• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.219-222
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• 2004

The effects of short fiber and particle hybrid reinforcement on fatigue crack propagation behaviors in aluminum matrix composites have been investigated. Single and hybrid reinforced 6061 aluminum containing same 20 $Al_2O_3\;volume\%$ with four different constituent ratios of short fibers and particles were prepared by squeeze casting method and tested to check the near-threshold and stable crack growth behavior. The fatigue threshold of the composites increased with portion of particle contents and showed the improved crack resistance especially in low stress intensity range. Addition of particle instead of short fiber also increased fracture toughness due to increase of inter-reinforcement distance. These increase in both fatigue threshold and fracture toughness eventually affected the fatigue crack growth behavior such that the crack growth curve shift low to high stress intensity factor value. Overall experimental results were shown that particle reinforcement was enhanced the fatigue crack resistance over the whole stress intensity factor range.

• 한국재료학회지
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• 제2권6호
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• pp.461-467
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• 1992

최근 선진국에서 강화되고 있는 CAFE(Corporate Average Fuel Economy :기업평균연비) 규제를 극복하기 위해서는 차량의 경량화가 필수적이며 이를 위해 기존의 금속재료에 비하여 비강도, 탄성계수, 인성등이 우수한 기계적 성질을 가지면서 고분자 기지의 복합재료에 비해서 고온강도, 전기 및 열전도도와 내마모성이 우수한 금속기지 복합재료의 개발은 필수적이고도 중요한 위치를 차지한다. 따라서 본 연구에서는 자동차용 부품재 및 일반산업용 재료로 사용되고 있는 AC4A Al합금에 Si$C_w$prefohm을 용탕 단조법으로 강화하여 복합재료를 제조란 후 matrix와 함계 기계적성질, 마멸특성, 조직실험을 행한 결과 용탕 단조법에 의한 AC4A/Si$C_w$ 복합재료의 최적 제조조건은 용탕온도 80$0^{\circ}C$, 금형은도 40$0^{\circ}C$, preform은도 750-80$0^{\circ}C$, 가압압력 75MPa이었으며 Si$C_w$강화재가 I/M재에 비하여 경도값은 두배이상으로 상승하였고 Si$C_w$ 20v/o에서는 가압에 의한 큰 효과는 없었다.

• 한국분말재료학회지
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• 제13권5호
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• pp.366-370
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• 2006

The microstructure and mechanical properties of hot-pressed $Al_2O_3/Cu$ composites with a different sintering temperature have been studied. The size of matrix grain and Cu dispersion in composites increased with increase in sintering temperature. Fracture toughness of the composite sintered at high temperature exhibited an enhanced value. The toughness increase was explained by the thermal residual stress, crack bridging and crack branching by the formation of microcrack. The nanocomposite, hot-pressed at $1450^{\circ}C$, showed the maximum fracture strength of 707 MPa. The strengthening was mainly attributed to the refinement of matrix grains and the increased toughness.

• Composites Research
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• 제12권5호
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• pp.12-22
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• 1999

알루미늄 기지 금속복합재료는 비강도, 비강성, 경도가 뛰어난 것으로 널리 알려져 있으며, 높은 마모 저항으로 인해 점점 중요한 재료로 인식되고 있다. 본 연구에서는 AC2B 알루미늄 합금을 기지재로 하고, 알루미나($Al_2O_3$) 및 탄소를 단섬유를 보강재로한 혼합금속복합재료를 제조하였다. 다양한 상대 마모 속도하에서의 연삭 마모 시험을 통해 금속복합재료의 상온 및 고온 마모 거동을 규명하였다. 금속복합재료의 마모 저항은 고속에서 보강재로 인해 향상되었다. 탄소 혼합 금속복합재료의 마모 저항은 탄소의 고체 윤활 효과로 인해 알루미나($Al_2O_3$) 복합재료보다 우수하였으며, 특히 고속에서의 내마모성이 가장 향상되었다. 금속복합재료의 마찰계수는 상온과 고온에서 상대 속도의 변화에도 큰 차이를 보이지 않았다.

