• 한국재료학회지
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• 제28권9호
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• pp.499-505
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• 2018

This investigates the microstructure and mechanical properties of Al hybrid material prepared by electromagnetic duo-casting to determine the effect of heat treatment. The hybrid material is composed of an Al-Mg-Si alloy, pure Al and the interface between the Al-Mg-Si alloy and pure Al. It is heat-treated at 373, 573 and 773K for 1h and T6 treated (solution treatment at 773K for 1h and aging at 433K for 5h). As the temperature increases, the grain size of the Al-Mg-Si alloy in the hybrid material increases. The grain size of the T6 treated Al-Mg-Si alloy is similar to that of one heat-treated at 773K for 1h. The interface region where the micro-hardness becomes large from the pure Al to the Al-Mg-Si alloy widens with an increasing heat temperature. The hybrid material with a macro-interface parallel to the tensile direction experiences increased tensile strength, 0.2 % proof stress and the decreased elongation after T6 heat treatment. On the other hand, in the vertical direction to the tensile direction, there is no great difference with heat treatment. The bending strength of the hybrid material with a long macro-interface to the bending direction is higher than that with a short macro-interface, which is improved by heat treatment. The hybrid material with a long macro-interface to the bending direction is fractured by cracking through the eutectic structure in the Al-Mg-Si alloy. However, in the hybrid material with a short macro-interface, the bending deformation is observed only in the limited pure Al.

• 한국재료학회지
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• 제30권3호
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• pp.111-116
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• 2020

Two different casting speeds of 60 and 80mm/min are adopted to determine the effect of casting speed on the microstructure and mechanical properties of Al-Mg-Si/Al hybrid material prepared by duo-casting. The obtained hybrid material has a uniform and straight macro-interface between the pure Al side and the Al-Mg-Si alloy side at both casting speeds. When the casting speed is increased to 80mm/min, the size of primary α phases in Al-Mg-Si alloy decreases, without change of shape. Although the Al-Mg-Si alloy produced at higher casting speed of 80mm/min shows much higher ultimate tensile strength (UTS) and 0.2 % proof stress and lower elongation, along with higher bending strength compared to the case of the 60mm/min in casting speed, the tensile properties and bending strength of the hybrid material, which are similar to those of pure Al, are the same regardless of the increase of casting speed. Despite the different casting speeds, deformation and fracturing in hybrid materials are observed only on the pure Al side. This indicates that the macro-interface is well-bonded, allowing it to endure tensile and bending deformation in all hybrid materials.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.268-271
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• 2001

When compared to other composite materials such as FRP and MMC, hybrid composite material is more attractive one due to the high specific strength and the resistance to fatigue. However, the fracture mechanism of hybrid composite material is extremely complicated because of the bonding structure of metals and FRP. Recently, nondestructive technique has been used to evaluate the fracture mechanism of these composite materials. In this study, AE technique has been used to clarify the fracture mechanism and the degree of damage for Al 7075/CFRP hybrid composite material. It was found that AE event, energy and amplitude among AE parameters were effective to evaluate fracture process of Al 7075/CFRP composite material. In addition, the relationship between the AE signal and the characteristics of failure surface using optical microscope was discussed.

• 한국안전학회지
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• 제24권2호
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• pp.23-29
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• 2009

The hybrid composite materials are recently used in many field as an advanced material due to their high resistance to fracture. However, hybrid composite materials have several problems, especially delamination, compared with homogeneous materials such as an aluminum alloy, etc. In this study, we carried out the tensile test to study the tension failure appearances and tensile ultimate strength of CFRP/Al/CFRP hybrid composite materials. The CFRP material used in the experiment is a commercial material known as CU175NS in unidirectional carbon prepreg. Also Al/CFRP/Al hybrid composites with three kind length of a single edge crack were investigated for the relationship between an aluminium volume fraction and a crack length. The crack length was measured by a traveling microscope under a universal dynamic tester. Futhermore the stress intensity factor behavior was examined according to a volume fraction and an initial crack length ratio to a width.

