• Title/Summary/Keyword: nano-glass

Search Result 503, Processing Time 0.026 seconds

High Temperature Gas Leak Behavior of Glass-Ceramic Fiber Composite Seals for SOFC Applications (SOFC용 유리-세라믹섬유 복합기밀재의 고온 기체누설 거동)

  • Lee, Jae-Chun;Kwon, Hyuk-Chon;Kwon, Young-Pil;Park, Sung;Jang, Jin-Sik;Lee, Jongho;Kim, Joosun;Lee, Hae-Won
    • Journal of the Korean Ceramic Society
    • /
    • v.42 no.12 s.283
    • /
    • pp.842-845
    • /
    • 2005
  • Glass composites containing ceramic fiber have been developed for Solid Oxide Fuel Cell (SOFC) seals. Effect of glass type, loading pressure and thermal cycle the leak rates of composite seals was investigated. Seal performance of two commercial glasses was compared with that of $SiO_2BaO-B_2O_3$ glass synthesized in this work. The leak rate for seals made of pyrex(R) increases from $\~0.0005\;to\;\~0.004sccm/cm$ as the gas pressure increases from 10 to 50 kPa. The soda lime silicate glass seal shows the leak rate two times higher than the one made of pyrex(R) or $SiO_2BaO-B_2O_3$ glass. The viscosity of glass at the seal test temperature is presumed to affect the leak rate of the glass seal. As the applied loading pressure increases from 0.4 to 0.8 MPa at $750^{\circ}C$, the leak rate decreases from 0.038 to 0.024 sccm/cm for composite seals. It has been found that during 50 thermal cycles between $450^{\circ}C\;to\;700^{\circ}C$ leak rates remained almost constant, ranging from 0.025 to 0.03sccm/cm. The results showed an excellent thermal cycle stability as well as sealability of the glass matrix ceramic fiber composite seals.

Dependence of Xe Plasma Flat Fluorescent Lamp On the Electrode Gap and Dielectric Layer Thickness

  • Kang, Jong-Hyun;Lee, Yang-Kyu;Heo, Sung-Taek;Oh, Myung-Hoon;Lee, Dong-Gu
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2007.08b
    • /
    • pp.1519-1521
    • /
    • 2007
  • In this work, a coplanar-type plasma flat fluorescent lamp having cross type of electrode was fabricated by screen printing and sealing technique. Cross type of electrode with a dielectric layer were screen-printed on a rear glass plate, and then fired at $550^{\circ}C$. Phosphor was printed on and fired at $450^{\circ}C$. Finally, the lamp was sealed by frit glass at $450^{\circ}C$. The lamp of cross electrode type was studied depending on the electrode gap and the thickness of dielectric layer.

  • PDF

Experimental study of filamentation using ultra fast pulse laser in transparent material (극초단 펄스 레이저를 사용한 유리 내부의 필라멘테이션에 대한 실험적 연구)

  • Choi, Won-Suk;Yoon, Ji-Wook;Kim, Joohan;Choi, Jiyeon;Chang, Won-Seok;Kim, Jae-Goo;Choi, Doo-Sun;Whang, Kyoung Hyun;Cho, Sung-Hak
    • Laser Solutions
    • /
    • v.16 no.1
    • /
    • pp.5-9
    • /
    • 2013
  • We have successfully formed filament inside of a transparent soda-lime glass using a Ti:sapphire based femtosecond laser. To make filament form, keeping the laser intensity higher than critical intensity is essential. Also each of the machining parameters plays an important role for the formation of filament. In this paper, we study what parameter can possibly influence for formation of filament, and we introduce an application using filamentation by femtosecond laser for transparent material.

  • PDF

Synthesis and Properties of Amorphous Matrix Composites using Cu-based/Ni-based Amorphous Powders (Cu계 및 Ni계 비정질 합금 분말을 이용한 비정질기지 복합재의 제조 및 특성)

