In the present study, carbon black activated by CO₂ gas was examined through XRD analysis, especially with regard to changes in its structural parameters. Based on the results, its activation process was thoroughly analyzed. The activation process was controlled by isothermally activating the carbon black inside a reaction tube through which CO₂ gas flowed. With this approach, the degree of activation was varied as desired. At an early stage of the activation process, the amorphous fraction on the carbon black surface was preferentially activated, and later the less-developed crystalline carbon (LDCC) region inside the carbon black particles started to be activated. The latter process was attributable to the formation of pores inside the carbon black particles. As the activation process proceeded further, the more-developed crystalline carbon (MDCC) region started to be activated, thereby causing the pores inside the carbon black particles to grow larger. At the last stage of the activation process, L_a was found to be decreased to about 40 Å. This implied that the edges of the graphite crystals had been activated, thus causing the internal pores to grow and coalesce into larger pores. Activated conductive Super-P with enhanced pore properties is expected to have wide applications.

In the present study, graphite blocks were fabricated using synthetic graphite scrap and phenolic resin, and the effect of the heating rate during carbonization on their mechanical and electrical characteristics was examined. While varying the heating rate from 1, 3, 5, and 7 to 9 °C/min, the microstructure, density, porosity, flexural strength, compressive strength, and electrical resistivity of the fabricated graphite blocks were measured. As the heating rate increased, the pores in the graphite blocks increased in size, and the shape of the gas release paths became more irregular. Overall, it was found that increases in the heating rate led to the degradation of the graphite blocks’ mechanical and electrical properties.

The quantification of the phase fraction is critical in materials science, bridging the gap between material composition, processing techniques, microstructure, and resultant properties. Traditional methods involving manual annotation are precise but labor-intensive and prone to human inaccuracies. We propose an automated segmentation technique for high-tensile strength alloy steel, where the complexity of microstructures presents considerable challenges. Our method leverages the UNet architecture, originally developed for biomedical image segmentation, and optimizes its performance via careful hyper-parameter selection and data augmentation. We employ Electron Backscatter Diffraction (EBSD) imagery for complex-phase segmentation and utilize a combined loss function to capture both textural and structural characteristics of the microstructures. Additionally, this work is the first to examine the scalability of the model across varying magnifications and types of steel and achieves high accuracy in terms of dice scores demonstrating the adaptability and robustness of the model.

In this study, changes in the microstructure of coal-tar pitch (CTP) during successive processes, including pyrolysis, polycondensation, and crystallization, were examined in connection with the resulting variations in structure factors, as measured by X-ray diffraction (XRD) analysis, and functional groups, as confirmed by Fourier transform infrared (FTIR) spectroscopy. To this end, four zones were defined based on variations in crystallinity, which were indicated by d₀₀₂ and L_c. Each zone was further characterized by interpreting crystallinity development in relation to changes in functional groups and specimen height. At around 400 °C, polycondensation occurred as the C-H_ar and C-H_al peaks decreased in intensity. These peak reductions coincided with the formation of mesophase spheres, resulting in enhanced crystallinity. Subsequently, at around 500 °C, the peak intensity of C-H and COOH decreased, which was attributed to the release of large amounts of gases. This led to sharp volume changes and a temporary reduction in crystallinity. All these results suggest that changes in the functional groups of CTP at lower temperatures (600 °C or less) during the carbonization process are closely associated with variations in its crystallinity. The major findings of the present study provide valuable insights for designing highly effective processes in the manufacturing of synthetic graphite blocks using CTP as a binder material, including by selecting appropriate temperature ranges to minimize volume expansion and crystallinity degradation and determining the lowest possible carbonization temperature to ensure adequate binder strength.

This study examined the pore development of carbon black according to burn-off (BO) ratio of carbon black activated in CO₂atmosphere. A horizontal tube furnace was charged with carbon black when the internal temperature reached 1000 °C, and activation time was adjusted to obtain BO ratios of 7.2%, 15.4%, 30.4%, 48.2%, 59.9%, and 83.2%. SEM observations showed that the primary particles of carbon black were aggregated, and varying BO ratios did not cause significant differences in shape and size. Carbon black was presumed to contain pores since the size of primary particles remained largely the same with varying BO ratios, and TEM observation revealed that pores existed within primary particles. The nitrogen adsorption isotherms were of type IV, which is characterized by a hysteresis loop. The specific surface area of raw carbon black was 61.4 m²/g, while that of BO at 83.2% increased 18.0 times to 1107.6 m²/g.