• 대한환경공학회지
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• 제30권3호
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• pp.331-338
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• 2008

본 연구에서는 국내에서의 생산되는 강관의 도복장 재료 및 방법별로 관체 시편을 이용하여 도복장강관의 성능을 시험하였다. 도복장강관의 원관의 물성 및 화학조성의 분석결과 모두 기준에 적합하였다. 강관의 도복장 재료의 물성시험 결과, 블론아스팔트와 콜타르에나멜은 비용이 저렴하고 기계적 성질은 매우 우수하나, 유기용매에 녹는 단점을 지니고 있고, 도복장강관이 도복장재료로서 성능이 떨어지는 것으로 나타났다. 또한 두껍게 도복할 경우, 강관 자체의 하중이 필요 이상으로 높아지는 문제가 발생할 수 있다. 당김강도 시험과 음극박리 시험결과, PE-3층 도복장방식이 우수하였으며, PE의 도복장방법에 따라서는 압출식(T-Die) 3층 폴리에틸렌(PE 3-Layer)이 분말용착식 폴리에틸렌(PE Fluidized)보다 당김강도가 강하며 음극박리 면적도 작았다. 압출식(T-Die) 3층 폴리에틸렌(PE 3-Layer)은 기계적 특성, 열적 특성 모두 우수하였고, 내화학성도 뛰어났다. 액상에폭시는 수지 선정과 경화 조건에 따라서 도장재의 특성을 변화시킬 수 있다. 본 시험에서 사용된 폴리우레탄은 강관과의 접착력도 에폭시에 비하여 낮았으며, 수분 흡수율은 에폭시 보다 높은 결과를 나타내었다. 폴리우레탄을 도복장재료로 사용하기 위해서는 우레탄의 기본물성과 최적의 도장조건을 도출하는 연구가 진행되어야 할 것으로 판단된다. 본 연구에서 실험한 시편 중에서는 현재 압출식으로 제조한 PE-3층 도복장방법이 가장 우수한 것으로 평가되었지만, 앞으로 기타 다른 도복장재료와의 추가 검증시험이 필요할 것으로 판단된다.

• 한국세라믹학회지
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• 제34권9호
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• pp.963-968
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• 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.

• Journal of Preventive Medicine and Public Health
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• 제30권1호
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• pp.145-155
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• 1997

Interview survey and dermatological examination have been performed to investigate the health problems of workers continuously exposed to coal-tar pitch. The phototoxicity of coal-tar pitch was confirmed by the photopatch tests for six healthy adults. The main results are followings; 1. There was no special history of allergic diseases in both the exposed and non-exposed group. 2. The frequency of the phototoxic dermatosis and the coal-tar acne in the exposed group was significantly greate.(p<0.05) than that of the control group. In the exposed group, the phototoxic dermatosis and the coal-tar acne were observed in nine workers(90%) and seven workers(70%), respectively. However, those, disease were not observed in the control group. 3. Five results(83%) were positive to the photopatch test for coal-ta. pitch 48 hours after UVA irradiation. But the lesion was subsiding 72 hours after UVA irradiation. 4. Malignant cancers were not reported among workers ever exposed to coal-tar pitch. In conclusion, it appears that workers exposed to coal-tar pitch have high risks of phototoxic dermatosis and coal-tar acne. A health policy should be provided to prevent phototoxic dermatosis among coal-tar pitch workers. More studies are required to determine malignancy.

• 한국세라믹학회지
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• 제35권7호
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• pp.740-748
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• 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.

• 한국환경보건학회지
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• 제31권5호
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• pp.423-430
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• 2005

This research was performed to evaluate the effectiveness of one- and dual-stage recycled-water systems in slurry bioreactor treatment for coal tar-contaminated soil. Silty loam soil was used for this research. Coal tar and 14 target PAHs (Polycyclic Aromatic Hydrocarbons) concentration in the soil were determined with gas chromatography. There was no significant difference between removal efficiencies of one- and dual-stage recycled water systems in case of about 4,000 mg coar tar/kg. However, the dual-stage system increased significantly the removal efficiency in case of about 20,000 mg coar tar/kg and the first-order kinetic constant of the system was over 1.5 times higher than that of one-stage recycled water system. 3-Ring compounds in PAHs was removed completely within 30 days of operation. Coar tar was removed in over 96% through biodegradation and removed in about 4% by evaporation. High correlation coefficient($r^2=0.91$) was found between water solubility and removal efficiency of the cyclic compounds.

• 한국표면공학회지
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• 제50권6호
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• pp.516-522
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• 2017

We report the growth of carbon nanotubes (CNT) on Invar-42 plates using coal tar pitch (CTP) by chemical vapor deposition (CVD) method. The solid phase CTP is used as an inexpensive carbon source since it produces a bunch of hydrocarbon gases such as $CH_4$ and other $C_xH_v$ by thermal decomposition over $450^{\circ}C$. The Invar-42 is a representative Ni-based ferrous alloy and can be used repetitively as a substrate for CNT growth because Ni and Fe are used as very active catalytic elements. We changed mixing ratio of carrier gases, argon and hydrogen, and temperature of growth region. It was found that the optimum gas ratio and temperature for high quality CNT growth are $Ar:H_2=400:400$ sccm and $1000^{\circ}C$, respectively. In addition, the carbon nanoball (CNB) was also obtained by just changing the mixing ratio to $Ar:H_2=100:600$ sccm. Finally, CTP can be employed as a versatile carbon source to produce various carbon-based nanomaterials, such as CNT and CNB.

