• Asian-Australasian Journal of Animal Sciences
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• v.9 no.3
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• pp.341-347
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• 1996

An experiment was conducted to evaluate the effects of dietary levels of chromium in the form of chromium picolinate on growth performance, nutrient utilizability, carcass composition, serum traits, and in vitro lipolysis and lipogenesis in adipose tissues of Arbor Acre broiler chicks. Experimental diets containing six different levels of chromium (0, 100, 200, 400, 600 and 800 ppb) were fed for 6 weeks. Individual treatment had six replicates of eight birds each and their average initial weight was 59.2 g. Dietary addition of chromium did not affect growth performance and nutrient utilizability. However, mortality appeared to be reduced with addition of chromium to the diet. It was obvious that chromium supplementation significantly decreased serum cholesterol and increased serum HDL cholesterol (p < 0.05), but serum insulin, glucose, triglyceride and non-esterified fatty acid concentrations were inconsistent among dietary supplementation levels of chromium. The in vitro lipolysis and lipogenesis in adipose tissues were significantly influenced by dietary addition of chromium (p < 0.05). Chicks fed diets containing 200 or 400 ppb chromium showed the highest protein content and the lowest fat content in their carcass.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4270-4274
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• 2011

A method is proposed for determining chromium content in the carbon steel pipes of a nuclear power plant (NPP) to evaluate wall thinning caused by flow-accelerated corrosion (FAC). A flat file was used to obtain filings samples. To assess sampling quality, a disk form of SRM 1227 was ground with the flat file, and the amount of Cr in the filings was determined by ICP-AES. The content of chromium in the filings of SRM 1227 was estimated as six times higher than the certified value due to the contamination of chromium in the file. To eliminate chromium contamination from the file, it was coated with WC-12Co using high-velocity oxygen-fuel (HVOF) spraying systems. After obtaining filings samples using the coated file, Cr content in four types of disk-form SRMs was determined by ICP-AES. The recoveries of Cr in the disk-form SRMs were in the range of 95.4-102.6%, with relative standard deviations from 0.43 to 3.0%. The Cr contents in the filings collected from the used outlet headers of the nuclear power plants using the flat file coated were in the range of 0.11-0.19%.

• Corrosion Science and Technology
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• v.9 no.5
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• pp.196-200
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• 2010

Recently porous metal has been used as supporting metal in planar type SOFC. In order to search optimum alloys for porous metal support and estimate the stability of metal-supported SOFC at high temperature, it is necessary to investigate the oxidation behaviors of porous material for metal support in comparison with dense material. Oxidation tests of porous and dense stainless steels were conducted at $600^{\circ}C$ and $800^{\circ}C$. Since the specific surface area of porous material is much larger than that of dense material, surface area should be considered in order to compare the oxidation rate of porous stainless steel with that of dense stainless steel. The specific surface area of porous body was measured using image analyzer. The weight gain of porous stainless steel was much greater than those of dense stainless steels due to its larger specific surface area. considering the specific surface area, the oxidation rate of porous stainless steel is likely to be the same as that of dense stainless steel with the same surface area. The change in chromium content in stainless steel during oxidation was also investigated. The experimental result in chromium content in stainless steel during oxidation corresponded with the calculated value. While the change in chromium content in dense stainless steel during oxidation is negligible, chromium content in porous stainless steel rapidly decreases with oxidation time due to its large specific surface area. The significant decrease in chromium content in porous stainless steel during oxidation may affect the oxidation resistance of porous stainless steel support and long term stability of metal-supported SOFC.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.3
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• pp.349-354
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• 1996

An Experiment was conducted to evaluate the effects of dietary excessive chromium picolinate on growth performance, nutrient utilizability and the content of serum cholesterol, HDL cholesterol, glucose, triglyceride and non-esterified fatty acid in broiler chicks. Experimental diets based on corn-soybean meal were supplemented at 0, 800, 1,600 and 2,400 ppb chromium in the form of chromium picolinate. Each treatment had six replicates of six female chicks each (average initial weight=45.6 g). Experimental period lasted for six weeks. Excessive supplementation of chromium as chromium picolinate had no effect on body weight gain, feed intake, feed conversion and nutrient utilizability of broiler chicks. Mortality was improved with a supplementation of chromium (p < 0.05). However, serum glucose decreased as chromium level increased (p < 0.05). Up to 2,400 ppb chromium as chromium picolinate, signs of toxicity were not noticed in this study.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.1
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• pp.1-7
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• 1997

This experiment was conducted with total 960 brown layers, consisted of 8 treatment to investigate the effects of dietary chromium as chromium picolinate on egg production, egg quality, nutrient utilizability, serum traits and mortality in brown layers. Layers were fed diets with two levels of dietary protein (14% and 16%) and supplemented with 0, 200, 400, 800 ppb/kg of chromium as chromium picolinate, respectively. The highest egg production, egg weight and egg mass were found in 800 ppb chromium picolinate supplementation group with high protein level (16%) (p < 0.05). Although there was no significant difference, layers receiving 400 ppb of chromium picolinate with high protein (16%) represented the lowest broken eggs. The utilization of energy, dry matter and crude protein of 400 ppb chromium picolinate group with low protein level (14%) were significantly higher than those of control or other chromium picolinate group (p < 0.05). 400 ppb chromium picolinate with low protein level (14%) showed the lowest serum glucose concentration. But serum glucose concentrations in all treatments showed no significant differences. Present date revealed that the lowest serum cholesterol concentration of layers was found at 400 ppb chromium picolinate group with high protein level (16%) (p < 0.05). Crude protein content in yolk was significantly higher in eggs of layers received 800 ppb chromium picolinate and the lowest in eggs from layers received 400 ppb chromium picolinate among chromium picolinate levels (p < 0.05). Mortality was remarkably decreased by chromium picolinate supplementation and the lowest mortality value was found in layres receiving 800 ppb chromium picolinate with high protein level.

