• 한국세라믹학회지
• /
• 제37권2호
• /
• pp.128-133
• /
• 2000

In this work, soft carbons produced by pyrolysis of petroleum and coal-tar pitch were used as the negative electrode for Li-ion batteries. We studeid the charge/discharge capacity and the interfacial reaction of these electrodes by constructing a half cell. Charge/discharge property was studied by a constant-current step and the interfacial reaction between the electrolyte and the surface of a carbon electrode was studied by the cyclic voltammetry. The initial charge/discharge capacity for the coal-tar pitch carbon increased exceedingly with the heat treatment temperature. On hte other hand, the capacity of the petroleum pitch carbon increased with temperature up to 1000$^{\circ}C$, thereafter decreased continuously. While the charge capacity decreased with the cycle number, the reversibility increased above 90%. In addition, the thermal stability and crystallization of petroleum and coal-tar pitches were analyzed by TGA and XRD, respectively.

• 공업화학
• /
• 제32권2호
• /
• pp.174-179
• /
• 2021

인조흑연 제조용 바인더로 주로 이용되는 콜타르 핏치와 페놀 레진은 soft carbon 및 hard carbon의 초기 탄소화합물 구조에 차이가 있다. 따라서 탄화 온도에 따른 열분해 거동, 미세조직, 결정성의 변화 과정도 다를 것으로 예상할 수 있다. 본 연구에서는 콜타르 핏치 및 페놀 레진의 열분해 거동, 미세조직, 결정성 변화에 관하여 비교 분석하였다. 콜타르 핏치는 액상을 경유한 탄화 과정을 거치며, 탄화 온도가 증가함에 따라 미세조직이 점차 변화되는 것을 확인할 수 있었다. 탄화 온도가 증가함에 따라 콜타르 핏치 및 페놀 레진 모두 결정성은 증가하는 경향을 나타냈지만, 콜타르 핏치는 미세조직이 급변하는 500 및 600 ℃ 구간에서 결정성도 급격히 변화는 것을 확인할 수 있었다. 또한 미세조직과 결정성은 서로 밀접한 연관성이 있었다.

• 한국세라믹학회지
• /
• 제33권12호
• /
• pp.1387-1393
• /
• 1996

A study on mesophase pitch as a matrix precursor of carbon fiber reinforced carbon (C/C) composite has been recently presented. This study is concerned with the production of mesophase pitch as matrix precursors for C/C composite from coal tar pitch. A commercial coal tar pitch was heat-treated at 25$0^{\circ}C$ for 2 hours to remove low molecular weight fraction from the pitch then increasing the temperature of the pitch to between 350~45$0^{\circ}C$ to produce mesophase pitch. The pitch was continuously stirred during this time and nitrogen gas was continuously bubbled through the pitch. Spherical and bulk mesophases were formed in the pitch after heat-treatment,. Parent and mesophae pitches were characterized by elemental analysis coke yield solubi-lity in tetrahydrofuran and hexane and an optical microscopy to measure the mesiophase content. It was neces-sary to produce C/C composite that a mesophase pitch with about 30-40 vol% mesophase spherulites can be infiltrated into a fiber preform without a filter effect as a matrix precursor conditions. This condition was satisfied with mesophase pitch heat treated at 40$0^{\circ}C$ for 2 hours. The other heat treatment conditions showed the nuclei of mesophase or bulk mesophae which were not satisfied with the matix precursor condition.

• 한국재료학회지
• /
• 제26권9호
• /
• pp.460-467
• /
• 2016

Activated carbons (ACs) have been used as EDLC (electric double-layer capacitor) electrode materials due to their high specific area, stability, and ecological advantages. In order to prepare ACs with high density and crystallinity, coal tar pitch (CTP) was activated by $K_2CO_3$ and the textural and electrochemical properties of the obtained ACs were investigated. Although the CTP ACs formed by $K_2CO_3$ activation had much smaller specific surface area and pore volume than did the CTP ACs formed by KOH activation, their volumetric specific capacitance (F/cc) levels as electrode materials for EDLC were comparable due to their higher density and micro-crystallinity. Structural characterization and EDLC-electrode performance were studied with different activation conditions of $CTP/K_2CO_3$ ratio, activation temperature, and activation period.

• 한국세라믹학회지
• /
• 제35권7호
• /
• pp.740-748
• /
• 1998

The inertia friction properties of C/C composites manufactured by the processes of pressure and at-mospheric carbonizaton with a commerciallized and two kinds of modified coal-tar pitch as a matrix pre-cursor were investigated. The modifications of a pitch such as the introduction of mesophase and the ad-dition of sulphur into a raw pitch were not effective for a impregnation efficiency conducted in a vacuum and at the same time in a pressure of 5kg/cm2 due to the increase of the pitch viscosity. There was not a difference in the densification increment between the pitch modifications however it was revealed that a pressure carbonization was more advantageous than an atmospheric in the densification and the formation of anisotropic carbon matrix. The friction and wear propertis of C/C having higher degree of matrix cry-stallization higher density and hardness of friction surface showed superiority. As the braking energy was increased the friction coefficients were decreased and reached almost same level at the high kinetic energy of 99.6kJ. The wear trends at 99.6kJ were different from the behaviors of friction ceofficient under the same energy in which an oxidation wear is being considered along with a mechnical wear although the wear rates were almost similar to the friction coefficient at the low energy.

