Papers by Author: Wei Chen

Abstract: The highly pure acicular nanosize Mg,Al-hydrotalcite was synthesized by the one-step liquid reaction method at atmospheric pressure. The favorable growth unit in the reaction liquid, the requirements of Al3+ entering the Mg2+-(OH-)6 octahedral and forming the growth unit M-(OH-1)6 (M=Mg2+, Al3+) and growth mechanism that the nanosize Mg,Al-hydrotalcite crystal embryo follows are studied according to the test results of XRD, TEM, SEM and IR. Later, that the nanosize Mg,Alhydrotalcite crystal embryo growth follows the gathering growth theory was deeply investigated.

Abstract: (1-x)La2/3TiO3-xLa(Mg1/2Ti1/2)O3 ceramics with x ranging from 0.01 to 0.3 were prepared by the conventional solid-state reaction method. Microstructure and microwave dielectric properties were studied. The perovskite compound La2/3TiO3 is stabilized when x = 0.1. The content of La2/3TiO3 increases with increasing x from 0.01 to 0.1, and thereafter decreases when x > 0.1. The same tendency was also observed on measuring the dielectric constant, temperature coefficient of resonant frequency and Q× ƒ. A maximum permittivity of 77.35 was achieved with these stabilized La2/3TiO3 ceramics. Close to zero τf value (1 ppm/°C) was obtained at x=0.3, but its Q× ƒ value was relative low.

Abstract: The microstructure and the coercivity of nanocomposite Nd4.5Fe76.5-xGaxCo1.0B18 (x=0~0.6at%)bonded magnets were studied. The results showed that addition of small amount of Ga in Nd4.5Fe76.5-xGaxCo1.0B18 made the grains finer and more uniform. A notable peak of coercivity was observed in the variational curve of coercivity with annealing time when Ga content was low (x=0.2). This phenomenon could be explained by the microstructure and the exchange coupling interaction of two-phase nanocomposite.

Abstract: : According to the theory of liquid metal forging and liquid metal extrusion, a new kind of fabricating method for particles reinforced metallic matrix composite was put forward by author. In this paper, the extrusion process to semisolid thick liquid after the mixture was studied by means of the theoretical analysis and experimental methods. Mechanical characteristics of solidification during flowing and plastic deformation during solidification of the composite were found. So the base was built up for selecting technology parameters and for building a stabile process