• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.631-632
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• 2006

Cr-C-Ni composites were synthesized in situ from elemental powders of Cr, Ni and C by high energy milling followed by reactive sintering. The milled powders with the grain size in nano-scale were pressed to compacts and sintered. During the following thermal treatment at first the chromium carbide was formed and then the $Cr_3C_2-Ni$ cermets were sintered in one cycle. The interface between the binder phase and the carbide grains of the in situ composite has a good bonding strength as it is not contaminated with oxidation films or other detrimental surface reactions.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.319-319
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• 1999

From isothermal and cyclic oxidation tests on thermomechanically treated Ti-5%Al, Ti47%Al-4%Cr, and Ti-48%Al-2%Cr-2%Nb alloys at 800, 900, 1000℃ in air, it was found that Ti-48%Al-2%Cr-2%Nb and Ti-47%Al-4%Cr had the best and the worst oxidation resistance, respectively. The oxide scales consisted primarily of TiO₂and Al₂O₃, with and without a small amount of dissolved Cr and 7b ions, depending on the alloy composition. These ions were slightly enriched inside the inner oxide layer, and strongly enriched around the scale-matrix interface. The outer TiO₂-rich layer was formed by the outward diffusion of Ti ions, while the inner (TiO₂+A1₂O₃,) mixed layer was formed by the inward transport of oxygen. The outward movement of Al ions farmed the intermediate Al₂O₃-rich Iayer, above talc prepared alloys.

• Journal of Welding and Joining
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• v.29 no.5
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• pp.58-62
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• 2011

Stainless steels are alloy steels with a nominal chromium content of at least 11 percent, with other alloy additions. The stainlessness and corrosion resistance of these alloy steels are attributed to the presence of a passive oxide film on the surface. When exposed to conditions like Resistance Spot Welding (RSW) process that remove the passive oxide film, stainless steels are subject to corrosive attack. And exposure to elevated temperatures causes oxidation (discoloration) of areas around indentation in Spot welding. In this paper, deal with the effect of shielding gas (Ar) preventing the corrosion, oxidation of stainless steel. And find the optimal shielding gas flow rate. In addition, suggest effective purging method for direct/indirect spot welding process.

• Korean Journal of Metals and Materials
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• v.50 no.4
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• pp.300-309
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• 2012

Low-carbon steels and a stainless steel were oxidized isothermally and cyclically between $1050^{\circ}C$ and $1200^{\circ}C$ for up to 100 min in air to find the effect of alloying elements of Si, Mn, Ni, and Cr on their oxidation. The most active alloying element of Si was scattered inside the oxide scale, at the scale-alloy interface and as internal oxide precipitates beneath the oxide scale. Manganese, which could not effectively improve the oxidation resistance, was rather uniformly distributed in the oxide scale. Nickel and chromium tended to present at the lower part of the oxide scale. Excessively thick porous scales formed on the low-carbon steels, whereas thin but non-adherent scales containing $Cr_2O_3$ formed on the stainless steel.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.85-92
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• 1999

The complete catalytic oxidation of vinyl chloride was investigated over chromium oxide supported ${\gamma}$-alumina using a fixed bed micro-reactor at temperature between 240 and $300^{\circ}C$ and concentration between 600 and 3500 ppm. The oxidation of vinyl chloride was nonlinear in the concentration of vinyl chloride and zeroth order in the concentration of oxygen. The addition of HCl and $H_2O$ as products to the feed stream didn't influence the conversion of vinyl chloride. Several kinetic rate model were tested to describe the data over the range of condition investigated, and developed a model which provide the best correlation of experimental data. The resulting model of kinetic rate was derived by assuming that the reacting occurred via adsorption and subsequent decomposition of the vinyl chloride onto the oxygen covered chromium oxide surface, with the reaction being inhibited by the adsorption of vinyl chloride. The percent standard deviation between the predicted and experimental was about 5.2%, and the activation energy was 18.9 kcal/mol.

• Applied Biological Chemistry
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• v.33 no.2
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• pp.174-176
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• 1990

Oxidation of artemisinic acid was attempted with chromium trioxide-pyridine complex. Epi-Deoxyarteannuin B was formed almost quantitatively, while expected keto artemisinic acid was not the major product. The physical and spectral data of the product are presented(Received March 9, 1990, Accepted May 25, 1990)

• Proceedings of the Materials Research Society of Korea Conference
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• 2006.05a
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• pp.35.1-35.1
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• 2006

• Proceedings of the Materials Research Society of Korea Conference
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• 2004.05a
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• pp.43-43
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• 2004

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.534-538
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• 1990

Chromium(Ⅵ) compound, [$C_9H_7$NH]$_2Cr_2O_7$ has been prepared by the reaction of isoquinoline with chromium trioxide under the presence of water. [$C_9H_7$NH]$_2Cr_2O_7$ is nonhydroscopic and dissolved in water very well. Structure of [$C_9H_7$NH]$_2Cr_2O_7$ is identified by FTIR spectra and elemental analysis data. The ability of [$C_9H_7$NH]$_2Cr_2O_7$ for the oxidation of alcohols were examined in methylene chloride. [$C_9H_7$NH]$_2Cr_2O_7$ was found as efficient oxidizing agent for the conversion of allyl, primary and secondary alcohols to the corresponding aldehydes or ketones.

• Journal of Korea Foundry Society
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• v.30 no.5
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• pp.179-186
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• 2010

To elucidate the effects of alloying elements on the characteristics of microstructure and high temperature oxidation of cast austenitic stainless steel, a thermodynamic calculation, a cyclic oxidation test, a X-ray diffraction, a scanning electron microscopy-back scattered electron, a electron probe microanalysis were conducted. The thermodynamic calculation for the effect of vanadium (V) addition on the formation of various precipitates leads to a decrease of chromium (Cr)-rich $M_{23}C_6$ carbides due to the formation of M (C, N) carbo-nitrides containing V and / or niobium (Nb). The V added alloy increased the resistance to high temperature oxidation due to a decrease of Cr-depleted zone deteriorating the oxidation resistance and due to the V-enriched oxide layer formed in inner oxide layer blocking the outward transport of cations.