http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
논문 : 용접 및 접합 ; Al-Si-Mg-Cu-Ge 필러합금에 의한 6061알루미늄합금의 진공브레이징
이태원 ( Tae Won Lee ),이지환 ( Chi Hwan Lee ),이두면 ( Doo Myun Lee ),김종훈 ( Jong Hoon Kim ) 대한금속재료학회 ( 구 대한금속학회 ) 1998 대한금속·재료학회지 Vol.36 No.6
The vacuum brazing of 6061 aluminium alloy with Al-12Si-1Mg-5Cu-xGe(x=0, 10, 20wt.%) braze alloy has been conducted at temperatures ranged 530~570℃ for 60min under brazing pressure of 1MPa to investigate the braze joint microstructure. the joint strength and the wettability of braze alloy. The liquidus temperatures of braze alloys with Ge=0, 10, 20wt.% were 572℃, 558℃ and 541℃, respectively. The wettability of braze alloy was found to be improved with increasing the brazing temperature. Braze joint microstructure was varied with the brazing temperature. Under low brazing temperatures(≤550℃, the silicon and germanium, which are expected to be the elements present in the braze alloy, are observed at the braze joint. On the other hand, these elements were not detected under the brazing temperature of 570℃. This may be due to the diffusion of the elements into 6061 aluminium alloy. The joint strength was found to be increased with increasing the brazing temperature. The maximum joint strength was obtained at 570℃ brazing temperature and its value was 73% of tensile strength of the base metal.
무전해 도금 SiC 입자강화 Al기 복합재료의 인장특성에 미치는 제조공정의 영향
이지환,서병권,이두면,장갑돈 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.9
The effect of extrusion on tensile properties of the Ni-P coated SiC particle reinforced Al composites has been studied. The X-ray diffraction and DTA analysis revealed that the amorphous Ni deposits is crystallized into brittle Ni₃P intermetallic compound and Ni crystallite. After hot presssing, the tensile strength and elongation of composites reinforced with Ni-P coated SiC particle were decreased comparing with the uncoated SiC particle reinforced composites. It was suggested that the Ni₃P compound layer in Ni-P deposits acts as a crack initiation site during tensile loading. After hot extrusion, the tensile strength of the Ni-P coated composites was higher than that of uncoated composites, because Ni₃P intermetallic compound layers in Ni-P deposits were pulverized and then dispersed to the matrix by plastic deformation of Al matrix during hot extrusion. It is obviously shown that the micro-vickers hardness of the Ni-P coated composites is higher than that of uncoated composites. This is due to the disperssion of Ni₃P compound in AI matrix during extrusion process.
SiC 입자강화 Mg 합금기 복합재료의 제조에 관한 연구
이지환,이두면,이준서 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.2
The aim of this paper was to optimize the fabrication of SiC_P/Mg alloy composite using AZ91D Mg alloy machined chips which have the difficulty of the recycling. The mixtures of Mg alloy machined chips and SiC particles were consolidated by vacuum hot pressing(pressing pressure : 100MPa, pressing temperature : 410℃). Extrusion was conducted at 300℃ with ram speed of 13㎝/min under hot extrusion ratios 25 : 1 and 40 : 1. Tε treatment was performed up to 150h at 170℃ after extrusion. Mg alloy chips was also extruded and heat-treated at the same condition as a reference material. Microstructural observation and tensile test were carried out to investigate the effects of extrusion on the microstructure and mechanical property of the composite. Microstructural observation showed that both extruded composite and extruded Mg alloy chips have fine grain sizes due to dynamic recrystallization during hot extrusion. It has been observed that tensile strength of extruded composite is superior than that of extruded Mg alloy machined chips. This may be attributable to the effect of SiC particles and the fine grain size along the periphery of SiC particle. In the T_6 condition, extruded Mg machined chips showed a small decrease of tensffe strength, whereas extruded composite showed an increase of tensile strength. This may be because SiC particles restricted the grain growth of the Mg matrix during solution treatment.
다이캐스팅한 SiC p/Al 합금기 복합재료의 미세조직과 기계적성질
이태원,서병권,이두면,이지환 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.3
This study was focused to investigate the effect of die casting on the microstructure and mechanical properties of SiC_p(10 and 20vol.%)/Al alloy composites. Die casting was performed using the preheated mold at the pouring temperature of 650∼700℃ under the pressure of 916 ㎏f/㎠. The speeds of slow and high speed injection were 0.3∼0.4 and 1.4 m/s, respectively. It was found that the SiC particles were homogeneously distributed in refined Al matrix. This results from the rapid mixing of molten Al and SiC particles during injection and the improvement of segregation due to rapid solidification. Therefore, the tensile strength of SiC_p/Al alloy composites die cast at 700℃ appeared to be superior to that of the composites die cast at 650℃ with 10 and 20 volume fractions.
