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후란자경성 (自硬性) 주형용 (鑄型用) 국산인조규사의 (國産人造硅砂) 활용에 관한 연구
최창옥,이상윤 ( Chang Ock Choi,Sang Yun Lee ) 한국주조공학회 1981 한국주조공학회지 Vol.1 No.3
N/A An emphasis has been placed on the importance of selecting a sand for furan sand process, which ie affected by the properties of sand. Investigations have been carried out to use the domestic artificial sands for the furan sand process. For laboratory investigations, the sands have been prepared and tested for chemical analysis, loss on ignition, sieve analysis, AFS grain fineness number, grain shape, PH value, acid demand, surface shape, theoretical surface area, moisture absorption, crushing durability and compressive strength and S. S. I. of molding sands. Most commercial sands have been found to be able to be used. The main requirement of the sands has been shown to be that 3 or 4 screen sands, AFS no.40-70 (or 100), of low acid demand, good surface area and good grain shape require less resin and catalyst to give an adequate strength.
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.
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.
연청동주물의 (鉛靑銅鑄物) 조직에 미치는 용해 및 주입조건의 영향에 관한 연구
이운환,최창옥 ( W . W . Lee,C . O . Choi ) 한국주조공학회 1987 한국주조공학회지 Vol.7 No.1
The effects of melting and casting conditions on cast structures of Cu-Sn-Pb alloys were studied. Specimens were prepared at different pouring temperatures of 1100℃ to 1260℃ with use of various kind of molds, green sand mold, CO₂sand mold, shell mold, furan sand mold and metallic mold. (1) The transition of equiaxed to columnar structure greatly influenced by adding elements and mold binders. (2) The change of equiaxed structure according to pouring temperatures were expressed by separation theory. Lower pouring temperature and rapid cooling rate increase hardness and it`s further increase was shown in the region of columnar structure. (3) Proper controls of pouring temperature, cooling rate and mold binder were important factors to improve wear properties of Cu-Sn-Pb alloys castings.
오스템퍼링 처리한 회주철의 파괴특성에 미치는 오스템퍼링 온도의 영향에 관한 연구
김창규,이성열,최창옥 ( Chang Gyu Kim,Sung Yul Lee,Chang Ock Choi ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.6
N/A Grey cast iron containing a small amount of Cu and Mo to improve the effect of heat treatment and microstructure were cast and them austenitized. After austenitizing the specimens of castings were austempered at 250℃, 300℃ and 350℃. The effects of matrix structures on mechanical properties and fracture characteristics at the different austempering temperature were investigated. Tensile strength, hardness and impact toughness of austempered grey cast iron showed maximum valve 359㎫, 321 HB, 3.9 CVN respectively at the lowest austempering temperature, 250℃. K_(IC) of gref cast iron at a austempering temperature, 250℃, showed maximum 44㎫.m^(½) even though the amount of retained austenite in it is only 16%. This mainly comes from the refinement of the retained austenite. Quasi-cleavage pattern with a little fit of fibrous pattern was shown on the fractured surface of austempered grey cast iron at all of the temperatures tested.
복염에 (複鹽) 의한 청도주물의 (靑銅鑄物) 탈린에 (脫燐) 관한 연구
이성용,황용길,최창옥 ( Sung Yong Lee,Yong Kil Whang,Chang Ok Choi ) 한국주조공학회 1984 한국주조공학회지 Vol.4 No.3
This study has been carried out to investigate into the dephosphorization by using fluxes containing Na₂CO₃-CaF₂-Na₂B₄O_7., l0H₂O and CaO-CaF₂-Na₂B₄O_7. 10H₂O system in molten bronze alloy. The dephosphorization degree of about 80% and 70% were obtained by Na₂CO₃-CaF₂-Na₂B₄O_7. 10H₂O and CaO-CaF₂-Na₂B₄O_7. 10H₂O system, respectively. When the contents of phosphorous in the molten bronze alloy were kept constant, although the amounts of fluxes exceed a given amount, it showed to give little effect in the degree of dephosphorization. The effects of dephosphorization in the molten bronze alloy was increased proportionally with increasing the contents of both phosphorous and amounts of fluxes. The slag formed from the Na₂CO₃-CaF₂-Na₂B₄O_7. 10H₂O system was found to be NaCaPO₄, Na₄P₂O_7 and NaF. The slag of CaO-CaF₂-Na₂B₄O_7. 10H₂O system was composed of Ca_5F (PO₄)3, CaO and CaF₂.
금형주조한 Al-10%Si 합금의 응고조직과 기계적 성질에 미치는 금형의 냉각효과에 관한 연구
이동윤,천병욱,최창옥 ( Dong Youn Lee,Byung Wook Cheon,Chang Ock Choi ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.2
N/A This study has been focused on the influence of the metallic mold cooling effects on the solidification structures and the mechanical properties for Al-10%Si alloy castings by the variation of pouring temperatures, metallic mold temperatures and Cooling part of metallic mold. The dendrite arm spacing of Al-10%Si alloy was decreased with increasing cooling rate. In case of bottom cooling of metallic mold, DAS was appeared to be 20-22㎛ and in the middle cooling, it was increased to 36-40㎛. The DAS decreased proportionally with(cooling rate)^(-3/2) at pouring temperatures 680℃ and (cooling rate)^(-½) at pouring temperature 760℃, but it was proportionally increased to(local solidification time)^(½-⅓) at pouring temperature 680℃ and 760℃. The maximum tensile strength of Al-10%Si alloy casting was obtained in case of bottom cooling of mold at pouring temperature 680℃ and metallic mold temperature 320℃.
오스템퍼링 처리한 회주철의 마멸특성에 미치는 잔류 오스테나이트 조직의 영향에 관한 연구
신호철,이종훈,김홍범,김창규,최창옥 ( Ho Chul Shin,Jong Hoon Lee,Hong Beam Kim,Chang Gyu Kim,Chang Ock Choi ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.6
N/A Grey iron containing a small amount of Cu and Mo to improve the effect of heat treatment and microstructures were poured in to the mold and them austenized at 900℃. After austenitizing the specimens of castings were austempered 210℃, 250℃, 300℃ and 350℃. The effects of matrix structures, mechanical properties and wear characteristics were investigated by austempering temperatures. Tensile strength and hardness of austempered grey iron are increased and the amount of retained austenite is decreased as austempering temperature is lower even though the amount of retained autenite in it only 4%. The amount of rolling wear loss are increased as rolling revolution is increased and wear loss of austempered grey iron under dry rolling condition is characterized by three models; initial wear, stationary wear and abnormal wear. It has been found that the amount of wear loss was increased with increasing maxium compressive stress and rolling revolution.
고 Mn 강 주강품의 내마모성에 미치는 Ni 첨가의 영향에 관한 연구
이영훈,천병욱,김성한,최창옥 ( Young Hun Lee,Byung Wook Cheon,Sung Han Kim,Chang Ock Choi ) 한국주조공학회 1992 한국주조공학회지 Vol.12 No.2
N/A This study has been performed in increase the wear resistance characteristic and the mechanical properties of high Mn steel castings with an addition of Ni to 1∼4% range. The initial structure of plastic cememtite has been possible to transform perfect austenite with watertoughening treatment. Increasing Ni content, the most wear loss has shown that ore has crushed until 100㎏ and decreased with increasing ore amount at ascast, the similar tendency has shown at heat treatment. Chang of hardness has shown high values that ore has been crushed until 300㎏, both as cast and treatment added 2%Ni.