• Journal of Conservation Science
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• v.30 no.1
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• pp.95-101
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• 2014

Silver objects tarnish with black from reaction with sulfurous acid or hydrogen sulfide of atmospheric. Blackening of silver objects results from formation of silver sulfide($Ag_2O$) on the surface. Silver sulfide usually is usually removed by conservation treatment. There are several cleaning methods such as chemical, electrochemical and micro-abrasion cleaning, but all of them consume silver. This study investigated the safe and effective parameter of laser cleaning by test on silver coupons. Laser cleaning is a selective process for the removal of specific substances. At first, laser cleaning applied to plain silver coupons, which were not corroded, to find out the safe range of laser energy density. From results, plain silver coupons were not changed at 1064nm below $4.00J/cm^2$ and at 532nm below $2.39J/cm^2$. The corrosion layer(silver sulfide) of artifical corroded silver coupons was removed at 1064nm with $2.39J/cm^2$ by 5~10 pulses and at 532nm with $1.19J/cm^2$ by 5~10 pulses. The removal thickness of corrosion layer was about 13-25nm per a laser pulse using AES analysis. In addition, laser cleaning tested the tarnish silver rings based on the results of silver coupons. As a result of test, the black surface were clean successfully and gave luster of silver, which showed the application possibility of laser cleaning for silver objects.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.55-57
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• 2005

기존의 장신구 은제품은 무르고 주조공정 특유의 미세한 표면결함을 가져서 착웅 중 쉽게 변색되는 문제가 있었다. 본 연구에서는 내식성을 향상시키기 위해 $92.5\%Ag-6.5\%Cu-1\%Zn$의 삼원계 은합금을 기초 소재로 해서 반지장신구를 상정하여 기존의 주조공정으로 대략의 형태를 만들고 금형과 유압프레스로 성형 가압시켜서 적극적으로 주조 시에 발생한 미세기공을 제거하고 결정립을 미세화하여 표면경도와 밀도를 향상시켰다. 선반가공과 미세연마를 실시하여 내식성이 향상된 표면과 기존 주조공정에 비해 3배 이상 향상된 경도를 가져서 스프링백 효과에 의해 귀보석을 세팅할 수 있는 개선된 텐션형 은장신구 공정을 개발하였고 이때의 최적 성형 정도를 확인하였다.

• Conservation Science in Museum
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• v.9
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• pp.31-49
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• 2008

We have investigated and conserved three small Buddha statues dating from Joseon period that were purchased by the National Museum of Korea. Chemical analysis and investigation of internal structures were enabled us to identify its compositions and hollow spaces which have various materials just like fabrics, silver ornaments, beads and wood fragments. The fabrics date from the early years of the Joseon dynasty to the middle one. The compositions of matrix of the Buddha statues vary 80-90 wt% Ag and 7-15 wt% Cu. And its surface layers were gilt with amalgam. Mechanical and chemical cleaning with EDTA-2Na were applied together during the cleaning process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.5
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• pp.805-810
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• 2006

Defects in the conventional casting process of silver jewelry can result in famished products of mediocre hardness. To overcome the shortcomings of conventional methods, we proposed new press forming process, which involves applying uniaxial pressure on casting 92.5%Ag-6.5%Cu-1%Zn ring elements and shaping with a lath. We investigated Vickers hardness, density, and microstructure evolution by changing the applied uniaxial pressure. We report that our newly proposed process can increase the hardness up to 2.3 times and decrease average grain size by 50%. Our method leads to drastic mechanical property enhancements, and is thus suitable for casting tension-style jewelry.