• YAKHAK HOEJI
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• v.19 no.4
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• pp.219-226
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• 1975

Physical and chemical properties on the aging inhibition mechanism of hydrous aluminum oxide were studied by means of dehydration velocity, activation energy, DTA, TGA, IR spectra, X-ray diffraction and TMA. During aging, changes may occur in the hydrous aluminum oxide structure which results in a loss of acid reactivity and in crystal formation to the hydrated hydrous alumina. The results obtained from the X-ray diffraction pattern and DTA, TGA thermogram studies showed that the aging product stabilized with either sorbitol or mannitol was hydrous aluminum oxide ($Al_{2}O_{3}{\cdot}xH_{2}O$) but the aging product not stabilized with either sorbitol or mannitol product not stabilized was hydrated hydrous aluminum oxide $Al_{2}O_{3}{\cdot}xH_{2}O{\cdot}yH_{2}O$. The activation energy of dehydration of the hydrous almina was about 17 Kcal. mol$^{1}$ deg$^{-1}$ which was observed a little less than that of 22 kcal.mol.$^{-1}$ deg.$^{-1}$ of or mannitol, the inhibition mechanism in the aging process from oxide is assumed to prevent the formation of the hydrated hydrous aluminum oxide and the aging process is thought of as analogous to the polymorphic transformations which occur as a system converts to its most stable state.

• Korean Journal of Materials Research
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• v.12 no.7
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• pp.540-544
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• 2002

Hydration treatments were performed on the pure aluminum substrate at $100^{\circ}C$ followed by anodizing and heat treatments on the layers. The transformation behaviors of the oxide layers according to the hydration treatment were studied using TEM, XRD, RBS etc. Above $90^{\circ}C$ the hydrous oxide film could be formed, which were turned out to be hydrous oxides(AlOOH $nH_2$O). The anodization on the hydrous oxide film was more effective for the transition of amorphous anodic oxides to the crystalline $\Upsilon-Al_2$ $O_3$ comparing with the case for anodizing on the aluminum substrate without hydration treatment And additional heat treatments were also helpful for the acceleration of the transformation of the hydrous oxide to $\Upsilon-Al_2$ $O_3$. During the heat treatment the interface between $\Upsilon-Al_2$ $O_3$and the hydrous oxide layers migrated to the outer side of hydrous layer.

• YAKHAK HOEJI
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• v.35 no.4
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• pp.277-282
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• 1991

Rheological, colloidal and micromeritical properties were followed to investigate aging mechanisms of hydrous aluminum oxide suspension using Zeta-meter systems, BET adsorption apparatus, Master sizer and electronmicroscope. The results indicate that hydrous aluminum oxide suspension revealed plastic flow with thixotropy. The viscosity, thixotropy and yield value were increased with increasing concentration. During aging process, the viscosity and thixotropic index were increased by an addition of glycerin, however, sorbitol stabilized aging process of the suspension being accompanied with growth of particle size and reduction in specific surface area, pore area and pore volume, and consistency. Diminution of adsorptive power of the particles was also protected by addition of sorbitol to hydrous aluminum oxide suspension. From these results, one of aging mechanism of hydrous aluminum oxide suspension assumed growth and/or crystallization of colloidal particles in aqueous suspension.

• Journal of Pharmaceutical Investigation
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• v.6 no.2
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• pp.95-100
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• 1976

A study on the effect of the pH of precipitation on the acid consuming capacity, aging stability, physical and chemical properties of hydrous aluminum oxide prepared by the reaction of aluminum chloride and ammonium hydroxide solution was carried out by means of X-ray diffraction, IR spectra and differential thermal analysis. The results from these experiments are as follows: 1. Hydrous aluminum oxide precipitated at lower pH showed better acid consuming capacity, higher stability and more anion contained in the structure than that prepared at higher pH. 2. The hydrous aluminum oxide prepared at lower pH is amorphous and that prepared at higher pH is crystalline hydrated hydrous aluminum oxide, i.e., Bayerite and these results are conformed to Rhee's hypothesis. 3. The rate of loss of reactivity and the end-point reactivity are related to the pH of precipitation.

• YAKHAK HOEJI
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• v.21 no.2
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• pp.101-109
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• 1977

The effect of humidity on the aging process of hydrous aluminum oxide prepared by the reaction of aluminum chloride and sodium bicarbonate solution at pH 7.8, which was then kept in various atmosphere under relative humidity at 37.deg. was observed by the measurements of acid consuming capacity, X-ray diffraction and IR absorption. The humidity was one of the important factors influencing the aging process of hydrous aluminum oxide during storage. The higer the humidity, the more was accelerated age, crystalize and loss in acid reactivity. Depending on the humidity, the aging product was different, especially, in the case of up to the relative humidity of 72%, it forming bayerite. On the other hand, the hydrous aluminum oxide aged below the relative humidity of 50% was still amorphous even after 120 days storage. When hydrous aluminum oxide was aged under higher humidity, definite IR absorption bands develop as the hydroxys become part of an ordered structure, and it showed their characteristic absorption band around 1630 and 1060 cm$^{-1}$.

