Advanced Materials Research Vols. 535-537

Abstract: MgO-CaO-ZrO₂ composite materials were prepared in oxidizing atmosphere at 1550 oC with sintered magnesia, calcium oxide and partial stabilized zirconia as raw materials. Sintering performance of the composites was measured by the checking of the bending strength, the apparent porosity, the thermal expansivity and the thermal shock resistance of samples, respectively. The phase compositions and microstructures of the composites were investigated by XRD, SEM and EDS. The results showed that CaZrO₃ phase was formed by high temperture reaction between ZrO₂ and CaO, and phase compositions of the composites consisted of two phases of CaZrO₃ and MgO. The sintering performance of composites were promoted further with increasing the content of ZrO₂ due to the volume expansion caused by the reaction of the added ZrO₂ and CaO to form CaZrO₃ phase in the refractories.

Abstract: The low cerium oxygen-storage materials of Ce-Zr-Mn composite oxide were prepared by co-precipitation method. The materials were characterized by XRD,BET, OSC and so on. The results show that the precursor is prepared using ammonia as the precipitant at pH=10-13, T≥20°C. The precursor is calcined to form a fresh oxygen-storage materials at 700 °C for 5h. It has single crystalline phase -the solid solution Ce _0.45 Zr0_.45-x Mn _x Y _0.1 O _1.95 ,which has the cube structure of ZrO₂ and contains Mn,Y. Phase structure in the materials is stable in the aging process.The addition of Mn in the oxygen-storage materials contributes to raise oxygen-storage performance of the materials. The materials has the better oxygen-storage performance and heat stability when Mn content in the materials is 0.03.

Abstract: Based on aluminum powder, Silicon powder, activated alumina and flake graphite as the main starting materials, SiAlON-Graphite composites were produced in N₂ atmosphere. The influence of firing temperature and atmosphere on Si-Al-O-C-N system was investigated. It is proposed that the introduction of graphite produces a certain CO partial pressure and affects the nitridation of metal silicon, therefore reducing the mass change. In addition, large amount of 15R are formed through carbothermic reduction. CO hinders the growth of β-SiAlON. Z value of β-SiAlON in sample C with graphite is less than sample S without graphite.

Abstract: In order to investigate the energy absorption of carbon fiber reinforced polymer (CFRP) under different impact velocity, ABAQUS finite element analysis software was used to simulate the impact experiments under the velocities of 1～100m/s. The kinetic energy reduction of the bullet was analyzed. The results shows that: the energy absorption of the composites panel improves with the initial impact velocity increasing, while as the velocity increasing to a certain value, such energy absorption approaches a constant value. And taking further analysis found that property of impact resistance of CFRP has a speed effect, with the strain rate increasing, the dynamic mechanical properties improve.

Abstract: We reported the synthesis of a promising carbon nanofiber-titania-cordierite monolith composite (C/TiO2/monolith) and its application in citral hydrogenation. The composite was synthesized through two steps: TiO2 coating on the surface of the monolith with sol-gel method and the following carbon deposit by methane decomposition. C/TiO2/monolith was subsequently employed to prepare its supported palladium catalyst, Pd/C/TiO2/monolith and its catalytic performance was evaluated in selective hydrogenation of citral. Results revealed that 2.0 wt% tetrabutyl titanate sol in composite synthesis was the best in improving textural properties of C/TiO2/monolith. The optimal composite possessed a BET surface area of 39.4 m2/g and micropore area accounted for only 3.8% of its total BET surface area. It contained about 30 wt% of carbon, which was mainly composed of carbon nanofiber. Pd/C/TiO2/monolith exhibited the high citronellal selectivity (81%) at 90% citral conversion, which was attributed to the decrease of internal diffusion limitation due to its mesoporous structure.

Abstract: Due to numerous attractive properties, use of composites is in increasing trend. Efforts are being made to develop new composites securing their useful properties at optimum level for more demanding applications. The purpose of this project is to optimize the mechanical properties of composite (polypropylene + wood fiber) using Central Composite Design (CCD) technique. Accordingly experiments were conducted to develop mathematical models in terms of three process parameters - composition (percentage of PP and wood fiber), injection pressure (bar), and time (second) for functional characteristics such as tensile strength and water absorption. Design expert software was used for convenience to carry out the analysis with a view to identifying the optimum level of the processing parameters for securing the desirable properties of the composite.

Abstract: Cobalt-boron complex were prepared as a novel adhesion promoter. It was characterized by the infrared spectrum and the UV spectrum. The maximum absorption wavelength of cobalt-boron complex is in 285nm by the UV spectrum. And the fluorine rubber / metal composite sealing boards were prepared with cobalt-boron complex. The results show that the sample with cobalt-boron complex has better scratch resistance, higher impedance resistance than that without cobalt-boron complex; meanwhile the sample with cobalt-boron complex also has a better bonding situation. In the most optimal process conditions, the scratch resistance value of the composite sealing board is 3800g.

Abstract: This paper mainly uses nonlinear finite element software ANSYS/LS-DYNA to simulate the impact response of the sandwiched polyurethane composite steel tube as well as the traditional steel pipe. Comparative numerical simulation experiments were carried out in which sandwiched polyurethane tube and steel tube with the same mass were respectively collided with rigid balls in the same velocity. The paper mainly analyzes the maximum collision force, absorbing energy and the maximum collision depth of the rigid collision ball of the two different types of tube. Then it concludes that the sandwiched polyurethane composite pipe crashworthiness of the collision is better than that of the traditional steel tube.

Abstract: In order to get high microwave absorbing properties, a new kind of three-layer structure composite absorption material was designed and prepared for optimal attenuation. Manganese Oxide was used as the absorbent in the matching layer. Nickel-Zinc ferrite (Ni-Zn ferrite) was used as the absorbent in the dielectric layer and Graphite was used as the absorbent in absorbing layer. The effects of different proportions of absorbents on the microwave absorbing properties were investigated. The results shows that the maximum wave absorbing peak of the 11# sample with the thickness of 5mm is −38.54dB at 14.35GHz and had a bandwidth of 7.1GHz (R<−10dB). This is very important in the design and application of absorbing material.

Abstract: In situ Al_0.983Cr_0.017 intermetallic compounds reinforced aluminum matrix composite was fabricated by the mechanical stirring casting method in this paper. In addition, microstructure and corrosion resistance of composite was investigated by XRD and SEM. The results show that the Al_0.983Cr_0.017 intermetallic compounds reinforcement distribute in the matrix uniformly. The clean interface between reinforcement and matrix has good interfacial bond. The corrosion resistance of Al_0.983Cr_0.017/Al composite materials presented a U-shaped curve, the best corrosion resistance present in the composite with 12% volume fraction reinforcement. The Al_0.983Cr_0.017 has a high corrosion resistance, which promoted the nucleation of pitting. Furthermore, the reinforcement interrupt the continuity of the matrix, inhibits the further expansion of pitting, which increases the corrosion resistance of composites.