• 한국세라믹학회지
• /
• 제34권9호
• /
• pp.963-968
• /
• 1997

Coal tar pitch was used to study the effect of the pyrolysis conditions to produce mesophase pitch used as a matrix precursor for carbon/carbon composites. The pyrolysis conditions were presented in all cases that the total pressure was 1 atm and the first stage temperature was changed from 25$0^{\circ}C$ to 34$0^{\circ}C$ to remove the low molecular weight compounds in the pitch, and then, heated to 40$0^{\circ}C$ to form anisotropic mesophase as the second stage temperature. The first stage temperature was very affected to form resulting anisotropic mesophase pitch. The resulting mesophase pitches show a significantly increased anisotropic contents upto 30$0^{\circ}C$. However, the contents of mesophase were decreased above 30$0^{\circ}C$. It was the reason that the first stage temperature had been control the number of free radicals to react the aromatic compounds in the pitch to form high molecular weight compound. Therefore, the two stage pyrolysis method could be very effectively used to control various contents of anisotropic polyaromatic mesophase compared to continuous to continuous heating method.

• Carbon letters
• /
• 제1권1호
• /
• pp.6-11
• /
• 2000

Coal tar pitch was chemically modified with 10 wt% benzoquinone (BQ) to raise the softening point of isotropic pitch precursor and the precursor was melt-spun into pitch fibers, stabilized, carbonized and activated with steam at $900^{\circ}C$. The weight loss of carbon fiber-benzoquinone (CF-BQ) increased with the increase of activation time like other fibers, but was lower than those of Kureha fiber at the same activation time in spite of larger geometric surface area. Those adsorption isotherms fitted into 'Type I' according to Brunauer, Deming, Deming and Teller classification. However, there was very thin low-pressure hysteresis that lower closure points of the hysteresis are about 0.42-0.45. From the pore size distribution curves, there might be some micropores having narrow-necked bottle; a series of interconnected pore is more likely than discrete bottles. FT-IR studies showed that the functional groups such as carboxyl, quinone, and phenol were introduced to ACFs-BQ surface after steam activation. Methylene blue decolorization and iodine adsorption capacity of ACF-BQ increased linearly with the increase of specific surface area and was larger than that of ACF-Kureha at the same specific surface area.

• 한국세라믹학회지
• /
• 제40권10호
• /
• pp.985-990
• /
• 2003

콜타르 피치를 450∼50$0^{\circ}C$로 가열하여 메조페이스 피치를 제조하였다. 열처리된 피치는 시편의 부풀림과 변형을 줄이기 위해 공기 중 160∼24$0^{\circ}C$로 산화안정화하였다. 고온열처리핏치를 이용한 부피를 가진 성형체의 산화안정화 원리를 조사하기 위해 열중량감소, FT-IR을 측정하였다. 부피를 가진 성형체에 대한 산화안정화의 영향은 쇼아경도, 곡강도를 측정하여 파악하였다.

• 한국섬유공학회:학술대회논문집
• /
• 한국섬유공학회 1996년도 추계 학술발표회
• /
• pp.117-123
• /
• 1996

Cabon fiber of general purpose was prepared from coal tar pitch modified with 10% benzoquinine(BQ) at 380C for 3 hours. Such a modified pitch raised the softening of the pitch from 85C to 271C at the yield of 40%. The modified pitch was spun smoothly at a rate of 480m/min into a fiber of 20um diameter. The fiber was stabilized stepwise at 236C (5C/min) and 312C (1C/min) for 3 hours each. Both carbonized and graphitized fibers exhibited tensile strength of 570MPa which appears large enough as a precursor for active carbon fiber. The activated carbon fiber prepared exhibited relatively high surface area of 2062m2/g at 76% burn-off and rather narrow distribution pore size of 20A.

• Carbon letters
• /
• 제19권
• /
• pp.72-78
• /
• 2016

Spinnable pitches and carbon fibers were successfully prepared from petroleum or coal pyrolysis residues. After pyrolysis fuel oil (PFO), slurry oil, and coal tar were simply filtered to eliminate the solid impurities, the characteristics of the raw materials were evaluated by elemental analysis, ¹³C nuclear magnetic resonance spectrometer, matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS), and so on. Spinnable pitches were prepared for melt-spinning carbon fiber through a simple distillation under strong nitrogen flow, and further vacuum distillation to obtain a high softening point. Carbon fibers were produced from the above pitches by single-hole melt spinning and additional heat treatment, for oxidization and carbonization. Even though spinnable pitches and carbon fibers were processed under the same conditions, the melt-spinning and properties of the carbon fiber were different depending on the raw materials. A fine carbon fiber could not be prepared from slurry oil, and the different diameter carbon fibers were produced from the PFO and coal tar pitch. These results seem to be closely correlated with the initial characteristics of the raw materials, under this simple processing condition.