• 한국주조공학회지
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• 제21권1호
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• pp.7-14
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• 2001

The research on new DRA(discontinuous reinforced alloy) and CRA(continous reinforced alloy) composites has been carried out to improve the properties of ceramic fiber and particle reinforced metal matrix composites(MMCs). Effects of alloying elements and aging conditions on the microstructures and aging behavior of Al-Si-Cu-Mg-(Ni)-SiCp composite have been examined. The specimens used in this study were manufactured by duplex process. The first squeeze casting is the process to make precomposite and the second squeeze casting is the process to make final composite. The hardening behavior was accelerated with decreasing the size of SiCp particle in the composites. It is considered that the dislocation density increased with increasing SiCp size, due to the different thermal deformation between Al matrix and SiCp during quenching after the solution treatment. Peak aging time to obtain the maximum hardness in 3 ${\mu}m$ SiCp reinforced Al composite was reduced than that in large size(5, 10 ${\mu}m$) of SiCp because of difference in dislocation density. Aging hardening responce(${\Delta}H$ = $H_{Max}.-H_{S.T}$) of composites was greater than that of unreinforced Al alloy because of higher density of second phases in matrix.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.687-691
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• 2001

Al alloy matrix composite with TiNi shape memory fiber as reinforcement has been fabricated by hot pressing to investigate mechanical properties. The stress-strain behavior of the composites was evaluated at temperatures between 363K and room temperature as a function of pre-strain by using experimental and finite element analysis, and both cases showed that the tensile stress at 363K was higher than that of the room temperature. Especially, the tensile stress of this composite increases with increasing the amount of pre-strain, and it also depends on the volume fraction of fiber and heat treatment. The smartness of the composite is given due to the shape memory effect of the TiNi fiber which generates compressive residual stress in the matrix material when heated after being pre-strained.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.188-191
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• 2002

3-D orthogonal woven carbon/Al composites were fabricated using a pressure infiltration casting method. Especially, to minimize geometrical deformation of fiber pattern and $Al_4C_3$ formation, the process parameters of the minimum pressurizing force, melting temperature, delay and holding time of molten aluminum pressurizing was optimized through the PC-controlled monitoring system. Resonant ultrasound spectroscopy (RUS) was utilized to measure the effective elastic constants of 3-D orthogonal woven carbon/Al composites. The CTE measurement was conducted using strain gages in a heating oven.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.135-138
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• 2002

The purpose of this study is to investigate the lubricated wear properties of Saffil/Al, Saffil/$Al_2O_3/Al$ and Saffil/SiC/Al hybrid metal matrix composites fabricated by squeeze casting method. Wear tests were done on a pin-on-disk friction & wear tester with long sliding distance. The wear properties of the three composites were evaluated in many respects. The effects of Saffil, $Al_2O_3$ particles and SiC particles on the wear behavior of the composites under lubricated conditions were elucidated. Wear mechanisms were analyzed by observing the worn surfaces of the composites. The variation of coefficient of friction (COF) during the wear process was recorded by using a computer. Comparing with the dry sliding condition, all three composites showed excellent wear resistance when lubricated by liquid paraffin. Under intermediate load, Saffil/Al showed best wear resistance among them, and its COF value is the smallest. The dominant wear mechanism of the composites was microploughing, but microcracking also occurred for them to different extent.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.250-253
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• 2004

Emphasis has been placed on thin plate fabrication of plain woven carbon fabric reinforced Al matrix composites using liquid pressing process. The composite has potential applications for PDP rear plate. The process is to use the low pressure for infiltration of Al melt into plain woven carbon fabric as the Al melt is pressurized directly. The minimum pressure required for the infiltration was calculated from force balance equation, permeability measurements and compaction behavior of carbon fiber. Also, the melting temperature and the holding time have been optimized. In order to measure coefficient of thermal expansion (CTE) of the composites, the thermal strain measurement using strain gage was performed and the thermal conductivity of the composites was measured using laser flash method. The constituent materials of the composite are PAN type carbon fibers as reinforcements and 6061 Al alloys as matrices.

