• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.75-80
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• 2005

In this thesis, We Fabricated Cu thin films of 1000 $\AA$, 3000 $\AA$, and 6000 $\AA$ thickness on the single crystal sapphire, polycrystal alumina, and amorphous slide glass substrates deposited by electron beam evaporation(EBE) method. We investigated properties of resistivity and adhesion of these Cu thin films under various conditions, substrate temperature(room temperature, 10$0^{\circ}C$, 20$0^{\circ}C$ under vacuum) and annealing temperatures(400 $^{\circ}C$, 600 $^{\circ}C$ for 30 min after the deposition). We found that these adhesion was increased in order of slide glass, sapphire, and alumina. The adhesion of the Cu thin films on alumina was high value about 4 times, compared with that of the Cu thin films on slide glass. We found that these resistivities were decreased with increasing substrate temperature and thin film thickness. The resistivity(2.05 $\mu$Ω\ulcornercm) of the Cu thin films with 6000 $\AA$ thickness at 200 $^{\circ}C$ on the slide glass was low value, compared with that of aluminum(2.66 $\mu$Ω\ulcornercm).

• Journal of the Korean Ceramic Society
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• v.28 no.7
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• pp.568-576
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• 1991

The powder characterization and sintering behavior of alkoxide-derived alumina powders prepared by esterification were investigated. The dried powders were calcined at 700$^{\circ}C$, 900$^{\circ}C$, 1080$^{\circ}C$, 1170$^{\circ}C$ for 1 h. and the resulting crystalline forms were amorphous, {{{{ gamma }} phase, {{{{ theta }}+{{{{ alpha }} phase, and {{{{ alpha }} phase, respectively. The sinterability was best in the case of being calcined at 1170$^{\circ}C$. It was most effective to disperse sintering additive in the initial stage from which acetate was formed. At 1600$^{\circ}C$ for 4 h, 98.5% of relative density was obtained when MgO and Fe2O3 were simultaneously doped, and dense sintered body whose density was near theoretical value was obtained when heating schedule was controlled.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.692-693
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• 2002

Well-aligned multi-wall carbon nanotubes (MWNTs) were fabricated by utilizing a radio frequency plasma-enhanced chemical vapor deposition (rf-PECVD) system from Ni particles at the bottom of anodic alumina nanoholes (AAN). To remove the amorphous graphite layers on the AAN surface and to eliminate the protrusion of MWNT tips, the AAN surface with MWNTs were treated by external rf plasma source. As a result, the AAN surface almost became flat without having any protrusion of MWNT tips. The diameter, length of MWNTs and AAN were investigated by using a scanning electron microscopy (SEM). Raman spectroscopy was also used to characterize wall structure of the carbon nanotube. And the emission properties of the MWNTs were measured for the application of field emission display (FED) in near future.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.111-116
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• 1988

Aluminum hydrates were prepared by precipitation method using Al2(SO4)3$.$18H2O as a starting material and NH4OH as precipitation agent. The phases of aluminum hydrate were changed from amorphous aluminum hydrate to pseudo-boehmite of AlOOH form and bayerite, gibbsite, hydragillite and norstrandite of Al(OH)3 form with increasing pH. As pH increased, agglomeration phenomena were reduced. Aluminum hydrates of AlOOH and Al(OH)3 form represented dehydration of structural water near 175$^{\circ}C$ and 385$^{\circ}C$, and 280$^{\circ}C$, respectively. As the ratio of Al(OH)3 to AlOOH increased, specific surface area was reduced.

• Journal of the Korean Ceramic Society
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• v.41 no.6
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• pp.485-492
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• 2004

We prepared cylindrical y-alumina pellets using amorphous alumina and pore generating agent. The pellets were immersed in an aqueous solution of the mixture of Fe(NO$_3$)$_3$ㆍ9$H_{2}O$ and $CH_3$COOH. They were then hydrothermally treated at 20$0^{\circ}C$ for 3 h in autoclave, dried and calcined. For the application of environmental catalyst for its, we investigated the decomposition characteristics of 4-chlorophenol and the initiation characteristics of OH' conversion action in $O_3$ environment with or without the Fe$_2$O$_3$ supported ${\gamma}$-alumina catalyst and $O_3$ molecule.

