• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2003년도 춘계학술발표회 초록집
• /
• pp.61-61
• /
• 2003

It is important to know SIze distribution of defects In electroplated trivalent chrome layers because it significantly influences on performance of the layers. Most of the nano-scale defects are able to be introduced by hydrogen evolution during the plating. Little information is available on the nano-size defects. In this study, SANS was applied to determine the size distribution of nano-scale defects in the trivalent chrome layers prepared in a formate bath. The defect size and distribution was dependent upon plating conditions such as current density and applied voltage. SANS is one of useful techniques to determine the nano-scale defect in the electroplated layers.

• 한국표면공학회지
• /
• 제37권3호
• /
• pp.175-178
• /
• 2004

The size and number of nano-size defects of thin trivalent chrome layers were determined by small angle neutron scattering (SANS) without breaking the thin chrome layers. Most of defect size of the trivalent chromium prepared in this test conditions is in the range of about 40nm. The number of nano-size defects less than about 40nm of the trivalent chromium layer increases with plating voltage at constant current density From this study, SANS is proved as one of useful techniques to evaluate nano-size defects of thin film layer.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2009년도 춘계학술대회 논문집
• /
• pp.129-129
• /
• 2009

Much attention has been recently paid to the trivalent chromium electro-plating for the application of surface finishing, mainly because of the environmental issues. Nevertheless, trivalent chromium plating has several critical issues to be figured out for such applications, including instability of the plating solution, poor property of plates and etc.

• 한국표면공학회지
• /
• 제49권2호
• /
• pp.111-118
• /
• 2016

A method to quantitatively analyze the defects formed by the hydrogen evolution during electroplating was suggested based on the theoretical approach of the small angle neutron scattering technique. In case of trivalent chrome layers, an isolated defect size due to the hydrogen evolution was about 40 nm. Direct and pulse plating conditions gave the average defect size of about 4.9 and $4.5{\mu}m$ with rod or calabash shape, respectively. Current density change of the pulse plating from $1.5A/dm^2$ to $2.0A/dm^2$ enlarged the average defect size from 3.3 to $7.8{\mu}m$. The defect morphology like rod or calabash was originated by inter-connecting the isolated defects. Small angle neutron scattering was useful to quantitatively evaluate defect morphology of the deposit.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.335-338
• /
• 2001

With the use of the electron microscopy and X-ray phase analysis the regularities of carbon deposit formation in process of methane and propane pyrolysis on the zeolites, Kazakhstan natural clays, chrome and bauxite sludge containing metal oxides of iron subgroup, have been studied. In process of over-carbonization the trivalent iron was reduced to metal form. In addition, the carbon tubes of divers morphology had been impregnated with ultra-dispersed metal particles. The kinetic parameters of carbon formation in process of methane decomposition on the zeolite CoO mixture surface were investigated by method of thermo-gravimetric analysis. The morphology and structure of formed carbon fibrils, with the metal particles fixed at their ends, have been investigated, the formation of branched carbon fibrils pattern, so called octopus, being found.

• Transactions on Electrical and Electronic Materials
• /
• 제2권2호
• /
• pp.5-15
• /
• 2001

The experiment established optimal conditions for over-carbonization. With the use of the electron microscopy and X-ray phase analysis the regularities of carbon deposit formation in process of methane and propane pyrolysis on the zeolites, Kazakhstan natural clays, chrome and bauxite sludge containing metal oxides of iron subgroup, have been studied. In process of over-carbonization the trivalent iron was reduced to metal form. In addition, the carbon tubes of divers morphology had been impregnated with ultra-dispersed metal particles. The kinetic parameters of carbon formation in process of methane decomposition on the zeolite - CoO mixture surface were investigated by method of thermo-gravimetric analysis. The morphology and structure of formed carbon fibrils, with the metal particles fixed at their ends, have been investigated, the formation of branched carbon fibrils pattern, so called octopus, being found. Also, the walnut shells and grape kernel carbonization, their immobilization by the cells of selective absorption of heavy metal and sulfur dioxide ions have been studied. The example of metal-carbon composites used as adsorbents for wastewater purification, C$_3$- C$_4$ hydrocarbon cracking catalysts and refractory materials with improved properties have been considered.

• 월간산업보건
• /
• 통권356호
• /
• pp.16-25
• /
• 2017

크롬은 환경 중에서 산화 환원 반응을 일으키며, 0가, 3가 및 6가 크롬 등 다양한 형태로 존재한다. 이 중 6가 크롬은 발암물질로 알려져 있기 때문에, 6가 크롬 종의 산화 환원 상태를 고려하는 것은 매우 중요하다. 6가 크롬은 3가 크롬 상태로 환원될 수 있지만 작업장환경 내에서 이에 대한 구체적인 정보는 미흡하다. 본 연구는 다양한 조건 하에서 시간에 따른 6가 크롬 환원양상을 파악하기 위해 전기도금 조를 설치하여 파일럿 연구를 실시하였다. 연구 결과, 6가 크롬이 미스트 형태로 방출된 이후 시간이 경과함에 따라 환원이 발생한다는 증거를 발견할 수 있었다. 미스트 방출 직후 6가 크롬 대 총 크롬의 퍼센트 비율(95% 신뢰구간)은 거의 100%(99.1~102.3%)에 달했으나, 1시간 경과 후 87.4%(84.8~89.9%)로, 2시간 경과 후엔 81%(78.3~83.5%)까지 환원됐다. PVC 여과지에 채취된 6가 크롬의 경우 시료채취 이후 시간이 경과함에 따라 환원이 진행됐다. 시료채취 후 2시간이 경과한 후 6가 크롬은 90.8%(88.2~93.3%)까지 환원되었으며, 또한 공기 중에 보관한 시료에서 6가 크롬의 환원이 가장 많이 진행되었다. 이에 따라, 6가 크롬 공기시료 보관 시 환원방지를 위한 각별한 주의가 요구된다.