• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 추계학술발표회초록집
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• pp.11-11
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• 2003

Electroplated hexavalent chromium coatings have been used in many technical applications since it was invented by G.J. Sargent in 1920. Because of the environmental problems and health risks associated with the use of hexavalent chromium, there has been an extensive search for alternative coatings with properties such as corrosion resistance and wear resistance, at a reasonable cost. However there is no single substitute that meets all the desirable performance characteristics of chromium. Advanced techniques, such as alloy plating, electroless plating, trivalent chromium plating, plasma and thermal spray coating, PVD and ion implantation, have been applied for replacing hexavalent chromium plating.

• 한국표면공학회지
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• 제36권1호
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• pp.48-58
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• 2003

This paper will present an overview of toxicity of hexavalent chromium as well as effort for its replacement by a wide spectrum of alternative materials and technologies. Cr-based materials such as trivalent electrodeposit will be one of strong candidates for hard chromium by surface modification of its surface hardness. Ni-base alloy deposits has proved its application in specific mold for glass. HVOF has been studied in aircraft and military sector. There are still under way of development for commercially available alternatives. To date, no single coating has been identified as universal process as comparable to conventional hard chromium electroplating.

• 한국표면공학회지
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• 제16권4호
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• pp.188-194
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• 1983

The method of trivalent chromium plating has been studied. The relations between the mixing ratio of chromic chloride and DMF, and the corrosion resistance and throwing power of plated chromium have been investigated. As a result, the best result has been obtained, when the mole ratio of chromic chloride and DMF are 0.8 and 5.4M respectively, and it has been learned that the amounts of DMF added have particularly the delicate effects in chromium plating procedures. The results of measuring of pH and reduction potentials of chromium plating bath with addition of DMF showed that the functions of DMF have both the buffer actions for the solution and the complex formation of trivalent chromium.

• Nuclear Engineering and Technology
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• 제53권10호
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• pp.3158-3163
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• 2021

Chromium material is commonly used for fusion plasma facing applications because of the low neutron activation property. The Monte Carlo method is one of the useful ways to investigate the ion-target interactions. In this study, Chromium target irradiated by protons was investigated using Monte Carlo based simulation tools. In this context, the calculations of radiation damage on Chromium material irradiated with protons at 17.9 and 22.3 MeV energies were carried out using GEANT4 and SRIM codes. Besides, the cross sections for proton interaction with Chromium target were calculated by the TALYS 1.9 code using CTM + FGM, BSFGM, and GSFM level densities. As a result, GEANT4, SRIM and TALYS 1.9 codes provide a suitable tool for the predictions of radiation damage and cross cross section with proton irradiation.

• Asian-Australasian Journal of Animal Sciences
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• 제22권10호
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• pp.1414-1419
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• 2009

The study was conducted to evaluate the effects of trivalent chromium from different sources on growth, carcass composition, and serum parameters in finishing pigs. Ninety-six crossbred pigs with an initial average body weight of 65.57${\pm}$1.05 kg were blocked by body weight and randomly assigned to four treatments with three replicates. Pigs were offered one of four diets including a control diet or the control diet supplemented with 200 ${\mu}g/kg$ chromium from either chromium chloride ($CrCl_{3}$), chromium picolinate (CrPic) or chromium nanocomposite (CrNano) for 40 days. After completion of the feeding trial, eight pigs from each treatment were selected to collect blood samples, and slaughtered to measure carcass composition. The results showed that supplemental chromium had no significant effect on growth performance, while CrNano increased carcass lean proportion and loin Longissimus muscle area (p<0.05), and decreased carcass fat proportion and 10th rib backfat depth (p<0.05). CrPic supplementation also resulted in lower fat proportion and larger Longissimus muscle area (p<0.05). The addition of Cr from CrNano or CrPic decreased serum glucose (p<0.05) and increased concentrations of total protein and free fat acid in serum (p<0.05). Serum urea nitrogen, triglyceride and cholesterol were decreased (p<0.05), and serum high density lipoprotein and lipase activity were increased (p<0.05) with the supplementation of CrNano. Serum insulin was decreased (p<0.05) by supplemental Cr from CrNano or CrPic, and serum insulin-like growth factor I was increased significantly in the CrNano treated group. These results suggest that chromium nanocomposite has higher efficacy on carcass composition in pigs compared to the traditional chromium sources.

• Asian-Australasian Journal of Animal Sciences
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• 제18권2호
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• pp.235-240
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• 2005

Two hundred and eighty-eight 21-week-old Hyline Brown laying hens were randomly allotted to 9 treatments, 32 birds for each treatment. A 3${\times}$3 (chromium${\times}$L-carnitine) factorial experiment was designed to investigate the single and interactive effects of adding yeast chromium (0, 400 and 600 ${\mu}g/kg$) and L-carnitine (0, 50 and 100 mg/kg) to corn-soybean diets on lipid metabolism of laying hens for 7 weeks. The results showed that 600 ${\mu}g/kg$ chromium or 100 mg/kg L-carnitine had significant effects on most indices of lipid metabolism (p<0.05 or 0.01). There were significant interactions on the concentration of liver triglycerides, egg yolk cholesterol, abdominal fat percentage between chromium and L-carnitine (p=0.0003-0.0500). Adding 400 ${\mu}g/kg$ chromium and 100 mg/kg Lcarnitine simultaneously was the best for reducing egg yolk cholesterol and adding 400 ${\mu}g/kg$ chromium and 50 mg/kg L-carnitine at the same time was the best for reducing abdominal fat percentage. There was no side effect on production performance of laying hens while chromium or (and) L-carnitine reduced liver lipid, abdominal fat and egg yolk cholesterol.