• Applied Chemistry for Engineering
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• v.9 no.7
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• pp.1047-1052
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• 1998

The porous alumina membrane was prepared from aluminum metal(99.8%) by anodic oxidation using DC power supply of constant current mode in aqueous solution of sulfuric, oxalic, phosphoric and chromic acid. Pore size and distribution, membrane thickness, morphology and crystal structure were examined with several anodizing conditions : reaction temperature, electrolyte concentration, current density and electrolyte type. It was found that ultrafiltration membrane was fabricated in electrolyte of sulfuric, and oxalic acid. On the other hand, microfiltration membrane was fabricated in electrolyte of phosphoric, and chromic acid. Also, it was shown that crystal structure of porous alumina membrane prepared in sulfuric, oxalic, and phosphoric acid was amorphous, whereas porous alumina membrane prepared in chromic acid had ${\gamma}$ type of crystal structure.

• Journal of the Korean Ceramic Society
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• v.30 no.12
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• pp.1045-1053
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• 1993

Alumina hydrates were prepared by the neutralization of AlCl3.6H2O solution with NH3 gas diluted with N2 gas. The values of pH in reaction solution influenced the formation of alumina hydrates minerals. Amorphous alumina hydrates, for example, were formed at ${\gamma}$-Al2O3longrightarrow$\delta$-Al2O3longrightarrow$\theta$-Al2O3longrightarrow$\alpha$-Al2O3. (2) Bayeritelongrightarrowamorphouslongrightarrow${\gamma}$-Al2O3longrightarrow$\delta$-Al2O3longrightarrowη-Al2O3longrightarrow$\theta$-Al2O3longrightarrow$\alpha$-Al2O3. On the other hand, the shape of alumina hydrates whichw ere prepared by the reacton of Al2(SO4)3.16H2O solution and NH3 gas was spherical, the progress of its phase transformation with increasing temperature was amorphouslongrightarrow${\gamma}$-Al2O3longrightarrow$\alpha$Al2O3 in sequence.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.772-775
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• 2003

The development of new improved type of dielectric materials on the conception of multiphase structure has been carried out in this paper. Metal alkoxides solutions were used for application of thin film by electrophoretic deposition technique. We succeeded in preparation of amorphous and composite dielectric films from Al alkoxides. Specific features of the preparation technique were considered. Microstructure of the films was examined as well as their dielectric properties. TEM analyses reveals that films deposited from aging sols and heat-treated at temperatures as low as $400^{\circ}C$ contain small whiskers of ${\delta}-Al_2O_3$.

• Journal of the Korean Ceramic Society
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• v.26 no.3
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• pp.445-451
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• 1989

Hydrolysis of aluminum isopropoxide with excess water in the presence of excess isopropyl alcohol resulted in the formation of boehmite in independence of temperature of hydrolysis and aging. Stoichiometric and substoichiometric amount of water hydrolyzed aluminum isopropoxide to pseudo-boehmite and amorphous one, respectively. $\alpha$-Al2O3 with 0.3${\mu}{\textrm}{m}$ in median size was produced by calcination of boehmite, bseudo-boehmite and amorphous boehmite at 125$0^{\circ}C$, 120$0^{\circ}C$, and 115$0^{\circ}C$ for one hour, respectively. Singnificant reduction in particle size was found during transition from $\theta$-Al2O3 to $\alpha$-Al2O3. $\alpha$-Al2O3 produced in this study was relatively uniform spherical and its purity was found to be over 99.9%.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.1
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• pp.47-56
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• 2017

In this study, the higher temperature thermal property of the fly ash-blast furnace slag system Geopolymer including alumina aggregate was investigated whether that Geopolymer will be or not useful as thermal-resistant construction materials. Under every mixing conditions, the crack on the surface of hardened body was not observed up to $800^{\circ}C$ and it corresponded with fact that level of changes was not significant before and after heating process. Residual compressive strength is most high when mixing Blast-Furnace Slag ratio is 60 wt% until temperature reaches $800^{\circ}C$. The major hydrates of hardened body of Geopolymer; amorphous halo pattern between $20{\sim}35^{\circ}$ (2theta) and mullite ($3Al_2O_3{\cdot}2SiO_2$) and quartz ($SiO_2$) was found during the experiment. Amorphous halo pattern was a aluminosilicate gel generated by geopolymeric polycondensation and it was found that the halo pattern of aluminosilicate gel was preserved up to $800^{\circ}C$. The patterns of aluminosilicate gel disappeared from $1,000^{\circ}C$ and crystal phases like gehlenite, calcium silicate, calcium aluminum oxide, microcline was observed with the increase of exposure temperature.