Rheological properties, structural and thermal elucidation of coal-tar pitches used in the fabrication of multi-directional carbon-carbon composites

Ali, Nisar; Zaman, Hira; Zaman, Wajed; Bilal, Muhammad

doi:10.1016/j.matchemphys.2019.122564

Cited by 9 publications

(6 citation statements)

References 24 publications

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“…Graphitization represents the transition from amorphous to crystalline state, signifying a transformation at the microscopic level where the carbon atom arrangement evolves from disorderly to orderly [24,25]. The carbonaceous mesophase contains various aromatic formats with many sp 2 -hybridized carbon atoms, and the aromatic molecules are highly analogous to the ortho-hexagonal arrangement of carbon atoms in the graphite lattice.…”

Section: Introductionmentioning

confidence: 99%

Pyrolytic Modification of Heavy Coal Tar by Multi-Polymer Blending: Preparation of Ordered Carbonaceous Mesophase

Zhang,

Liu,

Jia

et al. 2024

Polymers

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In order to achieve the high-value utilization of heavy tar for the production of enhanced-performance graphite foam carbon, the carbon mesophase was ready from the heavy component of low-temperature coal tar, and the coal tar was modified by styrene-butadiene-styrene (SBS), polyethylene (PE) and ethylene-vinyl-acetate (EVA) copolymers. The order degree of the carbonite mesophase was analyzed using a polarizing microscope test, Fourier transform infrared spectroscopy and X-ray diffraction to screen out the most suitable copolymer type and addition amount. Furthermore, the mechanism of modification by this copolymer was analyzed. The results showed that adding SBS, PE and EVA to coal tar would affect the order of carbonaceous mesophase; however, at an addition rate of 10.0 wt.%, the linear-structure SBS copolymer with a styrene/butadiene ratio (S/B) of 30/70 exhibited the optimal degree of ordering in the carbonaceous mesophase. Its foam carbon prepared by polymer modification is the only one that forms a graphitized structure, with d002 of 0.3430 nm, and the maximum values of Lc and La are 3.54 nm and 2.22 nm, respectively. This is because, under elevated pressure and high-temperature conditions, SBS underwent chain scission, releasing a more significant number of methyl and other free radicals that interacted with the coal tar constituents. As a result, it reduced the affinity density of heavy coal tar molecules, enhanced fluidity, promoted the stacking of condensed aromatic hydrocarbons and increased the content of soluble carbonaceous mesophase, ultimately leading to a more favorable alignment of the carbonaceous mesophase.

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Section: Introductionmentioning

confidence: 99%

Pyrolytic Modification of Heavy Coal Tar by Multi-Polymer Blending: Preparation of Ordered Carbonaceous Mesophase

Zhang,

Liu,

Jia

et al. 2024

Polymers

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“…At 500 °C, the quinoline soluble MP becomes liquid, but QI-MP does not even soften [6]. MP is destroyed and the C/H ratio increases when CTP is pyrolyzed above 800 °C [7]. As the graphitization temperature increases, the ash content decreases.…”

Section: Introductionmentioning

confidence: 99%

“…When the pitch particle size was increased, the wettability decreased [11]. CTP exhibited non-Newtonian behavior as a result of the QI particles, and viscosity decreased as temperature increased [7]. When the viscosity of the CTP increased, the strength of the finished graphite decreased due to a decreased in the strength of the binder bridge [15,16].…”

Section: Introductionmentioning

confidence: 99%

Effect of Mesophase particles on the Electrographite carbon brush tribology behavior under no-load condition

Karuthakannan¹,

Thenmuhil²

2022

Surf. Topogr.: Metrol. Prop.

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Electrographite (EG) has partial electrical conductivity and is used as a current collector in direct current motors. EG is prepared from a suitable carbon source through a multi-step process to convert it to conductive carbon. In this work, EG was prepared with coal tar pitch (CTP) having different mesophase (MP) content (4, 8, 19, and 33%) and their characteristics were compared. The microstructural analysis of CTP indicated that increase in MP lead to increase in mesophase particle size. MP was found to have a significant impact on the physical and binding properties of CTP. X-ray diffraction studies, showed EG to be a partially graphitized material with a degree of graphitization (DOG) ranging from 30% to 60%. Since coke-based materials graphitize more easily than lamp black, the DOG, crystal size, and d-spacing of coke-based material were higher. Graphitization in tube furnaces was better than induction and Acheson furnaces because of its concentrated heat in small size susceptor. The Design of Experiments (DOE) method with Face Centre Factorials was used to generate 14 different combinations of load (20N,60N, and 100N) and velocity (1 m/s, 3 m/s and 5 m/s) for wear and COF analysis which were done on pin on disc apparatus. Response surface method (RSM) was used to investigate the relationship between wear, COF, and MP content. The CTP binder properties had a significant impact on wear. The COF decreased as the number of Brooks and Taylor structure MP particles increased. On the EG wear characteristics, adhesive wear was a more dominant factor than abrasive wear.

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“…A large amount of H 2 , CH 4 , C 2 H 2 , and other gases will be generated in this process, which causes shrinkage of the carbon matrix and forms defects such as pores and cracks. [26][27][28] CF is a product of carbonization treatment at about 1400 C and has a low thermal expansion coefficient (0-1.1 Â 10 À6 /K), good thermal stability and dimensional stability. 29,30 The volume of CF hardly changed during the composite sintering.…”

Section: Introductionmentioning

confidence: 99%

Improving carbon/carbon composites mechanical and thermal properties by the co‐carbonization of pre‐oxidized carbon fiber and pitch

Yang

et al. 2021

J of Applied Polymer Sci

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The interfacial cracks generated during the high-temperature carbonization process, caused by the mismatch of thermal shrinkage rate between the fiber and matrix, limit the huge application potential of C/C composites. In this study, pre-oxidized carbon fiber (OPF) prepared from pitch, as a reinforcement, was introduced into the pitch-based carbon matrix to realize the co-carbonization of OPF and pitch. The results showed that the mechanical and thermal properties of the OPF-reinforced C/C composites were significantly improved. The compressive strength and flexural strength were 136.97 and 46.71 MPa, respectively, both were about 2.5 times higher than those of pristine C/C composites. And OPF-C/Cs had a carbon residual of about 30% at 800 C, which was 2.8, 4.4, and 2.1 times higher than that of Pristine-C/Cs, CF-C/ Cs, and MCF-C/Cs, respectively. The rough surface and abundant active sites of OPF could promote the growth of the graphite microcrystalline structure, resulting in an excellent fiber/matrix interface. Moreover, the adaptive expansion of OPF occurred during the co-carbonization process with pitch, which inhibited the generation of cracks at the fiber/matrix interface. Owing to its excellent affinity with pitch, OPF is believed to have a wide range of promising applications in highperformance C/C composites that require high-temperature treatment.

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Rheological properties, structural and thermal elucidation of coal-tar pitches used in the fabrication of multi-directional carbon-carbon composites

Cited by 9 publications

References 24 publications

Pyrolytic Modification of Heavy Coal Tar by Multi-Polymer Blending: Preparation of Ordered Carbonaceous Mesophase

Pyrolytic Modification of Heavy Coal Tar by Multi-Polymer Blending: Preparation of Ordered Carbonaceous Mesophase

Effect of Mesophase particles on the Electrographite carbon brush tribology behavior under no-load condition

Improving carbon/carbon composites mechanical and thermal properties by the co‐carbonization of pre‐oxidized carbon fiber and pitch

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