• 대한치과교정학회지
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• 제19권1호
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• pp.245-256
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• 1989

Translational movement along an arch wire requires sufficient force to overcome frictional forces between bracket and arch wire. The orthodontist must appreciate the importance of friction in this process, and study out the influencing factors on the level of friction. The purpose of this study was to evaluate the effect of artificial saliva on frictional resistances generated between the bracket and arch wire. Independent variables of this study were arch wire material, angulation and environment. Static frictional forces of cobalt-chromium, heat-treated cobalt-chromium, beta-titanium, stainless steel wires were measured under non-angulated dry, angulated dry, non-angulated saliva, angulated saliva conditions. The results were as follows: 1. Stainless steel wires showed lower friction values in non-angulated dry condition, and heat-treated cobalt-chromium wires showed higher friction values in angulated dry condition. Higher friction values were showed in order of cobalt-chromium. stainless steel, heat-treated cobalt-chromium and beta-titanium wires in non-angulated saliva condition. and were showed in order of stainless steel, cobalt-chromium, heat-treated cobalt-chromium, beta-titanium wires in angulated saliva condition. 2. Angulation increased friction for stainless steel wires under dry condition. 3. Artificial saliva decreased friction for cobalt-chromium wires and increased friction for stainless steel wires under non-angulated condition. 4. Artificial saliva decreased friction for all wires except beta-titanium wires under angulated condition. 5. Regardless of angulation or environment. heat-treated cobalt-chromium and beta-titanium wires showed higher friction values, and stainless steel wires showed lower friction values.

• 한국잠사곤충학회지
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• 제38권1호
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• pp.25-30
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• 1996

견 피브로인 섬유에 의한 Cr(VI)의 흡착 특성을 분석하였다. Cr(VI)의 흡착평형은 초기 흡착속도에 큰 영향을 받고 있으며 평형흡착량의 52% 정도에 이르고 있다. 견 피브로인 섬유에 의한 Cr(VI)의 흡착은 크롬염의 산화반응을 일으키는 산성의 pH 범위에서 흡착량이 증가한다. Cr(VI)의 흡착온도에 대한 엔탈피($\Delta$H)의 변화는 39.7KJ.mol-1로 얻어졌다. 이것은 Cr(VI)의 흡착이 착제 화학적 반응이라는 것을 의미하며 IR 스펙트럼의 결과에서도 아미드 형 카르보닐의 배위에 의한 착물형성이 확인되었다. 또한, 견 피브로인 섬유의 크롬 흡착처리에서 물성의 과도한 저하를 고려한 조건은 온도 5$0^{\circ}C$ pH 2.4, 3시간의 처리가 적당하고 5 X 10-3M의 농도에서 흡착평형에 도달하였다.

• 대한화학회지
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• 제20권6호
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• pp.494-499
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• 1976

추출폴라로그래프법을 이용하여 6가 크롬을 정량하는 방법에 대하여 검토하였다. 수용액중의 Cr(Ⅵ)을 초산완충용액 (pH = 5.4)에서 diethyldithiocarbamate를 킬레이트제로 사용하여 methylisobuthylketone용매로 추출하여, 이 추출액에 지지전해제로 sodium perchlorate를 넣어 직류 폴라로그램을 얻었다. 이 추출착물의 환원파는 확산지배적이었으며, 이 파의 반파전위는 -0.81 volts vs. SCE 였다. 이 환원파의 확산전류는 Cr(Ⅵ)의 양이 8 ppm 에서 160 ppm 까지의 농도범위에서 Cr(Ⅵ)의 농도에 비례하였다. 더욱이 2배량의 Cr(Ⅲ)이 공존해도 Cr(Ⅵ)의 정량에 별 영향이 없으므로 Cr(Ⅲ)와 Cr(Ⅵ)의 분별정량이 가능하며 또 Mn(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Ag(Ⅰ), Mg(Ⅱ), Ni(Ⅱ) 등이 약 1000배 정도 공존하여도 Cr(Ⅵ)의 정량에는 별 영향이 없었다

• 한국지하수토양환경학회지:지하수토양환경
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• 제22권6호
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• pp.22-28
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• 2017

The accuracy of analytical results in response to the use of different additives ($NH_4Cl$, KCl, $LaCl_3$) and oxidant gases was evaluated and compared by using Atomic Absorption Spectrometry (AAS). Identification of spectroscopic interferences and possible improvements in Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) analysis were also discussed. The average accuracies of total chromium using Certified Reference Materials (CRMs) were found to be 72.1~94.2% in air/acetylene flame condition by AAS, and they were improved to 100.5~110.5% when the oxidants was changed to nitrous oxide rather than adding the additives. The field samples showed similar trends to CRMs, but chromium concentrations were highly variable depending on analytical conditions. The average accuracies using CRMs were estimated to be 89.3~166.1% by ICP-AES, and improved to below 121.7% after eliminating iron interference. Field samples with low chromium and high iron concentration were measured to be > 30% lower in total chromium concentrations by ICP-AES than AAS in nitrous oxide/acetylene flame. Total chromium concentrations in soil could be analyzed with better accuracy under nitrous oxide/acetylene flame by AAS because it was more effective to increase the temperature of the flame than to eliminate the chemical interference for maximizing atomization of chromium. When using ICP-AES, interference substances, total chromium levels, and analytical conditions should be also considered.