• Composites Research
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• 제15권5호
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• pp.1-6
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• 2002

하이브리드 복합재료는 FRP나 MMC와 같은 복합재료에 비하여 높은 비강도, 내피로 특성을 가지고 있기 때문에 많은 관심을 받고 있다. 그러나 하이브리드 복합재료는 금속과 FRP의 결합구조로 되어있기 때문에 매우 복잡한 파손기구를 가지고 있다. 최근에는 비파괴 기법을 이용하여 이러한 복합재료의 파손기구를 평가하고자 하는 연구가 수행되어지고 있다. 본 연구에서는 음향방출 기법을 이용하여 Al7075/CFRP 하이브리드 복합재료에 대한 손상정도 및 파손기구를 명확히 하고자 하였다. 특히 AE 사상수, 에너지, 진폭과 같은 AE 파라미터들은 Al7075/CFRP 하이브리드 복합재료의 파손과정을 평가하는데 효과적이었다. 더불어, 광학현미경을 이용하여 AE 신호와 시험편의 표면소상 특성과의 관계를 비교, 검토하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.89-94
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• 2003

Hard coatings are known to improve the performance of cutting tools in aggressive machining applications, such as high speed machining. New superhard Ti-Al-Si-W films, characterized by a nanocomposite nano-sized (Ti,Al,Si)N crystallites embedded in amorphous $Si_3 N_4$ matrix, could be successfully synthesized on WC-Co substrates by a hybrid coating system of arc ion plating(AIP) and sputtering method. The hardness of Ti-Al-Si-N film increased with incorporation of Si, and had the maximum value ~50 GPa at the Si content of 9 at.%, respectively. And the X-ray diffraction patterns of Ti-Al-Si-N films with various Si content is investigated. In this study, Ti-Al-Si-N coatings were applied to end-mill tools made of WC-Co material by a hybrid coating system. Cutting tests fir the high-hardened material (STD11,$H_R$)C62 and their performances in high speed cutting conditions were studied. Also, the tool wear and tool lift of Ti-Al-Si-N with various si(6, 9, 19) contents were measured.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2328-2335
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• 2002

A hybrid composite material has many potential usage due to the high specific strength and the resistance to fatigue, when compared to other composite materials such as fiber reinforced plastic(FRP) and metal matrix composite(MMC). However, the fracture mechanism of hybrid composite material is extremely complicated because of the bonding structure of metals and FRP. In this study, Al 7075 sheets and carbon epoxy preprags were used to fabricate the hybrid composite. Recently, nondestructive technique has been used to evaluate the fracture mechanism of these composite materials. AE technique was used to clarify the microscopic damage behavior and failure mechanism of A17075/CFRP hybrid composite. It was found that AE paralneters such as AE event, energy and amplitude were effective to evaluate the failure process of Al 7075/CFRP composite. In addition, the relationship between the AE signal and the characteristics of fracture surface using optical microscope was discussed.

• 한국분말재료학회지
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• 제21권4호
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• pp.301-306
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• 2014

Titanium alloys are extensively used in high-temperature applications due to their excellent high strength and corrosion resistance properties. However, titanium alloys are problematic because they tend to be extremely difficult-to-cut material. In this paper, the powder synthesis, spark plasma sintering (SPS), bulk material characteristics and machinability test of hybrid $Ti_2AlC$ ceramic bulk materials were systematically examined. The bulk samples mainly consisted of $Ti_2AlC$ materials with density close to theoretical value were synthesized by a SPS method. Random orientation and good crystallization of the $Ti_2AlC$ was observed at $1100^{\circ}C$ for 10 min under SPS sintering conditions. Scanning electron microscopy results indicated a homogeneous distribution and nano-laminated structure of $Ti_2AlC$ MAX phase. The hardness and electrical conductivity of $Ti_2AlC$ were higher than that of Ti 6242 alloy at sintering temperature of $1000^{\circ}C{\sim}1100^{\circ}C$. Consequently, the machinability of the hybrid $Ti_2AlC$ bulk materials is better than that of the Ti 6242 alloy for micro-EDM process of micro-hole shape workpiece.

• 대한기계학회논문집
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• 제17권10호
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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.

• 한국분말재료학회지
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• 제20권4호
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• pp.285-290
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• 2013

$Ti_2AlN$ composites are a laminated compounds that posses unique combination of typical ceramic properties and typical metallic(Ti alloy) properties. In this paper, the powder synthesis, SPS sintering, composite characteristics and machinability evaluation were systematically conducted. The random orientation characteristics and good crystallization of the $Ti_2AlN$ phase are observed. The electrical and thermal conductivity of $Ti_2AlN$ is higher than that of Ti6242 alloy. A machining test was carried out to compare the effect of material properties on micro electrical discharge drilling for $Ti_2AlN$ composite and Ti6242 alloy. Also, mixture table as a kind of tables of orthogonal arrays was used to know how parameter is main effective at experimental design. Consequently, hybrid $Ti_2AlN$ ceramic composites showed good machining time and electrode wear shape under micro ED-drilling process. This conclusion proves the feasibility in the industrial applications.