• Korean Journal of Materials Research
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• v.29 no.11
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• pp.709-714
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• 2019

In order to observe the microstructure and morphology of porous titanium -oxide thin film, deposition is performed under a higher Ar gas pressure than is used in the general titanium thin film production method. Black titanium thin film is deposited on stainless steel wire and Cu thin plate at a pressure of about 12 Pa, but lustrous thin film is deposited at lower pressure. The black titanium thin film has a larger apparent thickness than that of the glossy thin film. As a result of scanning electron microscope observation, it is seen that the black thin film has an extremely porous structure and consists of a separated column with periodic step differences on the sides. In this configuration, due to the shadowing effect, the nuclei formed on the substrate periodically grow to form a step. The surface area of the black thin film on the Cu thin plate changes with the bias potential. It has been found that the bias of the small negative is effective in increasing the surface area of the black titanium thin film. These results suggest that porous titanium-oxide thin film can be fabricated by applying the appropriate oxidation process to black titanium thin film composed of separated columns.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.851-858
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• 2001

One of the important phase of black titanium oxide is $Ti_4O_7$ which has the excellent properties such as the greatest electrical conductivity among the titanium oxides, chemical resistance against acidic and alkalic conditions and electro-wave absorption etc., so it has been considered as a promising material to be used widely all over the parts of industries. In this study, $Ti_4O_7$ phase was successfully synthesized by the reaction of TiO$_2$/ Mg system. With the change of the mole of TiO$_2$to Mg, the most excellent blackness was appeared in the 3.5 mole which was the smaller amount than the stoichiometric 4.0 mole. In addition, we found that the blackness decreased as the mole ratio of reactent increased. With decreasing particle size of magnesium, blackness of titanium oxide increased. The reaction property was changed with the compaction pressure, and optimum pressure was found to be 10 MPa. At 55$0^{\circ}C$ of reduction temperature, the blackness increased as the reaction time increased. The blackness of synthesized black titanium oxide was 14 to 18, and the average particle size was 0.2 $\mu\textrm{m}$.

• Journal of Powder Materials
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• v.12 no.5 s.52
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• pp.336-344
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• 2005

In the present study, the focus is on the effect of cobalt oxide powder in the carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fine TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under flowing argon atmosphere. Changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. Titanium-cobalt-oxygen based oxide powder desalted at $600^{\circ}C$ had a mixture of $TiO_2\;and\;Co_{3}O_4$. And the one desalted at $800^{\circ}C$ had a mixture of $TiO_2\;and\;CoTiO_3$. In the case of the former powder, the reduction of cobalt oxide powder in the titanium-cobalt-oxygen based oxide powder occurred at lower temperature than the latter one. However, the carbothermal reduction of titanium dioxide powder in the titanium-cobalt-oxygen based oxide powder with a mixture of $TiO_2\;and\;Co_{3}O_4$ occurred at higher temperature than the one with a mixture of $TiO_2\;and\;CoTiO_3$. And also, the former powder showed a lower TiC formation ability than the latter one.

• Journal of Powder Materials
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• v.11 no.1
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• pp.28-33
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• 2004

In the present study, the focus is on the analysis of carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fined TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. The synthesized titanium-cobalt-oxygen based oxide powder has a mixture of $TiO_2$ and $CoTiO_3$. This oxide powder was transformed to a mixed state of titanium car-bide and cobalt by solid carbon through four steps of carbothermal reduction steps with increasing temperature; reduction of $CoTiO_3$ to $TiO_2$ and Co, reduction of $TiO_2$, to the magneli phase($Ti_nO_{2n-1}$, n>3), reduction of the mag-neli phase($Ti_nO_{2n-1}$, n>3) to the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases, and reduction and carburization of the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases to titanium carbide.

• Journal of Powder Materials
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• v.10 no.4
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• pp.228-234
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• 2003

In the present study, the focus is on the synthesis of titanium carbide/cobalt composite powder by the spray thermal conversion process using metallic salt solution as the raw materials. Two types of oxide powders of Ti-Co-O system were prepared by the spray drying of two types of metallic salt solutions : titanium chloride-cobalt nitrate and $TiO_2$ powder-cobalt nitrate solutions. These oxide powders were mixed with carbon black, and then these mixtures were carbothermal reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixtures during carbothermal reduction were analysed using XRD and TG-DTA. In the case of using the titanium chloride-cobalt nitrate solution, it could not be obtained TiC/Co composite powder due to contamination of the impurities during the spray drying of the solution. However, in tile case of using the $TiO_2$ powder-cobalt nitrate scullion, TiC-15 wt. %Co composite powder could be synthesized by the spray thermal conversion process. The synthesized TiC-15 wt. %Co composite powder at 120$0^{\circ}C$ for 2 hours has average particle size of 150 nm.

