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수분 : 점토비에 (粘土比) 따른 주물사의 (鑄物砂) 기계적 성질에 관한 연구
이계완,이추림 ( Kye Wan Lee,Choo Lim Lee ) 한국주조공학회 1984 한국주조공학회지 Vol.4 No.2
A Study on the Mechanical Properties of Molding Sand with Various Water/Clay Ratio A standard sample of molding sand was prepared by adding a various amount of bentonite, which has water/clay ratio from 0.4 to 0.6, into artificial sand, Hanyoung #6. The results obtained by measuring the room temperature properties of green mold are as follows. 1. This compressive strength of green molds which have 4% and 10% of bentonite decreased with increasing water/clay ratio, but the maximum strengths of 4.3 (psi) and 7.2 (psi) were observed in the samples with 6%, 8% bentonite respectively when the water/clay is 0.45. 2. The optimum water/clay ratio for strength and permeability increased from 0.4 to 0.5 with increasing clay. 3. The green compressive strength was proportional to the hardness. 4. Deformation increased with increasing water/clay ratio. 5. Flowability decreased with increasing water/clay ratio and clay content in molding sand.
구상흑연주철에서 초음파 전파속도에 미치는 흑연형상의 영향
이계완,양노석,박은수 ( Kye Wan Lee,No Seok Yang,Un Su Park ) 한국주조공학회 1989 한국주조공학회지 Vol.9 No.3
N/A The relationships between nodularity, tensile property and ultrasonic velocity were studied in ductile iron castings having similar matrix structure. Also, the effects of heat treatment and the number of graphite nodules on the ultrasonic velocity were investigated. The results were as follows 1. The ultrasonic velocity increased proportionally with increassing nodularity and tensile strength. 2. The ultrasonic velocity in annealed and normalized state decreased average 1.7% and 3.4% respectively than that in as cast state. 3. The ultrasonic velocity increased with increasing the number of graphite nodules. Therefore, ductile iron castings can be evaluated in the only case of castings having the same manufacturing history by ultrasonic velocity.
순 (純) Al 주괴의 (鑄塊) 응고조직에 미치는 주형 (鑄型) 점결재의 (粘結材) 영향에 관한 연구
최창옥,이계완 ( Chang Ock Choi,Kye Wan Lee ) 한국주조공학회 1985 한국주조공학회지 Vol.5 No.1
The effects of mold binders on the formation of equiaxed zone of 99.8% AL ingots were studied with various sand molds and metal mold. The formation of equiaxed crystals are increased by furan, cement, CO₂and metal mold, and decreased by greensand and shell mold. Pouring temperature moat be kept as low as possible to get a fine grain Structure and to increase of volume of equiaxed zone. The effect of surface roughness on volume of equiaxed zone were depend upon by the kind of mold binders. These are caused by separation of crystals from the mold wall in the initial stage of solidification before formation of the stable solid skin.
주형점결재에 (鑄型粘結材) 의한 Al-Cu 합금의 응고조직에 관한 연구
최창옥,이계완 ( Chang Ock Choi,Kye Wan Lee ) 한국주조공학회 1986 한국주조공학회지 Vol.6 No.1
The effects of various kind of molds on cast structures were studied. Al-4.5% C1i and Al-8% Cu alloys. Five kinds of sand molds which were mixed with different binders and a metal mold were used. Density, dendrite arm spacing and dendrite arm length of the cast alloys were greatly affected by quantities and materials of mold binders. The macrostructures examined were entirely equiaxed grains with little influences of types of molds. It is possibly due to the separation of growing crystals from the mold wall at the inital stage of solidification.
성연수,이계완 ( Yeon Soo Song,Kye Wan Lee ) 한국주조공학회 1987 한국주조공학회지 Vol.7 No.4
To investigate the grain refining mechanism of Al by the addition of Ti-B, the unidirectional solidifications of 99.9%Al and 99.7%Al were performed under the condition of varing the pouring temperature. The solidification modes of Al were studied by the cooling curve analyses, metallographic and microprobe examinations. The results were as follows: 1) Grains were most refined with an addition of 0.15wt.%Ti-0.021wt.%B but the grain size with 0.2wt.%Ti-0.028wt.%B was increased. 2) The grain size of 99.7wt.%Al was even more refined than that of 99.9wt,%Al with the same amount of Ti-B. 3) As the pouring temperature increased, the grain size of pure Al and an alloy with 0.lwt,%Ti-0.014wt.%B was increased. However, an alloy with 0.2wt.%Ti-0.028wt.%B did not show any effects of temperature. 4) TiC(Al-Ti) and (Al-Ti-C) were identified as nucleants for Al.
