• Journal of the Korean Society of Safety
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• v.38 no.2
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• pp.30-35
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• 2023

Acetone is a widely used Volatile Organic Compound (VOC) in industries and laboratories. However, acetone affects human health adversely and causes fires and explosions. Early acetone detection and improved personnel training in safety and emergency management are necessary to prevent acetone-related accidents. The multi-VOC acetone detectors used currently have a sensitivity and selectivity limit. In this study, we discovered that Pt-loaded iron oxide (a metal oxide semiconductor) conversely, has high detection and selectivity for very low-levels of acetone gas. The loaded Pt catalyzes the reaction between the sensing materials' surface and the oxygen molecules in the air; this optimizes acetone detection and can decrease acetone-related illnesses, fires and explosions.

• Journal of the Korean Society for Heat Treatment
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• v.37 no.5
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• pp.207-214
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• 2024

This study examines the effects of post-oxidation treatment on the microstructure and corrosion resistance of GC250 cast iron. The nitriding process was conducted at 570℃ for 180 minutes with a fixed nitriding potential (Kn) of 1.5, followed by post-oxidation at 450℃, 500℃, and 550℃ for 120 minutes. The post-oxidized specimens showed increased surface hardness and case depth compared to the nitrided specimens, with a maximum surface hardness of approximately 890 HV0.1. The oxidation process increased the thickness of the nitrided layer by more than 3 ㎛, with the oxide layer thickness reaching up to 2.5㎛ as the oxidation temperature increased. XRD analysis identified the presence of ε-phase, γ'-phase, and Fe₃O⁴ phase on the surface. Polarization tests revealed that the specimen treated at the highest oxidation temperature had a corrosion current density of 20.26 ㎂/cm² and a corrosion potential of -0.22V, indicating enhanced corrosion resistance compared to the nitrided specimen. This improvement is attributed to the formation and increased thickness of the oxide layer, which enhances corrosion resistance. In conclusion, the oxide layer formed through post-oxidation treatment significantly improves the corrosion resistance of GC250 cast iron, with the effect becoming more pronounced at higher oxidation temperatures.

• Journal of Conservation Science
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• v.37 no.6
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• pp.738-747
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• 2021

This study attempted to investigate the metallurgical characteristic through material scientific analysis of hammer scale produced as a direct smelting method restoration experiment for each raw material of iron. To this end, four hammer scale groups were set up, respectively, by experimenting with Gyeongju-Gampo Iron sand and Yangyang Iron ore. For the analysis, principal component analysis, compound analysis, microstructure observation, and chemical composition were confirmed. As a result of principal component analysis, as forging and refining progressed, the content of Fe increased and the content of non-metallic objects decreased. As a result of compound analysis, iron oxide-based compounds were identified. As a result of confirming microstructure and chemical composition, Wüstite and Fayalite were observed overall, and agglomerated Wüstite were observed in some. Magnetite on shape of polygon and pillar was observed. In addition, it was confirmed that internal defects, impurities, and non-metallic interventions gradually decreased. In the future, it is necessary to investigate the metallurgical characteristic through material scientific analysis of hammer scale produced through restoration experiments using various raw material of iron, and compare them with those excavated from Iron manufacture ruins.

• 보존과학연구
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• s.32
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• pp.89-98
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• 2011

It is quite difficult to identify its corrosion compound because they have a wide variety of crystal structures and they are mixed with two component. This study was conducted with the standard iron corrosion compounds through the analysis by Raman Micro-Spectroscopy, which aims to obtain standard Raman Data. To assess the reliability of standard iron corrosion compounds, SEM-EDS analysis and XRD analysis were conducted. Through SEM-EDS analysis, the elements of corrosion compound matched with those of standards iron corrosion compounds except Goethite. XRD analysis showed that the structures of corrosion compounds were identical to those of standard iron corrosion compounds, however, it was identified that Iron sulfate ($FeSO_4{\cdot}6H_2O$) is the Rozenite ($FeSO_4{\cdot}4H_2O$). Through Raman Micro-Spectroscopy analysis, the new peak was detected from the wavenumbers of hydroxide and iron oxide. It is considered that it is due to changes in the wavelength of the laser. As the wavenumbers of iron chloride and iron sulfate have been identified, eight kinds of Raman Data were obtained. It can be considered to contribute to cultral heritage for iron objects that Raman Micro-Spectroscopy analysis which is relatively easy to compare material properties and structures can be highly applicable to the research on cultural heritage with the limited amount of samples.