• Bulletin of the Korean Chemical Society
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• v.30 no.1
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• pp.219-223
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• 2009

$TiO_2$ doped with $Er^{3+\;and\;Yb^{3+}$ was used for fabricating a scattering layer and a nano-crystalline $TiO_2$ electrode layer to be used in dye-sensitized solar cells. The material was prepared using a new sol-gel combustion hybrid method with acetylene black as fuel. The $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide powder synthesized at 700oC had embossed structure morphology with a size between 27 to 54 nm that agglomerated to produce micron size particles, as observed by the scanning electron micrographs. The XRD patterns showed that the $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide had an amorphous structure, while using the same method without doping $Er^{3+}\;or\;Yb^{3+},\;TiO_2$ was obtained in the crystallite form with thea dominance of rutile phase. Fabricating a bilayer structure consisting of nano-crystalline $TiO_2$ and the synthesized $Er^{3+}$-$Yb^{3+}$ co-doped titanium oxide showed better scattering property, with an overall increase of 15.6% in efficiency of the solar cell with respect to a single nano-crystalline $TiO_2$ layer.

• Journal of Powder Materials
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• v.16 no.1
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• pp.43-49
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• 2009

Titanium carbides are widely used for cutting tools and grinding wheels, because of their superior physical properties such as high melting temperature, high hardness, high wear resistance, good thermal conductivity and excellent thermal shock resistance. The common synthesizing method for the titanium carbide powders is carbo-thermal reduction from the mixtures of titanium oxide($TiO_2$) and carbon black. The purpose of the present research is to fabricate nano TiC powders using titanium salt and titanium hydride by the mechanochemical process(MCP). The initial elements used in this experiment are liquid $TiCl_4$(99.9%), $TiH_2$(99.9%) and active carbon(<$32{\mu}m$, 99.9%). Mg powders were added to the $TiCl_4$ solution in order to induce the reaction with Cl-. The weight ratios of the carbon and Mg powders were theoretically calculated. The TiC and $MgCl_2$ powders were milled in the planetary milling jar for 10 hours. The 40 nm TiC powders were fabricated by wet milling for 4 hours from the $TiCl_4$+C+Mg solution, and 300 nm TiC particles were obtained by using titanium hydride.

• Journal of Powder Materials
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• v.16 no.5
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• pp.310-315
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• 2009

Ultra-fine TiC/Co composite powder was synthesized by the carbothermal reduction process without wet chemical processing. The starting powder was prepared by milling of titanium dioxide and cobalt oxalate powders followed by subsequent calcination to have a target composition of TiC-15 wt.%Co. The prepared oxide powder was mixed again with carbon black, and this mixture was then heat-treated under flowing argon atmosphere. The changes in the phase, mass and particle size of the mixture during heat treatment were investigated using XRD, TG-DTA and SEM. The synthesized oxide powder after heat treatment at 700$^{\circ}C$ has a mixed phase of TiO$_2$ and CoTiO$_3$ phases. This composite oxide powder was carbothermally reduced to TiC/Co composite powder by the solid carbon. The synthesized TiC/Co composite powder at 1300$^{\circ}C$ for 9 hours has particle size of under about 0.4 $\mu$m.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.31-35
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• 2002

The possibility of producing the pigments from potash feldspar was studied by adopting the mechanical alloying technique under various gas environments. The experiments were carried out by varying grinding time with the addition of copper metal and titanium oxide in N₂, O₂, He, CO₂, H₂and air atmospheres. The mixture of the potash feldspar concentrate and copper and titanium dioxide are finely ground by a planetary ball mill, and then the composite powders were calcined at 1200℃ for 20 minutes. As a result, the calcined feldspar with 1 wt% of Cu has shown various colors like green in air, black in O₂, dark green in CO₂, brown in H₂, purple in He, and pale green in N₂ atmospheres, respectively.

• Journal of Korea Foresty Energy
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• v.22 no.2
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• pp.36-43
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• 2003

This study was carried out to evaluate the fungicidal, anti-sapstain and termiticidal efficacy of commercial Dan-Chung which are currently being used for painting to decorate and to provide durability with structures of temples. Two binders (Polysol and Gelatine), and eleven pigments (Iron Oxide Red, Lead Red, Toluidine Red, Chrome Yellow, Titanium Dioxide, Ultramarine Blue, Chrome Oxide Green, Permanent Black, Cyanine Green and Ho-bun(Chalk)) were applied for the evaluation. The fungicidal and anti-sapstain activity of each pigment were depended on the types of binders. When the Polysol was used as a binder, the fungicidal efficacy of Toluidine Red treated specimen was close to the standard value (above 80) with grater than 70 against to two wood decay fungi (T. palustris and T. versicolor). The anti-sapstain efficacy of Lead Red treated specimens was excellent against to three sapstain fungi (P. funiculosum, T. viride and R. nigricans), and that of Ultramarine Blue treated specimens was also excellent to T. viride. The other pigments had little efficacy to these micro-organisms. Although there were some different trends of the effectiveness depending on the types of binders, the anti-termite effectiveness of Chrome Oxide Green and Chrome Yellow was outstanding to termite tests.