• Title/Summary/Keyword: inorganic oxide

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Gas Sensitization of Tin Oxide Film by Resistance

  • Chwa, Sang-Ok;Park, Hee-Chan;Kim, Kwang-Ho
    • The Korean Journal of Ceramics
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    • v.4 no.3
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    • pp.183-188
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    • 1998
  • Gas sensitizations of tin oxide film were investigated by measuring the change of film resistance in various gas atmospheres such as $N_2,\; O_2,\; H_2O$. The main test sample, polycrystalline $SnO_2$ film containing small Sb as a dopant was prepared by a sputtering technique and showed a long term stability in base resistance and thus, in gas sensitivity. The adsorption of oxygen on the film surface as a type of $(O_{ads})$ at the temperature of around $300^{\circ}C$ played important roles in sensor operating mechanism. The roles were ⅰ) the increase of base resistance in ambient air, which consequently lead to high sensitivity and ⅱ) the promotion of fast recovery. The reaction of hydrogen gas with the already adsorbed $(O_{ads})$ ions was considered as a decisive sensitization mechanism of tin oxide film. However, the dissociation of hydrogen molecules on film surface, by direct donation of electron to film also took a major part in the sensitization. The effect of humidity on gas sensitization was found to be negligible at the sensor operating temperature of around $300^{\circ}C$.

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Analysis of microstructural characteristics and components of red and yellow ink pigments used in permanent makeup

  • Hyun Sook Jin;Byung Soo Chang
    • Applied Microscopy
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    • v.52
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    • pp.3.1-3.8
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    • 2022
  • Our purpose in this study is to analyze the microstructural characteristics and constituent elements of inorganic substances added to the yellow ink and red ink pigments used in permanent makeup. We observed the microstructural properties of inorganic pigments added to the ink using a scanning electron microscopy (SEM) and analyzed the constituent elements of the inorganic pigment particles using an energy dispersive X-ray spectroscopy (EDX). In red wine-colored ink, cubic titanium dioxide with a diameter of 110 to 200 nm was the major component, and rod-shaped iron oxide was rarely observed. Most of the ingredients of taupe yellow ink were rod-shaped yellow iron oxide, and a small amount of cubic titanium dioxide was observed. Red wine-colored ink and taupe yellow ink contained lumps composed of titanium dioxide particles. In red wine-colored ink, lumps were formed by agglomeration. However, we observed that the surface of the lump composed of titanium dioxide in the taupe yellow ink had a smooth surface caused by external physical compression. The titanium dioxide particle mass which found in taupe yellow ink in this study is an artificial product. When this mass accumulates in the dermis, it may cause a color mismatch. Therefore, permanent makeup using fine pigments should be free of foreign substances that may cause trouble in the skin. In addition, there is a need to improve the quality of the ink so that the required color can be safe and long lasting in the dermis.

Aspects of Nanotechnology In Inorganic Sunscreen Dispersions: Efficacy and Aesthetics

  • Arthur Georgalas
    • Proceedings of the SCSK Conference
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    • 2003.09a
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    • pp.97-97
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    • 2003
  • Chemists must take into consideration more factors to formulate with inorganic sunscreens than many other active ingredients including organic sunscreens. Because the UV radiation attenuation grade particles of Titanium Dioxide and Zinc Oxide are in the nanometer range, the state of their dispersion in the product film on the skin governs their efficacy and aesthetics.(omitted)

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Preparation and Characterization of $TiO_2$Filled Sulfonated Poly(ether ether ketone) Nanocomposite Membranes for Direct Methanol Fuel Cells

  • Kim Han-Joo;Kalappa Prashantha;Son Won-Keun;Park Jong-Eun;Oshaka Tetsuya;Kim Hyun-Hoo;Hong Ji-Sook;Park Soo-Gil
    • KIEE International Transactions on Electrophysics and Applications
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    • v.5C no.4
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    • pp.165-170
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    • 2005
  • A series of inorganic-organic hybrid membranes were prepared with a systematic variation of titanium dioxide nanoparticle content. Their water uptake, methanol permeability and proton conductivity as a function of temperature were investigated. The results obtained show that the inorganic oxide network decreases the proton conductivity and water swelling. It is also found that increase in inorganic oxide content leads to decrease of methanol permeability. In terms of the morphology, membranes are homogeneous and exhibit good adhesion between inorganic domains and the polymer matrix. The properties of the composite membranes are compared with the standard nafion membrane.