• Journal of the Korean institute of surface engineering
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• v.37 no.2
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• pp.80-85
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• 2004

Chromium-carbon (Cr-C) and chromium-carbon-phosphorus (Cr-C-P) alloy deposits using trivalent chromium sulfate baths containing potassium formate were prepared to study their current efficiency, hardness change and phase transformations behavior with heat treatment, respectively. The current efficiencies of Cr-C and Cr-C-P alloy deposits increase with increasing current density in the range of 15-35 A/dm$^2$. Carbon content of Cr-C and phosphorous of Cr-C-P layers decreases with increasing current density, whereas, the carbon content of Cr-C-P layer is almost constant with the current density. Cr-C deposit shows crystallization at $400^{\circ}C$ and has (Cr+Cr$_{ 23}$$C_{6}$) phases at $800^{\circ}C$. Cr-C-P deposit shows crystallization at $600^{\circ}C$ and has (Cr+Cr$_{23}$ $C_{6}$$+Cr_3$P) phases at $800^{\circ}C$. The hardness of Cr-C and Cr-C-P deposits after heating treatment for one hour increase up to Hv 1640 and Hv 1540 and decrease about Hv 820 and Hv 1270 with increasing annealing temperature in the range of $400～^{\circ}C$, respectively. The hardness change with annealing is due to the order of occurring of chromium crystallization, precipitation hardening effect, softening and grain growth with temperature. Less decrease of hardness of Cr-C-P deposit after annealing above $700^{\circ}C$ is related to continuous precipitation of $Cr_{23}$ $C_{6}$ and $Cr_3$P phases which retard grain growth at the temperature.

• Journal of Welding and Joining
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• v.16 no.2
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• pp.64-72
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• 1998

This study aims a investigating the effect of volume fraction of chromium carbide phase(VFC) of hardfaced iron/chromium alloys on fracture toughness. The alloys were deposited twice on a mild steel plate using self-shielding flux cored arc welding process. In order to examine VFC effect, different VFC (0.28∼0.62) were employed by changing the Cr and C content, while the ratio of Cr/C was fixed in the range of 5.7∼6.6. Fracture toughness was constant as increasing VFC because fracture surface was developed in the eutectic phase which was growing parallel with introduced sharp notch in the hypoeutectic alloys, but fracture toughness did not decreased in spite of increasing volume fraction of coarse primary chromium carbide phase which was easily craced at the low stress because the growth direction of chromium carbide phase were more irregular as increasing VFC in the hypereutectic alloys.

• Journal of the Korean institute of surface engineering
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• v.23 no.1
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• pp.16-26
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• 1990

The standrd electrolyte for the electrodeposition of chromium were preparwith reagent grade chromic acid(200g/L), sulfuric acid(pH=1.8)and oxalic acalic acid(640g/L)as additive. Carbon content in chromium plating varied about2.0-3.8 wt% with current density and temperatures of the bath. The hardeness of chromium platings incresed with increasing the annealing temperatures and showed maximum value of about Hv 1700 after annealing at$ 700^{\circ}C$for 60min. But, decreased it as annealing at above $700^{\circ}C$. The reason for varing thee hardness of chromium codeposited with carbon gradually foumed chromium carbide(Cr7C3), but that changed to Cr23C6 as annealing temperature at above $^700{\circ}C$. The X-ray diffraction pattern indicated that chromium carbides, such as Cr7C3 or Cr3C2, formed at formed at above $300^{\circ}C$. titanium coating sputtered on the on surface of chromium plating had performed and determined the hardness after annealing at 500, 600, $700^{\circ}C$ for 60min. the maximum hardeness was about Hv 2400 as annealing at $700^{\circ}C$. The titanium carbide formed in layer was identified by X-ray diffraction. It was confirmed that chromium and titanium carbide has effect of increasing the hardness.

• Bulletin of the Korean Chemical Society
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• v.13 no.6
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• pp.605-612
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• 1992

Chromium oxide/zirconia catalysts were prepared by dry impregnation of powdered $Zr(OH)_4$ with ($NH_4$)$_2$CrO$_4$aqueous solution. The characterization of prepared catalysts was performed using FTIR, XPS, XRD and DTA methods, and by the measurement of surface area. The addition of chromium oxide to zirconia shifted the transitions of $ZrO_2$ from amorphous to tetragonal phase and from tetragonal to monoclinic phase to higher temperature due to the strong interaction between chromium oxide and zirconia, and the specific surface area of catalysts increased in proportion to the chromium oxide content. Since the $ZrO_2$ stabilizes supported chromium oxide, chromium oxide was well dispersed on the surface of zirconia, and ${\alpha}$-$Cr_2O_3$ was observed only at the calcination temperature above 1173 K. Upon the addition of only small amount of chromium oxide (1 wt% Cr) to $ZrO_2$, both the acidity and acid strength of catalyst increased remarkably, showing the presence of two kinds of acid sites on the surface of $CrO_x$/$ZrO_4$-Bronsted and Lewis.

• Toxicological Research
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• v.8 no.1
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• pp.119-129
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• 1992

Present study was carried out to investigate the cytotoxicity of cadmium, chromium and mercury on cultured rat fibroblasts. The colorimetric assays of neutral red (NR) and tetrazolium MTT, the measurement of total content of protein and electron microscopic studies were performed on the fibroblasts cultured in the media containing various concentrations of cadmium, chromium and mercury. The results are as follows' 1. In cadmium-treated group, the NR and MTT values were dose-dependent increase. The NR90, NR50, MTT90 and MTT50 values of cadmium were 0.2mM, 19.5mM 1.0mM and 60.0mM, respectively.