Preparation of Copper-coated Mesophase Pitch-based Carbon Fibers by Electroless Plating Technique with the APTES Grafting Modification

Jiangfan Shi,Yize Liu,Jianxiao Yang,Jun Li,Chong Ye,Dong Huang,Jinshui Liu,Xuanke Li 한국섬유공학회 2020 Fibers and polymers Vol.21 No.8

An upgrade synthesis method of electroless copper plating was developed to prepare the copper-coated mesophasepitch-based carbon fibers (Cu@CF) with APTES (3-Aminopropyl triethoxysilane) grafting modification. The microstructureand properties of the fibers which were prepared by the APTES sensitization method were investigated and compared withthose prepared by the conventional SnCl2 sensitization method. The results showed that as-coated fibers sensitized by APTESdemonstrated to have better interfacial cohesion between the copper layer and the fiber surface than those sensitized by SnCl2did. Moreover, the resistivity of Cu@CF-APTES declined to 2.3±0.9 μΩ·cm, while that of Cu@CF-SnCl2 was 9.3±3.7μΩ·cm. Besides, not only the strength of Cu@CF-APTES increased, but the strength discreteness of them reduced due to thefact that no peeling phenomenon was observed between the copper layer and fiber during the stretch test.

A Multi-keyword Ranked Search over Encrypted Cloud Data Supporting Semantic Extension

Zhihua Xia,Li Chen,Xingming Sun,Jianxiao Liu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.8

With the emergence of cloud computing, many data owners outsource their local data to cloud server so as to enjoy high-quality data storage services. For the protection of data privacy, sensitive data has to be encrypted before outsourcing, which makes effective data utilization a challenging task. Although existing searchable encryption technologies enable data users to conduct secure search over encrypted data, the functionality of these schemes need to be further improved. In this paper, we construct a secure and efficient multi-keyword ranked search scheme which supports both the semantic extension search and the multi-keyword ranked search. The semantic extension is achieved through the mutual information statistical analysis of keywords. And the multi-keyword ranked search is achieved through a balanced binary tree whose nodes are the vectors of term frequency (TF) values. The splitting operation and secure transformation are utilized to encrypt the vectors of index and query. Note that, the encrypted vectors can be well used to calculate accurate relevance scores. Phantom terms are added to the index vector to blind the search results to resist statistical attacks. Due to the use of tree-based index structure, the proposed scheme can achieve the sub-linear search time. Finally, the experiments are conducted to demonstrate the efficiency of the proposed scheme.

Effect of anion species on preparation and properties of pitch-based activated carbon fibers by in-situ catalytic activation of metal nanoparticles

Gou Genchang,Wei Wenjie,Yang Jianxiao,Liu Jiahao,Liu Yue,Li Jun,Shi Kui 한국탄소학회 2022 Carbon Letters Vol.32 No.6

The pitch-based activated carbon fibers (ACFs) were prepared from ethylene tar-derived pitches containing nickelocene (CNi) or nickel nitrate (NiN). The effects of different anions and contents of metal salts on the microstructure and surface chemical properties of fibers were investigated. The results revealed that Ni2+ from CNi mainly remained its pristine molecule in the organometal salt-derived pitch (OP-xCNi), while Ni2+ from NiN occurred complexation reaction with polycyclic aromatic hydrocarbons (PAHs) in the inorganic metal salt-derived pitch (IP-xNiN) due to the weaker binding ability between anions and Ni2+ of CNi than CNi. The XRD and SEM results confirmed that IP-3NiN-ACF contained Ni, NiO, Ni2O3 nanoparticles with different size distributions, while OP-3CNi-ACF only contained more uniformly distributed Ni nanoparticles with small size. Furthermore, OP-3.0CNi-ACF presented higher specific surface area of 1862 m2/g and a pore volume of 1.69 cm3/g than those of IP-3.0NiN-ACF due to the formation of pore structure during the in-situ catalytic activation of different metal nanoparticles. Therefore, this work further pointed out that the desired pore structure and surface chemistry of pitch-based ACFs could be obtained through regulating and controlling the interaction of anion species, metal cations and PAHs during the synthesis of pitch precursors.