  • Kim Taek-Soo;Lee Jin-Kyu;Kim Hwi-Jun;Bae Jung-Chan
    • Journal of Powder Materials
    • /
    • v.12 no.6 s.53
    • /
    • pp.406-412
    • /
    • 2005
  • This work is to present a new synthesis of metallic glass (MG)/metallic glass (MG) composites using gas atomization and spark plasma sintering (SPS) processes. The MG powders of $Cu_{54}Ni_6Zr_{22}Ti_{18}$ (CuA) and $Ni_{59}Zr_{15}Ti_{13}Nb_7Si_3Sn_2Al_1$(NiA) as atomized consist of fully amorphous phases and present a different thermal behavior; $T_g$ (glass transition temperature) and $T_x$ (crystallization temperature) are 716K and 765K for the Cu base powder, but 836K and 890K for the Ni base ones, respectively. SPS process was used to consolidate the mixture of each amorphous powder, being $CuA/10\%NiA\;and\;NiA/10\%CuA$ in weight. The resultant phases were Cu crystalline dispersed NiA matrix composites as well as NiA phase dispersed CuA matrix composites, depending on the SPS temperatures. Effect of the second phases embedded in the MG matrix was discussed on the micro-structure and mechanical properties.

Effect of Ga-doping on the properties of ZnO films grown on glass substrate at room temperature by radio frequency magnetron sputtering (RF 마그네트론 스퍼터링 방법으로 상온에서 유리기판 위에 성장시킨 ZnO의 성질에 미치는 Ga 도핑 효과)

  • Kim, G.C.;Lee, J.S.;Lee, S.K.;Kim, D.H.;Lee, S.H.;Moon, J.H.;Jeon, M.H.
    • Journal of the Korean Vacuum Society
    • /
    • v.17 no.1
    • /
    • pp.40-45
    • /
    • 2008
  • We present the effect of Ga-doping on the electrical, structural and optical properties of ZnO layers with a thickness of ${\sim}500nm$ deposited on glass substrates. Polycrystalline ZnO and Ga-doped ZnO (GZO) layers were deposited by radio frequency (rf) magnetron sputtering at room temperature. Based on the X-ray diffraction (XRD) and transmission electron microscopy (TEM) data, the crystalline quality of Ga-doped ZnO film was improved and GZO film has a preferred orientation along with the (002) crystal direction. The transmittance of the GZO film was enhanced by 10% in the visible region from that of the ZnO film. From photoluminescence (PL) data, the ratio of intensity of near band edge (NBE) emission to deep level (DL) emission was as high as 2.65:1 and 1.27:1 in the GZO and ZnO films, respectively. The res istivities of GZO and ZnO films were measured to be 1.27 and 1.61 $\Omega{\cdot}cm$, respectively. The carrier concentrations of ZnO and GZO film were approximately 1018 and 1020 $cm^2$/Vs, respectively. Based on our experimental results, the Ga-doping improves the electrical, structural and optical properties of ZnO film with potential application.

The Holding Characteristics of the Glass Filter Separators of Molten Salt Electrolyte for Thermal Batteries (열전지용 용융염 전해질의 유리필터분리판의 담지특성)

  • Cho, Kwang-Youn;Riu, Doh-Hyung;Huh, Seung-Hun;Shin, Dong-Geun;Kim, Hyoun-Ee;Cheong, Hae-Won;Cho, Sung-Baek
    • Journal of the Korean Ceramic Society
    • /
    • v.45 no.8
    • /
    • pp.464-471
    • /
    • 2008
  • The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten salt. Ceramic fibers, especially fibrous commercial glass filters were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. During the infiltration, ions of $Li^+$ and $F^-$ in the molten salts were reacted with the glass fiber and caused to be weaken the fiber strength.

A Study on Hybrid material of Making Dental restorations by CAD/CAM System (치과 CAD/CAM용 복합소재를 이용한 치과보철물의 제작에 대한 연구)

  • Choi, Beom-Jin
    • Journal of the Korean Academy of Esthetic Dentistry
    • /
    • v.23 no.2
    • /
    • pp.86-94
    • /
    • 2014
  • In recent years, perhaps the biggest driver in new material development is the desire to improve crown and bridge esthetics compared to the traditional PFM or all-metal restorations. As such, zirconia, leucite-containing glass ceramic and lithium disilicate glass ceramic have become prominent in the dental practice. Each material type performs differently regarding strength, toughness, ease of machining and the final preparation of the material prior to placement. For example, glass ceramic are typically weaker materials which limits its use to single-unit restorations. On the other hand, zirconia has a high fracture toughness which enables multi-unit restorations. This material requires a long sintering procedure which excludes its use for fast chair side production. Developed hybrid material of CAD/CAM is contained nano ceramic elements. This new material, called a Resin Nano Ceramic is unique in durability and function. The material is not a resin or composite. It is also not a pure ceramic. The material is a mixture of both and consists of ceramic. Like a composite, the material is not brittle and is fracture resistant. Like a glass ceramic, the material has excellent polish retention for lasting esthetics. The material is easily machined chair side or in a dental lab, polishes quickly to an esthetic finish and if necessary, can be useful restoratives.

