• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.83-87
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• 1999

The fabrication process and thermal properties of 50~71vol% SiCp/Al metal matrix composites (MMCs) were investigated. The 50~71vol% SiCp/Al MMCs fabricated by pressure infiltration casting process showed that thermal conductivities were 118~170W/mK and coefficient of thermal expansion (CTE) were 9.5~$6.5{\times}10^{-6}/K$. Specially, the thermal conductivity and CTE of 71vol%SiCp/Al MMCs were 115~156W/mK and 6~$7{\times}10^{-6}/K$. respectively, which showed a improved themal properties than the conventional electronic packaging materials such as ceramics and metals.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.58-62
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• 2000

The fabrication process and analysis of thermal properties of 50~76vo1% SiCp/Al metal matrix composites(MMCs) for heatsink materials in electronic packaging were investigated. The 50~76vo1% SiCp/Al MMCs fabricated by pressure infiltration casting process showed that thermal conductivities were 85~170W/mK and coefficient of thermal expansion(CTE) were ranged 10~6ppm1k. Specially, the thermal conductivity and CTE of 71vo1%SiCp/Al MMCs were ranged 115~156W/mK and 6~7ppm/K. respectively, which showed a improved thermal properties than the conventional electronic packaging materials such as ceramics and metals.

• 한국재료학회지
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• 제31권6호
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• pp.313-319
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• 2021

Understanding of effects of changes in the particle size of the matrix material on the mullite whisker growth during the production of porous mullite is crucial for better design of new porous ceramics materials in different applications. Commercially, raw materials such as Al₂O₃/SiO₂ and Al(OH)₃/SiO₂ are used as starting materials, while AlF₃ is added to fabricate porous mullite through reaction sintering process. When Al₂O₃ is used as a starting material, a porous microstructure can be identified, but a more developed needle shaped microstructure is identified in the specimen using Al(OH)₃, which has excellent reactivity. The specimen using Al₂O₃/SiO₂ composite powder does not undergo mulliteization even at 1,400 ℃, but the specimen using the Al(OH)₃/SiO₂ composite powder had already formed complete mullite whiskers from the particle size specimen milled for 3 h at 1,100 ℃. As a result, the change in sintering temperature does not significantly affect formation of microstructures. As the particle size of the matrix materials, Al₂O₃ and Al(OH)₃, decreases, the porosity tends to decrease. In the case of the Al(OH)₃/SiO₂ composite powder, the highest porosity obtained is 75 % when the particle size passes through a milling time of 3 h. The smaller the particle size of Al(OH)₃ is and the more the long/short ratio of the mullite whisker phase decreases, the higher the density becomes.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.201-202
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• 2002

The abrasive wear behaviour of $Al_2O_3$ particle-reinforced aluminium composite was investigated. The wear rate of the composite and the matrix alloy has been expressed in terms of the applied load, sliding distance and particle size using linear factorial design approach.

• Tribology and Lubricants
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• 제19권5호
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• pp.274-279
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• 2003

$Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

• 한국결정성장학회지
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• 제16권4호
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• pp.172-179
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• 2006

[ $Al_2O_3-MoO_3$ ]의 혼합물을 환원소성하면 $MoO_3$만 $900^{\circ}C$에서 Mo로 환원되고 $1300^{\circ}C$까지 $Al_2O_3$와 Mo간의 화합물은 형성되지 않았다. $Al_2O_3-MoO_3-MnO_2$, 혼합물의 경우, $900^{\circ}C$에서 먼저 $MnO_2$가 $MoO_3$와 반응하여 중간화합물 $Mn_2Mo_3O_8$를 형성하였다가. $1100^{\circ}C$와 $1300^{\circ}C$에서 $Mn_2Mo_3O_8$ 화합물은 사라지고 새로운 화합물 $MnAl_2O_4$가 생성되었다. $Al_2O_3$와 $MoO_3,\;MnO_2$의 혼합분말 중 Mo만이 선택적으로 환원되는 selective reduction process에 의해 $Al_2O_3/Mo/MnO_2$ 복합재를 제조하였다. $Al_2O_3/Mo$ 복합재의 경우 Mo의 함량이 증가함에도 불구하고 Mo입자가 $Al_2O_3$ matrix의 입성장을 억제하여 평균입경의 변화는 거의 없었다. 파괴강도는 $Al_2O_3$ matrix의 입성장 억제 현상 때문에 Mo의 함량이 증가함에 따라 증가하였다. 경도는 Mo의 낮은 경도값 때문에 약간 감소하였으나 반면에 파괴인성은 증가하였다. $Al_2O_3/Mo/MnO_2$ 복합재의 경우 $MnO_2$는 matrix의 입성장을 촉진시켰고, Mo와 $MnO_2$의 함량이 증가함에 따라 $MnO_2$의 입성장효과 때문에 오히려 낮은 파괴강도를 보였다. 경도는 입계에 존재하는 coalesced Mo 입자들과 matrix의 입성장 때문에 더욱 감소하였으나 반면에 파괴인성은 더욱 증가하는 경 향을 보였다.

