• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.541-546
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• 2011

This study was numerically investigated on thermal deformation of AC4C and AC7A aluminum alloy casting material for manufacturing the automobile tire mold. The metal casting device was used in order to manufacture the mold product of automobile tire at the actual industrial field. The temperature distribution and the cooling time of these materials were numerically calculated by finite element analysis. Thermal deformation with stress distribution was also calculated form the temperature distribution results. The thermal deformation was closely related to the temperature difference between the surface and inside of the casting. As shown by numerical analysis result, the thermal deformation of AC7A casting material became higher than AC4C casting material. In addition, the results of displacement and stress distributions appeared to be larger at the center parts of casting than on its sides because of the shrinkage caused by the cooling speed difference.

• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.7-12
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• 2012

In this study, the solidification characteristics inside the AC7A casting material was analyzed using the numerical analysis method and was verified using the experimental method by the pre-heated temperature conditions of metal casting device. For the numerical analysis, "COMSOL Multiphysics", the commercial code based on the finite element analysis(FEA), was used in order to predict the thermal deformation of the AC7A casting material including temperature, displacement and stress distribution. Also, in order to verify the results calculated by the numerical analysis, the experiment for temperature measurement inside the AC7A casting material was performed using the K-type thermocouple under the same condition of numerical analysis method. In the numerical results, thermal deformation inside AC7A casting material was well-suited for manufacturing products when the pre-heated temperatures of the metal casting device was $250^{\circ}C$. When the results of the temperature distribution were experimentally measured and were compared with those of the numerical result, it appeared that there was some temperature difference because of the latent heat by phase change heat transfer. However, the result of cooling temperature and patterns were almost similar except for the latent heat interval. The solidification characteristics was closely related to the temperature difference between the surface and inside of the casting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2596-2603
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• 2013

The precision and endurance of tire mold are very important factors to decide the quality of tire. However, the investigation on the thermal deformation of tire mold has a lot of trouble because the tire mold is produced in airtight permanent casting material. In this study, the thermal deformations such as temperature, displacement and stress distributions inside the AC7A tire mold casting material were analyzed by numerical analysis according to the preheating temperature of permanent casting device. In order to verify the results of numerical analysis, the experiments for temperature measurement of the AC7A casting material were carried out under the same condition with numerical analysis. For the numerical analysis, "COMSOL Multiphysics" was used. The preheating temperatures were set up $150^{\circ}C$, $200^{\circ}C$, $250^{\circ}C$ and $300^{\circ}C$, respectively. The thermal deformations were calculated in each case. When the preheating temperature is $300^{\circ}C$, displacement and stress are the lowest with 0.25mm and 0.351GPa, but the temperature is the highest with $374.27^{\circ}C$. When the experimental results were compared with the numerical results, there were some temperature differences because of the latent heat by phase change heat transfer. However, the cooling patterns were almost similar except for the latent heat section.

• Journal of Korea Foundry Society
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• v.25 no.2
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• pp.88-94
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• 2005

The microstructure and mechanical property of the ceramic reinforced AC4C matrix composites processed by squeeze casting were investigated. In this study Kaowool and Saffil fiber which are ceramic reinforcements are used as preform materials. As a matrix material, Al-7wt.%Si-0.3wt.%Mg(AC4C) has been used. In case of Kaowool and Saffil/AC4C composites, 7.5 MPa squeezing pressure and minimum 7.0% binder amount are needed to produce sound composite materials. The tensile strength of Kaowool/ AC4C composite is lower than the matrix metal and this can be explained by the melt unfilling due to formed cluster of Kaowool reinforcements. But the mechanical properties of hardness, wear resistance and thermal expansion are better than the matrix materials due to the strengthening effect of ceramic reinforcements.

• Journal of Korea Foundry Society
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• v.25 no.2
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• pp.80-87
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• 2005

The microstructure and mechanical property of the Ni and Ni-Cr porous metal reinforced AC4C matrix composites fabricated by squeeze casting were investigated. In this study Ni, Ni-Cr porous metals which are estimated to be easy to fabricate by squeeze casting are used as strengtheners for composite materials. As a matrix material, Al-7wt.%Si-0.3wt.%Mg(AC4C) has been used. In case of Ni/AC4C and Ni-Cr/AC4C composite, $750^{\circ}C$ melt temperature and minimum 25MPa squeezing pressure are needed to produce sound composite materials. The observation of interfacial reaction zone at various heat treatment condition shows that atsolutionizing temperature of above $520^{\circ}C$, the interfacial reaction zone increases proportionally with heat treatment time and the reaction products formed by interfacial reactions are mainly composed by $Al_{3}Ni$ and $Al_{3}Ni_{2}$ phases.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1051-1057
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• 2003

