Papers by Author: Hong Bai Bai

Abstract: The figuration technique of grades extrusion for making metal rubber material is firstly put forward. Compared with normal uninterrupted extrusion technique, the elastic reversion of grades extrusion components increases 14.7%, so their elasticity is improved a lot. Measured by the static mechanics testing, the increment of bearing force at each height point is approximate 50N; it verifies that their mechanics property is excelled.

Abstract: Metal rubber material is a new type of elastic and porous material which develops from metal materials. The macro-structure of metal rubber is reticular just as high polymer, made up of fine metal wires. In this paper, the testing equipment which can test micro-motion of metal rubber is designed and the compressive force-displacement curve along molding of metal rubber has gain. The cure along molding of metal rubber has three different characteristic stages. In different characteristic stages, the deformation of metal rubber material has different micro physical mechanism. The micro physical mechanism of different deformation periods is summarized by the micro analyses of three different characteristic curve stages and the study of metal rubber molding technology. Based on the manufacture technology and molding process, the spring wires in metal rubber material have contacted adequately after molding. The micro physical mechanism of metal rubber material in this stage is produced by blank tear combination deformation in linear elastic of spring wires. Because of the deformation stage is very little; the stiffness of metal rubber material is represented linear characteristic in this stage. The contacted points of spring wires are slide along with deformation increasing. The stiffness of metal rubber material is reduced after early linear deformation stage. The compressive force-displacement curve represents soft characteristic stage in macro- expression. When the most contacted points of spring wires are slide along with deformation increasing, the stiffness of metal rubber material is rapid rise. The exponential reinforcement stage is caused by the strongly constraints among spring wires. The micro physical mechanism can explain the different characteristic stages of metal rubber material on compressive performance.

Abstract: By introducing ZrO2 (3Y) micron powder into the thermit, Al2O3/18%, 21%, 24%, 27% and 30%ZrO2 composite ceramics were obtained from in-situ growth in the melts produced by combustion synthesis. As the volume fraction of ZrO2 is below 27%, the ceramics is comprised of lath-shaped and rod-shaped α-Al2O3 matrix, within the rod-shaped grain the nano-micron fibers are oriented in essentially the same direction. As volume fraction of ZrO2 is over 27%, the ceramics is mainly composed of lamina-shaped grains with alternating α-Al2O3 and t-ZrO2 layers. The flexural strength and the fracture toughness measured simultaneously the maximum values with increasing volume fraction of ZrO2 to 24%, indicating that flexural strength and fracture toughness are simultaneously under the control of rod-shaped grains in which ZrO2 nano-micron monocrystal fibers are embedded.

Abstract: Al2O3/24%ZrO2 composite, which is mainly composed of lath-shaped and rod-shaped α-Al2O3 matrix containing ZrO2 nano-micron fibers, was obtained from in-situ growth in the melts produced by combustion synthesis. The results from XRD, SEM and EPMA showed that, besides the rod-shaped and lath-shaped α-Al2O3 grains, there are also t-ZrO2 or m-ZrO2 independent phases and Cr metallic particles at the boundaries of rod-shaped grains. The strength and toughness were measured to be 1186 MPa and 12.8MPa·m0.5 respectively. The procedure for toughening ceramics relies on coordinated action of multiple toughening mechanisms involving reinforcement-induced toughening by ZrO2 nano-micron fibers, deflection-induced toughening, stress-induced transformation toughening, crack-bridging toughening by lath-shaped α-Al2O3 grains as well as deformation-induced toughening by Cr metallic particles, and promises the occurrence of a sharp rising R-curved behavior.

Abstract: New nano-submicron textured Al2O3-ZrO2 ceramic eutectic composites were obtained from high-temperature melts produced by the SHS metallurgical process with intro-granular and 1-3 composite structures. Nano-micron textured ceramic composites were naturally self-assembled in one quick step by the SHS metallurgical process, in-situ synthesis and symbotic eutectic transformation under high degree of undercooling. The experimental results indicated that the Al2O3-ZrO2 ceramic eutectic composites with ZrO2 fibers at the nano-submicron scale are only suitable for the ceramic composite with hypoeutectic composition under the conditions of the experiment.