Medium- and low-temperature coal tar pitch can be prepared as coal-based mesophase pitch for its high value-added utilization. However, its lower aromaticity and higher content of heteroatoms (especially O atoms) led to a higher content of the resulting mesophase pitch mosaic structure. In this study, mesophase pitch was prepared by co-carbonization of high aromaticity, low oxygen content high-temperature refined pitch (RHCTP) with medium- and low-temperature coal tar refined pitch (RCTP). The impact of various blending ratios on the optical and microcrystalline structures of mesophase pitch was analyzed using polarized light microscopy, X-ray diffraction, and Raman spectroscopy. The addition of RHCTP to modify RCTP significantly enhanced the optical and microcrystalline structures of the co-carbonized products. The optimal blending ratio (R-25%) was obtained. Needle coke prepared from mesophase pitch obtained from R-25% had superior fine fiber structure, lowest average resistivity (157.37 μΩ·m) and high true density (2.125 g/cm3). The thermal conversion behavior of the blended refined pitch during co-carbonation was analyzed using thermogravimetric data of the R-25% sample through four isoconversion methods. The thermal conversion of the R-25% sample occurs in three stages: the first stage follows the Parabola law model, while the second and third stages adhere to the random nucleation and nuclei growth model. This analysis of thermal conversion kinetics offers theoretical insights for optimizing mesophase pitch preparation process conditions and reactor design.

The constituents of coal tar pitch (CTP) significantly impact the wettability of calcined coke (CC) and the performance of prebaked anodes (PA) used in aluminum electrolysis. However, balancing wettability and carbon residue within CTP remains a central challenge in material applications. In addition, limited pore permeability and structural stability in these composites hinder the effective utilization of PA. Enhancing CTP fluidity is crucial for overcoming these challenges. In this work, a novel method was developed to modify CTP utilizing various coal tar fractions, enabling controlled modulation of CTP composition and wettability. Incorporating different fractions allowed for substantial control over interfacial bonding and pore structure. The chemical composition, functional groups, and elemental content of the CTP were analyzed via X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and proton nuclear magnetic resonance (1H NMR). Subsequently, systematic comparisons of PA materials produced from different CTP formulations demonstrated improved wettability and enhanced mechanical properties. Moreover, DFT calculations were performed to compare the adsorption energies of small molecules from different coal tar fractions with coke, reflecting the interaction strength between the molecules and the solid surface. Using micro-computed tomography (μ-CT), the refined pore structure was examined, resulting in a PA composite with an optimized balance of high strength and toughness.

The aromatization degree of coal liquefaction pitch is closely related to its molecular structure evolution and the properties of derived carbon fibers. Using refined coal direct liquefaction pitch (RCLP) as raw material, pitches with different aromatization degrees were prepared by the self-pressurization/N₂ blowing two-stage thermal condensation method. Carbon fibers were then produced through melt spinning, oxidative stabilization, and carbonization. As the aromatization degree advanced, the C/H atomic ratio rose from 1.55 to 2.01, with the mesophase content nearing 100%. During RCLP thermal polymerization, large toluene-insoluble molecules were readily generated, yet the enrichment of the mesophase was comparatively sluggish. The spinnable pitch from RCLP had a relatively high aliphatic hydrogen content (33.40% ~ 13.69%) and a lower aromaticity (91.62% ~ 96.90%). Increasing aromatization made the carbon fiber cross-section’s radial transverse texture more distinct and ordered. The carbon layers stacked closely and parallelly, leading to a continuously rising tensile modulus. Due to the inhomogeneity from isotropic and anisotropic component changes, the carbon fiber tensile strength first decreased and then increased. When the spinnable pitch C/H ratio was 1.84, the mesophase pitch-based carbon fiber had an average diameter of 14.78 μm, a tensile strength of 1140 MPa, and a tensile modulus of 209 GPa.

Modifying the softening point (SP) of pitch is crucial owing to its substantial influence on pitch applicability. This study presents a novel fluorination technique for engineering the SP of mesophase pitch (MP). Low-concentration fluorine gas was used to modify the edge sites of the MP, allowing for either an increase or decrease in the SP by controlling the gas reactivity. The fluorination was conducted with 20 vol% F2 gas under reaction temperature of 25, 50, and 75 ℃ for 2 h in atmospheric pressure. A reduction in SP was achieved through edge alkylation, with a decrease of up to 14.1% observed after the fluorination. Conversely, an increase in SP resulted from edge dealkylation at higher reaction temperatures. As the modified MPs retained perfect anisotropy, this study offers an effective strategy for adjusting the SP to meet application needs without causing structural deterioration.

