Advanced Materials Research Vols. 557-559

Abstract: Vanadium nitride (VN) particulate reinforced Fe-based composite was produced with ferrovanadium, Ferromolybdenum, ferrochromium and nitrogen gas by in situ synthesis process. The microstructure of the composites was characterized by X-ray diffraction and scanning electron microscopy. With the help of differential thermal analysis, reaction process of Fe-V-N system was discussed. The results show that the composite consists of VN and α-Fe phase. VN particles exhibit fine size and homogeneous distribution in Fe matrix. Formation of VN at 674°C is due to the reaction between ferrovanadium and nitrogen gas.

Abstract: In-situ Al3Ti /A356 composites were synthesized by direct melt reaction method in Al-K2TiF6 system. The preparation techniques was discussed and the effects of Si, Mg, La (0.30%), Ce (0.30%) and multiple rare earth (0.15% La + 0.15%Ce) addition on microstructures of Al3Ti /A356 composites were investigated by X-ray diffraction and scanning electron microscope. The results show that the morphology and size of Al3Ti reinforcement are influenced significantly by Si, Mg and the optimal preparation process is composition with latter Si, Mg alloying. The Al3Ti precipitations during solidification process are restrained by 0.30% La addition or 0.30% Ce addition and lead in the uniform of Al3Ti size and morphology. The radial growth of Al3Ti is strongly restrained by rare earth composite addition, and the main morphology is slender-spherical like.

Abstract: TiO₂/SBA-15 and AgCl loaded on TiO₂/SBA-15(AgCl-TiO₂/SBA-15) composites were synthesized by a facile method. All products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and N₂ adsorption-desorption analysis. Photocatalytic activities of the composites were assessed by the photocatalytic decomposition of methyl orange (MO). The results indicated that TiO₂ or TiO₂-AgCl existed in the matrix SBA-15, which reduced the specific surface area, pore volume and pore size of the matrix. The photocatalytic performances of TiO₂/SBA-15 were higher than that of pure TiO₂, and the resultant AgCl-TiO₂/SBA-15 composites showed much higher photocatalytic performances than TiO₂/SBA-15.

Abstract: Abstract. Polypyrrole (PPy)-coated Cu nanocomposites were synthesized in aqueous solution at ambient temperature by situ polymerization of pyrrole. The morphology and structure of the nanoparticles had been studied by scanning and transmission electronic microscopes (TEM), X-ray diffractometer and Fourier Transform Infrared Spectroscopy (FTIR) and the results indicated the nanocomposites were core-shell structure. The electrical conductivity of nanocomposites was 0.0413 S/cm measured by four-probe technique.

Abstract: A chemical modification was adopted to treat the surface of aramid fibers.The influences of aramid fibers on the friability and compression behavior of phenolic foam before and after modification were studied.Compared with unmodified aramid fiber-reinforced phenolic foam ,foam reinforced with modified aramid fibers exhibits significantly lower friability, higher compressive strength and compressive modulus. The thermal conductivity and Oxygen index of modified aramid fiber- reinforced phenolic foam hasn’t obviously been changed compared with the unmodified counterpart.

Abstract: The Carbon nano-tubes (CNTs) reinforced Cu-based (CNTs/Cu) composites were obtained by powder metallurgy processes. The effects of CNTs content on the microstructure, density and hardness of the Cu-based composites were investigated. The tribological properties of the composites were studied by using a ball/disk friction tester. The results indicate that the density values of the composites gradually decrease with the increment of CNTs content, while for the hardness values, firstly increase and then decrease; and the maximal hardness values was obtained when the composite contains 0.75% CNTs. The CNTs content exerts a great effect on the friction coefficient of the composite. It has been found that the anti-wear property of the CNTs/Cu composites is excellent, at the same time, the hardness and density values are also in the reasonable ranges when the CNTs content is relatively low. The concerning mechanism has been analyzed in the present paper.

Abstract: The Al₂O₃ particle reinforced Cu-based composites (Al₂O₃/Cu) were prepared by internal oxidation technology. The electrical arc ablation performance of Al₂O₃/Cu composite was compared with copper H62 through a series of ablation experiments. The results indicate that both the quality lost and ablation diameter of copper H62 samples are larger than those of Al₂O₃/Cu composites in condition of the same ablating current. The large ablation pits observed by scanning electron microscopy (SEM) indicated that the arc ablation of copper H62 is concentrate and serious. The result of energy dispersive spectrometer (EDS) shows that the molten copper alloy of H62 has been transferred and sprayed. However, the arc ablation pits of Al₂O₃/Cu composites are dispersing and slight. The transferring and spaying material of Al₂O₃/Cu composite is mainly from Cu-matrix. The anchoring effect and protection function of the uniformly dispersing Al₂O₃ grains, which are executed onto the Cu-matrix, has been considered to contribute to the excellent arc ablation performance of composite Al₂O₃/Cu.

Abstract: In this work we investigate mechanical properties and structure of PA6/ZnO and PA6/Al₂O₃ nanocomposites to understand the effect of different nanoparticles on the polymer matrix. Mechanical experiment results show that the mechanical reinforcement effect after loading ZnO nanoparticles is better than that of loading Al₂O₃ nanoparticles. At 10% ZnO loading, the elastic modulus increases to about two times of that of pure PA6, and the yield stress increases about 30%. And the elongation at break has no obvious decrease even at high ZnO loading. In order to understand the reason of better mechanical reinforcement after incorporating ZnO nanoparticles, microstructure and crystallization behavior of the samples were investigated. The results indicate that the better reinforcement of mechanical properties after loading ZnO was attributed to enhanced interfacial adhesion between ZnO nanoparticles and PA6 matrix at high ZnO content.

Abstract: Bamboo fiber reinforced resin matrix brake materials were selected as research object, dry and wet friction experiment was conducted on MM200 abrasion tester. Results show that: friction coefficient drops down to a very low level under wet condition, wear rate of samples and counterparts also decreases, but the values of friction coefficient are still in the range of dry friction. Under dry and wet conditions, the tribilogical performance of sample has different relationships with the pressure and speed, especially with the speed. Friction surface was lubricated and cooled by water, in the meantime, the formation of friction film is suppressed, which leads to the differences of the tribilogy performance between dry and wet conditions. Morphologies of fricion surface was observed by SEM, worn surface in wet braking was not covered by friction film, many fine cracks and some patches were scattered over the substrate.

Abstract: Biodegradable composites of wood fiber/PLA were fabricated by using stearic acid and titanate’s regulation on the interface of wood fiber/PLA with injection molding processing. The effects of the dosage of regulation agent on the mechanical and biodegradable properties were discussed. The results reveal that the tensile strength and impact strength were fabricated greatly after the process of regulation agent on wood fiber, however, the effect of titanate is much better than that of stearic acid as regulation agent. Both of them could improve the biodegradable properties of the composite.