• 한국분말재료학회지
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• 제9권1호
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• pp.43-49
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• 2002

Microstructural and mechanical characteristics of P/M 6061 Al alloy subjected to equal channel angular pressing (ECAP) were investigated. The P/M 6061 Al alloy had an intial grain size of approximately $20\mutextrm{m}$. An equiaxed ultra-fine grained structure with the mean grain size of $~50 \mutextrm{m}$ was obtained by four repetitive ECAP at 473 K. The microhardness of P/M 6061 Al alloy was drastically increased from about 40 Hv to 80 Hv by two repetitive ECAP at 373 K. However, the microhardness decreased with increasing ECAP temperature. The tensile stength of as-hot-pressed P/M 6061 Al alloy before ECAP was 95 MPa, whereas it increased to both 248 MPa after two repetitive ECAP at 373 K and 130 MPa after four repetitive ECAP at 473 K. The tensile properties of the ECAPed sample were compared with those of commercial cast 6061-O and 6061-T4 Al alloys.

• Journal of the Optical Society of Korea
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• 제11권3호
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• pp.133-137
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• 2007

We compare electroabsorption modulators (EAMs) with multiple quantum wells (MQWs) based on InGaAs(P)/InP and InGa(Al)As/InAlAs material systems. We carefully choose the quantum-well structures so that the structures based on different material systems have similar band-offset energies and excition-peak wavelengths. Assuming the same light wavelength of $1.55{\mu}m$, we show the transfer functions of EAMs with each quantum-well structure and calculate the escape times of photogenerated charge carriers. As the heavy-hole escape time of the quantum well based on InGaAs(P)/InP is much longer than those of photogenerated charge carriers of InGa(Al)As/InAlAs, the EAM based on the InGa(Al)As/InAlAs material seems to be more suitable for high-optical-power operation.

• 한국주조공학회지
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• 제20권2호
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• pp.89-96
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• 2000

The effects of modification processing on the refinement of primary Si and the wear behavior of hyper-eutectic Al-Si alloys have been mainly investigated. Refining effects of primary Si in Al-17%Si alloy was more efficient than that of B.390 alloy. Optimum condition of getting the finest primary Si microstructure was when AlCuP modifier is added into the melt at $750^{\circ}C$ and held it at $700^{\circ}C$ for 30 minutes. Wear loss in the specimens of as-cast condition decreases as the size of primary Si decreases, in the order of B.390 alloy, B.390 alloy with AlCuP addition, Al-17%Si alloy and Al-17%Si alloy with AlCuP addition. Wear loss in the aged condition of Al-17%Si alloy, B.390 alloy and B.390 alloy with AlCuP addition decreased due to the increase of compressive residual stress in the matrix by the aging treatment. While, wear loss increased in the aged specimens of Al-17%Si alloy with AlCuP addition and Hepworth addition in which compressive residual stress decreases by the aging treatment. Therefore, it is assumed that higher compressive residual stress in the matrix can reduce the wear loss in composite materials such as hyper-eutectic Al-Si alloys.

• Composites Research
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• 제12권3호
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• pp.36-44
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• 1999

In-situ process에 의한 $Al_2O_{3p}/Al$기 복합재료 제조시, Mg의 첨가형태와 함량, 공정온도 및 유지시간이 응용Al의 침투거동과 미세조직 및 경도에 미치는 영향을 조사하였다. Mg분말과 $Al_2O_3$입자의 혼합분말에 순 Al을 침투시켜 복합재를 제조하는 경우, 침투율에 영향을 주는 가장 유력한 변수는 Mg분말의 함량이며, Mg의 활발한 반응으로 $700^{\circ}C$의 낮은 온도에서도 침투가 가능했다. 한편 Al-Mg합금을 $Al_2O_3$입자에 침투시켜 복합재를 제조하는 경우 Mg함량과 공정온도에 관계없이 거의 동일한 침투율을 나타냈으며 침투 가능한 공정온도는 $800^{\circ}C$이었다. Mg과 $Al_2O_3$의 혼합분말로 제조한 복합재가 Al-Mg합금으로 제조한 복합재 보다 월등히 높은 경도를 나타냈으나, 과도한 계면방응에 의한 불균일한 강화상의 분산으로 경도의 산포도는 컸다.

• Tribology and Lubricants
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• 제26권1호
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• pp.68-72
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• 2010

A ceramic coating is a surface treatment method that is being used widely in the industrial field, recently. Ni-P plating is also being used widely because of its corrosion resistance and low cost. An anodizing method is applicable to aluminum alloy. An anodizing method generates a thick oxide layer on the surface and then, that heightens hardness and protects the surface. These surface treatments are applied to various mechanical components and treated surfaces relatively move one another. In this study, tribological characteristics of Ni-P plating and TiAlN coating on anodized Al alloy are compared. The counterpart, anodized Al alloy, is worn out abrasively by Ni-P plating and TiAlN coating that have higher hardness. Abrasively worn debris accumulated on the surfaces of Ni-P plating and TiAlN coating, and then transferred layer is formed. This transferred layer affects the amplitude of variation of friction coefficient, which is related to noise and vibration. The amplitude of variation of friction coefficient of Ni-P plating is lower than those of TiAlN coating during the tests.