• Animal cells and systems
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• v.6 no.2
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• pp.171-180
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• 2002

Nitric oxide has high affinity for iron, and thus it can cause intracellular iron loss. We tested the idea that intracellular iron can be the primary target of NO toxicity by comparing the signaling mechanisms involved in cell death caused by iron depletion and that caused by NO. Treatment of HL-60 cells with a NO donor, S-nitroso-N-acetyl-DL-penicillamine (SNAP), decreased the intracellular iron level rapidly as that observed with the iron chelator deferoxamine (DFO). Iron chelators such as DFO and mimosine could induce death of human leukemic HL-60 cells by a mechanism requiring activation of p38 kinase, c-Jun N-terminal kinase, caspase-3 and caspase-8. DFO and SNAP also caused release of cytochrome c from mitochondria. Inhibition of p38 kinase by a selective inhibitor, SB203580, abolished the NO and DFO-induced cell death, release of cytochrome c, and activation of caspase-3 and caspase-8, thus indicating that p38 kinase lies upstream in the cell death processes. In a parallel situation, the cells that are sensitive to NO showed similar sensitivity to DFO. Moreover, simultaneous addition of ferric citrate, an iron-containing compound, inhibited the SNAP and DFO-induced activation of caspases and also blocked the NO-mediated cell cycle arrest at $G_1$ phase. Collectively, our data implicate that the NO-induced cell death of tumor cells including HL-60 cells is mediated by depletion of iron and further suggest that activation of p38 kinase lies upstream of cytochrome c release and caspase activation involved in this apoptotic process.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.2
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• pp.81-88
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• 2001

The effects of post-oxidation and sulfnitriding treatments on the phase transformation in the nitrided case of tool steels have been studied. Dense and compact $Fe_3O_4$ layer was formed at the outer surface of nitride compound layer by post-oxidation treatment and multi layer of iron sulfide(FeS) was formed in the compound layer by sulfnitriding treatment. The surface hardness decreased because of formation of the soft oxide or sulfide at the nitride surface. Diffusion layer of nitride case was not affected by post-oxidation treatment or sulfnitriding treatment of nitrided alloy tool steels.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.179-184
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• 1999

When the steel containing Si is oxidated in hi temperature, Re2O3, Red scale is made on the metal side as the spike phase, and this scale invasion into matrix. Therefore, it affects the feature, after rolling. It is reported that the role of Si is FeO/Fe2SiO4 eutectic compound, but Si can not affect pure iron independently. There must be Ni, then the spike phase can exist. Prominence and depression made by Ni that is necessity at the process to work iron. Therefore, in this study after the change of the amount of Ni in pure iron and steel and oxidation, the structure of the oxide and the surface, and the distribution of the elements were considered. In conclusion, at 100$0^{\circ}C$, 110$0^{\circ}C$, 120$0^{\circ}C$ the curves of oxidation weight are all S curves. Especially, in the beginning of oxidation as the amount of Ni increase, the amount of oxidation also increase. Practical steel has less oxidation than pure steel added Ni. There is much FeO in Fe-Ni alloy, compare to practical steel which has much Fe3O4. Especially, we could know considerable Ni was concentrated on the metal side in Fe-Ni alloy, practical steel. and the surface of the scale.