Multi-cue Integration Object Tracking Based on Blocking

Lichuan Gu,Chengji Wang,Jinqin zhong,Jianxiao Liu,Juan Wang 보안공학연구지원센터 2014 International Journal of Security and Its Applicat Vol.8 No.3

The microstructures and mechanical properties of ultra‑high‑strength PAN‑based carbon fibers during graphitization under a constant stretching

Chong Ye,Huang Wu,Dong Huang,Baoliu Li,Ke Shen,Jianxiao Yang,Jinshui Liu,Xuanke Li 한국탄소학회 2019 Carbon Letters Vol.29 No.5

Commercial ultra-high-strength PAN-based carbon fibers (T1000G) were heat-treated at the temperature range of 2300– 2600 °C under a constant stretching of 600 cN. After continuous high-temperature graphitization treatment, microstructures, mechanical properties and thermal stability of the carbon fibers were investigated. The results show that the T1000G carbon fibers present the similar round shape with a smooth surface before and after graphitization, indicating the carbon fibers are fabricated by dry–wet spinning. In comparison, the commercial high-strength and high-modulus PAN-based carbon fibers (M40JB and M55JB) present elliptical shapes with ridges and grooves on the surface, indicating the carbon fibers are fabricated by wet spinning. After graphitization treatment from 2300 to 2600 °C under a constant stretching of 600 cN, the Young’s modulus of the T1000G carbon fibers increases from about 436 to 484 GPa, and their tensile strength decreases from about 5.26 to 4.45 GPa. The increase in Young’s modulus of the graphitized T1000G carbon fibers is attributed to the increase in the crystallite sizes and the preferred orientation of graphite crystallites along the fiber longitudinal direction under a constant stretching condition. In comparison with the M40JB and the M55JB carbon fibers, the graphitized T1000G carbon fibers are easier to be oxidized, which can be contributed to the formation of more micropores and defects during the graphitization process, thus leading to the decrease in the tensile strength.

The microstructures and mechanical properties of ultra-high-strength PAN-based carbon fibers during graphitization under a constant stretching

Ye Chong,Wu Huang,Huang Dong,Li Baoliu,Shen Ke,Yang Jianxiao,Liu Jinshui,Li Xuanke 한국탄소학회 2019 Carbon Letters Vol.29 No.5

Commercial ultra-high-strength PAN-based carbon fibers (T1000G) were heat-treated at the temperature range of 2300–2600 °C under a constant stretching of 600 cN. After continuous high-temperature graphitization treatment, microstructures, mechanical properties and thermal stability of the carbon fibers were investigated. The results show that the T1000G carbon fibers present the similar round shape with a smooth surface before and after graphitization, indicating the carbon fibers are fabricated by dry–wet spinning. In comparison, the commercial high-strength and high-modulus PAN-based carbon fibers (M40JB and M55JB) present elliptical shapes with ridges and grooves on the surface, indicating the carbon fibers are fabricated by wet spinning. After graphitization treatment from 2300 to 2600 °C under a constant stretching of 600 cN, the Young’s modulus of the T1000G carbon fibers increases from about 436 to 484 GPa, and their tensile strength decreases from about 5.26 to 4.45 GPa. The increase in Young’s modulus of the graphitized T1000G carbon fibers is attributed to the increase in the crystallite sizes and the preferred orientation of graphite crystallites along the fiber longitudinal direction under a constant stretching condition. In comparison with the M40JB and the M55JB carbon fibers, the graphitized T1000G carbon fibers are easier to be oxidized, which can be contributed to the formation of more micropores and defects during the graphitization process, thus leading to the decrease in the tensile strength.