• 제목/요약/키워드: graphite coating

검색결과 141건 처리시간 0.028초

수계-비수계 용매를 이용한 흑연분말의 $ZrO_2$ 수열코팅 (Preparation of $ZrO_2$ Coated Graphite Powders in Aqueous and Nonaqueous Solution)

  • 김정환;이태근;이기강;이석근
    • 한국결정학회지
    • /
    • 제14권2호
    • /
    • pp.67-72
    • /
    • 2003
  • Graphite powders were coated with ZrO₂ by the controlled hydrolysis of a DI water, ethanol and DI water+ethanol solutions. The hydrolysis process was carried out with temperature control because of the low wettability of Zr ions to the surface of the graphite. PVA was added to the solution for the enhancement of metal ion adsorption. The surface of the graphite powders coated with ZrO₂ was observed by SEM and TEM. There are two types of ZrO₂ particles with the condition of ZrOCl₂°§8H₂O aqueous solutions were used; (a) primary particles a few nm in size and (b) secondary particles with ∼0.1 ㎛ size were obtained. The graphite powders coated in 50% ethanol-50% DI water solution of Zr(SO₄)₂ㆍ4H₂O have the relatively uniform coating layer and the starting temperature of oxidation was 100℃ higher than the raw graphite.

실리카-그라파이트 이원 충진제를 이용한 SBR 컴파운드의 성질 (Properties of SBR Compound using Silica-graphite Dual Phase Filler)

  • 신지항;;이평찬;정선경;류승훈
    • Elastomers and Composites
    • /
    • 제49권1호
    • /
    • pp.66-72
    • /
    • 2014
  • 실리카 입자에 팽창흑연을 그라프트 시킴으로 카본코팅을 실시하였으며, 이를 확인하기 위하여 FT-IR, TGA, XPS 그리고 TEM 분석을 실시하였다. 코팅된 흑연의 결정특성은 XRD를 이용하여 확인하였으며, 카본 코팅된 실리카가 SBR 컴파운드의 유변학적 그리고 기계적 성질에 미치는 영향에 대하여 살펴보았다. 카본 코팅된 실리카를 이용한 경우 순수 실리카를 이용한 경우에 비하여 SBR 컴파운드의 유변학적 그리고 기계적 성질이 크게 향상됨을 알 수 있었다. 이러한 현상은 평형팽창비율과 bound 고무 양 변화로도 확인 할 수 있었다.

Effect of Carbon-coated Silicon/Graphite Composite Anode on the Electrochemical Properties

  • Kim, Hyung-Sun;Chung, Kyung-Yoon;Cho, Byung-Won
    • Bulletin of the Korean Chemical Society
    • /
    • 제29권10호
    • /
    • pp.1965-1968
    • /
    • 2008
  • The effects of carbon-coated silicon/graphite (Si/Gr.) composite anode on the electrochemical properties were investigated. The nanosized silicon particle shows a good cycling performance with a reasonable value of the first reversible capacity as compared with microsized silicon particle. The carbon-coated silicon/graphite composite powders have been prepared by pyrolysis method under argon/10 wt% propylene gas flow at $700{^{\circ}C}$ for 7 h. Transmission electron microscopy (TEM) analysis indicates that the carbon layer thickness of 5 nm was coated uniformly onto the surface silicon powder. It is confirmed that the insertion of lithium ions change the crystalline silicon phase into the amorphous phase by X-ray diffraction (XRD) analysis. The carbon-coated composite silicon/graphite anode shows excellent cycling performance with a reversible value of 700 mAh/g. The superior electrochemical characteristics are attributed to the enhanced electronic conductivity and low volume change of silicon powder during cycling by carbon coating.

