• Proceedings of the KWS Conference
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• 2003.05a
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• pp.114-116
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• 2003

The multi function sprayed coating is used for direct-heating, wear resistance and high bonding strength. The merits of surface direct-heating coatings are short warming time, low power consumption and better wear resistance that can be used in many organization parts. In this study, the surface direct-heating and wear resistance can be improved by spraying the proper materials on the surface $Al_2$O$_3$40%TiO$_2$ powder and Ni-20%Cr powder that had the properties of conduction and high wear resistivity are used in order to improve wear resistance, electrical properties and bonding strength.

• Korean Journal of Metals and Materials
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• v.47 no.8
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• pp.508-515
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• 2009

Ti-6Al-4V biomaterial is widely used as a bone alternative. However, Ti-6Al-4V ELI alloy suffers from numerous problems such as a high elastic modulus and high toxicity. Therefore, non-toxic biomaterials with low elastic moduli need to be developed. Ti-HA(hydroxyapatite) composites were fabricated in the present work by pulsed current activated sintering (PCAS) at $1000^{\circ}C$ under 60 MPa using mixed Ti and HA powders. The effects of HA content on the physical and mechanical properties of the sintered Ti-HA composites have been investigated. X-ray diffraction(XRD) analysis of the Ti-HA composites, including Ti-40 wt%HA in particular, revealed new phases, $Ti_{2}O$, CaO, $CaTiO_3$, and TixPy, formed by chemical reactions between Ti and HA during sintering. The hardness of the Ti-HA composites decreased with an increase in HA content. The corrosion resistance of these composites was observed to be an excellent candidate as a commercial Ti-6Al-4 V ELI alloy. A Ti-5 wt%HA composite fabricated by PCAS is recommended as a new biomaterial, because it offers good corrosion resistance, compressive strength, wear resistance, and biocompatibility, and a low Young's modulus.

• Journal of the Korean Institute of Gas
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• v.13 no.2
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• pp.23-29
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• 2009

This study investigated sensitivity of the gas sensor to chemical weapons with the sensor material doped with catalysts. The nano-sized SnO2 powder mixed with metal oxides (TiO2) was doped with transition metals(Pt, Pd and In). Thick film of nano-sized SnO2 powder with TiO2 was prepared by screen-printing method onto Al2O3 substrates with platinum electrode and chemical precipitation method. The physical and chemical properties of sensor material were investigated by SEM/EDS, XRD and BET analyzers. The measured sensitivity to simulant toxic gas is defined as the percentage of resistance of value equation, [(Ra-Rg)/$Ra\;{\times}100$)], that of the resistance(Ra) of SnO2 film in air and the resistance(Rg) of SnO2 film in acetonitrile gas. The best sensitivity and selectivity of these thick film were shown with 1wt.% Pd and 1wt.% TiO2 for acetonitile gas at the operating temperature of $250^{\circ}C$.

• Journal of the Korea Convergence Society
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• v.8 no.2
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• pp.157-162
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• 2017

Inorganic stiffening agents were prepared by mixing paper sludge incineration ash, blast furnace slag fine powder quicklime, anhydrous gypsum and fly ash. The main components of the solidifying agent developed for sludge treatment were SiO, $Al_2O_3$, $TiO_2$, $Fe_2O_3$, $Mn_2O_3$, CaO, MgO, $Na_2O$, $K_2O$, $P_2O$, and $SO_3$. Unlike cement, the developed solidifying agent did not contain $Cr^{6+}$, which is known as a carcinogen. Heavy metals and oil contaminated soil were mixed with solidifying agent and cured for 7 days and the heavy metal content was below the environmental standard. Sewage sludge cake, food waste and solidifying agent were mixed with each other, and after 7 days curing, soil component test showed that the heavy metal content was below the environmental standard. After mixing the sludge, solidifying agent and additive mixture into the beaker, the ammonia concentration was measured to be 0 after 3 days.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.04a
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• pp.11-11
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• 2000

Large-size ceramic/metal bulk FGMs have been fabricated on a recently developed and the world's largest Spark Plasma Sintering(SPS) systems, As a part of the development program for practical production processes and machines for FGMs by SPS, the processes, mechanical properties, dimensional size and shape effects, and production machine systems were investigated. In the past, $ZrO_{2}$/TiAI, $ZrO_{2}$/Ni, $Al_{2}O_{3}$/Ti, WC/Co, WC/Co/Steel, A1/P, Polymide, Cu/Polymide, nano-composites, porous and other combinations of bulk FGMs have already been processed using SPS. However, most of the specimen sizes were small, in a range of 20 to 30mm in diameter. Recently disk-shape sintered compacts with diameters of 100 and 150 mm, and thickness of approximately 15 and 17 mm, $ZrO_{2}$(3Y)/ stainless steel FGMs were homogenous consolidated in a shorter sintering time, while maintaining high quality and repeatability by utilizing a temperature gradient sintering method. The SPS heating up and holding time totaled less than one hour. Therefore, the SPS process in expected to find increased use in the fabrication of large-size FGMs as a new industrial processing technology. This paper introduces SPS systems, the processing principles, features and the characteristies of ceramic/metal bulk FGM.

