Oxidation Resistant SiC Coating for carbon/carbon Composites

Joo, Hyeok-Jong,Lee, Nam-Joo,Oh, In-Seok 한국탄소학회 2003 Carbon Letters Vol.4 No.1

In this study, densified 4D carbon/carbon composites were made from carbon fiber and coal tar pitch through the process of pressure impregnation and carbonization and then followed by carbonization and graphitization. To improve the oxidative resistance of the prepared carbon/carbon composites, the surface of carbon/carbon composites was coated on SiC by the pack cementation method. The SiC coated layer was created by depending on the constitution of pack powder, and reaction time of pack-cementation. The morpology of crystalline and texture of these SiC coated carbon/carbon composites were investigated by XRD, SEM/EDS observation. So the coating mechanism of pack-cementation process was proposed. The oxidative res istance were observed through the air oxidation test, and then the optimal condition of pack cementation was found by them. Besides, the oxidative mechanism of SiC formed was proposed through the observation of SiC coated surface, which was undergone by oxidation test.

Oxidation Resistant SiC Coating for carbon/carbon Composites

Hyeok-Jong Joo,Nam-Joo Lee,In-Seok Oh 한국탄소학회 2003 Carbon Letters Vol.4 No.1

In this study, densified 4D carbon/carbon composites were made from carbon fiber and coal tar pitch through the process of pressure impregnation and carbonization and then followed by carbonization and graphitization. To improve the oxidative resistance of the prepared carbon/carbon composites, the surface of carbon/carbon composites was coated on SiC by the pack cementation method. The SiC coated layer was created by depending on the constitution of pack powder, and reaction time of pack-cementation. The morpology of crystalline and texture of these SiC coated carbon/carbon composites were investigated by XRD, SEM/EDS observation. So the coating mechanism of pack-cementation process was proposed. The oxidative res istance were observed through the air oxidation test, and then the optimal condition of pack cementation was found by them. Besides, the oxidative mechanism of SiC formed was proposed through the observation of SiC coated surface, which was undergone by oxidation test.

Influence of carbon fibers on interfacial bonding properties of copper-coated carbon fibers

Zhang Guodong,Yang Weizhuang,Ding Jianan,Liu Mengxiang,Di Chengrui,Ci Shengzong,Qiao Kun 한국탄소학회 2024 Carbon Letters Vol.34 No.3

Copper-coated carbon fibers have excellent conductivity and mechanical properties, making them a promising new light-weight functional material. One of the main challenges to their development is the poor affinity between carbon fiber and metals. This paper selects different carbon fibers for copper electroplating experiments to study the effect of carbon fiber properties on the interface bonding performance between the copper plating layer and carbon fibers. It has been found that the interfacial bonding performance between copper and carbon fiber is related to the degree of graphitization of carbon fiber. The lower the degree of graphitization of carbon fiber, the smaller the proportion of carbon atoms with sp2 hybrid structure in carbon fiber, the stronger the interfacial bonding ability between carbon fiber and copper coating. Therefore, carbon fiber with lower graphitization degree is conducive to reducing the falling off rate of copper coating and improving the quality of copper coating, and the conductivity of copper-plated carbon fibers increases with the decrease of graphitization degree of carbon fibers. The conductivity of copper-plated carbon fibers increases by more than six times when the graphitization degree of carbon fibers decreases by 23.9%. This work provides some benchmark importance for the preparation of high-quality copper-plated carbon fibers.

Glucose-based carbon-coating layer on carbon felt electrodes of vanadium redox flow batteries

Jeong, Kwang Il,Song, Seung A.,Kim, Seong Su Elsevier 2019 Composites Part B, Engineering Vol.175 No.-