황산동 전해액을 사용한 동 전주층의 미세조직 및 기계적성질
이지환,이두면,김봉길 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.2
Effects of electrolysis conditions on the microstructure and mechanical properties of copper electro-formed layer have been investigated using the copper sulfate. Electroforming was conducted at bath temperature of 25 to 55℃ and current density of 3∼20A/d㎡ for 10 hours on silver mirror-treated silicon rubber. The microstructure of copper layer was found to be dependent upon the electrolysis condition. The microstructural observation revealed that fine grains in the copper electroformed layer were formed in low current density and at bath temperatures of 25∼35℃. The tensile strength and elongation of copper electroformed layer tended to increase with decreasing bath temperature, and the peak tensile strength showed 380 MPa at bath temperature of 25℃. The tensile strength showed the highest value of 300 MPa at 7A/d㎡ of current density, and decreased when the current density increased above 7A/ d㎡. The Ni coating, with a thickness of 20 ㎛, on the copper electroformed layer improved microhardness(Hv) significantly and tensile strength slightly because the thickness of the Ni coating is thin.
다이아몬드제트 용사법에 의한 NiCr 피막의 제조 및 열처리특성에 관한 연구
이지환,남기홍,이두면 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.8
The present study aims at investgating a spray condition and heat treatment effects on the microstructure and mechanical properties of NiCr coating layer by Diamond-Jet spray system. NiCr self fluxing powders were sprayed on the Cu-Ag substrate under various spray conditions such as distance and grit blasting of substrate, and then heat-treated at temperature range of 500∼1,000℃. Optimum spray condition was evaluated in relation with the mechanical properties and microstructure of the coating layer. In 150㎜ spray distance, the mechanical properties such as adhesive strength, microhardness and wear resistance approved to be excellent, comparing with 250 and 300 ㎜ spray distance is less than that of coating layer in 250㎜ and 300㎜. In grit blasting of the substrate, it was observed that the adhesive strength of coating layer blasted steel grit is superior to that of blasted Al₂O₃ #30 grit. After heat treatment of the NiCr coatings, it was found that the microhardness and wear resistance of the coatings increases with an increase of heat treatment temperature. In particular, the microhardness showed the highest value at 1,000℃. The porosity of the coatings was remarkably decreased with an increase of heat-treatment temperature. Also, diffusion layer(about 20㎛) was observed to be formed at the interface between the coating layer and Cu-Ag substrate at the temperature range of 900∼1,000℃.
SiCp/AZ91 Mg 기 복합재료의 인장특성에 미치는 강화상입도 및 열처리의 영향
이지환,이준서,이두면,김가연,안지환 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.7
The present study aims at investigating the effect of SiC particulates size and heat-treatment on the tensile properties of SiC_P/AZ91 Mg composites. The AZ91 Mg alloy powders were made by wet attrition milling from AZ91 Mg machined chips and the powders size was below 240㎛. The SiC particulates size used as a reinforcement was 8, 30 and 50㎛, respectively. The Mg powders and SiC particulates (10 vol%) were mixed using a V-blender for 2 hours. Both AZ91 Mg alloy powders and mixtures of AZ91 Mg alloy powders and SiC particulates were hot pressed at 400℃ to make round billets. The billets were hot extruded at extrusion temperature of 300℃ under extrusion ratio of 40:1. The extruded Mg matrix and SiC_P/AZ91 Mg composites were solution treated at 410℃ for 17 hours, quenched into ice water, and then aged at 170℃ for 40 hours. It was found that the ultimate tensile strength of as-extruded composites is much higher than that of the as-extruded Mg matrix. As SiC particulates size decreased, the U.T.S. of as-extruded composites tended to increase. This could be attributed to the matrix grain refinment caused by the present of SiC particulates and the reduction of crack formation by the fracture of SiC particulates during hot extrusion. After T_6 heat treatment, the U.T.S. of heat-treated composites was found to be superior to that of as-extruded composites. Also, the U.T.S. of the composites was considerably increased with decreasing particulates size after T_6 heat-treatment. The reason for this is the restriction of the matrix grain-coarsening by fine SiC particulates during solution treatment.
P 형 Bi0.5 Sb1.5 Te3 열전재료의 열간압출공정 및 열전특성
이지환,이두면,송준호,김성용 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.2
The thermoelectric properties of p-type Bi_(0. 5)Sb_(1. 5)Te₃ thermoelectric materials, which were fabricated by extrusion at temperature ranged from 300 to 500℃ with various amounts of Te dopants (0 to 6 %), were studied. The microstructure of the thermoelectric materials was investigated by optical microscopy and scanning electron microscopy. The microstructure of the extruded specimen was dense, fine-grained, and elongated along the extrusion direction. The relative density increased with increasing extrusion temperature. The highest relative density (99.6 %) was obtained by extrusion at 440℃. The value of figure of merit (2.94×10^(-3)/K) was the highest at the extrusion temperature of 440℃ and at the dopant of 4 wt% Te.