• Title/Summary/Keyword: graphite coating

Search Result 142, Processing Time 0.024 seconds

Surface Modification of Synthetic Graphite as an Electrode by Fluidized-bed Chemical Vapor Deposition for Lithium Secondary Batteries (유동상 화힉증착에 의한 리튬이차전지 전극용 탄소재료의 표면개질)

  • Ryu D. H.;Lee Joong Kee;Park D. G.;Yun K. S.;Cho B. W.;Shul Y. G.
    • Journal of the Korean Electrochemical Society
    • /
    • v.3 no.3
    • /
    • pp.173-177
    • /
    • 2000
  • The synthetic carbon was coated with tin oxide and copper by fluidized-bed chemical vapor deposition method. $(CH_3)_4Sn\;and\;Cu(hfac)_{2s}$ were employed as the metallic organic precursor, respectively. The modified synthetic carbons were used for lithium secondary battery anode to investigate their coating effects on electrochemical characteristics as alternative anode materials for lithium secondary batteries. The electrode which prepared by the synthetic carbons(MCMB) coated with tin oxide gave the higher capacity than that of raw material. Their capacity decreased with the progress of cycling possibly due to severe volume changes. But the cyclability was improved by coating with copper on the surface of the tin oxide coated carbon, which plays an important role as an inactive matrix buffering volume changes.

Properties of Chemical Vapor Deposited ZrC Coating Layer using by Zirconium Sponge Materials (지르코늄 스폰지를 원료로 사용하여 화학증착법으로 제조된 탄화지르코늄 코팅층의 물성)

  • Kim, Jun-Gyu;Choi, Yoo-Youl;Lee, Young-Woo;Park, Ji-Yeon;Choi, Doo-Jin
    • Journal of the Korean Ceramic Society
    • /
    • v.45 no.4
    • /
    • pp.245-249
    • /
    • 2008
  • The SiC and ZrC are critical and essential materials in TRISO coated fuel particles since they act as protective layers against diffusion of metallic and gaseous fission products and provides mechanical strength for the fuel particle. However, SiC and ZrC have critical disadvantage that SiC loses chemical integrity by thermal dissociation at high temperature and mechanical properties of ZrC are weaker than SiC. In order to complement these problems, we made new combinations of the coating layers that the ZrC layers composed of SiC. In this study, after Silicon carbide(SiC) were chemically vapor deposited on graphite substrate, Zirconium carbide(ZrC) were deposited on SiC/graphite substrate by using Zr reaction technology with Zr sponge materials. The different morphologies of sub-deposited SiC layers were correlated with microstructure, chemical composition and mechanical properties of deposited ZrC films. Relationships between deposition pressure and microstructure of deposited ZrC films were discussed. The deposited ZrC films on SiC of faceted structure with smaller grain size has better mechanical properties than deposited ZrC on another structure due to surface growth trend and microstructure of sub-deposited layer.

Characteristics of Fluorine-Doped Tin Oxide Film Coated on SUS 316 Bipolar Plates for PEMFCs (ECR-MOCVD를 이용하여 연료 전지 분리판에 코팅된 FTO막의 특성 연구)

  • Park, Ji-Hun;Hudaya, C.;Jeon, Bup-Ju;Byun, Dong-Jin;Lee, Joong-Kee
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.22 no.3
    • /
    • pp.283-291
    • /
    • 2011
  • Polymer electrolyte membrane fuel cells (PEMFCs) use the bipolar plate of various materials between electrolyte and contact electrode for the stable hydrogen ion exchange activation. The bipolar plate of various materials has representatively graphite and stainless steel. Specially, stainless steels have advantage for low cost and high product rate. In this study, SUS 316 was effectively coated with 600 nm thick F-doped tin oxide (SnOx:F) by electron cyclotron resonance-metal organic chemical vapor deposition and investigated in simulated fuel cell bipolar plates. The results showed that an F-doped tin oxide (SnOx:F) coating enhanced the corrosion resistance of the alloys in fuel cell bipolar plates, though the substrate steel has a significant influence on the behavior of the coating. Coating SUS 316 for fuel cell bipolar plates steel further improved the already excellent corrosion resistance of this material. After coating, the increased ICR values of the coated steels compared to those of the fresh steels. The SnOx:F coating seems to add an additional resistance to the native air-formed film on these stainless steels.

