms deposited. Conclusions obtained are as follows; 1. The powders produced by CSD process showed, in general, ligament type, and more than 60% of the powders produced were about 300 to 850 um in size. 2. AC8A droplets solidified during flight showed fine dendritic structure, but AC8A droplets mixed with SiC particles showed fine equiaxed grain structure, and eutectic silicon were formed to crystallize granularly between fine aluminum grains. 3. SiC particles seem to act as a nucleation sites for pro-eutectic silicon during solidification of AC8A alloy. 4. The microstructure of composite powders formed by CSD process showed particle embedded type, and resulted in dispersed type microstructure in preforms deposited. 5. The pro-eutectic silicon crystallized granularly between fine aluminum grains seem to prohibit grains from growth during spray deposition process. 6. The interfacial reactions between aluminum matrix and SiC particles were not observed from the deposit performs and the solidified droplets. 7. The continuum model seem to be useful in connecting the processing parameters with the resultant microstructures. From these results, it was concluded that the fabrication of aluminum matrix composites reinforced homogeneously with SiC particles was possible.

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Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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Microstructure and Strength Property of Liquid Phase Sintered $SiC_f$/SiC Composites (액상소결 $SiC_f$/SiC 복합재료의 미세조직 및 강도특성)

  • Lee, Moon-Hee;Cho, Kyung-Seo;Lee, Sang-Pill;Lee, Jin-Kyung
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.234-238
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    • 2008
  • The efficiency of fiber reinforced CMC(ceramic matrix composite) on the SiC materials have been investigated, in conjunction with the fabrication process by liquid phase sintering and the characterization. LPS-$SiC_f$/SiC composites was studied with the detailed analysis such as the microstructure, sintered density, flexural strength and fracture behavior. The applicability of carbon interfacial layer has been also investigated in the LPS process. Submicron SiC powder with the constant total amount and composition ratio of $Al_2O_3,\;Y_2O_3$ as sintering additives was used in order to promote the performance of the SiC matrix material. LPS-$SiC_f$/SiC composites were fabricated with hot press under the sintering temperature and applied pressure of $1820^{\circ}C$ and 20MPa for 1hr. The typical property of monolithic LPS-SiC materials was compared with LPS-$SiC_f$/SiC composites.

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Thermal Stability of Mechanically Alloyed Al-(6~3wt.%)Cr-(3~6wt/%)Zr Alloys (기계적 합금화법으로 제조된 Al-(6~3wt.%)Cr-(3~6wt.%)Zr 합금의 열적 안정성)

  • Yang, Sang-Seon;Lee, Gwang-Min
    • Korean Journal of Materials Research
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    • v.10 no.6
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    • pp.403-408
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    • 2000
  • The Al-Cr-Zr composite metal powders were prepared by mechanical alloying and consolidated by vacuum hot pressing. The microstructural characteristics and the thermal stability of the MA Al-Cr-Zr alloys were evaluated by means of microhardness measurement, XRD and TEM in order to develop high temperature, high strength aluminum alloys. The mechanical alloying was conducted in attritor with 300rpm for 20 hours. The density of the vacuum hot pressed Al-Cr-Zr alloy reached at 97% of theoretical one. After exposing at $300^{\circ}C$ for 100 hours, there is almost no variation in hardness change of the MA alloys. Even after exposing at $ 500^{\circ}C$ for 100 hours, the hardness of the alloy was decreased within 6% of the initial value. The fine stable $Al_3Zr\;and\; Al_{13}Cr_2$ intermetallics were formed at the stage of consolidation and heat treatment in aluminum matrix. The good thermal stability of the MA Al-Cr-Zr alloy can ab attributed to the role of the dispersoids, inhibiting grain growth of nanocrystalline, and the final grain size after heat treatment was less than 150nm.

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Aluminum Effect as Additive Material in Expanded Graphite/Sand Composite for High Thermal Conductivity

  • Areerob, Yonrapach;Nguyen, Dinh Cung Tien;Dowla, Biswas Md Rokon;Ali, Asghar;Oh, Won-Chun
    • Korean Journal of Materials Research
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    • v.27 no.8
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    • pp.422-430
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    • 2017
  • Al/expanded graphite was successfully synthesized through a facile method including ultrasonic and heat treatment. In the well-designed three dimensional structure, expanded graphite(EG) works as a conductive matrix to support coated Al particles. The effects of the fabrication parameters on the microstructures and thermal conductivities of these composites were investigated. As a result, it was found that composites with graphite volume fraction of 17.4-69.4 % sintered at $600^{\circ}C$/45MPa exhibit in-plane thermal conductivities of 380-940 W/mK, over 90 % of the predictions by rule of mixture. According to the non-destructive analysis results, the synergistic enhancement was caused by the formation of efficient thermally conductive pathways due to the hybrid of the differently sized EG. The structure integrates the advantages of expanded graphite as a conductive support, preserving the electrode activity and integrity and improving the electrochemical performance.

