• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.6
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• pp.634-641
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• 2001

Shape memory alloy has been used to improve the tensile strength of composite by the occurrence of compressive residual stress in matrix using its shape memory effect. In order to fabricate shape memory alloy composite, TiNi alloy and A16061 were used as reinforcing material and mix, respectively. In this study, TiNi/A16061 shape memory alloy composite was made by using hot press method. However, the specimen fabricated by this method had the bonding problem at the boundary between TiNi fiber and Al matrix when the load was applied to it. A cold rolling was imposed to the specimen to improve the bonding effect. It was found that tensile strength of specimen subjected to cold rolling was more increased than that of specimen which did not underwent cold rolling. In addition, acoustic emission technique was used to quantify the microscopic damage behavior of cold rolled TiNi/A16061 shape memory alloy composite at high temperature.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.367-370
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• 2009

Recently, ultra high strength products can be manufactured by the hot press forming process of Boron steel in automotive and electronics industries. In order to get high strength, the hot press forming should be accompanied by quenching process inducing phase transformation. In the study, the heat conductive die and the cooling channel were designed by the numerical simulation and the effect of three different parameters were determined to improve cooling characteristics.

• Polymer(Korea)
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• v.35 no.2
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• pp.136-140
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• 2011

The plasma resistances of nitrile curable perfluoro elastomer (NT PFE) and peroxide curable PFE (PO PFE) after exposing to $NF_3$ and $O_2$ remote plasmas were investigated by analyzing weight loss and morphology of O-ring made of PFE. The compounds were designed following the typical formulations of O-ring/seal which were applied in semiconductor and LCD production site. They were blended by an open roll mill, and then, O-ring was finally made by hot press molding and oven curing. The weight loss was calculated and morphology was observed for each atmosphere and temperature by a digital weighing machine and SEM. As results, it was confirmed the weight loss and related morphology were meaningfully different according to the cure type of PFE, filler system, and the species of remote plasma.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.5
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• pp.1106-1114
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• 1993

A composite material is composed of a reinforcement and a matrix, which determine mechanical characteristics of the molded part. There is no doubt that the properties of a composite material depend not only on the characteristics of the matrix but also on the structure of glass fiber mat and a fiber type of reinforcement. Therefore it is very important to study the composites of reinforcement and the matrix, and to control the fiber type in the process of molding of composite materials. In this study, the specimen was made of a glass fiber mat of 6-7mm thickness by scattering it in the air after cutting the glass fiber mat with needle punching makes change according to the type of needle and the number of times of stretching. First the sheet was made by means of a hot-press after accumulating a matrix and a glass fiber according to each mat structure of glass fiber. It was heated the manufactured sheet with the dry oven and molded it a secondary high temperature compression by a 30 ton oilhydraulic press. A definition of a correlation coefficient is showed up during this period and find it out with the relation of the fiber-matrix separation and the fiber orientation. We studied effects of the glass fiber mat structures on the correlation coefficient.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.45-51
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• 2009

Shape memory alloy has been used to improve the tensile strength of composite by the occurrence of compressive residual stress in matrix using its shape memory effect. In order to fabricate shape memory alloy composite, TiNi alloy fiber and Al2024 sheets were used as reinforcing material and matrix, respectively. In this study, TiNi/Al2024 shape memory alloy composite was made by using hot press method. In order to investigate bonding condition between TiNi reinforcement and Al matrix, the micro-structure of interface was observed by using optical microscope and diffusion layer of interface was measured by using Electron Probe Micro Analyser. And the mechanical properties of composite with three parameters(volume fraction of fiber, cold rolling amount and test temperature) were obtained by tensile test. The most optimum bonding condition for fabrication the TiNi/Al2024 composite material was obtained as holding for 30min. under the pressure of 60MPa at 793K. The strength of composite material increased considerably with the volume fraction of fiber up to 7.0%. And the tensile strength of this composite increased with the reduction ratio and it also depends on the volume fraction of fiber.