Thermal Radiative Properties of Multilayer Graphene/Glass Structure (다층 그래핀/유리 구조체의 적외선 열복사 특성 연구)

  • Park, Kyung-Ah;Lim, Mikyung;Jung, Hyun-June;Kim, Jae-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.34 no.1
    • /
    • pp.27-32
    • /
    • 2021
  • In this study, we fabricated multilayer graphene on a glass substrate by stacking the monolayer graphene synthesized via chemical vapor deposition. The electrical sheet resistance and optical transmittance were evaluated to confirm the quality of the stacked multilayer graphene. Using the fabricated multilayer graphene/glass structure, we characterized its thermal radiative property in terms of the integrated emissivity. The integrated emissivity of the multilayer graphene/glass structure was tuned from 0.91 to 0.72 when the number of graphene layers was changed from 1 to 12. We also demonstrated that the emissivity tunability provided a way to control the apparent temperature of an object that can be used in infrared stealth applications.

Failure and Phase Transformation Mechanism of Multi-Layered Nitride Coating for Liquid Metal Injection Casting Mold

  • Jeon, Changwoo;Lee, Juho;Park, Eun Soo
    • Korean Journal of Materials Research
    • /
    • v.31 no.6
    • /
    • pp.331-338
    • /
    • 2021
  • Ti-Al-Si target and Cr-Si target are sputtered alternately to develop a multi-layered nitride coating on a steel mold to improve die-casting lifetime. Prior to the multi-layer deposition, a CrN layer is developed as a buffer layer on the mold to suppress the diffusion of reactive elements and enhance the cohesive strength of the multi-layer deposition. Approximately 50 nm CrSiN and TiAlSiN layers are deposited layer by layer, and form about three ㎛-thickness of multi-layered coating. From the observation of the uncoated and coated steel molds after the acceleration experiment of liquid metal injection casting, the uncoated mold is severely eroded by the adhesion of molten metallic glass. On the other hand, the multi-layer coating on the mold prevents element diffusion from the metallic glass and mold erosion during the experiment. The multi-layer structure of the coating transforms the nano-composite structured coating during the acceleration test. Since the nano-composite structure disrupts element diffusion to molten metallic glass, despite microstructure changes, the coating is not eroded by the 1,050 ℃ molten metallic glass.

Fabrication and Characterization of MgO-Al2O3-SiO2-ZrO2 Based Glass Ceramic (MgO-Al2O3-SiO2-ZrO2계 글라스 세라믹의 제조 및 특성 평가)

  • Yoon, Jea-Jung;Chun, Myoung-Pyo;Shin, Hyo Soon;Nahm, San
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.27 no.11
    • /
    • pp.712-717
    • /
    • 2014
  • Glass ceramic has a high mechanical strength and low sintering temperature. So, it can be used as a thick film substrate or a high strength insulator. A series of glass ceramic samples based on MgO-$Al_2O_3-SiO_2-ZrO_2$ (MASZ) were prepared by melting at $1,600^{\circ}C$, roll-quenching and heat treatment at various temperatures from $900^{\circ}C$ to $1,400^{\circ}C$. Dependent on the heat treatment temperature used, glass ceramics with different crystal phases were obtained. Their nucleation behavior, microstructure and mechanical properties were investigated with differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Vicker's hardness testing machine. With increasing the heat treatment temperature of MASZ samples, their hardness and toughness initially increase and then reach the maximum points at $1,300^{\circ}C$, and begin to decrease at above this temperature, which is likely to be due to the softening of glass ceramics. As the content of $ZrO_2$ in MAS glass ceramics increases from 7.0 wt.% to 13 wt.%, Vicker's hardness and fracture toughness increase from $853Kg/mm^2$ to $878Kg/mm^2$ and $1.6MPa{\cdot}m^{1/2}$ to $2.4MPa{\cdot}m^{1/2}$ respectively, which seems to be related with the nucleation of elongated phases like fiber.