<P><B>Abstract</B></P> <P>Carbon felt, which is a textile material that consists of randomly oriented short carbon fibers, has been used as an electrode material of vanadium redox flow batteries owing to its high electrical conductivity, large specific surface area, and chemical stability. Despite these advantages, the inert surface of the carbon felt has been a critical drawback, leading to low electrode performance. The heat-treatment method has been principally proposed as one of the methods for activating the carbon felt surface. However, the heat-treatment method causes local damage on the carbon felt surface. In this study, glucose is selected as a coating material to protect the carbon felt during the heat treatment and provide abundant functional groups as active sites in the redox reaction. We confirm that the glucose-based carbon-coating layer on the carbon felt exhibits a higher crystalline graphitic structure than heat-treated carbon felt and promotes electrochemical properties such as electron-transfer kinetics and reversibility of the redox reaction. The carbon felt with a glucose-based carbon-coating layer exhibits an energy efficiency of 82.79% at 100 mA cm<SUP>−2</SUP>, which is 2.0% higher than that of a neat carbon felt.</P>

Superior lubrication of dense/porous-coupled nanoscale C/WS₂ multilayer coating on ductile substrate

Xu, Shusheng,Liu, Yuzhen,Gao, Mingyu,Kang, Kyeong-Hee,Shin, Dong-Gap,Kim, Dae-Eun Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.476 No.-

<P><B>Abstract</B></P> <P>Sputtered carbon material has been receiving much attention as a solid lubricant coating owing to its high hardness and low coefficient of friction. However, its relatively low wear resistance performance when applied on a ductile substrate has limited its use in certain applications. In this work, a porous WS<SUB>2</SUB> sublayer was introduced to the sputtered carbon-based nanoscale multilayer coating to improve its tribological properties. The microstructural, mechanical and tribological properties of the nanoscale C/WS<SUB>2</SUB> multilayer coating were systematically investigated using various analytical techniques. Through structural optimization, a durable coating with excellent wear resistance and low frictional performances could be attained for a ductile steel substrate. The excellent toughness allowed the coating to deform with the ductile substrate without fracturing during contact sliding process. Furthermore, the first self-destruction and then recombination behaviors of dense/porous-coupled nanoscale multilayer coating as well as the selective release of carbon component to the contact interface driven by the frictional interaction aided in maintaining low friction. As a result, the nanoscale multilayer coating showed approximately 100-fold greater wear resistance than that of pure hard carbon coating on a ductile steel substrate.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hard/soft-coupled nanoscale C/WS<SUB>2</SUB> multilayer coating was constructed by sputtering. </LI> <LI> The multilayer coating exhibited excellent synchronized deformation with the ductile steel substrate. </LI> <LI> Multilayer coating on ductile steel showed 100-fold longer wear life than that of a stiff C coating. </LI> <LI> The rearranged coating on the formed deep wear track resulted in improved lubrication performance. </LI> <LI> That provided a novel way to develop lubricant protection layer on ductile material surface </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

PTFE 크기 변화에 따른 Carbon Cloth 발수 코팅과 가스 투과도 변화

전현,조태환,최원경 한국수소및신에너지학회 2010 한국수소 및 신에너지학회논문집 Vol.21 No.4

Carbon cloth was impregnated into PTFE emulsion. PTFE is a fluoropolymer used as a coating material in various fields due to its hydrophobicity and excellent mechanical properties. In this study, PTFE emulsion was prepared different particle size of 5~500 nm and 3~5 ㎛. FE-SEM and FT-IR spectroscopy were used microscopic observation and investigation of chemical structure change after PTFE coating. Mass variations, gas permeability and water contact angles were analyzed to determine a GDL performance of PTFE coated carbon cloth. PTFE coated carbon cloth show different mass increase according as PTFE concentration and the number of coating times. Water contact angle of PTFE coated carbon cloth was not effected by size of PTFE particle and the number of coating time; meanwhile, gas permeability was rapidly changed at carbon cloth coated by emulsion with size of 3~5 ㎛ PTFE particle.

Carbon-based Materials for Atomic Energy Reactor

D. Sathiyamoorthy,A.K. Sur 한국탄소학회 2003 Carbon Letters Vol.4 No.1

Carbon and carbon-based materials are used in nuclear reactors and there has recently been growing interest to develop graphite and carbon based materials for high temperature nuclear and fusion reactors. Efforts are underway to develop high density carbon materials as well as amorphous isotropic carbon for the application in thermal reactors. There has been research on coated nuclear fuel for high temperature reactor and research and development on coated fuels are now focused on fuel particles with high endurance during normal lifetime of the reactor. Since graphite as a moderator as well as structural material in high temperature reactors is one of the most favored choices, it is now felt to develop high density isotropic graphite with suitable coating for safe application of carbon based materials even in oxidizing or water vapor environment. Carboncarbon composite materials compared to conventional graphite materials are now being looked into as the promising materials for the fusion reactor due their ability to have high thermal conductivity and high thermal shock resistance. This paper deals with the application of carbon materials on various nuclear reactors related issues and addresses the current need for focused research on novel carbon materials for future new generation nuclear reactors.

