• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.374.2-374.2
• /
• 2016

Volatile organic compounds (VOCs) in the atmosphere are harmful materials which influence indoor air environment and human health. Titanium dioxide ($TiO_2$) is photocatalyst extensively used in degradation of organic compound. To improve the photocatalytic activity in the visible light region, doping with non-metals element or loading noble metals on the surface of $TiO_2$ is generally proposed. In this study, N- doped $TiO_2$ having photocatalytic activity in visible light region was attached noble metal such as Pt, Ag, Pd, Au by coupling method. Catalytic activities of Noble metal coupled $N-TiO_2$ powders were evaluated by the improvement of their photocatalytic activities and the degradation of VOC gas. A UV-Vis spectrophotometer was used to measure the diffuse reflectance spectra of coupled $N-TiO_2$ sample. The photocatlytic activities of as prepared samples were characterized by the decoloration of aqueous MB solution under Xenon light source (UV and visible light). To measure of decomposition VOCs, ethylbenzene was selected for target VOC material and the concentration was monitored under UVLED irradiation in a closed chamber system. Adjusting the initial concentration of 10~12 ppm, to evaluate the removal characteristics by using the coupled $N-TiO_2$.

• Journal of Technologic Dentistry
• /
• v.36 no.3
• /
• pp.179-184
• /
• 2014

Purpose: This study was performed to investigate the release behavior of bioactive materials as a BMP-2 embedding on the porous titanium implant. Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders in a high vacuum furnace. Specimens diameter and height were 4mm and 10mm. Embedding materials were used to stamp ink. Sectional images, porosity and release behavior of porous Ti implants were evaluated by scanning electron microscope(SEM), mercury porosimeter and UV-Vis-NIR spectrophotometer. Results: Internal pore structure was formed fully open pore. Average pore size and porosity were $8.993{\mu}m$ and 8.918%. Embedding materials were released continually and slowly. Conclusion: Porous Ti implant was fabricated successfully by sintering method. Particles are necking strongly each other and others portions were vacancy. Therefore bioactive materials will be able to embedding to porous Ti implants. If the development of the fusion implant of the bioactive material will be able to have the chance to several patients.

• Laser Solutions
• /
• v.18 no.3
• /
• pp.1-5
• /
• 2015

A 3D printer based on laser powder deposition (LPD), also known as DED (direct energy deposition), has been developed for fabricating metal parts. The printer uses a ytterbium fiber laser (1070nm, 1kW) and is equipped with an Ar purge chamber, a three-dimensional translation stage and a powder feeding system composed of a powder chamber and delivery nozzles. To demonstrate the performance of the printer, a tapered cylinder of 320mm in height has been fabricated successfully using Ti-6Al-4V powders. The process parameters including the laser output power, the scan speed, and the powder feeding rate have been optimized. A 3D printed test specimen shows mechanical properties (yield strength, ultimate tensile strength, and elongation) exceeding the criteria to employed in a variety of Ti alloy applications.

• Journal of Technologic Dentistry
• /
• v.37 no.2
• /
• pp.57-62
• /
• 2015

Purpose: This study was performed to investigate mechanical properties of the porous Ti implants according to porosity. Porous Ti implant will be had properties similar to human bone such as microstructure and mechanical properties. Methods: Porous Ti implant samples were fabricated by sintering of spherical Ti powders(below $25{\mu}m$, $25{\sim}32{\mu}m$, $32{\sim}38{\mu}m$, and $38{\sim}45{\mu}m$) in a high vacuum furnace. Specimen's diameter and height were 4mm and 40 mm. Surface and sectional images of porous Ti implants were evaluated by scanning electron microscope(SEM). Porosity and average pore size were evaluated by mercury porosimeter. Young's modulus and tensile strength were evaluated by universal testing machine(UTM). Results: Porosity of Implant was increased according to larger particle size of the powder. Boundary portions of particles are sintered fully and others portions were formed pore. Young's modulus was decreased by formed porous structure. Tensile strength was decreased according to larger the particle size of the powder, but higher than human bone. Conclusion: If prepared by adjust the porosity of the porous Ti implant will be able to resolve the stress shielding phenomenon.

• Korean Journal of Materials Research
• /
• v.30 no.2
• /
• pp.57-60
• /
• 2020

Titanium aluminides have attracted special interest as light-weight/high-temperature materials for structural applications. The major problem limiting practical use of these compounds is their poor ductility and formability. The powder metallurgy processing route has been an attractive alternative for such materials. A mixture of Ti and Al elemental powders was fabricated to a mechanical alloying process. The processed powder was hot pressed in a vacuum, and a fully densified compact with ultra-fine grain structure consisting of Ti₃Al intermetallic compound was obtained. During the compressive deformation of the compact at 1173 K, typical dynamic recrystallization (DR), which introduces a certain extent of grain refinement, was observed. The compact had high density and consisted of an ultra-fine equiaxial grain structure. Average grain diameter was 1.5 ㎛. Typical TEM micrographs depicting the internal structure of the specimen deformed to 0.09 true strain are provided, in which it can be seen that many small recrystallized grains having no apparent dislocation structure are generated at grain boundaries where well-developed dislocations with high density are observed in the neighboring grains. The compact showed a large m-value such as 0.44 at 1173 K. Moreover, the grain structure remained equiaxed during deformation at this temperature. Therefore, the compressive deformation of the compact was presumed to progress by superplastic flow, primarily controlled by DR.