• 한국주조공학회지
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• 제13권4호
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• pp.359-368
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• 1993

Mg-9wt.%Al and Mg-9wt.%-1.6wt%Zn/SiCp(particle size $40{\mu}m$) metal-matrix-composite specimens were manufactured by rheo-compocasting method, known for its effect of improving the wettability. The ceramic reinforcement particles(SiCp) were dispersed in the semi-solid magnesium alloy matrix slurry being vigorously stirred in a high frequency induction furnace under inert atmosphere. A microstructural study of the dispersed particles in the specimens, prepared under different conditions as regards the time(10min, 20min, 30min) and temperature of the stirring, was made with the aid of optical microscope and SEM. The effect of superheating was also observed. It is revealed that 30 minutes' stirring time of the semi-solid at 40% solid fraction temperature(Mg-9wt.%Al : $590^{\circ}C$, AZ91 : $576^{\circ}C$), as determined by the lever rule, gives a satisfactorily uniform distribution of the particles. The superheating is observed to enhance further the uniformity.

• 한국주조공학회지
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• 제13권6호
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• pp.547-554
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• 1993

Aluminum alloy matrix composites reinforced with various amounts of $Al_2O_3$ short fibers have been produced by rheo-compocasting accompanied by hot pressing. When composites reinforced with fibers are produced by rheo-compocasting, S-L process is the most effective method for homogeneous dispersion of fibers. A sound composites with the improved orientation(3 dimension${\rightarrow}$2 dimension) of the fibers and increased volume fraction of them have been fabricated through the hot pressing of the casted composites. Fibers are broken down when rheo-compocasting, hot pressing, and $T_6$ treating. Among them fibers are broken down most heavily in the hot pressing. And even in the case of the composite reinforced with 30 vol% fibers, which showed the hardest fiber break down, aspect ratio(11.6) is higher than critical aspect ratio(10.7). The fiber strengthening effect in the composites has showed upto 573K. As the test temperature increases to the range of 573K, the effect has been higher. The fracture of composites is controlled by fiber from room temperature to 473K, but the fracture of composites is controlled by interface between fiber and matrix alloy above 473K.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.692-696
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• 2001

Thermo-mechanical behavior and mechanical properties of intelligent polymer matrix composite with SMA fiber are experimentally studied. It is found that increments of compressive thermal strain is observed as the pre-strain and TiNi volume fraction increase. The smartness of the SMA 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 prestrained. In the paper, alloy is based on the general purpose commercial code ANSYS. And for the purpose of easy and fast user's analysis, it is developed the Graphical User Interface by using Tcl/Tk language.

• 멤브레인
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• 제31권1호
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• pp.61-66
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• 2021

본 연구는 현재 올레핀/파라핀 분리에서 사용되는 극저온 분리법을 대체하기 위한 촉진수송 분리막에 대한 연구이다. 촉진수송 분리 막을 상업화하기 위해서는 비용 절감 또한 매우 중요한 요소이다. 하지만 많은 연구가 이루어지고 있는 AgBF4는 상대적으로 고가인 은 염이기 때문에 이를 대체하기 위해 비교적 저렴한 AgCF3SO3를 이용하여 PEBAX-2533/AgCF3SO3/Al(NO3)3 복합막을 제조하였다. 분리막의 특성은 SEM, FT-IR, RAMAN을 통해 분석되었으며, 이번 연구를 통해 고분자 매트릭스가 장기 안정성에 영향을 준다는 사실을 확인하였다.

• 한국분말재료학회지
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• 제7권4호
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• pp.212-217
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• 2000

An optimum route to fabricate the $Al_2O_3/Cu$ nanocomposites with sound microstructure and improved mechanical properties was investigated. Microstructural investigations for the composites prepared using $Al_2O_3/Cu$-nitrate showed that fine Cu particles with average size of 150 nm were homogeneously distributed within the $Al_2O_3$ matrix grains and at the grain boundaries. Fracture strength of 953 MPa and toughness of 4.8 Mpa(equation omitted)m were measured for the composite. The strengthening and toughening of the composites are explained by the refinement of the microstructure and the crack bridging/deflection, respectively.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1063-1064
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• 2006

Mechanical properties of 7xxx series Al metal matrix composite (MMC) powders containing different amounts of ceramic were investigated. The ceramic contents of the starting powders were 5 wt.% or 10 wt.%. The powders were uniaxially cold compacted using a cylindrical die with a compacting pressure of 250 MPa and were sintered at $620^{\circ}C$ in a dry $N_2$ atmosphere for 60 min. For the heat treatment, sintered parts were solution treated at $475^{\circ}C$ and aged at $175^{\circ}C$. Compression tests were conducted to reveal the effect of $Al_2O_3$ particle content on the mechanical properties of the composites. Fractography was examined using a scanning electron microscope.