• Journal of the Korean institute of surface engineering
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• v.21 no.2
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• pp.53-67
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• 1988

The high temperature corrosion of Fe-C alloys were studied at I atm SO gas in the temperature range 500~80$0^{\circ}C$ by means of a thermogravimetric analysis. The Na2SO4 induced high tempwrature corrosion rate was also measured at atm O2 gas under above the temperature renge. The reaction products were identified with the aid of X-ray diffraction technique, and micostruction of the alloy/scale interface was observed with a optical microscope and SEM. The experimental results were disussed by the themodeynamic calcutions. Under above the experimental condition. the reaction rates decrbon with increasing carbon content. The transfer of Fe ion was limited by a residue of carbon precipitated at alloy scale interface due to the oxidation of Fe-C alloys at alloy surface. The effect of cold working on reaction rate was different between the Fe containing low carbon and Fe-C Alloy containing carbon above 0,73 wt%. In a cold worked iron containing low carbon content, the crystallization of metal surface leads to the poor adherence between the alloy and the cavity formed between the alloy and scale. The outward diffusion of ion through the scale is estimated to be hindered by the cavity formed between the scale, consequently decreasing reaction rate. In the case Fe-C containing carbon above 0.73 Wt% alloy, the reaction rate was little affected by cold working, because the effect of content on reaction rats is greater than the effect of cold working.

• Korean Journal of Metals and Materials
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• v.50 no.10
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• pp.703-710
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• 2012

The effects of the ordering reaction on high temperature mechanical behavior is investigated by tensile tests at $2{\times}10^{-2}/s-3.3{\times}10^{-5}/s$ up to $745^{\circ}C$. The tensile deformed region is examined by differential scanning calorimeter (DSC), TEM, and high resolution neutron diffraction (HRPD). The results showed that a plateau of tensile strength appeared at $150-500^{\circ}C$ whereas the elongation minimum occurred at about $600^{\circ}C$. This suggests that the occurrence of a plateau does not cause the elongation minimum. The temperature of the elongation minimum decreases with the strain rate. HRPD results show a lattice contraction in the tensile deformed specimen at the temperature of the plateau occurring region. The plateau of tensile strength, the lattice contraction, and the occurrence of serration appeared in the same temperature region.

• Journal of the Korean Society of Safety
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• v.1 no.1
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• pp.27-32
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• 1986

To remove sulfur dioxide from flue gas by the method of metal oxide, copper powder of average diameter $2.4\mu\textrm{m}$and $51\mu\textrm{m}$ were used in a fixed bed reactor over a, temperature range of $300^{\circ}C-500^{\circ}C$. Copper oxide reacts with sulfur dioxide producing cupric sulfate and it can be regenerated from the latter by using hydrogen or methane. Experimental results showed that the reaction rate was increased by the increase of reaction temperature in the range of $300^{\circ}C-422^{\circ}C$ and the removal efficiency of sulfur dioxide was high in case of small size copper particle. However the removal efficiency was decreased at higher temperature due to decomposition of cupric sulfate. The rate controlling step of this reaction was chemical reaction and deactivating catalysts model can be applied to this reaction. The rate constants for this reaction and deactivation are as follows ： k＝8,367exp(-10,298/RT) Kd＝2.23exp(-8,485/RT)

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.134-134
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• 2010

Fuel cell is a device that directly converts chemical energy in the form of a fuel into electrical energy by way of an electrochemical reaction. In the anode for a high temperature fuel cell, nickel or nickel alloy has been used in consideration of the cost, oxidation catalystic ability of hydrogen which is used as fuel, electron conductivity, and high temperature stability in reducing atmosphere. Most MCFC stacks currently operate at an average temperature of $650^{\circ}C$. There is some gains with decreased temperature in MCFC to diminish the electrolyte loss from evaporation and the material corrosion, which could improve the MCFC life. However, operating temperature has a strong related on a number of electrode reaction rates and ohmic losses. Baker et al. reported the effect of temperature (575 to $650^{\circ}C$). The rates of cell voltage loss were 1.4mV/$^{\circ}C$ for a reduction in temperature from 650 to $600^{\circ}C$, and 2.16mV/$^{\circ}C$ for a decrease from 600 to $575^{\circ}C$. The two major contributors responsible for the change in cell voltage with reducing operation temperature are the ohmic polarization and electrode polarization. It appears that in the temperature range of 550 to $650^{\circ}C$, about 1/3 of the total change in cell voltage with decreasing temperature is due to an increase in ohmic polarization, and the electrode polarization at the anode and cathode. In addition, the oxidation reaction of hydrogen on an ordinary nickel alloy anode in MCFC is generally considered to take place in the three phase zone, but anyway the area contributing to this reaction is limited. Therefore, in order to maintain a high performance of the fuel cell, it is necessary to keep this reaction responsible area as wide as possible, that is, it is needed to keep the porosity and specific surface area of the anode at a high level. In this study effective anodes are prepared for low temperature MCFC capable of enhancing the cell performance by using zirconium hydride at least in part of anode material.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.51-59
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• 2011

Sulfur-Iodine (SI) cycle, which thermochemically splits water to hydrogen and oxygen through three stages of Bunsen reaction, HI decomposition, and $H_2SO_4$ decomposition, seems a promising process to produce hydrogen massively. Among them, the decomposition of $H_2SO_4$ ($H_2SO_4=H_2O+SO_2+1/2O_2$) requires high temperature heat over $800^{\circ}C$ such as the heat from concentrated solar energy or a very high temperature gas-cooled nuclear reactor. Because of harsh reaction conditions of high temperature and pressure with extremely corrosive reactants and products, there have been scarce and limited number of data reported on the pressurized $H_2SO_4$ decomposition. This work focuses whether the $H_2SO_4$ decomposition can occur at high pressure in a noble-metal reactor, which possibly resists corrosive acidic chemicals and possesses catalytic activity for the reaction. Decomposition reactions were conducted in a Pt-lined tubular reactor without any other catalytic species at conditions of $800^{\circ}C$ to $900^{\circ}C$ and 0 bar (ambient pressure) to 10 bar with 95 wt% $H_2SO_4$. The Pt-lined reactor was found to endure the corrosive pressurized condition, and its inner surface successfully carried out a catalytic role in decomposing $H_2SO_4$ to $SO_2$ and $O_2$. This preliminary result has proposed the availability of noble metal-lined reactors for the high temperature, high pressure sulfuric acid decomposition.