내화물 슬레이트용 고체윤활제의 연구 (Studies on solid inflammable lubricants for refractory slates)

  • 노승백;이학일;손기훈
    • 한국산학기술학회논문지
    • /
    • 제16권3호
    • /
    • pp.2308-2313
    • /
    • 2015
  • 본 논문은 내화물 슬레이트용 고체윤활제를 제조하기 위하여 Starch 및 Graphite의 함량 변화를 통하여 점도, 마찰계수 및 마모성능을 평가하여 Starch, Graphite와 water 간의 적절한 함량 조합을 찾고자 하였다. 먼저 starch 15 wt%일 때 점도는 graphite 함량에 따라 점도 상승이 커짐을 알 수 있었다. 또한 마찰계수 시험에서는 starch 15 wt%이고, graphite 30 wt%일 때 마찰계수가 가장 적었다. 이는 물의 함량이 줄어들고 고체의 비율이 높아짐에 따라 흡착력이 낮아져 표면에서 피막이 조금씩 탈락되며 마찰계수가 상승하는 것으로 판단된다. 마모 시험결과 starch 15 wt%이면서, graphite 25 wt% 혹은 30 wt%일 때 가장 양호한 결과를 얻었다.

Effects of Coating Materials on Fluidity and Temperature Loss of Molten Metals from Runner Systems in Full Moulds.

  • Cho, Nam-Don;Kim, Yong-Hyun;Choi, Jung-Kwon
    • 한국주조공학회지
    • /
    • 제10권1호
    • /
    • pp.31-42
    • /
    • 1990
  • The full mould casting process in one of the newly developed techniques which has many advantages. Unbonded sand mould has been prepared for the major mould and $CO^2$ gas mould has been used occasionally for comparison. Patterns were built up with expanded polystyrene and coated with three different materials. Silica, graphite and zircon were used for the coating layer. The effects on fluidity and temperature loss of molten metals were investigated. The molten metals were Al-5% Si alloy, Cu-30% Zn alloy and gray iron of approximately 4.0% of carbon equivalent. Experimental variables were runner section area, superheat, sprue height, coating materials, coating thickness and apparent density of EPS pattern. The effects of coating materials on fluidity and temperature loss of the molten metals during transient pouring are summarized as follows : As runner section area, superheat and sprue height increased, fluidity increased. Temperature loss decreased as runner section area and sprue height increased. However, reversed effects were observed in the case of superheat increment. The coating materials decreased the fluidity of each alloy in the order of silica, graphite and zircon. Zircon brought to the highest temperature loss among the coating materials used. The fluidity increased in the order gray iron, Cu-30% Zn and Al-5% Si alloy while temperature loss in the reverse order. Especially in case of reduced pressure process, the fluidity was increased apparently. Al-5% Si alloy showed the lowest temperature loss among the alloys. The increment of the apparent density of EPS pattern resulted in the fluidity decrease and temperature loss increase. The relation between fluidity and temperature loss of each alloy can be expressed by the following equation within the coating thickness limit of 0.5-1.5㎜. F^*={\frac{a}{T^*-b}}-c$ where, $F^*$ : fluidity in the Full mould, $T^*$ : temperature loss in the mould. a : parameter for full mould. b, c : constants.

  • PDF

Silicon Carbide Coating by Thermal Decomposition of tetramethylsilane

  • 윤경한
    • 한국세라믹학회:학술대회논문집
    • /
    • 한국세라믹학회 1986년도 Priceedings Of The Third Korea-Japan Seminar On New Ceramics
    • /
    • pp.211-225
    • /
    • 1986
  • Silicon carbide coating has been studied using a graphite substrate, a mixture of tetramethylsilane and hydrogen or argon at deposition temperature (T) of 950 to $1200^{\circ}C$ total pressure of 20 to 50 torr and carrier gas flow rate of 0 to 901/h. Deposition kinetic study has shown that a transition, from a surface reaction limited process to a diffusion limited one, takes place near $1100^{\circ}C$. Deposition rate depends directly upon the experimental parameters. The influence of the main process parameters is also discussed to relate the physiochemical properties of the coating to the deposition conditions.

