Advanced Materials Research Vols. 311-313

Abstract: The infrared radiation materials of transition metal oxides doped cordierite systems are synthesized using graded solid phase sintering. And the infrared radiation properties are investigated by means of X-ray diffraction, infrared spectrometry and scanning electron microscope. The results show that new compounds are developed during graded heat treatment from 900 °C to 1250 °C. The spinel phases produced are the main crystal material, and the different doped ions and impurity carbon cause the new phases, to different degree defect in this system ,which types can be classified into: (Mg,Zn,□)Fe₂O₄, (Mg,Zn,Co,□)Al₂O₄, (Co,□)Cr2O4,SiC etc., The main diffraction peaks of new phases formed are positioned at the zone (2θ) between 35.227o and 36.837o, and has stretching vibration peaks. And the main infrared absorption peaks located at the low wave number zone indicate to some degree deviation under different doped ions. The doped cordierites have infrared emissivity superior to that prepared with the conventional one-step synthesis. The full wave band integral emissivity of the spinel phases ranged between 0.88 and 0.94 at ambient temperature.

Abstract: In order to analyze the effect of embankment height to dynamic stability, Cross-section in the Beijing-Shanghai high-speed railway is chosen and the numerical simulation calculation method is applying. Distributing rules of dynamic displacement and dynamic stress of the subgrade surface and ground surface, attenuation rules of dynamic response and dynamic stress ratio between pile and soil on the vertical section were studied. It shows that the dynamic stress of pile and soil generally attenuates in depth and attenuation of dynamic stress ratio between pile and soil mostly concentrates into the scope of 10 meters beneath the ground. Moreover, with the increment of embankment height and attenuation of dynamic stress in direct proportion to the depth, the dynamic stress transferring to ground surface decrease and the dynamic displacement of ground surface minish. As a result, the scheme of CFG-pile with 3m scheme is superior to that of 2m scheme for enhancing dynamic stability and reducing dynamic displacement and stress in low embankment. It will be instructive to control design and construction for the low embankment in Beijing-Shanghai high-speed railway.

Abstract: Hemicellulose was separated from bamboo using alkaline method. Silver nanomaterials had been prepared using the hemicellulose as template and silver nitrate as precursor via a green approach. The synthesized samples were characterized by UV-vis, XRD, and SEM techniques. UV-visible spectrum and XRD diffraction pattern revealed that the silver ion (Ag+) had been reduced to the metallic silver nanoparticles (Ag⁰). The results demonstrated that after calcination at 500 °C in air atmosphere, nano Ag/C compound was obtained. The hemicellulose acted as an effective nanoreactor for the in situ synthesis of silver nanoparticles. This novel procedure provides a facile and environmental way to manufacture silver nanoparticles for various applications.

Abstract: Thorough constructing steel-plastic composite material model and using ANSYS finite element analysis software, this research make a CAE analysis and experimental verification to the elastic modulus and flexural modulus of reinforced HDPE composites under different steel structures. The research found that the tensile modulus of steel mash reinforced HDPE linearly increases with the increase of steel wire diameter and the number of steel wires on the specimen width. When the steel wire diameter is 3mm, the tensile modulus is up to 10 times of the pure HDPE’s. The number of steel wires on the specimen length does not affect the tensile modulus. Similarly, the flexural modulus of the composite material also linearly increases with the increase of steel wire diameter and the number of steel wires on the specimen width. However, when the steel wire diameter is 3mm, the flexural modulus is only 2 times of the pure HDPE’s. The data simulated by ANSYS software has a very good agreement with the experiment results. Therefore it can be applied to the actual design.

Abstract: Aluminum-bronze/steel duplex metal has been prepared by aluminum-bronze powder whose compact oxide film was removed by dilute HCl solution before sintering. Scanning electronic microscope (SEM), energy spectrum analysis (EDS), density measurement and compression shear strength test were used to investigate the structure, composition, relative density and bond strength of aluminum-bronze/steel duplex metal. The results show: liquid phase could wet the aluminum-bronze powder washed by acid, improve sintering activity of the powder and increase bond strength of aluminum-bronze/steel interface. The relative density of sintered aluminum-bronze is 99.6%, and shear strength of aluminum-bronze/steel interface is 132.6MPa.

Abstract: The effects of voids on the bending strength of T300/914 laminates that exposed to room temperature, hygrothermal and drying environment was discussed in this paper. The experimental results revealed that the saturated moisture content and the rate of water uptake increased with porosity increasing from 0.71% to 1.50%, which proved that voids facilitate moisture absorption. The bending strength of the unaged, aged and dried specimens were characterized and analyzed. The results revealed that the bending strength of the aged specimens decreased with the increasing void contents and immersion time. Compared to the unaged specimens, the bending strength of the aged specimens decreased 13.33% and 18.78% with porosity of 0.71% and 1.50%, respectively. The bending strength of the dried specimens was higher than that of the aged specimens and lower than that of the unaged specimens in the case of similar porosity.

Abstract: By comparing the Chinese CECS 146:2003, the American ACI 440.2R-02 and the Canadian ISIS Design manual No.4, discussion is extended in terms of ways to improve the performance of concrete structures. Although the Chinese code treats only carbon fibers, the basic concepts for FRP strengthening are common to all three examined design. However, safety factors differ because of the different backgrounds and application experience. The ACI 440.2R-02 goes into great detail concerning FRP materials and utilization where creep and fatigue are important factors. The ISIS manual No.4 gives many design examples and promotes the use of FRP through easy-to-use design charts. The CECS 146:2003 also mentions applications for seismic resistance. Further improvement in the area of design stipulations for use of FRP laminates will include standardization of safety factors, and also promotion of these guides for a wide use around the industry.

Abstract: Michelia macclurei wood with moderate strength is a fast-growing wood in South China. However, it has not been fully utilized. We first prepared it into wood-polymer composite with purpose of good performance by impregnating methyl methacrylate monomer (MMA) into wood pores and following in-situ polymerization. The micro structure of wood-polymer composite, and the morphology and reaction of polymer in wood were characterized by SEM, FTIR and XRD. The SEM observation showed that the MMA monomer polymerized into polymer under the employed conditions and filled up wood cell cavity. FTIR analysis indicated that the monomer rarely reacted with wood cell wall during its polymerization. XRD characterized that the polymer from MMA monomer mainly physically existed in wood pores and remained as an amorphous form.

Abstract: Through 14 group 42 individual specimens of glass fiber bars which diameter is ф10 and ф12 at 20°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, after high temperature, shear test is done , the changing nature and influent factor are analyzed. It indicates from the test results: the surface colour of glass fiber bars is deepening with temperature increasing, becourse combine、decomposition are aggravating with temperature increasing; shear strength is increasing with the diameter getting large; more than certain temperature the glass fiber bars of shear strength is suden drawdown.

Abstract: Fiber composite repair reinforced steel pipeline structure is new technology developed in the nineties of the twentieth century, the technology is highly regarded in the world, has already become a development trend of repair reinforced steel pipeline structure. This paper reviews the problem existing, such as interfacial debonding, layered, empty drum, blank holder and no or incomplete sealing in the repair and reinforcement technique of composite during engineering application. The corresponding formation reason is primarily analyzed according to the construction experience. On the basis, it is pointed out that it is very necessary to establish the check and evaluating indicator system of the field construction acceptance process and field application effect of the fiber composite used in repairing and reinforcing the pipeline, which of the aim is to improve the repair and reinforcement quality and to obtain a full and clear understanding about the repair status and effect of the repair points in the repaired service pipeline.