• 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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• 제14권6호
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• pp.354-361
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• 2007

The bi-materials with Al-Mg alloy and its composites reinforced with SiC and $Al_2O_3$ particles were prepared by conventional powder metallurgy method. The A1-5 wt%Mg and composite mixtures were compacted under $150{\sim}450\;MPa$, and then the mixtures compacted under 400 MPa were sintered at $773{\sim}1173K$ for 5h. The obtained bi-materials with Al-Mg/SiCp composite showed the higher relative density than those with $Al-Mg/Al_2O_3$ composite after compaction and sintering. Based on the results, the bi-materials compacted under 400 MPa and sintered at 873K for 5h were used for mechanical tests. In the composite side of bi-materials, the SiC particles were densely distributed compared to the $Al_2O_3$ particles. The bi-materials with Al-Mg/SiC composite showed the higher micro-hardness than those with $Al-Mg/Al_2O_3$ composite. The mechanical properties were evaluated by the compressive test. The bi-materials revealed almost the same value of 0.2% proof stress with Al-Mg alloy. Their compressive strength was lower than that of Al-Mg alloy. Moreover, impact absorbed energy of bi-materials was smaller than that of composite. However, the bi-materials with Al-Mg/SiCp composite particularly showed almost similar impact absorbed energy to $Al-Mg/Al_2O_3$ composite. From the observation of microstructure, it was deduced that the bi-materials was preferentially fractured through micro-interface between matrix and composite in the vicinity of macro-interface.

• 동력기계공학회지
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• 제3권2호
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• pp.57-63
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• 1999

The fabrication of $Al_2O_3/Al$ composites by pressureless infiltration technique was made to investigate the effects of processing variables such as content of Mg, processing temperature and time on the infiltration behavior of molten Al and microstructure. When the pure Al was infiltrated into mixtures of Mg and $Al_2O_3$ powder, processing temperature required to spontaneous infiltration was decreased and critical processing temperature and Mg content were $700^{\circ}C$ and 3wt% respectively. The content of Mg was found the most powerful variable for infiltration of molten Al. The infiltration ratio increased with Mg content and processing temperature, however the $Al_2O_3/Al$ composites which were fabricated by high Mg content and processing temperature resulted in non uniform dispersion of $Al_2O_3$ particles by excessive interfacial reaction. XRD pattern indicated that $MgAl_2O_4$ and AIN was observed at the interface of $Al_2O_3$ particles and in the Al matrix as reaction products.

• Journal of Electrochemical Science and Technology
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• 제14권4호
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• pp.377-387
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• 2023

Ni-W/Al₂O₃ nano-composites were electrodeposited on mild steel substrate for mechanical and corrosion resistance applications. This study focused on the preparation of Ni-W/Al₂O₃ nano-composite coating with various quantity of Al₂O₃ incorporations. The addition of Al₂O₃ in the electrolytes were varied from 1-10 g/L in electrolytes and the Al₂O₃ incorporation in Ni-W/Al₂O₃ nano-composite coatings were obtained from 1.82 to 13.86 wt.%. The incorporation of Al₂O₃ in Ni-W alloy matrix influenced the grain size, surface morphology and structural properties were observed. The distributions of Al₂O₃ particle in alloy matrix were confirmed using electron microscopy (FESEM and TEM) and EDAX mapping analysis. The crystal structure informations were studied using X-ray diffraction method and it confirms that the deposits having cubic crystal structure. The better corrosion rate (0.87 mpy) and microhardness (965 HV) properties were obtained for the Ni-W/Al₂O₃ nano-composite coating with 13.86 wt.% of Al₂O₃ incorporations.