Chemical Engineering and Material Properties

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Authors: Hui Xing Huang, Hai Chao Li, Shao Bin Huang, Shui Xia Chen
Abstract: PtRu hollow nanospheres catalysts supported on activated carbon fiber (ACF) and carbon nanotubes (CNTs) were simply prepared at room temperature in a homogeneous solution with Co nanoparticles as sacrificial templates. TEM measurements showed that the coreless PtRu nanospheres supported on ACF and CNTs were both from composed 20 to 30 nm with an average diameter of 24 nm. The shells of the nanospheres on ACF composed of PtRu nanocrystals with a size of 5 nm, while those on CNTs were 3 nm. Electrochemical measurements demonstrated that hollow-PtRu/ACF showed a lower oxidation current density towards methanol electroxidation but a better tolerance to poisoning effect than hollow-PtRu/CNTs. The poorer performance of hollow-PtRu/CNTs may be caused by the phase separation.
Authors: Huan Xia Zhang, Li Wei
Abstract: The deposition of coatings on the surface of carbon fiber will be helpful to their appli-cations. However, they are unsuitable to be deposited due to their low surface free energies, poor wettability and poor adhesions. The objective of this work is to modify carbon fibers by Dielect-ric barrier discharges (DBD) in ambient argon. The chemical and physical changes induced by the treatments on carbon fibers surface are examined using contact angle measurements and X-ray photoelectron spectroscopy (XPS). The interfacial adhesion of CF/EP composites are analysised by a single filament pull-out test. The contact angles of the plasma-treated samples are visibly reduced than the untreated samples. XPS results reveal that the carbon fibers modified with the DBD at an atmospheric pressure show a significant increase in oxygen-containing groups, such as C–O,C=O and O–C=O. The results of IFSS tests show that the treated carbon fibers composit-es could possess excellent interfacial properties with mixed resins. These results demonstrate that the surfaces of the carbon fibers samples are more active, hydrophilic and rough after plasma treatments using a DBD operating in ambient argon.
Authors: Dong Yu Zhao, Zheng Jin, Xue Qin Yang, Xiao Ying Jia
Abstract: Aniline monomer coated on the nanotubes in HCl solution was used to prepare a composite of multi-wall carbon nanotube/polyaniline (MWCNT/PANI) by in-situ polymerization. Multi-wall carbon nanotubes were treated by the mixed acid (HNO3:H2SO4 in a ratio of 1:3). The content of MWCNT in the samples was 0-20 wt%. The nanocomposites were characterized by Thermogravimetric analysis (TGA), Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy and scanning electron microscopy. The mechanical properties of the MWCNT/PANI nanocomposites were also measured. The results showed that the MWCNT was well dispersed in water after purification. Both FT-IR and Raman spectra illustrated the presence of MWCNT in the composites; the interaction between PANI and MWCNT was proved. The Young΄s modulus was 618MPa with 20wt% loading. The effects of treatment of MWCNT on the mechanical properties of MWCNT/PANI nanocomposites are discussed.
Authors: Zheng Jin, Dong Yu Zhao, Bo Hong Li, Xiao Min Ren, Shan Tao Yan, Chuan Li Qin, Rui Qi Li
Abstract: The purpose of this paper is to develop feasible composite electrodes with a long cycle life and large specific capacitance and to investigate optimal ratio between aniline and carbon aerogels (CA) materials. The characterization of the composite electrode materials was studied by using scanning electron microscopy (SEM), electrochemical impedance spectroscopy, cyclic voltammetry (CV) and the constant charge-discharge. The specific capacitance of the composite electrode materials, measured using cyclic voltammetry at scan rate of 1mV•s-1, was found to be 1139.66F•g-1. For a simple supercapcitor, the highest specific capacitance (127.53 F•g-1 at 30mA) is obtained at ratio between aniline and CA is 1:4.
Authors: Lu E Wang, Xu Mei Ren, Feng Wu
Abstract: Two nano-sized Sn-Ni alloy composites are synthesized as anode materials for Li-ion battery through chemical precipitation and hydrothermal method, respectively. The morphology characteristics and electrochemical performance of the materials are investigated. Results show that the Sn-Ni alloy composite prepared by hydrothermal method has a better crystal structure, higher specific capacity and more stable cycling. This material exhibits an initial discharge capacity of 799.1 mAh/g and the column efficiency of 90-94%. This Sn-Ni material shows to be a good candidate anode material for the lithium battery.
Authors: Ai Qin Wang, Jing Pei Xie, Wen Yan Wang, Luo Li Li
Abstract: In the present work, the Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys composite modified by P+RE was prepared by metal mold casting. The tribological properties against steel under lubrication conditions were experimentaled. The wear morphology characteristics and subsurface microstructure was characterized by means of optical microscope and scanning electron microscope. The effects of Si particle morphology, size, quantity and distribution on tribological properties were investigated. The wear mechanism based on lubricant abrasion was discussed. The results show that the wear mechanism of experimental alloy are mainly abrasire wear and fatigue spalling.
Authors: Bin Liu, Jing Huai Zhang, Zhong Yi Niu, Jun Qing Li
Abstract: The as-cast Mg-14Li-3Al-(0-0.9)RE alloys were prepared with vacuum melting method, then processed by hot extrusion. The microstructure and tensile properties were investigated. The results show that both addition of RE and extrusion deformation can refine the grain size. Al3La compounds are formed with addition of La-rich misch metal. The as-extruded Mg-14Li-3Al-0.6RE alloy obtains the finest grain size (4.28 μm) and the highest mechanical properties (σb =222.75 MPa, δ=23.8%), which is related to the grain refinement and the formation of Al3La.
Authors: Yu Mei Dai, Yong Qing Ma, Yu Jie Dai
Abstract: By analysis of the theoretical calculation, it is obvious that the bimetallic bonding of the copper clad aluminum wire by clad drawing at room temperature is the action results of collective gravitation of a great lot of two metal surface atoms reciprocally by outside force. The interatomic potential energy of the closer atoms of two metal surfaces is obvious lower, so as to change for electron within the distance. The interdiffusion of the bimetallic surface atoms by clad drawing at room temperature, is good for improving the bond strength, but is not necessary.
Authors: Yu Mei Dai, Sheng Long Zhu, Fu Hui Wang
Abstract: The basic theory of molecular dynamics and interface diffusion theory are used to simulate metal Ni/Al interface diffusion. The position image of the interface diffusion atoms and radial distribution function curve of Ni/Al interface reaction at initial time at a high temperature can be got. Through these images of diffusion atoms position, it is observed that there is a lot of change during the simulation process. The Al atoms layer of the matrix begins to melt at first. Ni atoms in the matrix begin to diffuse outward rapidly in large quantities. Al atoms overall diffuse to one side of the matrix at a relatively low speed, inter-diffusion layer thickness increases continuously and inter-diffusion atoms are solidified gradually from one side of the matrix to the surface. The process of change has been further verified in the corresponding radial distribution function curves. These conclusions can provide a theoretical reference for the technology of new materials preparation and the expansion of the environment of Ni/Al use.

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