• Korean Journal of Metals and Materials
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• v.47 no.10
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• pp.667-674
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• 2009

High temperature wear of STD 61 tool steels sliding against the Al-9%Si coated steels used for hot press forming has been studied in comparison with that of the tool steels sliding against the uncoated steels. Wear tests have been performed using a pin-on-disc configuration under an applied normal load of 50N for 20 min with heating the coated and uncoated steels up to 800$^{\circ}C$. It was found on the worn surface of the STD 61 tool steels sliding against the Al-9%Si coated steels that the formation of the glazed layers containing Al transferred from the coated tribopair may contribute to a reduction of the coefficient of friction, and detachment in part occur due to delamination wear, resulting in higher specific wear rate. On the other hand the Fe-oxide wear debris entrapped on the softer surface of the uncoated steels can act as a tribosurface, leading to decreased adhesive wear of the STD 61 tool steels, resulting in a lower specific wear rate.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.7
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• pp.1132-1137
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• 2003

This study dealt with the suppression of interfacial reaction between Nb and MoSi$_2$ for the fabrication of high toughness Nb/MoSi$_2$ laminate composites, based on the results of a thermodynamical estimation. Especially, the effect of ZrO$_2$ particle on the interfacial reaction of Nb/MoSi$_2$ bonding materials has been examined. Nb/MoSi$_2$ bonding materials have been successfully fabricated by alternatively stacking matrix mixtures and Nb sheets and hot pressing in the graphite mould. The addition of ZrO$_2$ particle to MoSi$_2$ matrix is obviously effective for promoting both the interfacial reaction suppression and the sintered density of Nb/MoSi$_2$ bonding materials, since it is caused by the formation of ZrSiO$_4$ in the MoSi$_2$-ZrO$_2$ matrix mixture. The interfacial shear strength of Nb/MoSi$_2$ bonding materials also decreases with the reduction of interfacial reaction layer associated with the content of ZrO$_2$ particle and the fabrication temperature.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.2
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• pp.62-70
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• 2001

As the ship hull is a compound-curved structure, plate bending process is indispensible. The process includes press bending process for forming major 1st curvature and heating process for forming the rest curvature. Especially the heating process that is above 50 percents of entire bending work is carried out exclusively by skillful workers. Many researches have been made to automate the heating process but most of these are about line heating process and researches for triangle heating process are rare. This study is a fundamental study to develop a efficient analysis method for triangle heating and focused on clarifying the deformation characteristics of plate by triangle heating. In this paper, we carried out heating experiments and analysed the deformation characteristics of plate to explain the deformation characteristics of plates rationally by showing the phase transformed high temperature region. Also we investigated the heating effect on the hull material properties by mechanical tests.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.4
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• pp.383-391
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• 2011

The hot-stamping technique is used to manufacture high-strength parts by press forming by heating at a temperature above the Austenite transformation temperature and then rapid cooling. Boron steel, which contains a very small amount of boron, is one of the materials used for hot stamping. The purpose of this study is to show the microstructures and to investigate the mechanical properties under different heat-treatment conditions. The heat treatment of water quenching was conducted at the various temperatures and different elapsed times. These can be practical data useful when boron steels are used for hot stamping. Furthermore, the microstructures and mechanical properties of the spot-welded specimen with coatings and counterpart materials (SPRC 340, SPRC 590) is investigated in order to determine the welding characteristics of boron steel at different welding condition.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.581-585
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• 2010

The surface of Alnico, one of the industrial dust waste, was treated with 1,3,5-trivinyl-1,3,5-trimethylcyclotrisilazane (VMS) as a surface treating agent and used as the filler for vibration isolator rubber. Maleated EPDM prepared from bulk polymerization of EPDM with maleic anhydride was copolymerized with ${\alpha},{\omega}$-bis(3-aminopropyl)polydimethylsiloxane to obtain maleated EPDM-polydimethylsiloxane copolymer (MEPDM-PDMS). EPDM/Alnico/MEPDM-PDMS vibration isolator rubber was prepared from compounding with Alnico treated with surface treating agent, 25 and 50 phrs to EPDM, respectvely based on 1 to 10 wt% of MEPDM-PDMS to EPDM. From the measurement of the thermal properties to the rubber, the glass transition temperatures (Tg) for the rubber containing maleated EPDM-PDMS copolymer was slightly lower temperature, $33^{\circ}C$ than EPDM rubber, and also DMA results showed higher tan ${\delta}$ peak to the rubber prepared from compounding with EPDM-PDMS copolymer. From the results, rubber prepared using EPDM-PDMS copolymer had better vibration isolator property.