• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.20-20
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• 1999

• 한국세라믹학회지
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• 제38권12호
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• pp.1097-1103
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• 2001

침전제적하법을 이용하여 점토 다공체에 TiO$_2$의 고정화를 행하였다. 1,15$0^{\circ}C$에서 10분간 급속가열하여 점토 다공체에는 수 mm~$\mu$M의 기공이 존재하였다. 침전제인 NH$_4$HCO$_3$의 주입속도에 의한 반응용액의 pH 변화, 반응온도 및 TiCl$_4$의 농도는 다공체 표면의 TiO$_2$입자 석출상태와 석출된 TiO$_2$입자의 결정구조에 영향을 미쳐 NH$_4$HCO$_3$의 주입속도가 0.8ml/min 및 pH가 6인 다공체 표면에는 TiO$_2$입자들이 균일하게 석출되었다. NH$_4$HCO$_3$의 주입속도와 반응온도가 증가하고 TiCl$_4$의 농도가 감소함에 따라 다공체 표면에는 anatase상 TiO$_2$입자가 석출되었다.

• 한국세라믹학회지
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• 제37권4호
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• pp.308-313
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• 2000

Hydrous titanium oxide particles with anatase phase were prepared from 0.05 mol TiCl4 solution using NH4HCO3 as precipitant by the droopping precipitant method. The sequential change of pH is completed by a sudden and steep increase in a pH value of the range of 6~7 to which the concentration of adsorbed OH- and H+ ions on TiO2 surface is equal. Rutile phase started precipitating with anatase phase as an increase of reaction temperature above 6$0^{\circ}C$ in aqueous 0.05mol TiCl4 solution and its specific surface area was found to decrease from 452 $m^2$/g($25^{\circ}C$) to 164$m^2$/g(8$0^{\circ}C$). Specific surface area decreased rapidly when anatase powders precipitated at 4$0^{\circ}C$ were heat-treated at temperature higher 40$0^{\circ}C$. FT-IR result confirmed that it was due to the decrease of OH species within hydrous titanium oxides. The loss of ethanol after illumination of the powder heated at $600^{\circ}C$ and $700^{\circ}C$ for 4 h was 66 and 68.8%, respectively.

• 한국재료학회지
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• 제12권5호
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• pp.334-340
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• 2002

$TiO_2$-coated fly ash was synthesized by dropping method of coating agent in order to get $TiO_2$ coating layer with high photocatalytic activity on the surface of coal fly ash. The properties of the $TiO_2$ coating layer such as morphology, crystal structure, crystal size and photocatalytic activity were compared with those of the $TiO_2$-coated fly ash prepared by the traditional method of precipitation. $TiCl_4$ aqueous solution was used as a titanium stock solution and $NH_4HCO_3$ was used as a precipitant. The $TiO_2$ coating layer obtained by dropping method of coating agent was more uniform than that coated by precipitation. However, the crystal of $TiO_2$ coated by dropping method of coating agent was easy to grow by heat treatment because of the small primary particle size and bulky morphology, and its photocatalytic activity was consequently lower than that of the $TiO_2$ coated by precipitation. The $TiO_2$ coating layer obtained by both methods had a crystal structure of anatase, and the temperature of phase transformation into rutile was 90$0^{\circ}C$. The minimum crystal size of $TiO_2$ for the highest photocatalytic activity was found to be about 10nm.

• 한국세라믹학회지
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• 제45권6호
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• pp.345-349
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• 2008

$TiO_2$ coating ceramic tile for self-cleaning purpose was prepared by the precipitant dropping method using $TiCl_4$ as a precursor. $TiO_2$ film was formed on the ceramic tile by spray-coating technique and heat-treated at $500^{\circ}C$ for 1 h. The size and crystalline structure of $TiO_2$ particles were 15.3 nm and anatase phase. The outdoor exposure tests were conducted and the effects of outdoor exposure test conditions, such as exhaust concentration of contamination materials (test places), the UV light intensity (irradiation direction) and coating amounts of $TiO_2$ on the self-cleaning properties were investigated by the brightness measurements. As a results, self-cleaning property of $TiO_2$ coating tile was affected by the coating amount of $TiO_2$ however, not affected by the UV light intensity included in sun's ray (irradiation direction). $TiO_2$ coating ceramic tile can be utilized for exterior finishing materials because of self-cleaning property of $TiO_2$ coating tile.

• 한국세라믹학회지
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• 제45권1호
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• pp.43-47
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• 2008

The photocatalyst of $TiO_2$ coated on a fly ash composites (TCF) was prepared from precipitant dropping method to remove the acetaldehyde by photocatalytic reaction. The TCF were characterized by crystal aize, crystal structure and specific surface area. The photodegradation of acetaldehyde has been investigated using a UV-illuminated fixed photocatalytic reactor with TCF catalyst and P-25 catalyst in gas phase. The effect of photodegradation reaction conditions, such as initial concentration of acetaldehyde, concentration of oxidant in mixed gas and the light intensity on the photodegradation of acetaldehyde were investigated. P-25 catalyst showed the highest photodegradation of acetaldehyde and anatase $TiO_2$ coated TCF showed higher decomposition rate than rutile coated TCF. The photodegradation rate of acetaldehyde increased with the decrease of flow rate, initial concentration of acetaldehyde ($C_i$) and water vapor, however, it was increased with the increas of UV light intensity. The optimum conditions were weight of TCF=10 g, flow rate=50 ml/min $C_i$=100 ppm, concentration of oxygen=20%, concentration of water vapor=100 ppm.

• 한국세라믹학회지
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• 제39권6호
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• pp.550-557
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• 2002

광촉매용 TiO$_2$코팅 석탄회 복합체를 침전제적하법을 이용하여 합성한 후, $700^{\circ}C$에서 2시간 열처리하여 제조하였다. 석탄회 표면의 TiO$_2$ 입자 석출상태와 결정상은 반응용액의 pH, 침전제인NH$_4$HCO$_3$의 주입속도, 교반속도, 반응온도 및 TiC1$_4$ 의 첨가량에 영향을 받았다. NH$_4$HCO$_3$의 주입속도=1.0ml/min, 반응용액의 pH=6, 교반속도=1,000rpm 및 반응온도=8$0^{\circ}C$인 석탄회의 표면에는 약 10m의 TiO$_2$ 입자가 균일하게 석출되었으나,NH$_4$HCO$_3$의 주입속도=0.3 및 0.5ml/min, 반응용액의 pH=2 및 11 ,교반속도=300~500rpm 및 반응온도=5$0^{\circ}C$ 이하인 석탄회의 표면에는 불균일한 TiO$_2$ 입자의 석출이 관찰되었다. NH$_4$HCO$_3$의 주입속도와 반응온도가 증가하고 TiC1$_4$의 농도가 감소함에 따라 석탄회 표면에 석출된 anatase상의 결정성은 열처리온도에 따라 증가하였으나,800"C에서 rutile로 전이하였다 반응온도와 NH$_4$HCO$_3$의 주입속도 및 Tic14의 농도가 증가함에 따라 rutile상이 생성되었다. $700^{\circ}C$에서 2시간 열처리하여 약 21m의 anatase상 TiO$_2$ 입자가 코팅된 석탄회 복합체는 1.25g/㎤의 밀도, 82.8%의 강도 및 69.5Lab의 백색도를 나타내었으며, 광촉매로 응용이 가능하였다.능하였다.