• Proceedings of the Korean Fiber Society Conference
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• 2003.10a
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• pp.71-72
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• 2003

The aim of our study is to prepare nanocomposites consisting polymer/inorganic nanoparticles and investigate their physical properties as a functional material. In this study, a nanocomposite of copper sulfide (CuS) nanoparticles introduced into a poly(acrylic acid) matrix was prepared and the optical absorption property was measured. The composite exhibited strong absorption of both ultraviolet and near-infrared rays, indicating that the composite is applicable to a solar radiation shielding filter. The wavelength of the near infrared absorption was controlled from ca.1000 nm to 1700 nm by heat and acidic solution treatments.

• Journal of Powder Materials
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• v.15 no.3
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• pp.227-233
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• 2008

Dynamic plastic deformation behavior of copper particles occurred during the cold spray processing was numerically analyzed using the finite element method. The study was to investigate the impact as well as the heat transfer phenomena, happened due to collision of the copper particle of $20{\mu}m$ in diameter with various initial velocities of $300{\sim}600m/s$ into the copper matrix. Effective strain, temperature and their distribution were investigated for adiabatic strain and the accompanying adiabatic shear localization at the particle/substrate interface.

• Tribology and Lubricants
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• v.29 no.1
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• pp.19-26
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• 2013

Cu-matrix sintered brake pads and low-alloy heat-resistant steel are commonly applied to basic brake systems in high-energy moving machines. In this research, we analyzed the tribological characteristics to determine the influence of the air velocity between the disk and pad. At a low brake pressure with airflow, the friction stability was decreased as a result of the lack of tribofilm formation at the disk surface. However, there were no significant changes in the friction coefficient under any of the test conditions. The wear rates of the friction materials were decreased with an increase in the airflow velocity. As a result, the airflow velocity influenced the friction stability, as well as the wear rate of the friction materials and disk, but not the friction coefficient.

• Tribology and Lubricants
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• v.29 no.2
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• pp.98-104
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• 2013

Cu-matrix-sintered brake pads and heat-resistant low-alloy steel are commonly applied to basic brake systems in high-energy moving machines. We analyzed how the tribological characteristics are influenced by the inertial mass. A high inertial mass decreased the friction coefficient by about 15% compared to a low inertial mass under all velocity conditions. The wear rates of the friction materials increased with the inertial mass. Thus, the inertial mass influences the friction coefficient and wear rate of the friction materials and disk but not the friction stability.

• Carbon letters
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• v.11 no.2
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• pp.117-121
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• 2010

The composites of alginate, carbon nanotube, and iron(III) oxide were prepared for the removal of heavy metal in aqueous pollutant. Both alginate and carbon nanotube were used as an adsorbent material and iron oxide was introduced for the easy recovery after removal of heavy metal to eliminate the secondary pollution. The morphology of composites was investigated by FE-SEM showing the carbon nanotubes coated with alginate and the iron oxide dispersed in the alginate matrix. The ferromagnetic properties of composites were shown by including iron(III) oxide additive. The copper ion removal was investigated with ICP AES. The copper ion removal efficiency increased greatly over 60% by using alginate-carbon nanotube composites.

• Journal of Korea Foundry Society
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• v.9 no.3
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• pp.237-246
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• 1989

This study has been carried out to investigate the difference of rolling life and rolling wear characteristics for various high strength ductile iron castings under unlubricative dry rolling condition by Amsler type wear test with 9.09% sliding ratio. The tensile strength of the castings have been obtained 80, 90 and $100kg.f/mm^2$ as cast-state with pearlitic, bainitic and martensitic matrix structures alloyed with Mo, Cu and Ni. It has been found that the amount of rolling wear is decreased when the tensile strength and hardnees of the castings are increased. The amount of rolling wear is increased, when the maximum compressive stress are increased. The maximum weight loss ratio of rolling wear of the castings are same at the 70000 numbers of revolution with out the maximum compressive stress.

• Journal of Korea Foundry Society
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• v.13 no.3
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• pp.285-294
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• 1993

Aluminum alloy 2024 matrix composites reinforced with $Al_2O_3$ particles, were prepared by rheo-compocasting, a process which consists of the incoporation distribution of reinforcement by stirring within a semi-solid alloy. The microstructures and characteristics of the interfaces have been studied using optical microscope and scanning electon microscope in 2024 aluminum alloy composites reinforced with $Al_2O_3$ particles. The main results are as follows: (1) $Al_2O_3$ particles were well distributed in composites by using rheo-compocasting. (2) As the addition of $Al_2O_3$ particle increases, the average dendrite numbers and the hardness were increased. (3) Interaction between $Al_2O_3$ particles and alloy 2024 resulted in the formation of Mg and Cu element rich region around the $Al_2O_3$ particles.

• Nuclear Engineering and Technology
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• v.32 no.4
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• pp.372-378
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• 2000

The effect of alloying elements on the creep resistance of Zr alloys was investigated using thermal creep tests that were performed as a part of advanced fuel cladding development. The creep tests were conducted at 40$0^{\circ}C$ and 150 MPa for 240 hr. A statistical model was derived from the relationship between the steady-state creep rate and the content of individual alloying elements. The creep strengthening effect decreased in the following sequence : Nb, Sn, Mn, Cr, Mo, Fe and Cu. The high creep resistance of Sn and the opposite effect of Fe on zirconium alloys seem to be associated with their lowering and enhancing, respectively, the self-diffusivity of the zirconium matrix.

• Journal of Korea Foundry Society
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• v.13 no.1
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• pp.50-61
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• 1993

Retained austenite in matrix of austempered ductile iron has been well-known as a parameter in controlling mechanical properties, but investigation to obtain quantitative relationship with mechanical properties lack. Therefore, this study executed austempering treatment at various temperatures on ductile iron alloyed with Mo, Ni, Cu. In consequence, microstructure of retained austenite transformed coarse, and quantity increased according as austempering temperature increased. After heat-treatment, microstructure of specimen alloyed with Ni was fine, and toughness improved. At austempering temperature up to $400^{\circ}C$, carbide precipitation started in retained austenite. In consequence, afforded cause of hardness increase, a lot of increase did not arise for coarse structure.

• Journal of Powder Materials
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• v.12 no.3
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• pp.208-213
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• 2005

Aluminum matrix composites strengthened by the quasi-crystalline (QC) phase were developed in the present study. The icosahedral $Al_{65}Cu_{20}Fe_{15}$ phase was produced by gravity casting and subsequent heat treatment. The mechanical milling process was utilized in order to produce the Al/QC composite powders. The microstructures of the composite powders were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The composite powders were subsequently canned, degassed and extruded in order to produce the bulk composite extrusions with various volume fractions of QC. The microstructure and mechanical properties of the extrusions were examined by OM, SEM, Vickers hardness tests and compression tests. It was found that the microstructures of the Al/QC composites were uniform and the mechanical properties could be significantly improved by the addition of the QC phase.