2020, Vol.30, No.3

Carbon Letters 2023 KCI Impact Factor : 1.35 KCI-WoS Impact Factor : 6.04

pISSN : 1976-4251 / eISSN : 2233-4998
https://journal.kci.go.kr/carbon

The composite PAN fbers which incorporated with CNTs and Titania were prepared by mean of wet spinning. These fbers were then pre-oxidized with microwave heating in an air atmosphere. A combination of characterizations was carried out to study the impact of nanoparticles fllers on the properties of as-spun fbers and their performance during the microwave pre-oxidation. The addition of an equal amount of fllers made obvious changes in the chemical and crystalline structure, consequently improves the strength, and this could lower the capability to creep over a wide range of temperatures in the subsequent processes. FTIR and NMR analyses results of the pre-oxidized fbers exhibited clear changes in the PAN structure, where the dehydrogenation reaction and the degree of cyclization were investigated. Additional confrmation of the occur�rence of cyclization reaction was achieved by XRD and thermal analysis. According to the TGA results, the pre-oxidized CNT1 /Ti-PAN fbers exhibit greater thermal stability suggesting high carbon content and good quality could result in the dependent carbon fbers.

Carbon short fbers/copper composites with diferent carbon short fber contents up to 15 wt.% as reinforcements are prepared to investigate the infuence of the carbon short fber surface coating on the microstructure, density, and electrical properties of the carbon short fbers/copper composites. The carbon short fbers were surface treated by acid functionalization followed by alkaline treatment before the coating process. It was observed from the results that coated type copper nanoparticles were deposited on the surface of the carbon short fbers. The surface treated carbon short fbers were coated by copper using the electroless deposition technique in the alkaline tartrate bath by using formaldehyde as a reducing agent of the copper sulfate. The produced coated carbon short fbers/copper composite powders were cold compacted at 600 MPa, and then sintered at 875 °C for 2 h under (hydrogen/nitrogen 1:3) atmosphere. A reference copper sample was also prepared by the same method to compare between the properties of pure copper and the carbon short fbers/copper composites. The phase composition, morphology, and microstructure of the prepared carbon short fbers/copper composite powders as well as the correspond�ing carbon short fbers/copper composites were investigated using X-ray difraction analysis (XRD) and scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS), respectively. The density and the electrical resistivity of the sintered composites were measured. It was observed from the results that the density was decreased; how�ever, the electrical resistivity was increased by increasing the carbon short fbers wt.%.

In aluminum electrolysis, sodium penetration into carbon cathodes is considered as the main cause of cell failure and ef�ciency loss, but the detailed mechanism is still not defnitely clear. Since the macroscopic properties of material depend on the microscopic structures, a large-scale atomistic model of anthracite cathodes was constructed to represent several important structural characteristics. Combined with Monte Carlo and molecular dynamics simulations, the adsorption and difusion behaviors of sodium were investigated, respectively. The results suggest that sodium adsorption mainly occurs in the larger micro-pores with the range of 10–19 Å, while it accords well with to type-I Langmuir adsorption model. The sodium is found to be preferentially adsorbed in arch-like structures with 5- or 7-membered rings or around heteroatom, especially oxygen. Moreover, the movements of sodium through carbon matrix mainly depend on the continuous difusive motion while most sodium particles tend to be trapped in voids with small mobility. The calculated transport difusion coefcient is equal to 6.132 × 10−10 m2 /s, which is in outstanding agreement with experimental results. This fundamental research would contribute to the understanding of sodium penetration mechanism and the optimization of cathode industry in the f