A Study on Unidirectionally Solidified Ni-base Eutectic Composites (일방향응고(一方向凝固)시킨 Ni기(基) 초내열(超耐熱) 공정복합재료(共晶複合材料)에 관(關)한 연구(硏究))

  • Lee, Joo-Hong;Hong, Yeong-Hwan;Hong, Jong-Hwi
    • Journal of Korea Foundry Society
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    • v.8 no.4
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    • pp.437-445
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    • 1988
  • The effect of interlamellar spacing on microstructural stability at high temperature was studied for unidirectionally solidified ternary $Ni\;/\;Ni_3Al-Ni_3$ Nb and binary $Ni-Ni_3Nb$ eutectic composite. The interlamellar spacing of both alloy systems were varied with the growth rate according to $"{\lambda}^2R=constant"$ relationship. As a result of isothermal heat treatments at high temperature it was considered that coarsening of lamellar structure was due to concentration gradient between the tip with a relatively small radius of curvature and the side of the thick lamellae with a larger radius of the opposite sign. Fault density was increased as the interlamellar spacing decreased. Therefore it is also considered that the higher coarsening rate of the specimen with the smaller interlamellar spacing was due to higher fault density. And the diference of coarsening rate between $Ni\;/\;Ni_3Al-Ni_3Nb$ and $Ni-Ni_3Nb$ eutectic composites was not observed when the interlamellar spacing was similar in size. This means that the presence of ${\gamma}'$ in ${\gamma}\;/\;{\gamma}'\;-{\delta}$ eutectic had no b arrier effect to diffusion through the ${\gamma}$ matrix.

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Effect of Hot Extrusion on the Mechanical Properties of 6061 Aluminum Alloy composites Reinforced with SiC whisker (SiC휘스커로 강화한 6061 Al합금 복합재료의 기계적 특성에 미치는 열간압출의 영향)

  • Kim, Jun-Su;Lim, Su-Geun
    • Journal of Korea Foundry Society
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    • v.16 no.2
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    • pp.132-140
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    • 1996
  • Both cast and extruded composites of SiC whisker reinforced 6061 Al alloy matrix were fabricated by high pressure infiltration of the alloy melt into the SiC preform and subsequent hot extrusion of the composite ingots. The micro structures, age hardening behavior and mechanical properties have been examined on the both cast and extruded composites of SiCw/6061. The cast composites of SiCw/6061 were obtained in which SiC whiskers were randomly oriented. Hot extrusion of these cast composites lead to alignment of the whisker in the direction of extrusion. Strengthening effect of whisker in the extruded composites is lower than that of the cast composites. The cast composites of SiCw/6061 showed higher thensile strength and lower elongation than extruded composites of SiCw/6061 at all testing temperatures. Lower tensile strength and higher elongation of the extruded composites were attributable to fine grain structures in which grain boundary sliding occruued preferentially at elevated temperatures.

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Efficient influence of cross section shape on the mechanical and economic properties of concrete canvas and CFRP reinforced columns management using metaheuristic optimization algorithms

  • Ge, Genwang;Liu, Yingzi;Al-Tamimi, Haneen M.;Pourrostam, Towhid;Zhang, Xian;Ali, H. Elhosiny;Jan, Amin;Salameh, Anas A.
    • Computers and Concrete
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    • v.29 no.6
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    • pp.375-391
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    • 2022
  • This paper examined the impact of the cross-sectional structure on the structural results under different loading conditions of reinforced concrete (RC) members' management limited in Carbon Fiber Reinforced Polymers (CFRP). The mechanical properties of CFRC was investigated, then, totally 32 samples were examined. Test parameters included the cross-sectional shape as square, rectangular and circular with two various aspect rates and loading statues. The loading involved concentrated loading, eccentric loading with a ratio of 0.46 to 0.6 and pure bending. The results of the test revealed that the CFRP increased ductility and load during concentrated processing. A cross sectional shape from 23 to 44 percent was increased in load capacity and from 250 to 350 percent increase in axial deformation in rectangular and circular sections respectively, affecting greatly the accomplishment of load capacity and ductility of the concentrated members. Two Artificial Intelligence Models as Extreme Learning Machine (ELM) and Particle Swarm Optimization (PSO) were used to estimating the tensile and flexural strength of specimen. On the basis of the performance from RMSE and RSQR, C-Shape CFRC was greater tensile and flexural strength than any other FRP composite design. Because of the mechanical anchorage into the matrix, C-shaped CFRCC was noted to have greater fiber-matrix interfacial adhesive strength. However, with the increase of the aspect ratio and fiber volume fraction, the compressive strength of CFRCC was reduced. This possibly was due to the fact that during the blending of each fiber, the volume of air input was increased. In addition, by adding silica fumed to composites, the tensile and flexural strength of CFRCC is greatly improved.

Manufacturing and Properties of CGI-based Composite Coating Layer Utilizing a Warm Spray Process and Cu-Ga and Cu-In Mixed Powders (Warm Spray 공정과 Cu-Ga 및 Cu-In 혼합 분말을 이용한 CGI계 복합 코팅층의 제조 및 특성)

  • Jeon, Min-Gwang;Lee, Myeong-Ju;Kim, Hyeong-Jun;Lee, Kee-Ahn
    • Journal of Powder Materials
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    • v.21 no.3
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    • pp.229-234
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    • 2014
  • This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and a mixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, the Cu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of $35.4{\mu}m$. Through the utilization of a warm spray process, a CIG-based composite coating layer of $180{\mu}m$ thickness could be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layer underwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, an annealing heat treatment was conducted at temperatures of $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ for 1 hour each. The microstructure analysis identified ${\alpha}$-Cu, $Cu_4In$ and $Cu_3Ga$ phases in the early mixed powder, while $Cu_4In$ disappeared, and additional $Cu_9In_4$ and $Cu_9Ga_4$ phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatment reduced from 0.75% (warm sprayed coating layer) to 0.6% (after $600^{\circ}C/1hr$. heat treatment), and hardness reduced from 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.