• 한국주조공학회지
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• 제15권4호
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• pp.416-421
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• 1995

Recently Al-Cu-P alloys are used to refine primary Si of hypereutectic Al-Si alloys. Because it has inside AlP compound that acts as nucleation site in the melt, Al-Cu-P alloy has good refinement effect in lower holding temperature and after shoter holding times. In this study Al-Cu-P refinement agent was made by mechanical alloying method. When Al-13.5wt%Cu-1.5wt%P was alloyed mechanically for 30hr in Ar atmosphere by high energy ball mill, it had the refinement effect that showed primary Si size of about $30{\mu}m$ in Al-20wt%Si at $760^{\circ}C$, treated for 15min.

• 한국재료학회지
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• 제11권8호
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• pp.655-660
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• 2001

Metalorganic chemical vapor deposition (MOCVD)으로 성장한 $In_{0.5}$ ($Gal_{1-x}$ $Al_{x}$ )0.5P/GaAS 이중 이종접합 구조의 특성을 표면 광전압 (surface Photovoltage ; SPV) 측정으로 연구하였다. $In_{0.5}$($Gal_{1-x}$ $Al_{x}$ )0.5P/GaAS 이중 이종접합 구조의 SPV 측정값을 Lorentzian 피팅한 띠 간격에너지 ($E_{0}$ ) 값과 조성비 (x)로 구한 이론 값이 잘 일치하였다. 그리고 변조 주파수 의존성을 측정한 결과 SPV 신호의 형태는 변하지 않고, 신호의 크기만이 변하는 것은 광 조사에 따른 전기적 상태의 과도 현상에 따른 것이고, GaAs와 InGaAlP의 특성시간의 차이는 광 캐리어의 수명의 차이로 분석된다. 그리고 온도 의존성 측정으로 $In_{0.5}$ /($Gal_{1-x}$ $Al_{x}$ )0.5P/GaAS 이중 이종 접합 시료의 균일한 변형분포와 계면상태가 양호함을 알 수 있었다.

• 한국진공학회지
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• 제17권4호
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• pp.353-358
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• 2008

AlGaInP 기반 수직형 적색 LED (Light Emitting Diode)의 광추출효율을 증가시키기 위하여 화학적 etching 기술을 이용하여 n-AlGaInP 표면에 삼각꼴 모양의 거칠기를 형성하였다. Etching은 $H_3PO_4$계의 용액을 이용하여 화학적 etching을 진행 하였다. AlGaInP etching은 광추출효율의 증가와 밀접한 관련을 갖고 있으며 AFM (Atomic Force Microscope)을 이용하여 AlGaInP 표면을 분석하여 약 44 nm의 RMS (root-mean-square) 거칠기가 형성됨을 알 수 있었다. 광추출효율은 기존 수직형 적색 LED보다 거칠기가 형성된 수직형 적색 LED에서 41%의 높은 발광 효율을 보임으로써 고효율 수직형 적색 LED의 가능성을 보였다.

• 청정기술
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• 제18권4호
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• pp.404-409
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• 2012

본 연구는 교반강도 및 응집제 주입량의 변화에 따라 플럭의 성장특성이 인의 제거에 미치는 영향을 파악하고자 수행되었다. 본 연구에서는 Al/P 몰비를 1.0, 1.5와 2.0으로 급속혼화강도 G값을 100, 300과 500 $s^{-1}$로 변화시켜 수행하였다. 응집시 발생되는 응집지수(floc size index, FSI)와 크기가 다른 여과지를 이용하여 인의 제거율을 측정하여 성장 특성을 파악하였다. 연구결과 교반강도가 높을수록 용존인의 제거효율이 증가하였으며 Al/P 몰비가 낮을수록 교반강도의 영향이 컸다. T-P의 제거율은 Al/P 몰비 1.0 이하에서는 급속혼화 교반강도가 높을수록 높았으나 Al/P 몰비 1.0 이상에서는 G값 300 $s^{-1}$에서 가장 높은 제거 효율을 나타내었다. Al/P 비 1.0 이하에서는 G값 500 $s^{-1}$에서 가장 큰 FSI값을 나타내었으며, Al/P 몰비 1.0 이상에서는 G값 300 $s^{-1}$에서 가장 큰 FSI값을 나타내었다. 실제하수처리장 유출수를 대상으로 응집에 의한 인 제거에 Al/P 몰비와 급속혼화 강도의 영향은 인공조제수의 결과와 유사하였다.

• 한국세라믹학회지
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• 제25권2호
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• pp.136-142
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• 1988

β-Al2O3, which is used for solid electrolyte membrances in sodium-sulfur batteries, was prepared by sol-gel process. Sodium-n-propoxide NaOC3H7 and aluminum-isopropoxide Al(OC3H7)3 were hydrolyzated in the solution at pH 3, pH 7, pH 9 and pH 11, respectively. The sol-gel processed samples were calcined at several temperature steps, respectively and analysed by thermal analyser(DT-TGA), infrared spectrum analyser and X-ray diffraction analyser. The gelling rate of solution at pH 7 was much higher than that of the solution at pH 3. Thermal exchanging behavior of the gels at pH 3 were similar to Na2O·Al2O3·6H2O and, above pH 7, were similar to Na2O·Al2O3·3H2O. When samples' composition ratio was 9.13 : 90.87 [NaOC3H7:Al(OC3H7)3] at pH 7, β-Al2O3 was formed at 1100℃.