• Journal of Sensor Science and Technology
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• v.17 no.1
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• pp.9-14
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• 2008

In this paper, the gas responses of tungsten oxide films prepared by anodic reaction was discussed. Sensing electrodes and heating electrodes were patterned by photolithography method on quartz substrate. Porous tungsten oxide was fabricated in electrolyte solutions of 5 % HF (HF :$C_2H_6OH:H_2O$=3 : 2 : 20) by anodic reaction. The anodic reaction with metal (platinum wire) as a cathode and the sensing device as an anode was conducted under the various reaction times (1-10 min) at 10 mA/$cm^2$ The surface structure and morphology of the fabricated sensor have been analysed by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). All the peaks of XRD results were well indexed to the pure phase pattern. The average diameter of the porous tungsten oxide surface were ranged about 100 nm. The fabricaed sensor showed good sensitivity to 200 ppm toluene at operating temperature of $250^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.300-308
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• 2004

The formation mechanism of anodic oxide films on Mg alloys when anodized in NaOH solution. was investigated by focusing on the effects of anodizing potential. Al content. and anodizing time. Pure Mg and Mg-Al alloys were anodized for 10 min at various potentials in NaOH solutions. $Mg(OH)_2$ was generated by an active dissolution reaction at the surface. and the product was affected by temperature. The intensity ratio of $Mg(OH)_2$ in the XRD analysis decreased with increasing applied potential. while that of MgO increased. The anti-corrosion properties of anodized specimens at each constant potential were better than those of non-anodized specimens. The specimen anodized at an applied potential of 3 V had the best anti-corrosion property. And the intensity ratio of $Mg_{17}Al_{12}$/Mg increased with aluminum content in Mg-Al alloys. During anodizing. the active dissolution reaction occurred preferentially in ${\beta}\;phase(Mg_{17}Al_{12})$ until about 4 mins. and then the current density increased radually until 7 mins. The dissolution reaction progressed in a phase(Mg) which not formed the intermetallic compound. which had a lower Al content. In the anodic polarization test of $0.017\;mol{\cdot}dm^-3$ NaCl and $0.1\;mol{\cdot}dm^-3\;Na_2SO_4$ at 298 K. the current density of Mg-15 mass% Al alloy anodized for 10 mins increased. since the anodic film that forms on the a phase is a non-compacted film. The anodic film on the phase for 30 mins was a compact film as compared with that for 10 mins.

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.975-980
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• 2003

The electrochemical properties and the mechanism of formation of anodic oxide films on Mg alloys containing 0-15 mass% Al, when anodized in NaOH solution, were investigated by focusing on the effects of anodizing potential, Al content, and anodizing time. The intensity ratio of Mg(OH)₂ in the XRD analysis decreased with increasing applied potential, while that of MgO increased. Mg(OH)₂ was barely detected at 80 V, while MgO was readily detected. The anti-corrosion properties of anodized specimens at each constant potential were better than those of non-anodized specimens. The specimen anodized at an applied potential of 3 V had the best anti-corrosion property. The intensity ratio of the β phase increased with aluminum content in Mg-Al alloys. During anodizing, the active dissolution reaction occurred preferentially in β phase until about 4 min, and then the current density increased gradually until 7 min. The dissolution reaction progressed in α phase, which had a lower Al content. In the anodic polarization test in 0.017 mol·$dm^{-3}$ NaCl and 0.1 mol·$dm^{-3}$ Na₂SO₄ at 298 K, the current density of Mg-15 mass% Al alloy anodized for 10 min increased, since the anodic film that forms on the α phase is a non-compacted film. The anodic film on the α phase at 30 min was a compact film as compared with that at 10 min.

• Transactions of the Korean hydrogen and new energy society
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• v.11 no.4
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• pp.179-188
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• 2000

The anodic reaction of hydrogen/oxygen gas mixture at platinum or palladium electrode interfacing with a solid polymer electrolyte was investigated using AC impedance method. The impedance spectrum of the electrode reactions of the mixture depends on the gas composition, electrode roughness, the mode of electrochemical operation and the cell potential. For electrolysis mode of operation, the spectrum taken for the reaction on a rough platinum electrode for the gas mixture revealed clearly that the local anodic reduction of oxygen gas takes place concurrently with the anodic oxidation of hydrogen gas.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2007.06a
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• pp.230-233
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• 2007

A system of anodic process of aluminum thin film has implemented for nanofabrication. The manufactured equipment consists of three main parts: chiller, reaction bath and power supply. The chiller module consists of refrigeration compressor, copper tube and coolant with a thermostat. The reaction bath has kept in same temperature as a thermodynamic canonical ensemble system during the anodic reaction process. The magnetic bar has stirred oxalic acid in bath for uniform reaction. The DC power supply has applied into two electrodes, aluminum for anode and platinum for cathode in the oxalic acid. The anodization process results in the formation of nanoporous thin films.

