Zhang Xuebin

Fabrication of Magnetic Fe3O4 Nanotubes by Electrospinning

Abstract Ferroferric oxide nanotubes were prepared by calcining and reducing the composite nanofiber precursors fabricated by electrospinning. Influences of the electrospun parameters (PVA concentration of solution, applied voltage and collector distance) on the preparation of the composite nanofiber precursors were discussed. The structural properties of the obtained nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The formation mechanism of the Fe3O4 nanotubes was investigated through the nonequilibrium heat-treatment procedure. Furthermore, the magnetic property of Fe3O4 was measured using a vibrating sample magnetometer. Results reveal that the tubes show a uniform and continuous morphology, whose outer and inner diameters are about 100 nm and 50 nm, respectively. Fe3O4 possesses saturation magnetization (Ms) of 54.2 A·m2/kg, coercivity (Hc) of 215×79.6 A/m and remanent magnetization (Mr) of 12.8 A·m2/kg, respectively.

Reactive Synthesis of Polycrystalline Ti3AlC2 and Its Sintering Behavior

Abstract A method for fabrication of ternary compound Ti3AlC2 powder by pressureless calcining (PC) technique was developed. Powders of Ti, Al and TiC were mixed as staring materials. The effects of calcining temperature and aluminum content on the purity of Ti3AlC2 were discussed. The reaction mechanism and the microstructure evolution of Ti3AlC2 prepared at different temperatures were investigated by X-ray diffraction, field emission scanning electron microscopy and high resolution transmission electron microscopy. Results indicate that the single-phase polycrystalline Ti3AlC2 powders are obtained at 1300 °C, which possesses a typical laminated structure, and the best molar ratio of raw Ti/Al/TiC materials is 1:1.2:2. The bulk samples sintered by hot pressing were from the Ti3AlC2 powders. After hot pressing of different temperatures, the fully dense bulk Ti3AlC2 shows the best properties when prepared at 1300 °C. The density of bulk Ti3AlC2 reaches to 99.9%. The average Vickers hardness is around 5.7 GPa, and the maximum flexural strength is over 630 MPa. Finally the strengthening mechanism of the bulk Ti3AlC2 was also proposed.