Properties of Glass-Ceramics in the System CaO-TiO2-SiO2 with the Additives of Al2O3, ZrO2 and B2O3 for Use in the Solid Oxide Fuel Cells.

  • Lee, Jun-Suk;Park, Min-Jin;Shin, Hyun-Ick;Lee, Jae-Chun
    • The Korean Journal of Ceramics
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    • v.5 no.4
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    • pp.336-340
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    • 1999
  • Glasses in the system $CaO-TiO_2-SiO_2-Al_2O_3-ZrO_2-B_2O_3$ were investigated to find the glass seal compositions suitable for use in the planar solid oxide fuel cell (SOFC). Glass-ceramics prepared from the glasses by one-stage heat treatment at $1,000^{\circ}C$ showed various thermal expansion coefficients (i,e., $8.6\times10^{-6^{\circ}}C^{-1}$ to $42.7\times10^{-6^{\circ}}C^{-1}$ in the range 25-$1,000^{\circ}C$) due to the viscoelastic response of glass phase. The average values of contact angles between the zirconia substrate and the glass particles heated at 1,000-$1,200^{\circ}C$ were in the range of $131^{\circ}\pm4^{\circ}$~$137^{\circ}\pm9^{\circ}$, indicating that the glass-ceramic was in partial non-wetting condition with the zirconia substrate. With increasing heat treatment time of glass samples from 0.5 to 24 h at $1,100^{\circ}C$, the DC electrical conductivity of the resultant glass-ceramics decreased from at $800^{\circ}C$. Isothermal hold of the glass sample at $1100^{\circ}C$ for 48h resulted in diffusion of Ca, Si, and Al ions from glass phase into the zirconia substrate through the glass/zirconia bonding interface. Glass phase and diffusion of the moving ion such as $Ca^{2+}$ in glass phase is responsible for the electrical conduction in the glass-ceramics.

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Permeability of (SiO2)1-x(ZnO)x Inorganic Composite Thin Films Deposited as a Passivation Layer of Ca Cell (Ca Cell의 보호막으로 증착된 (SiO2)1-x(ZnO)x 무기 혼합 박막들의 투습 특성)

  • Kim, Hwa-Min;Ryu, Sung-Won;Sohn, Sun-Young
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.22 no.3
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    • pp.262-268
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    • 2009
  • We investigated the properties of inorganic diatomic films like silicon oxide ($SiO_2$) and zinc oxide (ZnO) and their composite films are packed as a passivation layer around Ca cells on glass substrates by using an electron-beam evaporation technique and rf-magnetron sputtering method. When these Ca cells are exposed to an ambient atmosphere, the water vapor penetrating through the passivation layers is adsorbed in the Ca cells, resulting in a gradual progress of transparency in the Ca cells, which can be represented by changes of the optical transmittance in the visible range. Compared with the saturation times for the Ca cells to become completely transparent in the atmosphere, the protection effects against permeation of water vapor are estimated for various passivation films. The thin composite films consist of$SiO_2$ and ZnO are found to show a superior protection effect from water vapor permeation compared with diatomic inorganic films like $SiO_2$ and ZnO. Also, this inorganic thin composite films are also found that their protection effect against permeation of water vapor can be significantly enhanced by choosing their suitable composition ratio and deposition method, in addition, the main factors affecting the permeation of water vapor through the oxide films are found to be the polarizability and the packing density.

Heat Resistant Low Emissivity Oxide Coating on Stainless Steel Metal Surface and Characterization of Emissivity (스테인리스강 금속 표면에 내열 저방사 산화물 코팅제 적용과 방사 특성 평가)

  • Lim, Hyung-Mi;Kwon, Tae-Il;Kim, Dae-Sung;Lee, Sang-Yup;Kang, Dong-Pil;Lee, Seung-Ho
    • Korean Journal of Materials Research
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    • v.19 no.12
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    • pp.649-656
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    • 2009
  • Inorganic oxide colloids dispersed in alcohol were applied to a stainless steel substrate to produce oxide coatings for the purpose of minimizing emissive thermal transfer. The microstructure, roughness, infrared emissive energy, and surface heat loss of the coated substrate were observed with a variation of the nano oxide sol and coating method. It was found that the indium tin oxide, antimony tin oxide, magnesium oxide, silica, titania sol coatings may reduce surface heat loss of the stainless steel at 300${\circ}C$. It was possible to suppress thermal oxidation of the substrate with the oxide sol coatings during an accelerated thermal durability test at 600${\circ}C$. The silica sol coating was most effective to suppress thermal oxidation at 600${\circ}C$, so that it is useful to prevent the increase of radiative surface heat loss as a heating element. Therefore, the inorganic oxide sol coatings may be applied to improve energy efficiency of the substrate as the heating element.