This study examines the impact of Propeller blade pitch angle mismatch on Noise, thrust, and vibration in light aircraft. Tests were conducted using a simulator with one blade set at increased pitch angles (10°, 12°, 14°) compared to the standard 8°. Results showed that mismatches increased vibration (above 0.26 IPS), Noise levels, and caused operational issues such as fuel leakage and backfire. While thrust initially increased with pitch, it dropped at 14° due to fuel flow instability. These results highlight the need for strict pitch alignment tolerances to ensure optimal performance and safety in aircraft maintenance and operation.

Aircraft Noise is a sound that humans do not want. In this study, based on the Rotax 914 engine used in Korea, the Propeller blade angle was changed by 1 degree for the 3-leaf “K company” Propeller and the 3-leaf “G” wooden Propeller, and the engine RPM was changed to examine the Noise and thrust changes. The purpose of this study is to check whether Noise and thrust loss are the least at the engine's maximum RPM, and to propose an aircraft operation plan in the noisy aerodrome area based on the values. This research further seeks to identify optimal propeller configurations that balance acoustic performance and thrust efficiency. The results are expected to aid in formulating guidelines for quieter flight operations near populated areas.

Coal pitch mainly consists of aromatic hydrocarbons, phenolic substances, and aliphatic hydrocarbons, the macromolecular structures formed by these cyclic and chain hydrocarbons through chemical bonding possess diversity and complexity. In this study, medium- and low-temperature coal tar pitch (LCTP) served as the primary material for the production of mesophase pitch via co-carbonization with hydrogenated tail oil (HTO). Aimed to clarify the effects of different amounts of HTO addition and analyze the mechanism of introducing naphthenic and aromatic hydrocarbons on the liquid phase carbonization process. When HTO additive amount is 30%, the carbonized product with the largest content of mature graphite crystals at 25.01%, and the smallest degree of defects. The analytical mechanism demonstrates that the condensation of naphthenic hydrocarbons introduced by HTO produces hydrogen radicals, the hydrogen transfer reaction saturates a significant quantity of free radicals generated within the system, thereby impeding further rapid condensation and curing, and decreasing the viscosity of the system. On the other hand, the aromatic hydrocarbons introduced undergo dehydrogenation and condensation to produce additional polycyclic aromatic hydrocarbons, thereby contributing to a more abundant carbon structure conducive to the development of mesophase pitch. The combined effect of aromatic hydrocarbons and naphthenic hydrocarbons facilitates the slow development of the mesophase structure into a broad-area optical structure. This study provides an effective method for improving the performance of coal-based mesophase pitch, which reduces the production cost and promotes the clean and high value-added utilization of limited resources.

Plastic wastes such as polyethylene terephthalate have recently been incorporated into coal as additives in coke manufacturing. Plastic waste results in the reduction of high-quality coal usage while protecting the environment. Using coal tar pitch as an additive in the coal blend causes an increase in fluidity during carbonization. The volatile matter released during carbonisation affects coal thermoplasticity, hence the carbon structural parameters. This paper investigates the role of polyethylene terephthalate and the mixture of polyethylene terephthalate and coal tar pitch on carbon structure formation during coal to coke transformation. The additives were blended with coking coal in 2, 3, 4, 5, and 10% wt. The results imply that incorporating coal tar pitch into the coal/ polyethylene terephthalate mixture improves the crystallite height of the resulting semi-coke. The addition of coal tar pitch and polyethylene teraphthalate blend to coking coal at a percentage below 5%wt. leads a positive impact on the crystallite height of the resulting coal char. The incorporation of coal tar pitch into the blend decreased the average interlayer spacing. At elevated temperatures, the polyethylene terephthalate in the blend causes an increase in the mean tortuosity. However, incorporating coal tar pitch into the blend led to about 3.3% decrease in mean tortuosity.