  • PDF

알루미늄 기판에 코팅된 흑연입자의 배향도 변화와 열방사율 변화의 관계 (Relation between Thermal Emissivities and Alignment Degrees of Graphite Flakes Coated on an Aluminum Substrate)

  • 강동수;이상민;김석환;이상우;노재승
    • 한국재료학회지
    • /
    • 제24권3호
    • /
    • pp.159-165
    • /
    • 2014
  • This study is research on the thermal emissivity depending on the alignment degrees of graphite flakes. Samples were manufactured by a slurry of natural graphite flakes with organic binder and subsequent dip-coating on an aluminum substrate. The alignment degrees were controlled by applying magnetic field strength (0, 1, and 3 kG) to the coated samples. The alignment degree of the sample was measured by XRD. The thermal emissivity was measured by an infrared thermal image camera at $100^{\circ}C$. The alignment degrees were 0.04, 0.11, and 0.17 and the applied magnetic field strengths were 0, 1, and 3 kG, respectively. The thermal emissivities were 0.829, 0.837, and 0.844 and the applying magnetic field strengths were 0, 1, and 3 kG, respectively. In this study the correlation coefficient, $R^2$, between thermal emissivity and alignment degree was 0.997. Therefore, it was concluded that the thermal emissivities are correlated with the alignment degree of the graphite flakes.

흑연 금형 표면 보호용 PCS 코팅층의 열경화에 의한 조성비 조절 특성 연구 (Study on the Compositional Characteristics of the PCS Coating Layer by Curing Treatment for the Protection of Graphite Mold Surface)

  • 김경호;이윤주;신윤지;정성민;이명현;배시영
    • 한국표면공학회지
    • /
    • 제53권6호
    • /
    • pp.293-299
    • /
    • 2020
  • The characteristics of the polycarbosilane (PCS)-based composite ceramic layer was studied by controlling the curing temperature. The stress at the interface of the graphite and SiOC composite layer was evaluated v ia finite element analysis. As a result, the tensile stress was released as the carbon ratio of the SiC decreases. In experiment, the SiOC layers were coated on the VDR graphite block by dip-coating process. It was revealed that the composition of Si and C was effectively adjusted depending on the curing temperature. As the solution-based process is employed, the surface roughness was reduced for the appropriate PCS curing temperature. Hence, it is expected that the cured SiOC layer can be utilized to reduce cracking and peeling of SiC ceramic composites on graphite mold by improving the interfacial stress and surface roughness.

흑연분말을 이용한 다공성 니켈지지체의 제조에 관한 연구 (A Study on the Fabrication of Porous Nickel Substrates Using Graphite Powder)

  • 박성용;백지흠;조원일;조병원;윤경석
    • 한국표면공학회지
    • /
    • 제28권5호
    • /
    • pp.276-288
    • /
    • 1995
  • A nickel mesh and an expanded nickel sheet were used as a current collector for supporting active materials of cathode in rechargeable batteries, while a porous nickel substrate was extensively studied because of its 3-dimensional structure which has high capabilities for active materials and current collection. Optimum coating conditions were studied by SEM and two step d. c. constant current electrolysis for the graphite coating and electro-plated nickel on an urethane substance which was highly porous and 3-dimensional structure. The density and the porosity of nickel support obtained by using two step current density and 80 ppi urethane substance were 0.38∼0.40 g /㎤ and 94∼96%, respectively. It was possible to fabricate a highly porous and good packable nickel substrate using two step current density and surfactants at sulfamic acid nickel plating bath.

  • PDF

RECENT TRENDS ON RESEARCHES AND TECNOLOGIES IN FORGING PROCESSES IN JAPAN

  • Nakamura Tamotsu
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
    • /
    • pp.10-17
    • /
    • 2003
  • The amount of production orders from Japanese car and construction machine industries have slightly increased in 2002, but the costs of the forged parts have decreased due to severe competitions with the other Asian countries. Most of the forging industries and some universities are making more efforts for technological researches and developments to meet the demand for higher accuracy and higher quality products, shortening of delivery time, and development of forged parts for new industrial fields. Some helical gears of which surfaces can be net-shaped have been started for commercial base production to be shipped to car industries. Some non-graphite lubricants for hot forging and some conversion coating free lubricants for cold forging have been developed to improve some environmental problems.

  • PDF