Polymers and Inorganics: A Happy Marriage?

  • Wegner Gerhard;Demir Mustafa M.;Faatz Michael;Gorna Katazyrna;Munoz-Espi Rafael;Guillemet Baptiste;Grohn Franziska
    • Macromolecular Research
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    • v.15 no.2
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    • pp.95-99
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    • 2007
  • The most recent developments in two areas: (a) synthesis of inorganic particles with control over size and shape by polymer additives, and (b) synthesis of inorganic-polymer hybrid materials by bulk polymerization of blends of monomers with nanosized crystals are reviewed. The precipitations of inorganics, such as zinc oxide or calcium carbonate, in presence and under the control of bishydrophilic block or comb copolymers, are relevant to the field of Biomineralization. The application of surface modified latex particles, used as controlling agents, and the formation of hybrid crystals in which the latex is embedded in otherwise perfect crystals, are discussed. The formation of nano sized spheres of amorphous calcium carbonate, stabilized by surfactant-like polymers, is also discussed. Another method for the preparation of nanosized inorganic functional particles is the controlled pyrolysis of metal salt complexes of poly(acrylic acid), as demonstrated by the syntheses of lithium cobalt oxide and zinc/magnesium oxide. Bulk polymerization of methyl methacrylate blends, with for example, nanosized zinc oxide, revealed that the mechanisms of tree radical polymerization respond to the presence of these particles. The termination by radical-radical interaction and the gel effect are suppressed in favor of degenerative transfer, resulting in a polymer with enhanced thermal stability. The optical properties of the resulting polymer-particle blends are addressed based on the basic discussion of the miscibility of polymers and nanosized particles.

Effects of Wet Oxidation on the Nitride with and without Annealing (열처리 전후의 질화막에 대한 습식산화의 효과)

  • Yun, Byeong-Mu;Choe, Deok-Gyun
    • Korean Journal of Materials Research
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    • v.3 no.4
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    • pp.352-360
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    • 1993
  • A nitride layer was df'posited on the thermal oxide layer by LPCVD process. ONO(oxidenitricle oxide) capacitors with various thickness of component layer wore fabricated by wet reoxidation of the nitride with and without anrwalmg treatment and their properties were investigated. As a result of observation on the refrative index and etching behavior of the ONO fIlms, the nitride layer OF 40 A thick ness was not so dense that the bottom oxide during the reoxidation process and the capability of securing the capacitance decreased. The conduction current in the ONO multl-Iayer dielctric film was reduced as the bottom(or top) oxide layer became thicker. However, in the case of oxide with thickness more than 50A, it merely plays a factor of reduction in capacitance, and the effect of barrier for hole injection was not so much increased. Annealing of the nitride laypr bpfore reoxidation did not show a grpat effects on the refractive index and capacitance of the film, however, the annealing process increased the breakdown voltage by 2${\cdot}$V.

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Flame Retardant Properties of Basalt Fiber Reinforced Epoxy Composite with Inorganic Fillers (무기 필러가 첨가된 현무암섬유 강화 에폭시 복합재료의 난연 특성)

  • Mun, So Youn;Lee, Su Yeon;Lim, Hyung Mi
    • Composites Research
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    • v.32 no.6
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    • pp.368-374
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    • 2019
  • Basalt fiber reinforced epoxy composites with inorganic filler (BFRP-F) such as Mg(OH)2 (magnesium hydroxide), Al(OH)3 (aluminum hydroxide), Al2O3 (aluminum oxide) and AlOOH (boehmite) were prepared by hand lay-up and hot pressing. The combustive properties of BFRP-F were improved comparing with basalt fiber reinforced epoxy composite (BFRP) without inorganic filler. At a 30 wt% resin content, the limited oxygen index (LOI) of BFRP is 28.9, which is higher than that of epoxy (21.4), and the LOI of BFRP-F is higher than that of BFRP. The BFRP-F showed the lower peak heat release rate (PHRR), total heat release (THR) and total smoke release rate (TSR) than those of BFRP. We confirmed that the flame retardant properties of the composite were improved by the addition of inorganic filler through the dehydration reaction and oxide film formation.