• Journal of Korea Foundry Society
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• v.27 no.3
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• pp.135-139
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• 2007

To produce higher quality of titanium casting at a lower cost, the new titanium casting technology by using a permanent metal mold was developed and applied to fabricate hip joint for biomedical application. The present study was carried out to investigate the reactivity and fluidity of the Ti-6.0 wt%Al-4.0 wt%V alloy with metal mold by applying various ceramic powders coating on the mold surface. The molten titanium for manufacturing hip joint was poured into steel mold. No reaction layer was formed on the surface of specimens fabricated steel mold coated with $Y_2O_3$ powder.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1102-1103
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• 2006

The pretreatment for substrate was carried out in change of gun pressure of $0.5\sim3.5$ bar using wet blasting. The size of $Al_2O_3$ powder was about $50{\sim}150{\mu}m$. As the results, the surface roughness of cemented carbide substrate was improved with increment of gun pressure of wet blasting. A new surface layer was formed and Co particles were uniformly distributed over the entire surface after pretreatment. The adhesion of the pretreated substrate in same PVD-TiAlN film was improved and in approximately $Ra=90\sim120\;nm$ shown the best adhesion value.

• Journal of the Korean Applied Science and Technology
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• v.17 no.2
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• pp.67-75
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• 2000

Cosmetic industries have recently developed sun-block products, which are composed of W/O or O/W emulsion system. It was very difficult for waterproofing product to show the stability in W/O emulsion with $TiO_{2}$. To enhance the stability of W/O emulsion, it needs to be combined with the water and oil soluble components as the gelling agents. The emulsifiers used in W/O were 3.0% of cetyl dimethicone copolyol, 2.0% of sorbitan sesquioleate as the basic emulsifiers, and 0.6% of quaternium-18 bentonite and 1.5% of dextrin palmitate as stabilizer were used. The content of titanium dioxide was optimized up to 8.0%. Titanium dioxide was used as the UV scattering powder coated with $Al_{2}O_{3}$(UV-sperse T40/TN). The sunscreen cream prepared with W/O emulsion system by using QB and DP showed higher stability than that of W/O emulsion system by using each QB and DP. W/O emulsion from Formula 3 for passing one year was very durable more than F1 and F2. Within W/O emulsion by observing F1, F2 and F3 for one year, F3 was more excellent than F2 and F3 when they were observed at RT, $4^{\circ}C$, $40^{\circ}C$, because F3 used the mixed QB and DP in W/O emulsion. The zeta potential for F1, F2, and F3 after one year were 21, 30 and 43, respectively. From these result F3 was found best stable emulsion. The in-vitro SPF value for F3 was 35 for the initial product at room temperature and also, the in-vitro SPF values of F3 was 32 for after one year. Finally, the mean in-vivo SPF value of 10 volunteers for F3 was 27.3 by the Korea cosmetic association made the rules of SPF.

• Journal of the Korean Ceramic Society
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• v.22 no.6
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• pp.71-79
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• 1985

In order to fabricate the translucent electrooptic ceramics which are comparable to PLZT, $PNZT^*$ has been prepared from aqueous solutions of their itrate and chlorides. In the quarternary $Pb^{1-x} Nd_x(Zr_{0.63} Ti_{0.37})^{1-\frac{x}{4}O_3$, (PNZT) $(0.02\le x\ge 0.12)$ system cold-pressed PNZT slugs were sintered in $O_2$ in pt-crucible for 45 min. at 118$0^{\circ}C$ and were then heat-treated in air for 60 hrs. at 120$0^{\circ}C$ in Al2O3 crucibles containing $PbZrO_3$ powder to control the atmosphere. Mean particle size of calcined PNZT powders was 0.1~0.15${\mu}{\textrm}{m}$. It was found that the maximum value of optical transmission has been revealed at 6~8 at. % $Nd_2O_3$ added body and that their dielectric constant has been decreased as the frequency increased. Curic temperature has been varied inversely with $Nd^{3+}$ ion content up to 8 at. % and become constant above this value. $^*Pb_{1-x}Nd_x(Zr_{0.63} Ti_{0.37})_{1-2/4}O_3$

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.32-38
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• 2010

Hybrid material(ceramic+metal) processes were developed for micro filter using ceramics coating at metal filter surface by thermal spray method, micro hole drilling at ceramic coated filter surface by femtosecond laser, and fiber laser direct welding of ceramic and metal (SUS304, SM45C) by capillary effect. Thermal spray process was used for ceramic powders and metal filters. The used ceramic powders were $Al_2O_3+40TiO_2$(Metco 131VF) powder of maximum particle size $5{\mu}m$ and ${Al_2O_3}99+$(Metco 54NS) power of maximum particle size 45m. Ceramic coated filters using thermal spray method had a great influence on powder material, particle size and coating thickness but had a fine performance as a micro filter. CW fiber laser was used to drill the top ceramic layer and melt the bottom metal layer for joining applications.