Comparison of lithium iron phosphate blended with different carbon sources for lithium battery electrodes

Zhang Yiming 한국탄소학회 2024 Carbon Letters Vol.34 No.3

In response to the growing demand for high-performance lithium-ion batteries, this study investigates the crucial role of different carbon sources in enhancing the electrochemical performance of lithium iron phosphate (LiFePO4) cathode materials. Lithium iron phosphate (LiFePO4) suffers from drawbacks, such as low electronic conductivity and low lithium-ion diffusion coefficient, which hinder its industrial development. Carbon is a common surface coating material for LiFePO4, and the source, coating method, coating amount, and incorporation method of carbon have a significant impact on the performance of LiFePO4 materials. In this work, iron phosphate was used as the iron and phosphorus source, and lithium carbonate was used as the lithium source. Glucose, phenolic resin, ascorbic acid, and starch were employed as carbon sources. Ethanol was utilized as a dispersing agent, and ball milling was employed to obtain the LiFePO4 precursor. Carbon-coated LiFePO4 cathode materials were synthesized using the carbothermal reduction method, and the effects of different carbon sources on the structure and electrochemical performance of LiFePO4 materials were systematically investigated. The results showed that, compared to other carbon sources, LiFePO4 prepared with glucose as the carbon source not only had a higher discharge specific capacity but also better rate cycle performance. Within a voltage range of 2.5–4.2 V, the initial discharge specific capacities at 0.1, 0.5, and 1 C rates were 154.6, 145.6, and 137.6 mAh/g, respectively. After 20 cycles at a 1 C rate, the capacity retention rate was 98.7%, demonstrating excellent electrochemical performance.

Carbon-based Materials for Atomic Energy Reactor

Sathiyamoorthy, D.,Sur, A.K. Korean Carbon Society 2003 Carbon Letters Vol.4 No.1

Carbon and carbon-based materials are used in nuclear reactors and there has recently been growing interest to develop graphite and carbon based materials for high temperature nuclear and fusion reactors. Efforts are underway to develop high density carbon materials as well as amorphous isotropic carbon for the application in thermal reactors. There has been research on coated nuclear fuel for high temperature reactor and research and development on coated fuels are now focused on fuel particles with high endurance during normal lifetime of the reactor. Since graphite as a moderator as well as structural material in high temperature reactors is one of the most favored choices, it is now felt to develop high density isotropic graphite with suitable coating for safe application of carbon based materials even in oxidizing or water vapor environment. Carboncarbon composite materials compared to conventional graphite materials are now being looked into as the promising materials for the fusion reactor due their ability to have high thermal conductivity and high thermal shock resistance. This paper deals with the application of carbon materials on various nuclear reactors related issues and addresses the current need for focused research on novel carbon materials for future new generation nuclear reactors.

Improved cycle performance of silicon anode by fluorination and carbon-coating for lithium ion batteries

한정인,김경훈,최예지,이영석 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

Carbon coating is known as a method for preventing the rapid volume expansion of the silicon anode during charge/discharge process. In this study, Silicon was fluorinated by fluorine gas in variety partial pressure for more effective carbon-coating. Then, fluorinated silicon was coated by pitch from pyrolysis fuel oil (PFO) using heat treatment. Lithium-ion battery coin cell was fabricated with dual treated silicon as anode and Li metal as cathode. The surface property of fluorinated samples was investigated by X-ray photoelectron microscopy (XPS) and the amount of carbon-coating was investigated by thermogravimetric analysis (TGA). The electrochemical properties were investigated by charge/discharge test and electrochemical impedance spectroscopy (EIS). The amount of carbon-coating was increased by fluorination due to the improving the surface energy of silicon through fluorination. In addition, charge/discharge test showed improved capacity retention due to carbon-coating.