EFFECT OF ADDED Si ON DENSIFICATION OF Ni-AI INTERMETALLIC COATING ON SPHEROIDAL GRAPHITE CAST IRON SUBSTRATES

  • Kim, Tetsuro ata;Keisuke Uenishi;Akira Ikenaga;Kojiro F. Kobayashi
    • Proceedings of the KWS Conference
    • /
    • 2002.10a
    • /
    • pp.726-731
    • /
    • 2002
  • Reaction synthesis is a process to form ceramics, intermetallics and their composites from elemental powder mixture. Application of this process to a surface modification techniques has a possibilities to enable the process at a lower temperature or for a shorter time, although synthesized materials are likely to include voids and unreacted elements. This paper intend to examine the effect of Si addition to the mixture of Al and Ni on the densification of synthesized Ni-Al intermetallic compounds and to evaluate the surface properties of obtained coatings. By the Si addition, exothermic reaction temperature to form Ni-Al intermetallic was lowered to be below the melting point of Al. Si soluted $Al_3$Ni$_2$, $Al_3$Ni and $Al_{6}$Ni$_3$Si were mainly formed in the coating layer when powder mixture was heated to 973K for 300s. Besides, densification was enhanced by increasing hot press pressure, Si additions and heating rate. When the composition of eutectic Al-Si reaches 78%, void ratio of sintered compact reduced to 0.4%. It is caused by higher flowability of Al-Si liquid phase generated and its infiltration into the void. Since the hardness of NiAl(Si) compound (about 600HV) formed in the coating layer is higher than that of Ni-Al compound (about 400HV), coating layer with high density and superior wear property is obtained by hot press using reaction synthesis from Al-Ni-Si powder mixture.

  • PDF

Preparation and Characteristics of Photochromic Plastic Lenses by Hard Coatings (하드코팅에 의한 광변색 플라스틱 렌즈의 제조 및 특성)

  • Yu, Dong-Sik;Ha, Jin-Wook;Moon, Byeong-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.10 no.7
    • /
    • pp.1635-1641
    • /
    • 2009
  • In this study, we have prepared plastic lenses with both photochromic and hard properties by hard coating, and evaluated their optical properties and surface characteristics. Photochromic effects could be observed on the UV spectra of the closed forms and the visible spectra of the open forms. Visible light transmittance of photochromic lenses was from 83.44% for graphite(GP) to 85.15% for blue(BL) in colourless state and from 71.10% for red(RE) to 79.98% for yellow(YE) in colour state. Red photochromic lens was higher in optical density(${\Delta}$OD) and color difference(${\Delta}$$E^{\ast}_\;{ab}$) than the others. Photochromic lenses applied by hard coating showed good adhesion, hot water resistance, chemical resistance and surface appearance. Also, compared to the uncoated lens, hardness and abrasion resistance were increased. Consequently, this coating system could impart functional properties such as photochromic and hard coating property onto ophthalmic lenses.

Electrochemical Properties of Needle Coke through a Simple Carbon Coating Process for Lithium Ion Battery (침상 코크스의 피치 코팅에 따른 리튬 이차전지 탄소계 음극소재의 전기화학적 특성)

  • Hwang, Jin Ung;Lee, Jong Dae;Im, Ji Sun
    • Applied Chemistry for Engineering
    • /
    • v.31 no.5
    • /
    • pp.514-519
    • /
    • 2020
  • Graphite materials for lithium ion battery anode materials are the most commercially available due to their structural stability and low price. Recently, research efforts have been conducted on carbon coatings by improving side reactions at the edge site of carbon materials. The carbon coating process has classified into a CVD by chemical reaction, wet coating process with solvent and dry coating by mechanical impact. In this paper, the rapid crush/coating process was used to solve the problem of which only few parts of the carbon precursor (pitch) can be used and also environmental problems caused by solvent removal in the wet coating process. When the ratio of needle coke to pitch was 8 : 2 wt%, and the rapid crush/coating process was carried out, it was confirmed that the fracture surface was coated by pitch. The pitch-coated sample was treated at 2400 ℃ and 41.8% improvement in 10C/0.1C rate characteristic was observed. It is considered that the material simply manufactured through the simple crush/coating process can be used as an anode electrode material for a lithium ion battery.