• Journal of Environmental Health Sciences
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• v.36 no.6
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• pp.502-509
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• 2010

In this study, the (phosphorous removal) the characteristics of phosphorous removal due to (the iron compound precipitated) iron compound precipitation by iron electrolysis in (the anoxic. oxic process) anoxic and oxic processes (equipped with the) in an iron precipitation device were analyzed. During the device operation period, the average concentration of BOD, T-N, and T-P were 219.9 mg/l, 54.6 mg/l and 6.71 mg/l, respectively. The BOD/$COD_{Cr}$ ratio was 0.74, and the BOD/T-N and BOD/T-P ratios were 4.0 and 32.8, respectively. The removal rate of (the organic matters) organic matter (BOD and $COD_{Cr}$) was very high at 91.6% or higher, and that of nitrogen was 80.5%. The phosphorous concentration (of the final) in the treated water was 0.43 mg/l (0.05-0.74 mg/l) on average, and the removal efficiency was high at 90.8%. The soluble T-P concentrations in (an) the anoxic reactor, oxic reactor (II) and final treated water were 1.99 mg/l, 0.79 mg/l and 0.43 mg/l, respectively, which indicated that the phosphorous concentration in the treated water was very low. Regardless of the changes in the concentrations of (organic matters) organic matter, nitrogen and phosphorous in the influent, the quality of the treated water was relatively stable and high. The removal rate of T-P somewhat increased with the increase in the F/M ratio in the influent, and it also linearly increased in proportion to the T-P loading rate in the influent. In the treatment process used in this study, phosphorous was removed (using) by the precipitated iron oxide. Therefore, the consumption of organic (matters) matter for biological phosphorus removal was minimized and (most of the organic matters were) was mostly used as the organic carbon source for the denitrification in the anoxic reactor. This (can be an economic) treatment process (without the need for the supply of additional organic matters) is economic and does not require the supply of additional organic matter.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.299-307
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• 1996

The surface tension of PO added sodium poly(oxyethylene(EO), oxyisopropylene(PO)) dodecyl ether sulfate firstly were slightly lower than EO added sulfate in the concentration range of $10^{-6}{\sim}10^{-3}mol/{\ell}$. And they had lower critical micelle concentration ($10^{-4}{\sim}9{\times}10^{-5}mol/{\ell}$) than general anionic surfactants. The adsorptivity ($2.2{\times}10^{-10}mol/cm^2$) of sodium $(PO)_{10}(EO)_5$ dodecyl ether(compound of PO addition firstly) calculated by Gibbs' adsorption isotherm were higher than that of sodium $(EO)_{10}(PO)_5$, dodecyl ether(compound of EO addition firstly), but were lower than that of sodium dodecyl sulfate (${\Gamma}=3.2{\times}10^{-10}mol/cm^2$). These could be understood that the adsorption areas of compounds were very large because of their high molecular weight. Moreover, PO compounds showed better properties than EO compounds in foamability, emulsifying power for organics (n-hexane, benzene), detergency for the lard, tallow oil mixture and dispersability for iron oxide. It was interpreted in terms of surface properties of the PO compounds. These showed that the interfacial activity become higher when hydrophilic and hydrophobic portion existed in aggoromerated state respectively. The test results of emulsifying power for organics (n-hexane, benzene) showed better for benzene than n-hexane. Eight kinds of sodium (EO, PO) dodecyl ether derivatives showed irregular dispersibilities for polar iron oxide in water dispersed media.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.223-224
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• 2002

The mechanisms of formation of transfer film under the condition of wear of Steel AISI1020 by natural rubber were investigated. The transfer film was observed and the formation mechanisms were clarified. The formation process of transfer film on the worn surface of the steel could be divided into two stages. Firstly, the adhesive layer emerged on the worn surface of the steel by adhesion of natural rubber. in which the macromolecular chains of natural rubber joined to the surface of the steel by Van der Waals' force. And then, the iron atom and metal oxide reacted with the macromolecular of natural rubber in the adhesive layer and produced Fe-polymer compound. As a result, the transfer film was formed on the worn surface of the steel. The transfer film was joined to the worn surface of the steel by the chemical bonds and electrostatic force.