• Journal of Conservation Science
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• v.33 no.3
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• pp.155-165
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• 2017

As interest in the public display of art and outdoor sculptures is increasing, the conservation and treatment of these sculptures is becoming increasingly crucial. Long-term exposure to the natural elements and atmospheric pollution can cause corrosion and deterioration in outdoor sculptures. In the case of Kim Chan Shik's "Feeling", which was exhibited in the outdoor sculpture park at the National Museum of Modern and Contemporary Art (MMCA), the patina of the sculpture was damaged during a long outdoor exhibition. Therefore, the treatment process was as follows: recording of condition, sanding, repatination, and wax coating. Consequently, the sculpture was restored similar to the original. Chemical analysis revealed that the sculpture was crafted from bronze and was cast from a quaternary alloy of Cu-Pb-Sn-Zn. The welding is lower in Zn, Sn, and Pb content than the metal used in the sculpture itself. Bright strains contain about 13.0 wt% Sn and 10.5 wt% Pb. The strains are higher in Sn and Pb content than the rest of the metal in the sculpture (7.0 wt% Sn and 4.4 wt% Pb). As a result of component analysis and microstructure observation, the material is estimated to have been made by casting without artificial treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.718-723
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• 2016

The use of the scroll compressor in the air conditioning of medium-sized vehicles has increased because of its low torque fluctuation, high energy efficiency and low noise. In addition, the main components of the compressor have been changed from steel to aluminum to reduce its weight, following studies on the constituent materials. The processing precision of the fixed scroll and orbiting involute scroll wrap of the scroll compressor must be below $10{\mu}m$. To ensure this, the surface roughness and contour tolerance are measured. To improve the hardness of the orbiting scrolls using aluminum subjected to anodizing treatment and as the base material, we used a sealing treatment and measured the resulting characteristics. The aluminum materials were made of an Al-Mg-Cu based alloy including small amounts of Ni, Fe, and Zn. The surface roughness was less than $3{\mu}m$ and the processing accuracy was within $10{\mu}m$. Also, the hardness of the nanodiamonds with CNTs used in the sealing treatment was more than 450. This was found to improve the hardness of the material by 50% or more compared to the water sealing treatment and there was little difference between the use of carbon nanotubes and nanodiamonds as sealing materials.

• Restorative Dentistry and Endodontics
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• v.22 no.1
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• pp.1-33
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• 1997

The objective of this study was to analyze the in vitro and in vivo corrosion products of low and high copper amalgams. The four different types of amalgam alloy used in this study were Fine cut, Caulk spherical, Dispersalloy, and Tytin. After each amalgam alloy and Hg were triturated according to the directions of the manufacturer by means of the mechanical amalgamator(Amalgam mixer. Shinhung Co. Korea), the triturated mass was inserted into a cylindrical metal mold which was 12mm in diameter and 10mm in height. The mass was condensed by 150Kg/cm compressive force. The specimen was removed from the mold and aged at room temperature for about seven days. The standard surface preparation was routinely carried out by emery paper polishing under running water. In vitro amalgam specimens were potentiostatically polarized ten times in a normal saline solution at $37^{\circ}C$(potentiostat : HA-301. Hukuto Denko Corp. Japan). Each specimen was subjected to anodic polarization scan within the potential range -1700mV to+400mV(SCE). After corrosion tests, anodic polarization curves and corrosion potentials were obtained. The amount of component elements dissolved from amalgams into solution was measured three times by ICP AES(Inductive Coupled Plasma Atomic Emission Spectrometry: Plasma 40. Perkim Elmer Co. U.S.A.). The four different types of amalgam were filled in occlusal and buccal class I cavities of four human 3rd molars. After about five years the restorations were carefully removed after tooth extraction to preserve the structural details including the deteriorated margins. The occlusal surface, amalgam-tooth interface and the fractured surface of in vivo amalgam corrosion products were analyzed. In vivo and in vitro amalgam specimens were examined and analyzed metallographically by SEM(Scanning Electron Microscope: JSM 840. Jeol Co. Japan) and EDAX(Energy Dispersive Micro X-ray Analyser: JSM 840. Jeol Co. Japan). 1. The following results are obtained from in vitro corrosion tests. 1) Corrosion potentials of all amalgams became more noble after ten times passing through the in vitro corrosion test compared to first time. 2) After times through the test, released Cu concentration in saline solution was almost equal but highest in Fine cut. Ag and Hg ion concentration was highest in Caulk spherical and Sn was highest in Dispersalloy. 3) Analyses of surface corrosion products in vitro reveal the following results. a)The corroded surface of Caulk spherical has Na-Sn-Cl containing clusters of $5{\mu}m$ needle-like crystals and oval shapes of Sn-Cl phase, polyhedral Sn oxide phase. b)In Fine cut, there appeared to be a large Sn containing phase, surrounded by many Cu-Sn phases of $1{\mu}m$ granular shapes. c)Dispersalloy was covered by a thick reticular layer which contained Zn-Cl phase. d)In Tytin, a very thin, corroded layer had formed with irregularly growing Sn-Cl phases that looked like a stack of plates. 2. The following results are obtained by an analysis of in vivo amalgam corrosion products. 1) Occlusal surfaces of all amalgams were covered by thick amorphous layers containing Ca-P elements which were abraded by occlusal force. 2) In tooth-amalgam interface, Ca-P containing products were examined in all amalgams but were most clearly seen in low copper amalgams. 3) Sn oxide appeared as a polyhedral shape in internal space in Caulk spherical and Fine cut. 4) Apical pyramidal shaped Sn oxide and curved plate-like Sn-Cl phases resulted in Dispersalloy. 5) In Tytin, Sn oxide and Sn hydroxide were not seen but polyhedral Ag-Hg phase crystal appeared in internal space which assumed a ${\beta}_l$ phase.

• Journal of Conservation Science
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• v.38 no.2
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• pp.133-143
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• 2022

In this study, we analyzed the rickshaw (Owned by the Daegu Modern History Museum) by measuring each material. The purpose of the study was to identify the materials in modern cultural assets that utilize a variety of materials in a complex way, and establish basic data for preservation and management. Using portable X-ray fluorescence analyzers (P-XRF), species identification, fiber identification, paint film analysis (microscope observation, SEM-EDS, FTIR) on metal, wood, fiber and paint was carried out. Brass, an alloy of Copper, Zinc and Iron, was measured in the metal parts. Further, wooden parts, such as Oak (Quercus acutissima), Japanese Cedar (Cryptomeria japonica), Bamboo (Bambusoideae). Torreya nucifera (Torreya spp.) were identified in the body. Fiber parts consisted mainly of cotton, but some parts were also made of leather. In terms of paint, rickshaws were applied with multiple layers, using cashew (synthetic paint used in place of lacquer). In sum, the rickshaw body part appeared to overlap with layers of fiber, metal (soild), paint, and colored (black, red) layer.