• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.644-649
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• 2006

In this paper, the Cr(VI) adsorption behaviors of activated carbons (ACs) treated by various ozone treatment conditions were studied. The surface properties of the ACs studied were determined by pH, acid-base, and FT-IR measurements. $N_2$ adsorption isotherm characteristics at 77K were confirmed by BET equation, Boer's t-plot method, and Horvath-Kawazoe's slit pore model. Also, the total Cr adsorption amount onto the ACs was measured by ICP-AES. As a result, the ozone treatment led to an increase of oxygen-containing polar functional groups and total acidity as well. Meanwhile, the specific surface areas or micropore volumes were slightly decreased after the ozone treatment due to the micropore filling or blocking. Nevertheless, the total Cr adsorption of ACs was increased with increasing of the ozone treatment time, attributed to the good interaction between Cr ions and polar functional groups on the ACs.

• Analytical Science and Technology
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• v.11 no.1
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• pp.29-35
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• 1998

This study was performed to assess the levels of the Cr and Co in fisheries caught from the some areas of west coast in Korea. The samples were 26 kinds of fishes, 19 kindly of Mollusca and 3 kinds of Crustacea. They were ashed with 5 ml $HNO_3$ and then wet-decomposed with 10 ml of a mixture of $HNO_3:H_2SO_4:HClO_4$ (10:1:4). After ashing of samples, the amounts of Cr and Co in the samples were determined by ICP-AES analysis. The moisture content of molluscans was significantly higher than that of crustaceans (p<0.05), but there was no significant difference among fisheries in the Cr content. And the Co content of crustaceans was significantly higher than that of fishes and molluscans (p<0.001). There was no significance between contents of Cr and Co in fisheries. The Cr content of Arkshell was 422.00 ppm, which was the most amount compared with those of the other samples. And the Co in Myong-Ge was 3.78 ppm, which was the most amount. Areliscus honaleus (Cr:2.76 ppm, Co:0.97 ppm), Solen (Cr:6.56 ppm, Co:1.59 ppm) and dried barley shrimp (Cr:1.06 ppm, Co:0.90 ppm) contained great amount of Cr and Co.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.506-513
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• 2010

The composite coatings of $(ZrO_2-8Y_2O_3)$/(Ni-22Cr-10Al-1Y) were prepared by the air plasma spraying method. They consisted of (Ni,Cr)-rich regions,$(ZrO_2-Y_2O_3)$-rich regions, and $Al_2O_3$-rich regions that were formed by oxidation of Al from (Ni-22Cr-10Al-1Y) during spraying. The coatings corroded at 800 and $900^{\circ}C$ in NaCl-$Na_2SO_4$ molten salts up to 50 hr. Ni, Cr and Al oxidized to NiO, $Cr_2O_3$ and ${\alpha}-Al_2O_3$, respectively. These oxides and $(ZrO_2-Y_2O_3)$ were dissolved off into the molten salts during hot corrosion, which resulted in the ever-lasting corrosion of the composite coatings. Chromium diffused out from the (Ni,Cr)-rich regions and oxidized to $Cr_2O_3$, which was most frequently found as surface scales. Aluminum retained in the (Ni,Cr)-rich regions were similarly diffused out.

• Journal of the Korean institute of surface engineering
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• v.31 no.6
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• pp.393-399
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• 1998

The composition and the properred orientation of Co-Fe-Cr alloy electrodeposits were invesigated according to the electrolysis conditions using sulface bath. The current efficiency and the cathode overpotential decrased noticeably with the increase of Cr content in the bath. As the D.C. current density increased increased, the Cr content in the alloy increasd, while Co content decreased and Fe content remained constant, In the pulse current electrolysis, the Cr content of the alloy increased with the mean current density and off-time and then its content increased mord more noticeably with the peak current density than that of D.C. electrolysis. The preferred orientation of the alloy changed from (220)+(111) to (220) with decreasing cathode overpotential.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.81-87
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• 2003

Ti-20%Zr-X%Cr(X=0,5) based alloys not containing hamful Al and V were newly designed in order to reveal their possibility for dental casting alloys, and melted in argon-arc casting machine. The mechanical properties were evaluated by using universal testing machine. The tensile strength and %elongaton of the alloys markedly increased with Cr content. The Ti-20%Zr-5%Cr alloy showed a similar tendency with Ti-6%Al-4%V alloy in tensile strength, but surpassed in %elongation. From these results, it was concluded that new alloys for successful dental casting materials should be designed as Ti-Zr-Cr based alloys.