• 공업화학
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• 제10권5호
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• pp.690-695
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• 1999

석탄핏치로부터 제조된 메조페이스 핏치의 실험적 연구가 용융상태에서의 유변학적 거동을 알아보고자 수행되었다. 겉보기 점도, 전단변형율, 전단응력, 퀴놀린 불용분(QI), 연화점(SP) 변화 등을 조사하여 다음과 같은 결론을 얻었다. 중합시에 메조페이스의 적당한 함량을 증가시키기 위한 조건으로는 열처리 시간이 5시간, 촉매농도는 3%, 반응온도는 $420^{\circ}C$로 나타났다. 온도상승에 따른 겉보기 점도 변화는 핏치의 열처리 조건에 따라 달라지는데 열처리 온도가 높을수록, 열처리 시간이 길어질수록, 메조페이스 함량이 증가할수록 커지며, 유동도는 작아진다. $270^{\circ}C$ 이후의 용융 메조페이스 핏치의 유변학적 거동은 $375^{\circ}C$ 이하에서는 Newtonian fluid의 성질을 띠며 그 이상에서는 Non Newtonian fluid의 거동을 보이며 Casson 모델에 잘 일치됨을 알 수 있었다.

• 한국재료학회지
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• 제26권4호
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• pp.173-181
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• 2016

In order to use coal tar pitch (CTP) as a raw material for carbon fibers, it should have suitable properties such as a narrow range of softening point, suitable viscosity and uniform optical properties. In this study, raw CTP was modified by heat treatment with three types of polymer additives (PS, PET, and PVC) to make a spinnable pitch for carbon fibers. The yield, softening point, C/H ratio, insoluble yield, and meso-phase content of various modified CTPs with polymer additives were analyzed by changing the type of polymer additive and the heat treatment temperature. The purpose of this study was to compare the properties of CTPs modified by polymer addition with those of a commercial CTP. After the pitch spinning, the obtained green fibers were stabilized and carbonized. The properties of the respective fibers were analyzed to compare their uniformity, diameter change, and mechanical properties. Among three polymer additives, PS220 and PET261 pitches were found to be spinnable, but the carbon fibers from PET261 showed mechanical properties comparable with those of a commercial CTP produced by an air-blowing method (OCI284). The CTPs modified with polymer additive had higher ${\beta}$-resin fractions than the CTP with only thermal treatment indicating a beneficial effect of carbon fiber application.

• 한국재료학회지
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• 제24권6호
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• pp.293-300
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• 2014

Coal-tar pitch, a feedstock which can be heat-treated to create graphite, is composed of very complex molecules. Coal-tar pitch is a precursor of many useful carbon materials (e.g., graphite, carbon fibers, electrodes and matrices of carbon/carbon composites). Modified coal-tar pitch (MCTP) was prepared using two different heat-treatment methods and their properties were characterized and compared. One was prepared using heat treatment in nitrogen gas; the other was prepared under a pressure of 350 mmHg in air. The MCTPs were investigated to determine several properties, including softening point, C/H ratio, coke yield, formation of anisotropic mesophase and viscosity. The MCTPs were subject to considerable changes in chemical composition due to condensation and polymerization in the used-as-received coal-tar pitch after heat-treatment under different conditions. The MCTPs showed considerable increases in softening point, C/H ratio, and coke yield, compared to those of as-received coal-tar pitch. The MCTP formed by heat-treatment in nitrogen showed isotropic phases below $350^{\circ}C$ for 1 h of soaking time. However, MCTP heat-treated under high pressure (350 mmHg) showed isotropic phases below $300^{\circ}C$, and showed anisotropic phases above $350^{\circ}C$, for 1 h of soaking time. The viscosity of the MCTPs increased with increase in their softening points.

• Corrosion Science and Technology
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• 제16권3호
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• pp.115-127
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• 2017

Coal tar-coated pipes buried in a domestic nuclear power plant have operated under the cathodic protection. This work conducted the simulation of the coating performance of these pipes using a FEM method. The pipes, being ductile cast iron have been suffered under considerably high cathodic protection condition beyond the appropriate condition. However, cathodic potential measured at the site revealed non-protected status. Converting from 3D CAD data of the power plant to appropriate type for a FEM simulation was conducted and cathodic potential under the applied voltage and current was calculated using primary and secondary current distribution and physical conditions. FEM simulation for coal tar-coated pipe without defects revealed over-protection condition if the pipes were well-coated. However, the simulation for coal tar-coated pipes with many defects predict that the coated pipes may be severely degraded. Therefore, for high risk pipes, direct examination and repair or renewal of pipes are strongly recommended.