The structure and composition of coal tar pitch are critical in the production of superior needle coke. We used high-temperature refined coal tar pitch (HRCTP) to modify medium–low-temperature refined coal tar pitch (MLRCTP) for needle coke preparation. Various characterization techniques were applied to evaluate the effects of the HRCTP addition on the MLRCTP's structure and composition, and to investigate the microstructural and crystallographic differences in needle coke from different feedstocks. We identified the optimal HRCTP addition level and assessed how carbonization reaction conditions influenced needle coke quality. The findings indicated that HRCTP addition increased the aromatic hydrocarbons content while reducing the heterocyclic compounds and excess alkanes, leading to enhanced structure and composition, which supported the structured development of carbon-based structures during the thermal polycondensation process. Notably, higher HRCTP amounts did not equate to better outcomes. With a 25% HRCTP additive level, the needle coke’s microstructure showed a highly ordered fibrous texture with optimal orientation, the greatest degree of graphitization, and a mature graphite crystal content of 24.84%. Further optimization of the carbonization process demonstrated that very high temperatures might cause the formation of numerous mosaic structures due to disordered radical cross-linking. Properly reducing pressure at high temperatures could promote adequate directional airflow and apply shear force during orderly stacking of the mesophase, thus enhancing the carbon lamellae’s streamline and orientation. Following the carbonization process optimization, the mature graphite crystal content in the needle coke increased from 24.84% to 39.87%.

Carbonized blocks with different porosities were prepared by varying the particle size of the filler and subsequent impregnation. The impregnated carbonized blocks were re-carbonized. The use of smaller particles in the filler in the carbonized block was associated with larger porosity, smaller pore size, and a higher impregnation ratio. The block with the smallest average particle size (53 μm), CB-53, had a porosity of 35.9% and pores of approximately 40 μm, while the block with the largest average particle size (413 μm), CB-413, had a porosity of 30.5% and pores of approximately 150 μm. CB-53 had the highest bulk density, electrical resistivity, flexural strength, and impregnation ratio. This is due to the large porosity, which is believed to be due to the presence of more interfaces between particles during the re-carbonization of the impregnated carbonized block, resulting in a better pore-filling effect.

리튬이온배터리는 높은 에너지 저장 효율과 환경 지속 가능성으로 점점 더 많은 관심을 받고 있다. PU 기반 리튬이온배터리에 사용되는 기존의 고분자 (polyurethane, PU) 바인더는 높은 유연성과 기 계적 강도를 제공하여 전극의 부피 변화를 감소시키고 구조적 안정성을 확보하는데 효과적이지만, 이와같 은 고분자 계열의 바인더는 전기전도도가 낮고 생산 및 폐기 과정에서 환경 문제를 야기할 수 있다. 따라 서, 본 연구에서는 이러한 고분자계 바인더의 단점을 해결하고자 고분자계 바인더로 많이 사용되는 PU 기 반 리튬이온배터리에 비해 향상된 전기화학적 성능과 안정성을 가진 새로운 바인더로서 석유계 피치 (SM260)/고분자 (polyurethane, PU) 복합소재 기반 바인더를 개발하였다. 특히, PU 바인더가 적용된 리튬 이온배터리는 100 사이클 후 가역 용량이 80 mAh/g으로, 초기 용량의 25%의 용량 유지율을 나타낸 반면, 본 연구에서 개발한 석유계 피치 (SM260)/고분자 (polyurethane, PU) 복합소재 복합 바인더가 적용된 리 튬이온배터리는 100 사이클 후 가역용량이 208 mAh/g으로 유지되고, 초기 용량의 68% 용량 유지율을 나 타내었다.

Coal tar pitch is a raw material that can be made from various carbon materials such as activated carbon, carbon fiber, and artificial graphite through heat treatment. In particular, it is an important raw material used as a binder and impregnated pitch when manufacturing carbon composite materials. In order to improve the physical properties of such a carbon composite material, the content of β-resin is an important factor. Although β-resin plays the role of a binder, it also corresponds to fixed carbon, so it can determine the physical properties after carbonization. In this study, we compared the physical properties of coal tar pitch various temperature ramping rate, and found through Py-GC/MS analysis that intermediate materials were generated by heteroatoms such as oxygen and nitrogen. MALDI-TOF/MS analysis revealed that these intermediate materials overlapped with the molecular weight region of β-resin. Therefore, the content of β-resin is in the following order: 430–5 (12.8 wt%), 430–10 (10.2 wt%), and 430–2 (6.3 wt%), and when 430–5 is used as a binder, the highest density appeared at 1.75 g/cm3. However, such intermediate materials undergo thermal decomposition even at temperatures above 900 °C. As a result, after carbonization, 430–5 had a density of 1.60 g/cm3, which was similar or lower than that of 430–2 (1.72 → 1.63 g/ cm3) and 430–10 (1.73 → 1.61 g/cm3). From these results, it is expected that if the heteroatom content is distributed in an appropriate amount and the heating rate is well controlled, it will be possible to maintain a high density even after carbonization while ensuring a high beta-resin content.

