Materials Science Forum Vols. 561-565

Abstract: This study is considered as a method for producing multifunctional metal composite materials by using Single-walled Carbon Nanotubes (SWNTs). In this research, various metals (Ni, Cu, Ag ) were successfully deposited onto the surface of SWNTs. It has been found that homogenous dispersion and dense nucleation sites are the necessary conditions to form uniform coating on SWNTs. Functionalization has been applied to achieve considerable improvement in the dispersion of purified single-walled carbon nanotubes. A three-step electroless plating approach was used and the coating mechanism is described in the paper. The samples were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The application of coated SWNTs in Titanium will be discussed in this paper.

Abstract: Effects of solid particles on wear behavior of dispersion-hardened alloy were investigated using Cu-SiO2 alloys containing 0.6vol.%SiO2, 1.2vol.%SiO2 and 1.7vol.%SiO2 particles. Wear tests were made using pin-on-disc type wear machine. Wear property of the Cu-SiO2 alloys is improved by increasing volume fraction of SiO2 particles. Moreover, wear amounts of Cu-SiO2 alloys increase with increasing the sliding distance, and then are saturated at exceeding about 1km. This is why that SiO2 particle improves the strength of Cu-SiO2 alloy, and that the work hardening occurs on worn surface. Wear-induced layer is formed just below worn surface by severe plastic deformation due to wear, and its hardness increases as the volume fraction of SiO2 particles increases. From these obtained results, wear process of Cu-SiO2 alloy was discussed.

Abstract: Polystyrene fibers were fabricated by electrospinning. Polystyrene resin was dissolved in chloroform, N,N-dimethylformamide, or their mixtures. In experiments with 10 wt-% solutions of polystyrene in various solvents, a 1:1 solvent mixture was found to be optimal. In the 1:1 solvent, an increase in polystyrene concentration resulted in a decrease in the number of beads on the electrospun fibers and an increase in their diameter. A 20 wt% solution of polystyrene gave fibers with a diameter of about 1.8 $m with almost no beads. Polystyrene fibers containing nanoparticles were prepared by electrospinning 20 wt% polystyrene solutions containing dispersed nanoparticles of TiO2 or ZnO. The concentrations of nanoparticles in the electrospun fibers, determined by energy dispersive X-ray spectroscopic analysis, were less than expected.

Abstract: The surface nano-deformation behavior in metal matrix composite during tensile loading was investigated by in-situ atomic force microscope (AFM) observation. The composite material used was aluminum matrix reinforced with 10 and 20 percent volume fraction of SiC particles. The average size of the reinforcement was 3 μm. Tensile test and in-situ observations were conducted using a loading device equipped with an AFM. Surface morphologies of the composite specimens were acquired before the loading and at various stages of the loading. The microstructural damage and the evolution of surface roughness were studied. The effect of volume fraction of the reinforcement on the nano-deformation behavior and damage evolution process of the composite based on nanoscale in-situ AFM observation will be discussed.

Abstract: Results of the investigation of composite materials of new type, based on basalt fiber and polyester resin, are presented, in particular, a long-term resistance of the material in corrosive media: in caustic soda as well as in sulphuric and nitric acids of 1% concentration has been estimated. The service life of given composite is recommended in above-mentioned media.

Abstract: The effect of boron on the WC morphology and on the grain size of binders in sub micron WC composites containing Fe60Al40 and Ni3Al binders was investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composites were prepared under uniaxial hot pressing of milled powder samples at 1500 °C in inert argon atmosphere. Doped aluminides with boron levels ranging from 0 to 0.1 wt% were used as the binders. It was found that the microstructural characteristics of boron doped aluminide WC composites were similar to those of hot pressed WC-Co and commercial grade WC-10wt%Co (H10F) hardmetals. The contiguity of WC particles (WC/WC contact) and the grain sizes of aluminides decreased and the extent of faceting of tungsten carbide increased in the aluminide tungsten carbide composites in presence of boron.

Abstract: The damping capacities of B/Al composite subjected to thermal-mechanical cycling (TMC) were studied. The damping capacities, including the mechanical loss Q-1 and the logarithmic decrement δ , increase with increasing the TMC cycles. The damping capacities of B/Al composite increase more greatly under the elevated applied stresses at the same temperature interval and cycles. After the TMC, the damping capacities can increase 10 times than that of as-fabricated B/Al composite. The damping behavior of B/Al composite under the present test condition is primarily associated with the interfacial degradation during the TMC.

Abstract: 1,2-aceanthrylenedione was synthesized through the acylation reaction of anthracene and oxalyl chloride catalyzed by anhydrous AlCl3. The effects of various reaction conditions on the yield and selectivity of 1, 2-aceanthrylenedione were studied by GC analysis. The results show that the optimum synthesis conditions of the acylation reaction are as follows : the molar ratio of oxalyl chloride to anthracene being 1:2, the molar ratio of anhydrous AlCl3 to anthracene being 4:1, the reaction time being 5 h, the reaction temperature being 303k and the solvent of the reaction system being CS2. Under those conditions, the yield and selectivity of 1, 2-aceanthrylenedione is 83.8 % and 92.3% respectively. Pure 1, 2-aceanthrylenedione was prepared by extraction and recrystallation. The structure of 1, 2-aceanthrylenedione was identified by measure of melting point, GC/MS, FTIR and 1HNMR analyses.

Abstract: The high temperature oxidation behaviors of the Ti3SiC2-SiC ceramic composites fabricated by in situ synthesis under hot isostatic pressing were studied by DSC. The results show that the growth of the oxide scales on Ti3SiC2-SiC ceramic composites obeys a parabolic law in air. The oxidation resistance at 1400°C is better than that at 1200°C for long time. The oxidation resistance of the Ti3SiC2-SiC ceramic composites is much higher than that of monolithic Ti3SiC2. The mechanism of oxidation of Ti3SiC2-SiC ceramic composites is discussed.

Abstract: This paper deals with the microstructure and property of zinc based composites ZA27Six under the treatment of the sodium salt and the rare earth. The test material was prepared with pure zinc ingot (Zn≥99.99wt %) and the Al-Si matrix alloy. Basic composition of the test sample was Al (25~30 wt %), Si (2.5~6.0 wt %) and Zn for the rest. Impact toughness test, tensile test and wear test were conducted. The test results show that under the treatment of sodium the massive primary silicon crystal can transform to nodular silicon on which eutectic silicon crystal can form and grow in rod-like. It is also found that the combined effect of rare earth and sodium salt can obviously refine the silicon phase and the zinc based composites enhanced by nodular silicon has better hardness and wear- resistance.