• Journal of the Korean institute of surface engineering
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• v.49 no.4
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• pp.331-338
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• 2016

In this work, anodic oxidation behavior of AZ31 Mg alloy was studied as a function of $Na_2CO_3$ concentration in electrolyte by voltage-time curves and observation of surface appearances and morphologies after the anodic treatments, using optical microscopy and confocal scanning laser microscopy (CSLM). The voltage-time curves of AZ31 Mg alloy surface and surface appearances after the anodic treatments showed three different regions with $Na_2CO_3$ concentration : region I, below 0.2 M $Na_2CO_3$ where shiny surface with a number of small size pits; region II, between 0.4 M and 0.6 M $Na_2CO_3$ where dark surface with relatively low number of large size burned or dark spots; region III, more than 0.8 M $Na_2CO_3$ where bright surface with or without large size dark spots were obtained. The anodically treated AZ31 Mg alloy surface became significantly brightened with increasing $Na_2CO_3$ concentration from 0.5 M to 0.8 M which was attribute to the formation of denser and smoother surface films. Pits and porous protruding reaction products were found at relatively large size and small size spots, respectively, on the AZ31 Mg alloy surface in low concentration of $Na_2CO_3$ less than 0.2 M. The formation of pits is attributed to the result of repetition of the formation and detachment of porous anodic reaction products. Based on the experimental results obtained in this work, it is concluded that more uniform, denser and smoother surface of AZ31 Mg alloy could be obtained at more than 0.8 M $Na_2CO_3$ concentration if there is no other oxide forming agent.

• Korean Journal of Environmental Biology
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• v.22 no.2
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• pp.265-272
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• 2004

Biological characteristics of anodic electrolyzed water were investigated in this study. Linear DNAs which were incubated at $4^\circ{C}$ and $25^\circ{C}$ for 10 mins in the anodic electrolyzed water were degraded about 40% and 50%, respectively. But the DNA was amplified pretty well without any degradation through polymerase chain reaction in the presence of anodic electrolyzed water. Protein degradation hardly occurred in the distilled water during entire incubation time of 7 days, while protein began to be degraded from 4 days in the anodic electrolyzed water. Rice seeds could germinate in the distilled water and anodic electrolyzed water with the same germination ratio, however, the anodic electrolyzed water inhibited the growth of roots and total length of rice seedlings in the soil. Anodic electrolyzed water did not affect the growth curve and cell number of marine alga significantly. The anodic electrolyzed water inhibited the browning of potato by inactivating 50% of polyphenol oxidase activity.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.159-164
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• 2008

We investigated chloride ion effects on anodic dissolution of copper using potentiodynamic method, cyclic voltammtery, chronoamperometry and chronocoulometry. The anodic dissolution reaction of copper in NaCl solution under argon atmosphere is $Cu+2Cl^{-}{\rightleftharpoons}{CuCl_2}^{-}+e^-$ and chloride ion adsorption process in copper surface can be explained by Temkin isotherm.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.1
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• pp.107-115
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• 2005

The effects on the formation of anodic oxide films on Mg-Al alloy (AZ91) in 1M-NaOH solution was investigated using parameters of current density and time during anodizing The general tendency has been confirmed that the increase of anodizing time improves the corrosion resistance. It is considered that the formation of anodic oxide film was increased by increasing the applied current and the anodizing time to generate active dissolution reaction In anodizing at constant current density. passivity potentials shifted to noble direction with increasing current densities. It was confirmed that oxygen quantify in anodic oxide films increased with anodizing time. The compact films above 4 $mA/cm^2$ were formed with the shape of an island in grooves at early stage and then grew with combination of the islands

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_1
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• pp.47-53
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• 2001

We carroed our to measure the variations of potential with current density (polarization curves) for poly(ethyleneterephthalate). The results were particularly examined to identify the influences on corrosion potential and corrosion rate of various factors including temperature, pH, exposure time, salt, and enzyme. The Tafel slope for anodic dissolution was determined by the polarization effect depending on these conditions. The optimum conditions were established for each case. The second anodic current density peak and maximum passive current density were designated as the relative corrosion sensitivity$(I_r/I_f)$. The mass transfer coefficient value$(\alpha)$ was determined with the Tafel slope for anodic dissolution based on the polarization effect with optimum conditions.