Dang Z.-M.,University of ScienceandTechnology Beijing |
Zha J.-W.,University of ScienceandTechnology Beijing |
Yu Y.,Beijing University of Chemical Technology |
Zhou T.,Beijing University of Chemical Technology |
And 2 more authors.
IEEE Transactions on Dielectrics and Electrical Insulation | Year: 2011
Dielectric composite films of the micro-nanosize BaTiO3 (BT) particles embedded into a polyvinylidene fluoride (PVDF) matrix were prepared by using a simple blending and casting processing. Effects of the micro-nanosize cofilled model at different mciro-nanosize volume ratios of BT particles on microstructure and dielectric properties of the composite films were researched. The results show that the nanosize BT particles can be filled into the gaps between the micron-size BT particles so that a tightly stack structure in the BT/PVDF composite film is formed. As a result, the dielectric properties of the composite films with the micro-nanosize BT loading at 40 vol% is higher than these with single nanosize BT loading solely if the interactions between the BT fillers are considered. The maximum values of dielectric permittivity were about 55 because of the superior internal microstructure of composite films when the mciro-nanosize volume ratio of BT particles is close to 1/1. In this case, a remarkable synergistic effect for improving the dielectric properties was also observed. The microstructure and the assumed cofilled model of the composite films would used to explain the experimental results well. © 2011 IEEE.
Fu J.,University of ScienceandTechnology Beijing |
Fu J.,University of Jiaozuo |
Li J.,University of ScienceandTechnology Beijing |
Zhang H.,Control Iron and Steel Research Institute, China
Science China Technological Sciences | Year: 2011
The mechanism of broadening of slab in continuous casting was studied by numerical simulations and experimental measurements in factories. The mechanism is derived by gradual exclusion of various factors related to the broadening of slab. It is concluded that the slab exposes to no constraint at the direction of narrow face. Because of the static pressure of molten steel, the slab deforms creepily in the direction that consequently results in the broadening of slab. The broadening of slab increases with casting speed and static pressure of molten steel. The decrease of secondary cooling intensity and strength of steel at high temperature also contribute to the broadening of slab. The micro-alloying plays an important role in improving the strength of steel and in reducing the broadening of slab. © 2011 Science China Press and Springer-Verlag Berlin Heidelberg.