Advanced Materials Research Vols. 631-632

Abstract: Spherical LiMnPO₄/C composite micro-particles with different carbon content were prepared by spray drying followed by heat treatment in the range of spray drying temperature from 220°C to 270°C. The structure, morphology and electrochemical performance of the resulting spherical LiMnPO₄/C microparticles were characterized by X-ray diffraction, SEM and standard electrochemical techniques. Caron coated LiMnPO₄ could be prepared from the as-prepared powders followed by heat treatment at 600°C for 12h in a Ar+10%H2 atmosphere. The sample was identified as olivine structure of LiMnPO₄ without any impurity and spherical powders with approximately 3-5μm in primary particles size. Sample which was synthesized at 220°C SD temperature,10% carbon content showed the best electrochemical performance due to its small and homogeneous particle size diffusion, uniform carbon coating.

Abstract: This paper presents a fabricating process and microstructural features of TiB₂+TiC duplex particulates reinforced surface composite with carbon steel matrix. The effect of ferrous-titanium addition on microstructures is investigated and analyzed. The results showed that the surface compound layer do not exhibit at lower addition, but appear at higher addition. With increasing ferrous-titanium addition, the concentration and size of the synthesized particles at the surface compound layer are decreased, but the tendency of uniform distribution increased.

Abstract: The formation of CH₄ from two kinds of NBR with different raw rubber applied in transformer oil were investigated. In this study, work environment of transformer was simulated，thermal aging tests were conducted for different times in 70°C transformer oil. Surface morphology, the release of CH₄, and molecular structure were analyzed by using Gas Chromatography (GC), Scanning Electron Microscope (SEM), and Fourier Transform Infrared analysis (FTIR), respectively. In addition, the swelling property was also discussed in this work. The results illustrated that raw rubber with more content of acrylonitrile had excellent advantages in heat oil aging resistance and the formation of CH₄.

Abstract: Carbon nanotube-Mesocarbon microbead composites were synthesized from coal tar pitch with carbon nanotubes (CNTs) as additive. The effect of CNTs addition and process parameters on the growth and morphologies of Mesocarbon microbeads (MCMBs) was investigated. The results show that adding CNTs enhances the nucleation and inhibits the growth and coalescence of MCMBs. Under the same thermal condensation conditions, the MCMBs made in the presence of CNTs tend to have smaller size, lower yield and more uniform size distribution, but more CNTs can lead to poor spherical degrees. Compared with the raw CNTs, the CNTs treated with blended acid can achieve better sphere and more uniform MCMBs with increasing CNTs ratio.

Abstract: Ferrite particles were prepared by hydrothermal process at high temperature. The characterization of ferrite was examined by XRD, Mössbauer spectrum, and SEM. The XRD and Mössbauer spectrum confirmed that ferrite particles have a Fe₃O₄ inverse spinel structure, the SEM results show that each Fe₃O₄ particles were composed of many smaller magnetite nanoparticles. The as-synthesized Fe₃O₄ particles were modified by sodium citrate then further coated with SiO2 layer through the modified stöber method. The composited Fe₃O₄@SiO₂ microspheres exhibited outstanding monodispersity and magnetic property.

Abstract: Polyimide fibers and polyamide acid fibers was used as main materials to make polyimide fiber paper. The effect of the properties of polyimide fiber paper by hot pressing temperature and hot pressing pressure was discussed. The experimental results showed that when the pressure of hot pressing was 12Mpa and the hot temperature of hot pressing was 220°C, the sheet had excellent strength properties and electrical performance.

Abstract: The effects of high-energy ball milling and subsequent calcinations on the mixture of MgO and Nb₂O₅ are investigated. It is found that the pure MgNb₂O₆ phase can be synthesized at 800 °C for 5 h by using high-energy ball milling method. MgNb₂O₆ ceramics were prepared at 1220 °C by using calcined powders of milled 15 h, which is lower 100 °C than that required by using the conventional solid state reaction method. The microwave dielectric properties of MgNb₂O₆ ceramic with εr = 19.7 and Qf = 29 044 GHz were obtained by the High-energy ball milling method, which made it a potential candidate for application.

Abstract: Anatase titania (TiO₂) films with highly photocatalytic activity were prepared by hydrothermal treatment of amorphous TiO₂ nanotubes (NTs) via electrochemical anodization of titanium (Ti) in fluorine-containing electrolyte. The as-prepared TiO₂ films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The photocatalytic activity of the as-prepared TiO₂ films was evaluated by the photocatalytic degradation of methyl orange (MO) aqueous under UV-light irradiation. The effects of hydrothermal temperature and time on the morphologies, microstructure and photocatalytic activity of TiO₂ films were investigated and discussed. It was found that TiO₂ NTs were converted to nanoparticles after hydrothermal treatment. The mechanism of deformation of TiO₂ NTs was discussed. Hydrothermal treatment enhances the phase transformation of TiO₂ films from amorphous to anatase and crystallization of anatase. An optimal hydrothermal condition (150 oC for 8 h) was determined. The anatase TiO₂ films prepared under optimal hydrothermal conditions posses larger surface area and higher relative anatase crystallinity and its photocatalytic activity is higher than that of anatase TiO₂ films prepared under other hydrothermal conditions.

Abstract: The experiment was done in which the BF slag containing titanium produced by Pangang with vanadium-titanium magnetite was dealt with carbon and nitrogen. The possibility of the carbon nitriding reactions were analyzed theoretically. It is found by thermodynamic calculation that the carbon nitriding of TiO₂ is easier than that of other oxides and the temperature of carbon nitriding of perovskite can be reduced with the presence of Al₂O₃ and SiO₂ in slag. The phase composition and microstructure of production from carbon nitriding were studied using X-ray diffraction and SEM. It is approved that the main phase composition of production from carbon nitriding under N₂ was Ti(C,N). The influence factors, temperature, holding time and particle size were investigated. The results show, the phase compositions of the slag is mainly perovskite; the most suitable temperature and holding time of carbon nitriding is about 1450°C; the most appropriate holding time was about 2 hours and the most suitable size of the slag particle is about 180 meshes. With the optimization of the process, the size of Ti(C,N) can be increased which will benefit the recycle of Ti(C,N) in ore dressing.

Abstract: Owing to the lack of a good theory method to obtain the accurate equivalent elastic constants of hexagon honeycomb sandwich structure’s core, the paper analyzed mechanics performance of honeycomb sandwich structure’s core and deduced equivalent elastic constants of hexagon honeycomb sandwich structure’s core considering the wall plate expansion deformation’s effect of hexagonal cell. And also a typical satellite sandwich structure was chose as an application to analyze. The commercial finite element program ANSYS was employed to evaluate the mechanics property of hexagon honeycomb core. Numerical simulation analysis and theoretical calculation results show the formulas of equivalent elastic constants is correct and also research results of the paper provide theory basis for satellite cellular sandwich structure optimization design.