• 한국주조공학회지
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• 제17권2호
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• pp.195-206
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• 1997

AC8A matrix composites reinforced with Ni-aluminide were fabricated by squeeze casting process, and the characteristics and nature of the growth of Ni-aluminide phases at the interface between nickel and aluminurn were investigated. In the as-cast composites, the reaction layer between Ni skeleton and aluminum matrix was found to be $NiAl_3$, regardless of the casting temperatures and the kinds of preforms. During high temperature solution treatment the $NiAl_3$ layer grew and formed new $Ni_2Al_3$ layer. Because of presence of the porosity formed by Kirkendall effect at the interface between $NiAl_3$ and aluminum matrix, the tensile strength of composites was inferior to that of AC8A matrix alloy. However, the composites exhibited superior wear resistance due to the formation Ni-aluminide intermetallic phases. Composite A, of which Ni skeleton was fully transformed into Ni-aluminide, shows better wear resistance than that of composite B which still possessed some unreacted Ni skeleton.

• 한국분말재료학회지
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• 제10권3호
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• pp.195-200
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• 2003

Ni coated $Al_2O_3$ composite was successfully Prepared by the electroless deposition Process. The average size of Ni particles coated on the $Al_2O_3$ matrix powder was about 20 nm. It was hard to find any reaction compound as an impurity at interface between $Al_2O_3$ and Ni particles after sintering. The characterization of microstructure crystal structure and fracture behavior of the sintered body were investigated using XRD, TEM and Victors hardness tester, and compared with those of the sintered $Al_2O_3$ monolithic body. Many dislocations were observed in the Ni phase due to the difference of thermal expansion coefficient between $Al_2O_3$ and Ni phase, and no observed microcracks at their $Al_2O_3$ and Ni interface. In the $Al_2O_3$/Ni composite, the main fracture mode showed a mixed fracture with intergranular and transgranuluar type having some ,surface roughness. The fracture toughness was slightly increased due to the plastic deformation mechanism of Ni phase in the $Al_2O_3$/Ni composite.

• 동력기계공학회지
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• 제12권3호
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• pp.60-65
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• 2008

This study aims at investigating the wear properties of thermally sprayed $Al/Al_2O_3$ metal matrix composite(MMC) coating against different counterparts. $Al/Al_2O_3$ MMC coatings were fabricated using a flame spray system on an Al 6061 substrate. Dry sliding wear tests were performed using the sliding speeds of 0.2m/s and the applied loads of 1 and 2 N. AISI 52100, $Al_2O_3$, $Si_3N_4\;and\;ZrO_2$ balls(diameter: 8mm) were used as counterpart materials. Wear properties of $Al/Al_2O_3$ MMC coatings were analyzed using a scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDX). It was revealed that wear properties of $Al/Al_2O_3$ composite coatings were much influenced by counterpart materials. In the case of AISI 52100 used as counterparts, the wear rate of composites coating layer increased according to the increase of the applied load. On the contrary, in the case of ceramics used as counterparts, the wear rate of composites coating layer decreased according to the increase of the applied load.

• 한국분말재료학회지
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• 제11권3호
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• pp.259-264
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• 2004

Aluminum based metal matrix composite reinforced with SiC particles was fabricated by the powder-in sheath rolling method. A stainless steel tube with outer diameter of 12 mm and wall thickness of 1mm was used as a sheath. Mixture of aluminum powder and SiC particles of which volume content was varied from 5 to 20vol.% was filled in the tube by tap filling and then rolled to 75% reduction at ambient temperature. The rolled specimen was sintered at 56$0^{\circ}C$ for 0.5hr. The tensile strength of the (SiC)$_{p}$/Al composite increased with the volume content of SiC particles, and at 20vol.% it reached a maximum of 100㎫ which is 1.6 times higher than unreinforced material. The elongation decreased with the volume content of $Al_{2}$O$_{3}$ particles. The mechanical properties of the (SiC)$_{p}$/Al composite fabricated by the powder-in sheath rolling is compared with that of (Al$_{2}$O$_{3}$)$_{p}$/Al composite by the same process.ess.

• Composites Research
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• 제32권1호
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• pp.1-5
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• 2019

본 연구에서는 액상가압성형공정을 이용하여 고체적률 $TiB_2$ 입자가 균일하게 분산된 알루미늄 복합재료를 제조하고 미세조직과 기계적 물성을 분석하였다. 제조된 알루미늄 복합재료 내에 $TiB_2$는 약 56 Vol.% 존재하였으며 Al1050 기지재 내부에 $TiB_2$ 세라믹 강화재의 균일한 분산에 의한 분산강화 효과로 경도는 230.5 Hv로써 기지재(Al1050) 대비 약 10배, 인장강도는 306.4 MPa로 약 4.5배, 압축항복강도는 581.7 MPa로 약 9.8배 증가하였다.