고 MOLE 비의 규산소다를 사용한 CO2 주형의 (鑄型) 강도개선에 관한 연구
김봉완,이계완 ( Bong Wan Kim,Kye Wan Lee ) 한국주조공학회 1987 한국주조공학회지 Vol.7 No.4
The influences of some factors on the variation of compression strength of CO₂process were investigated with an attention given to use of high SiO₂/Na₂O silicate, addition of organics and gassing operation. 1) Higher ratio binder offers faster rates of hardening with lower CO₂consumption requiring more concentration for a good strength development. A mixture containing 4 percent of 2.7 : 1 ratio silicate produces the strength above 8㎏/㎠ after 80 seconds gassing, but 5% and 6% respectively of 3.0 : 1 and3.3 : 1 ratio silicate are necessary to achieve equivalent levels of strength. 2) The correct water content in sand mixtures containing higher ratio silicates is necessary for the better strength properties to be obtained. The addition of 1% water to the sand mixtures bonded with 5%, 3 : 1 ratio and 6%, 3.3 : 1 ratio silicates maintains near-maximum strength on extended gassing. 3) When higher ratio silicates with 3 : 1 and 3.3 : 1 ratios are used,the addition of organic additives such as oil, sucrose and polyol results in considerable changes in strength. The presence of 1.0 to 1.5 percent of polyol produces a noticiable improvement 4) Gas diluted with air raises the efficiency of gas utilization. When gas contains 50 percent CO₂, the efficience is significantly increased with the best strength in the silicates having high ratios of 3 : 1 and 3.3 : 1. 5) The strength of molds is liable to change on storage with the reduction in water content. The magnitude of the strength change is determinded with the mole ratio. The presence of polyol in the mixture with 3.3 : 1 ratio silicate has a pronounced effect on maintaining the gassed strength.
주철의 성질에 미치는 Sb 첨가의 효과에 관한 연구 ( 기계적 성질과 Pearlite 의 안정화효과를 중심으로 )
이병엽,이계완 ( Byeong Yehp Lee,Kye Wan Lee ) 한국주조공학회 1984 한국주조공학회지 Vol.4 No.4
It is very important to obtain gray and ductile cast irons with completely pearlitic structure by addition more economical alloying elements. In this study, 9 melts of gray iron and 5 melts of Mg-treated ductile cast iron were made according to Sb content (0-0.08% Sb). Each melt were casted to ø20㎜ test bars in sand mold under the same condition and inspected microstructure, mechanical and thermal properties. The results obtained from this study are as follows: 1. It is confirmed that Sb should be an economical, simple and useful additive for avoiding ferrite in gray and even in ductile cast irons. 2. For gray cast iron, the recommended ladle addition of metallic Sb amounts to 0.05%. At these levels, Sb has no detrimental influence on the mechanical properties of gray cast irons, which are normally modified according to their pearlite content without increasing the chilling tendency. 3. Despite its adverse influence on graphite shape in ductile iron, Sb can be used as a pearlite stabilizing alloying element even in the case of Mg - treated iron. The quantity to be added does not exceed 0.04% in the case of thinwalled castings. 4. The nodule count is increased very much and the shape of graphite particles become remarkably spheroidal. The matrix may be fully pearlitized, except for thin - walled castings, because the high nodule count results inevitably in some ferrite. 5. The Ac₁and pearlite decomposition temperature are rised in accordance with increasing of additive Sb amount.
국내규사를 (國內硅砂) 사용한 합성사의 (合成砂) 고온성질 ( 압축강도 , 팽장 ) 에 관한 연구
윤병국,이계완 ( Byung Guk Yun,Kye Wan Lee ) 한국주조공학회 1982 한국주조공학회지 Vol.2 No.4
N/A The behavior of sand and mold at high temperatures was generally agreed to importantly affect the quality of castings made. By changing water content through 2,4,6 and 8%, and bentonite content through 5,7,9 and 11%, specimens have been made according to the respective composition. Specimens have been subjected to hot compressive strength and thermal expansion at 400, 600, 800 and 1000℃ respectively. The results obtained were as follows ; 1. At each temperature, thermal expansion decreased and hot compressive strength increased with the increase in water content. 2. After thermal expansion was peaked at approximately 1000℃ the contraction and maximum hot compressive strength appeared. 3. At each temperature, maximum hot compressive strength appeared 2%, 4,6% and 8% water content for 7%, 9% and 11% bentonite content respectively. 4. When 2% H₂O was added, though bentonite content was increased, hot compressive strength did not rarely change. 5. Until the thermal expansion was completed the required time was 15-18 minutes at 400℃ and 600℃, and 10-13 minutes at 800℃. At 1000℃, the required time was 7-9 minutes in order to gain the maximum expansion, after that, contraction proceeded during 3-4 minutes before expansion was completed.
상향식 연속주조법에 의한 Al-Cu-Ni 3원합금의 응고조직에 관한 연구
권기균,이계완 ( Kee Kyun Kwon,Kye Wan Lee ) 한국주조공학회 1990 한국주조공학회지 Vol.10 No.5
N/A Continuous casting of the Al-Cu-Ni ternary eutectic alloys was carried out by the upward continuous casting process. The morphology of the ternary eutectic growth and the stability of solid-liquid interface were investigated under various growth conditions. It was possible to get the planar solid-liquid interface at the condition of G_L /R=3.59×10³sec/㎟ in Al-Cu-Ni ternary eutectic alloys. In Al-rich, Ni-rich and Cu-rich hypereutectics of Al-Cu-Ni ternary alloys, primary α, τ and θ dendrites have grown as the leading phase ahead of the ternary eutectic composites.