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.466-471
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• 2014

Hydrous zirconia particles were prepared from $ZrOCl_2$ aqueous solution using an electro-dialysis [ED] process. For the preparation of $(Zr,Y)(OH)_4$ precipitates, 3 mol% $YCl_3$ was added into $ZrOCl_2$ aqueous solution. During the hydrolysis of 0.5 mol/L $(Zr,Y)OCl_2$ solution at $90^{\circ}C$ a slurry solution was obtained. The ED process was used for the removal of chlorine from the slurry solution. Two kinds of slurry solution were sampled at the beginning and end of the ED process. The morphology of hydrous zirconia particles in the solution was observed using an inverted optical microscope and an FE-SEM. The hydrous zirconia particles were nano-crystalline, and easily coagulated with drying. Yttrium stabilized zirconia [YSZ] powder could be obtained by the calcination of $(Zr,Y)(OH)_4$ precipitates prepared from a $(Zr,Y)OCl_2$ solution by the ED process. The coagulated dry powders were shaped and sintered at $1500^{\circ}C$ for 2 h. The sintered body showed a dense microstructure with uniform grain morphology.

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.367-374
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• 2014

In this study, skin permeation enhancement was confirmed by designing it to have a structure and composition similarity to the intercellular lipids that improve miscibility with skin by cross-linked lipids poloxamer. The cross-linked lipids poloxamer was synthesized and analyzed by 1H NMR that structure dose had conjugated pluronic with ceramide3. Active component is released by modification of liquid crystal structure because PPO part, large-scale molecule block of pluronic, has hydrophobic nature at skin temperature of $35^{\circ}C$. Conjugated pluronic with ceramide3 was synthesized using Pluronic F127 and p-NPC (4-nitrophenyl chloroformate) at room temperature yielded 89%. Pluronic(Ceramide 3-conjugated Pluronic) was synthesized by reaction of p-NP-Pluronic with Ceramide3 and DMAP. The yield was 51%. This cross-linked lipids poloxamer was blended and dissolved at isotropic state with skin surface lipids, phospholipid, ceramide, cholesterol and anhydrous additive solvent. Next step was preceded by ${\alpha}$-Transition at low temperature for making the structure of Meso-Phase Lamella, and non-hydrous skin analogue liquid crystal using thermo-sensitivity smart sensor, lamellar liquid crystal structure through aging time. For confirmation of conjugation thermo-sensitivity smart sensor and non-hydrous skin analogue liquid crystal, structural observation and stability test were performed using XRD(Xray Diffraction), DSC(Differential Scanning Calorimetry), PM (Polarized Microscope) And C-SEM (Cryo-Scanning Electron Microscope). Thermo-sensitivity observation by Franz cell revealed that synthesized smart sensor shown skin permeation effect over 75% than normal liquid crystal. Furthermore, normal non-hydrous skin analogue liquid crystal that not applied smart sensor shown similar results below $35^{\circ}C$ of skin temperature, but its effects has increased more than 30% above $35^{\circ}C$.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.49-53
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• 2019

Hydrous $MnO_2$ nanowires were easily synthesized by an one-pot synthesis with a simple hydrothermal method. As prepared hydrous $MnO_2$ nanowires were characterized with scanning emission microscopy (SEM), transmit emission microscopy (TEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). They showed a good catalytic activity with the suitable nano-size of 4-5 nm and morphology. The furfuryl alcohol was selected as a substrate and the reaction was carried out in a toluene solvent at $100^{\circ}C$ under the atmospheric pressure of oxygen. The hydrous $MnO_2$ nanowire catalyst exhibited an excellent yield of furfural with the first-rate selectivity and conversion. The catalytic performance during recycle tests was also carried out and the catalyst showed a good mechanical strength with a negligible loss in the activity over five reaction cycles.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.451-456
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• 2002

This paper describes the properties of Temperature-Viscosity characteristics of hydrous and anhydrous ER fluids containing starch and titanium particle in silicone oil. ER effects arise from electrostatic forces between the starch particles and titanium particles dispersed in the electrically insulating silicone oil induced when electric field is applied. ER fluids under electric field have been found to provide resonable estimates of ER fluid viscosity variation characteristics. Yield shear stress of the ER fluids were measured on the couette cell type rheometer as a function of electric fields. The outer cup is connected to positive electrode(+) and bob becomes ground(-). The electric field is applied by high voltage DC power supply. In this experiment shear rates were increased from 0 to 200/equation omitted/ in 2 minutes.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.477-482
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• 1994

Structural changes of hydrous titania by heat-treatment was investigated with XRD, TEM, FT-IR, Rarnan spectral analyses. The hydrous titania was derived from a mixed solution of titanium tetrachloride and hydrogen peroxide at $30^{\circ}C$ and pH of 9.0. The precipitate was an anatase form of titania with less-developed crystalline structure. With increasing annealing temperature ranglng up to $700^{\circ}C$, the crystallinity of anatase increased, and the particles were grown at high temperature. The rutile form of titania was developed from the anatase at $700^{\circ}C$.