This study is about controlled impurities, which make metal alloys, especially AC4CH alloy that is made by restraining 0.2％ Fe and Aluminum to make a matrix material. A metal matrix composite is produced using the squeeze casting method. The first step in the squeeze casting method is to add some organic binder including aluminum borate whisker into the matrix. After the fabrication of a metal matrix composite, each is individually appended to an inanimate binder such as SiO$_2$, Al$_2$O$_3$, and TiO$_2$. Through experiments the mechanical property changes were investigated between the metal matrix composite and AC4CH alloy. This study proves the superiority of the mechanical property of a metal matrix composites over AC4CH according to the previous tests and results that were mentioned above. One excellent property of matrix material composites is the infiltrated TiO$_2$ reinforcement. This material is a good substitute for the existing materials that are used in the development of industries today.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.3
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• pp.160-168
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• 1994

This was studied about mechanical characteristic of AC4A/SiCw 10-30% reinforced composites. Tensile strength of pressed base metal(base metal) with SiCw preform was higher than without pressed base metal(AC4A). If SiCw whisker volume fraction was increased, tensile strength at room temperature was increased. And tensile strength of SiCw 30% was about $35kg/mm^2$. Tensile strength of SiCw 30 % $400^{\circ}C$ at same time aging was the most excellence, about $40kg/mm^2$. The fracture energy value of composite material at three point bending test was higher than AC4A. Dislocation at matrix of composite material was evenly distributed. But dislocation around whisker of composite material was more existed than matrix. The reasom was thought of pile-up around whisker.

• Journal of Korea Foundry Society
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• v.20 no.1
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• pp.21-28
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• 2000

Ni and Ni-Cr porous metals which are estimated to be easy to fabricate by squeeze casting are used as strengtheners for composite materials. As a matrix material, Al-7%wtSi-0.3 wt%Mg(AC4C) has been used. In case of Ni/AC4C and Ni-Cr/AC4C composite, $750^{\circ}C$ melt temperature and minimum 25 MPa squeezing pressure are needed to produce sound composite materials. The observation of interfacial reaction zone at various heat treatment condition showed that solutionizing temperature of above 520^{\circ}C$, the interfacial reaction zone increased proportionally with increasing heat treatment tim and reaction products formed by interfacial reaction are mainly composed of $Al_3Ni$ and $Al_3Ni_2$ phases. The tensile strength of Ni/AC4C and Ni-Cr/AC4C composite is lower than the matrix metal and this can be explained by the brittle intermetallic compounds formed at the interface of Ni and Ni-Cr reinforcements. But the properies of hardness, wear resistance and thermal expansion are better than the matrix due to the strengthening effect of Ni-Cr porous metals.

• Journal of Korea Foundry Society
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• v.17 no.4
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• pp.402-410
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• 1997

Developing a salt core for squeeze casting process, two different salt cores(pure salt core and mixed salt core) were fabricated and investigated. Pure salt core was composed of 100% NaCl and mixed salt core was made by mixtures of NaCl with MgO(1%), $Na_2B_4O_7$(2%), and talc(1%) as a binder or a strengthening agent. Salt cores were compacted to various theoretical density, heat treated, and then squeeze-cast with molten Al alloy(AC8A). The compression strength of salt cores were measured and the squeeze-cast products were examined for shape retention, infiltration of molten metal into the cores, and microstructures. The shape of salt core compacted at above 75% of the theoretical density was maintained stably. The higher theoretical density of salt cores gave higher compression strength, and the compression strength of mixed salt core was higher than that of pure salt core. Namely at 90% theoretical density, the compression strength of mixed salt core was $6.3 kg/mm^2$, compared to $4.6 kgmm^2$ for pure salt core. At a squeeze casting pressure of $1000 kg/cm^2$, molten Al alloy was infiltrated into pure salt core of under 85% of the theoretical density. At squeeze casting pressure of $1000 kg/cm^2$, only mixed salt core above 90% of the theoretical density were valid, but the shape of the core was altered in the case of pure salt core at 90% of theoretical density. A key factor for developing a salt core for squeeze casting process was estimated as the ultimate compressive strength of salt core.

• Journal of the Korea Institute of Building Construction
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• v.16 no.3
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• pp.237-245
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• 2016

Structural performance and durability of ultra high performance concrete could demonstrate optimal performance when unity was kept. Accordingly, it is necessary to involve the characteristics and quantitative surface treatment at the same time in order to retain oneness of Ultra-High-Performance Concrete(UHPC) according to construction joint occurrence. Therefore, this study derives a reasonable surface treatment method in a material's point of view through the shear adhesion performance evaluation according to the construction joints surface processing method as a part for securing the adhesion performance of the construction joints when casting UHPC. 180 MPa of required average strength was used for mix of UHPC and surface treatment method was set to totally 7 level that MN, GR-10-0, GR-20-0, GR-30-0, SH-30-5, SH-30-10. After the specimen were manufactured to a size of $150{\times}150{\times}150mm$, Direct shear test was performed to evaluate the shear adhesion strength. As a result, it was confirmed that the adhesion performance was improved when executing a surface treatment for the construction joint interface and standard of failure mode of specimen was over Type C. Also, It was considered that interface of cross section and depth of concavo-convex should be concerned.