Effect of $Cl_2$ Gas Concentration of the Surface Modified TiC on the Tribological Properties (TiC표면개질에서 $Cl_2$ 가스농도가 tribology 특성에 미치는 효과)

  • Bae, Heung-Taek;Lim, Dae-Soon;Na, Byung-Chul
    • Tribology and Lubricants
    • /
    • v.23 no.6
    • /
    • pp.261-265
    • /
    • 2007
  • Carbide-derived carbon coating has been synthesized by low temperature treatment of TiC disk with $H_2/Cl_2$ mixture gases. A variety of physical measurements indicated that Ti was extracted and carbon layer was formed by exposure of $Cl_2$ gas. The $I_D/I_G$ ratio increased with increasing $Cl_2$ gas concentration. Wear coefficient and frictional coefficient varied with $Cl_2$ gas concentration. When the $Cl_2$ gas concentration decreased to 3.3 vol%, the friction coefficient approach a minimum. The results showed that degree of graphite crystallinity and variation of porosity due to the $Cl_2$ gas content were responsible for different tribology performance.

Flexural properties, interlaminar shear strength and morphology of phenolic matrix composites reinforced with xGnP-coated carbon fibers

  • Park, Jong Kyoo;Lee, Jae Yeol;Drzal, Lawrence T.;Cho, Donghwan
    • Carbon letters
    • /
    • v.17 no.1
    • /
    • pp.33-38
    • /
    • 2016
  • In the present study, exfoliated graphite nanoplatelets (xGnP) with different particle sizes were coated onto polyacrylonitrile-based carbon fibers by a direct coating method. The flexural properties, interlaminar shear strength, and the morphology of the xGnP-coated carbon fiber/phenolic matrix composites were investigated in terms of their longitudinal flexural strength and modulus, interlaminar shear strength, and by optical and scanning electron microscopic observations. The results were compared with a phenolic matrix composite counterpart prepared without xGnP. The flexural properties and interlaminar shear strength of the xGnP-coated carbon fiber/phenolic matrix composites were found to be higher than those of the uncoated composite. The flexural and interlaminar shear strengths were affected by the particle size of the xGnP, while the particle size had no significant effect on the flexural modulus. It seems that the interfacial contacts between the xGnP-coated carbon fibers and the phenolic matrix play a role in enhancing the flexural strength as well as the interlaminar shear strength of the composites.

Effect of reaction factors on the characteristics of Ni-coating layer onto graphite (흑연표면의 니켈코팅층 특성에 미치는 반응인자의 영향)

  • Dong Jin Kim;Hun Saeong Chung;Myung Kyu Jung;Ki Byoung Youn
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.4 no.4
    • /
    • pp.395-404
    • /
    • 1994
  • Ni-graphite composite powders were prepared by reduction of $Ni^{++}$ from ammoniacal nickel sulfate solution on graphite core by hydrogen gas. Effect of reaction factors on the reduction rate and the properties of nickel layer were investigated by SEM, Optical Microscopy, size and chemical analysis. Induction period, a time lag between the injection of hydrogen gas and the start of the reduction, was 20~110 mins and affected by the reaction temperature and stirring speed. The reduction rate of $Ni^{++}$ was $4.5g/{\ell}/min$ at optimum condition and increased with increasing reaction temperature and stirring speed.

  • PDF

Characterization of Ni/YSZ Anode Coating for Solid Oxide Fuel Cells by Atmospheric Plasma Spray Method (고체산화물 연료전지를 위한 플라즈마 용사코팅 Ni/YSZ 음극 복합체의 특성평가)

  • Park, Soo-Dong;Yoon, Sang-Hoon;Kang, Ki-Cheol;Lee, Chang-Hee
    • Journal of Welding and Joining
    • /
    • v.26 no.4
    • /
    • pp.50-54
    • /
    • 2008
  • In this research, anode for SOFC has been manufactured from two different kinds of feedstock materials through thermal spraying process and the properties of the coatings were characterized and compared. One kind of feedstock was manufactured from spray drying method which includes nano-components of NiO, YSZ (300 nm) and graphite. And the other is manufactured by blending the micron size NiO coated graphite, YSZ and graphite powders as feedstock materials. Microstructure, mechanical properties and electrical conductivity of the coatings as-sprayed, after oxidation and after hydrogen reduction containing nano composite which is prepared from spray-dried powders were evaluated and compared with the same properties of the coatings prepared from blended powder feedstock. The coatings prepared from the spray dried powders has better properties as they provide larger triple phase boundaries for hydrogen oxidation reaction and is expected to have lower polarization loss for SOFC anode applications than that of the coatings prepared from blended feedstock. A maximum electrical conductivity of 651 S/cm at $800^{\circ}C$ was achieved for the coatings from spray dried powders which much more than that of the average value.