Noise is defined as ‘unwanted sound’ or ‘undesired sound’. Recently, the aviation industry has been rapidly developing through convergence with cutting-edge technologies such as UAM. Accordingly, it is expected that new aviation industry models will continue to be created in Korea. In addition, it is expected that aircraft noise will be raised as a new social problem. The characteristic of aircraft noise is that it has a wide transmission range. Therefore, the area affected by aircraft noise is extensive, and the damage area varies depending on the flight path and flight environment. Additionally, it tends to occur continuously in certain areas. This study is an extension of the previous studies 􋺷Study on noise measurement and analysis of C172 aircraft at Muan Airport􋺸 and 􋺷Study on noise measurement and analysis of SR20􋺸, and investigated the noise characteristics of various piston engine trainer aircraft operated in Korea. We want to measure and analyze noise.

This study involved the heterogenization of a binder pitch (BP) using a small amount of nanocarbon to improve physical properties of the resulting graphite electrode (GE). Heterogenization was carried out by adding 0.5–2.0 wt.% platelet carbon nanofiber (PCNF) or carbon black (CB) to a commercial BP. To evaluate the physical properties of the BPs, we designed a new model graphite electrode (MGE) using needle coke as a filler. The heterogenized binder pitch (HBP) with PCNF or CB clearly increased the coking value by 5–13 wt.% compared to that of the as-received BP. Especially, the model graphite electrodes prepared with HBPs containing 1.0 wt.% PCNF or CB showed significantly improved physical properties compared to the control MGE from the as-received BP. Although the model graphite electrodes prepared with HBPs showed similar properties, they had smaller pore sizes than the control. This indicates that heterogenization of the BP can effectively decrease the pore size in the MGE matrix. Correlating the average pore sizes with the physical properties of the model graphite electrodes showed that, for the same porosity, matrices formed by the HBP with a smaller average pore size can effectively improve the apparent density, tensile strength, and oxidation resistance of the model graphite electrodes.

In the present study, a coal-based pitch containing 12.1% quinoline insoluble (QI) underwent isothermal heat treatment, and changes in the mesophase microstructure were analyzed for the heat treatment duration. The nuclei creation and growth rate of mesophase were affected by the distribution of QI particles in the pitch. The growth process could be explained in four regions through the mesophase area fraction. During the carbonization of carbon blocks, mesophase formation was induced in the binder phase. The physical properties of carbon blocks were measured as a function of residence time. As residence time increased, bulk density decreased and porosity increased, but electrical conductivity increased. It was determined that forming a mesophase in the binder phase during carbonization reduced the size of large pores in carbon block and improved the connectivity between particles, thereby increasing electrical conductivity. These results are expected to show greater improvement in electrical properties after graphitization.

Industrial activities that utilize nuclear technology can cause radioactive contamination in the ecosystems. In particular, cesium (Cs) has problems, such as neurological diseases, when it is exposed and accumulated in the bodies of animals, plants, and humans for a long time. Therefore, the development of simple and economical adsorbents for Cs removal is required. In this study, the surface of petroleum residue pitch was modified using NaClO and it was used to remove Cs from an aqueous solution. Batch experiments and characterization of the modified adsorbent were performed to determine the adsorption mechanism between the adsorbent and Cs. From these results, chemical and monolayer adsorption were found to occur at the carboxyl groups on the adsorbent surface, along with a cation exchange reaction occurred due to the sodium ions on the surface. Through this modification process, the total acidity, including phenolic, lactonic and carboxylic functional groups, was improved to 1.563 mmol/g and the maximum adsorption capacity of Cs for the modified adsorbent was 65.8 mg/g.