Applied Mechanics and Materials Vols. 556-562

Abstract: This paper deals with the problem of braking process modeling. A subway train braking process simulation software is built, which composes of a GUI and a underlying model. The underlying model consists of a train model and a brake system model. The train model is simplified and built by assembling subcomponent element models of a railway vehicle. The brake system model is simplified and built based on experimental data in order to reduce computational effort. The GUI of the software can be use to input model parameters, display simulation results, and store simulation data. As a result of the simplifications of the modeling process, the developed software can perform real time simulation.

Abstract: SiC particles were coated with copper and nickel respectively through electroless plating process to investigate the plating effect on mechanical properties of SiCp/Fe composites. It shows that tensile strength and final elongation of the composite improve significantly after the plating treatment of SiC particles. Compared with the composite reinforced by uncoated one, the maximum increase of tensile strength is 20.1% reinforced by nickel-coated SiC particles with the particle size of 21μm and volume fraction of 20%. The maximum tensile strength among the SiCp/Fe composites reaches 928.3MPa where the composite is reinforced by nickel-coated SiC particles with the particle size of 13μm and volume fraction of 10%. In contrast with that reinforced by uncoated SiC particles, the highest increment of final elongation is 19.6% reinforced by copper-coated SiC particle with the particle size of 13μm and volume fraction of 20%. Electroless plating on SiC particle surface may effectively prevent the direct contact in the interfaces between the SiC particles which can reduce the risk of micro-crack formation, so as to improve the properties of composite.

Abstract: Through the classical molecular dynamics, the melting properties of the the tungsten and aluminum mixed clusters are explored. By using simulated annealing the structure of the mixed cluster is obtained. It is found that the Al atoms tend to locate on the surface of the clusters. The melting behaviors of the clusters are analyzed in detail by the atom-resolved Lindemann index. The curves of Lindemann index show that the melting process of the can experience three steps which is not common in the melting process of the nanoclusters.

Abstract: In this paper, we report a significant improvement in mechanical and oxidation properties of near eutectic Nb–Si alloys by the addition of aluminum (Al) and control of microstructural length scale. Thus in order to develop new alloys, we have to choose proper alloying elements keeping all the above issues in mind. Among the non-transition elements such as Al, Ga, Ge, Sn, and Al is most attractive from the point of view of enhancing the oxidation resistance and room temperature ductility due to substitution of Si with metallic Al . Al forms oxides which are even more thermodynamically stable than Si and Nb based oxides. Al is also soluble in Nb to a greater degree in conjunction with other refractory elementsFig.1 The figure shows composite X-ray diffraction patterns of each sample exposed to air for one hour in a TGA furnace at above mention temperatures.

Abstract: The effects of B₂O₃ on the sinterability and microwave dielectric properties of Ca [(Li_1/3Nb_2/3)_0.95Zr_0.05]O_3−δ ceramics were investigated. B₂O₃ doping can effectively reduce sintering temperatue by 150~200oC. The temperature coefficient of resonator frequency τ_f increased with an increase of B₂O₃ content and sintering temperatue. When B₂O₃ of 2wt% were added, the optimum microwave dielectric properties: ε_r =28.7,Qf =13580GHz and τ_f = − 7.8×10⁻⁶/oC were obtained at the sintering temperature of 950oC.

Abstract: The effects of ZnO-B₂O₃-Na₂O(ZBN) glass on the sinterability and microwave dielectric properties of Ca [(Li_1/3Nb_2/3)_0.92Zr_0.08]O_3−δ −0.05TiO₂ ceramics were investigated . ZBN glass doping can effectively reduce sintering temperatue by 100~150oC. The temperature coefficient of resonator frequency τ_f increased with an increase of ZBN glass content and sintering temperatue. When ZBN glass of 1.8wt% were added, the optimum microwave dielectric properties: ε_r =32.8, Qf =13420GHz and τ_f = − 4.3×10⁻⁶/oC were obtained at the sintering temperature of 1000oC.

Abstract: Aluminum salt flame retardants have been synthesized by the chemical method under different reaction conditions. And then, the influence of the reaction temperature, ammonia concentration, aluminum ion concentration and addition on the thermal decomposition characteristics of aluminum salt flame retardants is analyzed and discussed on the basis of the experimental results obtained by using thermogravimetric and differential thermal analysis. Seeding experiments with the current work may have significant potential towards the exploration and development of inorganic salt flame retardants with good thermal decomposition performance.

Abstract: Magnesium salt flame retardant is an additive flame retardant with environmental protection performance, which has been successfully applied in various industries because of its many advantages. In this paper, the chemical precipitation method is used to prepare magnesium salt flame retardants with different alkali sources (sodium hydroxide and ammonia) and reaction temperatures. And then, study on the thermal properties of all samples is systematically carried out on the basis of differential thermal analysis. These investigations could build up a link between the thermal property and growth behaviors of magnesium salt, which may offer us theoretical help.

Abstract: Based on the density functional theory method, the ab initio calculation with GGA+U was performed to investigate the electronic structure and properties of W-doped TiO₂. The results indicated that W-doping induced ferromagnetism and shifted the absorption spectra to visible light region. The ferromagnetism derived from the spin-split of O 2p and W 5d caused by p–d orbit hybridization. Several impurity bands under the conduction band decreased the band gap.

Abstract: Amorphous NiB supported on expanded vermiculite (EV) catalyst was prepared as an example to show the superior characteristics of EV as a novel carbon support material. EV and the prepared catalysts were characterized by ICP, SEM, TEM and SAED. The catalytic activity of prepared catalysts was tested by the hydrogenation of sulfolene to sulfalone, with the introduction of ultrasonication the NiB/EV-U catalyst performed very high catalytic activity.