• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.329-337
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• 2019

We synthesized potassium titanates having splinter and plate shape and evaluated frictional and wear properties of brake pad using them as reinforcements in friction materials. For splinter-shaped potassium titanates, potassium tetratitanate (K₂O·4TiO₂, PT4) with plate shape was prepared, then K ion of the titanate was leached by acid to make potassium hexatitanate (K₂O·6TiO₂, PT6), which was transformed to splinter-shaped PT6 by thermal treatment at 800℃. Plate-shaped potassium magnesium titanate (K_0.8Mg_0.4Ti_1.6O₄, PMT) was prepared by adding Mg in the potassium titanate using KCl as a flux. Using PT6 and PMT as reinforcements in friction materials of brake pad, we evaluated frictional and wear properties using 1/5-scale dynamometer. According to dynamometer test results, both reinforcements shows similar friction coefficient and fade & recovery behavior to conventional material and plate-shaped PMT exhibits higher wear resistance than splinter-shaped PT6.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.11a
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• pp.71-74
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• 1995

티타니아계의 흡착제로 최근 주목을 끄는 것은 티탄산칼륨 신소재를 들을 수 있다. 모서리의 chains sharing들과 b축을 따라서 TiO$_{6}$, 즉 8면체의 coner 결합으로 특징 지워지는 티탄산칼륨은 $K_2$O.nTiO$_2$로 표시되는 화합물로 플라스틱의 보강재나 단열재료 용도로 사용되었다. 공업재료로서 중요한 것은 n의 값이 2, 4, 6으로 각각 2티탄산칼륨(K$_2$Ti$_2$O$_{5}$), 4티탄산칼륨(K$_2$Ti$_4$O$_{9}$), 6티탄산칼륨(K$_2$Ti$_{6}$O$_{13}$)으로 불린다. 티탄산칼륨은 기계적 강도가 고강도재료 지르코이나에 해당하고 선팽창계수는 알루미나보다 작아 우수한 내열 및 단열 고강도재료이며 융막재, 이온교환재등으로 쓰인다. 층상구조의 티탄산칼륨을 산처리하여 칼륨을 추출하고 수소이온으로 치환한 결정질 티탄산칼륨 섬유(H$_2$Ti$_4$O$_{9}$.1.2~1.3$H_2O$)는 (H$^{-}$. H$_3$O$^{+}$)Ti$_4$O$_{9}$의 형태를 지니게 된다.

• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.92-97
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• 1993

Sol-Gel Process is a new method of synthesis of high-quality of glass and glass-ceramics. Ferroeletric material, $BaTiO_3$ powder was made by reacting $Ba(OH)_2$ and $Ti[OCH(CH_3)_2]_4$ in alcohol. There was about 16.5% weight loss in thermogravimetric analysis. It was crystallized to tetragonal structure by heat treatment at $700^{\circ}C$ for 2 hours and had a specific surface area, 16.0 $m^2/g.$ Shrinkage curve by sintering was began around $1100^{\circ}C$ in dilatometer analysis.

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.11a
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• pp.27-27
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• 1998

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.87.2-87
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• 2000

• Journal of the Korean Chemical Society
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• v.33 no.1
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• pp.65-69
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• 1989

Barium titanyl oxalate was synthesized by adding ethanol solution of oxalic acid to the mixed aqueous solution which contained barium or lanthanum radiotracers in addition to Ba(NO$_3)_2$ and TiO(NO$_3)_2$. The oxalate was finally converted to BaTiO$_3$ by calcination at 1000$^{\circ}$C in air. The chemical formula of the oxalate was confirmed to be BaTiO(CTEX>$_2O_4)_2{\cdot}4H_2O$ by the thermal analysis of the barium titanyl oxalate. When the mixture's molar ratio(Ba/Ti) was within a range of 0.950-1.05, the formation of stoichiometric Barium titanate was confirmed with the help of barium tracers. The homogeneity of lanthanum deposite in the final product was also confirmed through the behavior of lanthanum tracers. The results as well as those obtained by XRD and SEM have been explained on the basis of the fact that the reaction occurs on the molecular level in solution and the barium titanate is formed in crystals of single phase.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.163-166
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• 1997

• Korean Journal of Crystallography
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• v.3 no.1
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• pp.1-8
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• 1992

The morphology of lead titanate powders prepared by sol-gel and coprecipitation techniques was investigated as a function of firing temperature and soaking time. PbTiO3 precursor powders were derived from a mixed solution of lead nitrate and titanium tetrachloride at 40℃ to 43℃ and pH of 9.0 to 9.7, and fired at temperatures 350-1000℃ for 1-10h in air. An increase of particle size and agglomeration with increasing calcination temperature and duration could be observed. By annealing sol-gel derived powder at 700℃, the tially-formed acicular(and/or prismatic) primary particles transformed to polyhedral shape with soaking time, and further soaking caused coarsening the polyhedral particles with rounded edges. However, the morphology of the coprecipitated powders was not varied during crystallization.

• Analytical Science and Technology
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• v.12 no.3
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• pp.230-234
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• 1999

Barium titanyl oxalates (BTO) has been homogeneously prepared by thermal decomposition of dimethyl oxalate (DMO) in hydrochloric solution containing $Ba^{2+}$ and $Ti^{4+}$. Particles of BTO settled on the bottom of the beaker were collected at the aging time of 120 min using hydroxy propyl cellulose (HPC) as a dispersant. The reaction temperature, the concentration ratio of $[DMO]_0/([Ba^{2+}]_0+[Ti^{4+}]_0)$ and the existence of HPC were found to influence on morphologies of BTO, chemical yields and characteristics of barium titanates formed from their precursors.

• Electrical & Electronic Materials
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• v.13 no.1
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• pp.63-64
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• 2000