Publications by authors named "Byung-Rok Lee"

3 Publications

  • Page 1 of 1

Mechanical and electrical properties of MCMB/Chopped carbon fiber composite with different bead size.

Sci Rep 2019 May 8;9(1):7065. Epub 2019 May 8.

Department of Advanced Energy and Technology, Korea University of Science and Technology, 102 Gajeong-ro, Yuseong-gu, Daejeon, 305350, Republic of Korea.

The carbonization and graphitization of carbon/carbon (C/C) composites prepared from mesocarbon microbeads (MCMB) and chopped carbon fiber (CCF) have been studied with a wide range of temperatures, CCF contents and MCMB sizes. Three different sizes of MCMB were prepared with coal tar pitch at three temperatures, 420, 430 and 440 °C, and identified as about 12.8, 16.0 and 20.1 µm, respectively. Each size of MCMB was mixed with CCFs at ratios of 2, 4, 6 and 8 wt. % and formed into block shape. After carbonization at 1200 °C, carbonized C/C blocks (CCBs) were graphitized at 2000, 2400 and 2800 °C. The CCB prepared with CCF content of 2 wt. % and an MCMB size of 16.0 µm exhibited the highest flexural strength of about 151 MPa. The graphitized C/C block (GCB) with CCF content of 2 wt. %, which was graphitized at 2000 °C showed the highest flexural strength of about 159 MPa.
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http://dx.doi.org/10.1038/s41598-019-43480-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6506510PMC
May 2019

Manufacture of high density carbon blocks by self-sintering coke produced via a two-stage heat treatment of coal tar.

Heliyon 2019 Mar 19;5(3):e01341. Epub 2019 Mar 19.

Advanced Energy and System Engineering, University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon, 34113 Republic of Korea.

High-strength and high-density carbonized carbon blocks from self-sintering coke were manufactured using coal tar and two-stage heat treatments (1 and 2 stage treatments). First, the molecular weight distribution of the refined coal tar was controlled through a pressured heat treatment (1 stage treatment). Second, the 1 stage heat-treated coal tar (1S-CT) was treated using a delayed coking system (2 stage treatment) to become the self-sintering coke. Finally, carbon blocks were molded from 2 stage heat-treated coke (2S-C) and carbonized at 1200 °C for 1 h. Through rapid decomposition of the high molecular weight components in the coal tar at 360 °C in the 1 stage treatment, the molecular weight distribution of coal tar was confirmed to be controllable by the 1 stage treatment. Swelling during carbonization was observed in carbon blocks manufactured from 2S-C containing more than 15 wt% of volatile matter from 150-450 °C. The optimum conditions of the two-stage heat treatments were confirmed to be 300 °C for 3 h and 500 °C for 1 h. The highest density and flexural strength of the carbonized carbon blocks manufactured from 2S-C were 1.46 g/cm and 69.2 MPa, respectively.
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http://dx.doi.org/10.1016/j.heliyon.2019.e01341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6430006PMC
March 2019

Improving the mechanical properties of a high density carbon block from mesocarbon microbeads according to oxidative stabilization.

Sci Rep 2018 Jul 23;8(1):11064. Epub 2018 Jul 23.

Advanced Energy and System Engineering, Korea University of Science and Technology, Yuseong-gu, Daejeon, 305350, Republic of Korea.

In this study, a high density carbon block without binder was manufactured by mesocarbon microbeads (MCMB) from coal tar pitch. To develop the high density carbon block without a binder, MCMBs were oxidized at different levels of temperature. To verify the effect of oxygen content in the carbonized carbon block (CCB), an elementary analysis (EA) and X-ray photoelectron spectroscopy (XPS) were performed. The morphological and mechanical properties of the CCBs were investigated by using scanning electron microscopy (SEM), a shore hardness test, and a flexural strength evaluation. The results revealed that the oxygen content increased with stabilization temperature and the physical properties of the CCBs were considerably improved via oxidative stabilization. Small cracks between MCMB particles were observed in the CCBs that were stabilized over 250 °C. From the results of this study, the CCB from MCMBs stabilized at 200 °C for 1 h showed optimum mechanical properties and high density.
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http://dx.doi.org/10.1038/s41598-018-26971-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6056457PMC
July 2018
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