• Environmental Engineering Research
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• v.17 no.4
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• pp.217-225
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• 2012

In this study, the treatability of two target contaminants during the Fenton reaction, n-hexadecane and 1-methylnaphthalene, was evaluated as a function of the amounts of $FeCl_2$ and $H_2O_2$ injected into open and closed reaction systems. In the Fenton reaction of n-hexadecane and 1-methylnaphthalene, the mass recovery of the target contaminants was above 95% in the closed system. However, when the Fenton reaction was performed with high amounts of $H_2O_2$ and $FeCl_2$ injected in the open system, a reduction of approximately 40% of the initial mass of 1-methylnaphthalene was observed. This trend may be explained by the unique physical properties of 1-methylnaphthalene, which has higher volatility than n-hexadecane. Further, this trend was well correlated with the rise in high temperature at the initial reaction stage. Considering the mass recovery of the two target contaminants, the reaction temperature, and the residual concentration of $H_2O_2$ at different amounts of $FeCl_2$ and $H_2O_2$ injected, it can be suggested that the Fenton reaction should be performed with controlled conditions that can provide a suitable reaction environment between oxidant and contaminants.

• Journal of Powder Materials
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• v.2 no.2
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• pp.149-157
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• 1995

In this study, an attempt was made to fabricate TiAl as well as its in situ composite via combustion synthesis. The processing variable of the combustion synthesis which include aluminum content and the heating rate were found to affect the combustion temperature. The combustion temperature measured, however, was lower than the melting temperature of TiAl and the reaction product were found to include incomplet reaction products. Carbon was added in order to increase the combustion temperature as well as to form in situ reinforcements. The reaction products showed homogeneous microstructures with carbide phases formed within indicating that the addition of carbon increased the combustion temperature above the melting temperature of TiAl.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.696-700
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• 2002

The Ti-aluminide intermetallic compound was formed from high purity elemental Ti and Al foils by self-propagating, high-temperature synthesis(SHS) in hot press. formation of $TiAl_3$ at the interface between Ti and Al foils was controlled by temperature, pressure, heating rate, and so on. According to the thermal analysis, it is known in this study that the heating rate is the most important factor to form the intermetallic compound by this SHS reaction. The V layer addition between Al and Ti foils increased SHS reaction temperatures. The fully dense, well-boned inter-metallic composite($TiA1/Ti_3$Al) sheets of 700 m thickness were formed by heat treatment at $1000^{\circ}C$ for 10 hours after the SHS reaction of alternatively layered 10 Ti and 9 Al foils with the V coating layer. The phases and microstructures of intermetallic composite sheets were confirmed by EPMA and XRD.

• Resources Recycling
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• v.30 no.6
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• pp.12-18
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• 2021

The water-gas shift reaction is the subsequent step using steam for hydrogen enrichment and H₂/CO ratio-controlled syngas from gasification. In this study, a water-gas shift reaction was performed using syngas from an RPF gasification system. The water-gas shift using a catalyst was performed in a laboratory-scale tube reactor with a high temperature shift (HTS) and a low temperature shift (LTS). The effects of the reaction temperature, steam/carbon ratio, and flow rate on H₂ production and CO conversion were investigated. The operating temperature was 250-400℃ for the HTS system and 190-220℃ for the LTS system. Steam/carbon ratios were between 1.5 and 3.5, and the composition of reactant was CO : 40 vol%, H₂ : 25 vol%, and CO₂ : 25 vol%. The CO conversion and H₂ production increased as the reaction temperature and steam/carbon ratio increased. The CO conversion and H₂ production decreased as the flow rate increased due to reduced retention time in the catalyst bed.

• Journal of the Korean Wood Science and Technology
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• v.22 no.3
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• pp.32-38
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• 1994

The methods in wood processing are so limited at present that a scope of its utilization is restricted. This often makes wood itself less valuable as a material comparing with other materials, that is, plastics, metals, and glass. Such differences are due to a lack of plasticity in wood, i.e. it cannot be melted, dissolved, or softened sufficiently for molding. However, once plastic properties are added to wood, it becomes more useful material. This further broadens the method in wood processing to a variety of fields. In this way, wooden material which is limited in use can be modified into a high quality product with additional value. Furthermore, utilization of wastes from wood, for example, would be made viable. In this study, thermoplasticization was carried out by benzylation of wood(sawdust). Various factors those affect the reaction were tested to produce benzylated wood with different degrees of substitution. Reaction temperature and time were the quite important factors. Optimum reaction temperature was 110$^{\circ}C$, and weight percent gains(WPG) of final products increased gradually with the increase of reaction time. The pretreatment (or preswelling) of wood with alkaline solution had a critical effect on benzylation. and the concentration of alkaline solution should be above 30% to obtain high weight percent gain. The thermal flow temperature of the benzylated wood decreased with the increase in weight percent gain, that of 80% weight percent gain is about 200$^{\circ}C$.