• Journal of Nutrition and Health
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• v.35 no.8
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• pp.834-839
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• 2002

This study aimed to investigate the effects of chromium picolinatec (CrP) supplementation on the glucose and lipid metabolism of rats. Five-week-old male Sprague-Dawley rats were fed a high-fat diet fir 110 days and further treated with CrP or placebos for 6 weeks. The effect of CrP supplementation on body weight, blood glucose, insulin and lipid levels was examined. The results suggested that body weight gain was not significantly different between the control and the CrP supplemented group. Plasma glucose, triglyceride and cholesterol levels in the CrP treated group significantly decreased compared to those of the control group (p < 0.05). The total lipid, triglyceride and cholesterol concentrations in the livers of the CrP treated group significantly decreased compared to those of the control group (p < 0.05). These results indicate that supplementation of chromium picolinate ran reduce triglyceride and glucose concentrations in the blood and total lipid and total cholesterol levels in the liver.

• Journal of Powder Materials
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• v.7 no.1
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• pp.19-26
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• 2000

Al-Cr-Zr metal powders were prepared by cryo-milling(-75$^{\circ}C$),ambi-milling(25$^{\circ}C$) and warm-milling(200$^{\circ}C$) to investige the effect of milling temperature. The morphogical changes and microstructural evolution of Al-6wt.%Cr-3wt.%Zr metal powder ball milling were investigated by SEM, OM and XRD. The cryo-milling at -75$^{\circ}C$ caused the more refinement of powder particle size than ambi-milling and warm-milling. The partic morpholgy of Al-Cr-Zr metal powders changed changes into spheroidal particles at 25$^{\circ}C$and spherical particles at 200$^{\circ}C$The spherical particles were formed by agglomertion and contiuous wrapping of the spheroidal particles. The calculated Al crystallite size in Al-Cr-Zr metal powders by the Scherer equation were refined rapidly for short milling time -75$^{\circ}C$compared with milling at 25$^{\circ}C$ and 200$^{\circ}C$.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.6
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• pp.687-693
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• 1992

To improve dielectric, piezoelectric and temperature stability in 0.50Pb(SnS11/2TSbS11/2T)OS13T - 0.35PbTiOS13T - 0.60PbZrOS13T + 0.4[wt%]MnOS12T piezoelectric ceramics which is used for surface acoustic wave devices, CrS12TOS13T was added and the specimens were fabricated by Hot Press method, and their characteristics were measured with CrS12TOS13T addition. From the results, in the specimen added by 0.2[wt%]CrS12TOS13T, dielectric constant and mechanical quality factor were 380 and 2307, respectively, and it was suited for surface acoustic wave device and the temperature coefficient of the resonant frequency in the specimen added by 0.4[wt%]CrS12TOS13T was the least value of 74.96[ppm/$^{\circ}C$].

• Journal of Ceramic Processing Research
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• v.19 no.6
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• pp.455-460
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• 2018

Chromium plating is a common surface treatment technique extensively applied in industry due its excellent properties which include substantial hardness, abrasion resistance, corrosion resistance, surface color, and luster. In this study, the effect of PTFE on corrosion behavior of Cr-P plating, low carbon steel substrates are electroplated in Cr(III) baths without and with PTFE. Trivalent chromium carbon plating was electroplated from trivalent chromium sulfate-based baths with different PTFE dispersion contents. The study focused on the microstructure, PTFE content, roughness, and corrosion resistance of the Cr-P-PTFE composite plating. Scanning electron microscopy and atomic force microscopy images showed a smoother plating and a decrease in the surface roughness of the electrodeposited. The results demonstrate that PTFE eliminates the cracks within plating by reducing internal stress. Therefore, the corrosion resistance of Cr-P-PTFE composite platings were better than that of Cr-P alloy platings.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1887-1892
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• 2021

The effect of gadolinium and boron on the texture development and magnetic properties of the texture controlled 23Cr-10NiCu duplex stainless steels were studied to develop a high performance neutron and electromagnetic shielding material. The 23Cr-10NiCu base alloy is composed of 60% of austenite and 40% of ferrite, whereas, the 23Cr-10NiCu-0.5Gd-0.8B modified alloy is composed of 66% of austenite, 27% of ferrite and 7% of CrFeB intermetallic compounds. The gadolinium and boron addition to the 23Cr-10NiCu base alloy increased mechanical properties. Microstructure observation showed that the small addition of 0.5 wt% gadolinium and 0.8 wt% boron to the alloy retarded to form texture at the same hot rolling conditions, and improved the maximum magnetism, residual magnetism and coercive force about 3%, 122% and 120%, respectively.