• Journal of Powder Materials
• /
• v.20 no.3
• /
• pp.221-227
• /
• 2013

$TiB_2$-reinforced iron matrix composite (Fe-$TiB_2$) powder was in-situ fabricated from titanium hydride ($TiH_2$) and iron boride (FeB) powders by the mechanical activation and a subsequent reaction. Phase formation of the composite powder was identified by X-ray diffraction (XRD). The morphology and phase composition were observed and measured by field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The results showed that $TiB_2$ particles formed in nanoscale were uniformly distributed in Fe matrix. $Fe_2B$ phase existed due to an incomplete reaction of Ti and FeB. Effect of milling process and synthesis temperature on the formation of composite were discussed.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.3981-3986
• /
• 2012

Anatase nanocrystalline and its tungsten-doped (0.4, 2, and 4 mol %) powders have been synthesized by microwave irradiation through hydrolysis of titanium tetra-isopropoxide (TIP) in aqueous solution. The materials are characterized by XRD, Raman, SEM-EDX, TEM, FT-IR and UV-vis techniques. The nanocrystalline $TiO_2$ particles are 30 nm in nature and doping of tungsten ion decreases their size. As seen in TEM images, the crystallites of W (4 mol %) doped $TiO_2$ are small with a size of about 10 nm. The photocatalytic activity was tested on the degradation of 4-nitrophenol (4-NP). Catalytic activities of W-doped and pure $TiO_2$ were also compared. The results show that the photocatalytic activity of the W-doped $TiO_2$ photocatalyst is much higher than that of pure $TiO_2$. Degradation decreases from 96 to 50%, during 115 min, when the initial 4-NP concentration increases from 10 to 120 ppm. Maximum degradation was obtained at 35 mg of photocatalyst.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.1 no.2
• /
• pp.27-32
• /
• 2008

A current research basically diverted towards an increase in the operational output with the minimization of the materials used, which ultimately scaled down the dimensions of ceramic electronic components. In this direction the nano-technology pave the revolutionary changes in particular the electronic industries. The applications of nano-sized particles or nano-sized materials are hence, playing a significant role for various purposes. The PZT(lead, zirconium, titanium) based ceramics which, are reported to be ferroelectric materials have their important applications in the areas of surface acoustic waves (SAW), filters, infrared detectors, actuators, ferroelectric random access memory, speakers, electronic switches etc. Moreover, these PZT materials possess the large electro mechanical coupling factor, large spontaneous polarization, low dielectric loss and low internal stress etc. Hence, keeping in view the unique properties of PZT piezoelectric ceramics we also tried to synthesize indigenously the small sized PZT ceramic powder in the laboratory by using the modified sol-gel approach. In this paper, propyl alcohol based sol-gel method was used for preparation of PZT piezoelectric ceramic. The powder obtained by this sol-gel process was calcined and sintering to reach a pyrochlore-free crystal phase. The characterization of synthesized material was carried out by the XRD analysis and the surface morphology was determined by high resolution scanning electron microscopy.

• Korean Chemical Engineering Research
• /
• v.54 no.2
• /
• pp.152-156
• /
• 2016

Experimental research on the preparation of photocatalyst for the decomposition of brilliant blue FCF ($C_{37}H_{31}O_9N_2S_3Na_2$) was performed. $TiO_2$ and ZnO powders were prepared from titanium (IV) sulfate and zinc acetate at low reaction temperature and atmospheric pressure by hydrothermal precipitation method without calcination. In addition, $TiO_2$ was prepared with cationic surfactant CTAB (Hexadecyltrimethyl ammonium bromide) at the same conditions. The physical properties of prepared $TiO_2$ and ZnO, such as crystallinity, average particle size and absorbance, were investigated by XRD, Zeta-potential meter and DRS. And, the photocatalytic degradation of brilliant blue FCF has been studied in the batch reactor under UV radiation. For the photocatalysts prepared without CTAB, $TiO_2$ has smaller particle size and larger absorbance and photocatalytic reaction rate than ZnO. And $TiO_2$, prepared with CTAB whose concentration is 1/10 of that of precursor, shows 15% higher than that prepared without CTAB in final photocatalytic degradation ratio of brilliant blue FCF.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.47 no.1
• /
• pp.41-48
• /
• 2021

Formulations which are dispersed in water are often used in color cosmetics because they are characterized by no powder flying, not sticky, and high adherence while giving a light feeling of use. However, little research has been considered on the effect of the pigment on the above formulations used in color cosmetics. In this study, experiments were conducted to measure and analyze the effect of pigments on the formulation of pigments, organic pigments, and pearl polish, which are mainly used in the manufacture of color cosmetics, on appearance changes, pH changes, and photometric stability. Carmine or ferric ferrocyanide coated titanium dioxide mica-based pigments were not suitable for use due to poor photostability, with colors appearing on the surface from low viscosity formulations. Organic pigments had a good photostability of 1% of the formulation which are dispersed in water, but were not suitable for use because they came out of color on the water surface and did not spread well due to the clumping of powders. The titanium dioxide mica system pigments coated with pearl polish, inorganic pigments, and iron oxide were suitable for use due to their excellent appearance and optical stability in the formulation. Furthermore, the pH of all samples distributed by each pigment seems to be within the range of 3.0 to 9.0, which is suitable for cosmetic applications. This is expected to help manufacture color cosmetics with a stable water dispersible formulations by selecting and using stable pigments in anticipation of the behavior of pigments in the formulations.