Advanced Materials Research Vols. 150-151

Abstract: ZnO thin films were deposited by DC reactive magnetron sputtering, and the samples were annealed from 100°C to 400°C, respectively. With the help of x-ray diffractmeter (XRD), spectrophotometer, and photoluminescence (PL) spectroscopy system, the microstructure, intrinsic stress, optical properties, and PL properties were investigated, respectively. The XRD results reveal that all the ZnO films are found to have the hexagonal wurtzite structure with prominent (002) peak. With the annealing temperature increasing, the grain size increased accordingly. All the samples exhibit compressive stress, and the stress value decreasing with annealing temperature increasing. Optical transmittance spectra investigated that all the samples have high transmittance in visible range. With annealing temperature increasing, peak transmittance rising of the sample were observed. The fundamental absorption edge, which associated with band gap of materials, shifting to longer wavelength is observed too. PL results shows that the sample annealed with 300°C have higher intensity emission peak.

Abstract: In this paper, a novel no-asbestos brake composite reinforced by natural bamboo fibers is studied. The bamboo fibers are modified by heat treatment, alkali treatment and coupling treatment respectively. Tribological performance of different fibers reinforced composites are developed by means of friction test and microstructure observation. The results show that heat treatment of bamboo fibers at 140 for 4 hours makes the friction and wear characteristics of brake composites more stable than the untreated ones, but poor wear resistance at low temperature and heat fade still exist. There is no significant change on fiber surface. The alkali treatment of 17% NaOH solution for 12 hours contributes to desirable combination of higher friction coefficients and lower wear rates, and the surface morphology shows a number of deep grooves that avail the interface bonding. The effect of coupling treatment with KH550 on tribological performance of composites have the similar rule to that of the alkali treated ones except of heat fade, and the fiber surface is evenly coated with the coupling agent, which enhances the bonding of fibers and resin but fails at elevated temperature.

Abstract: Copper-iron-based friction materials were prepared by powder metallurgy process. The effects of friction velocity and friction pressure on friction and wear behavior of the material under dry and wet friction conditions were investigated with a constant-speed friction machine. The results show that, at low speed friction, the dry friction coefficient is higher than wet friction coefficient and the friction coefficient increases with increasing friction pressure. The reason is that the water film plays an important role in cleaning and lubricating. At high speed friction, there is not much difference between dry and wet friction coefficients and the friction coefficient is not sensitive to friction pressure changes. This is due to the metal matrix high-temperature softening, caused by high speed friction, which controls the friction properties.

Abstract: The low-stress properties of PTT/wool blended fabrics were investigated by comparing with PET/wool blended fabrics. The results show that, the elongation of PTT/wool fabrics at the maximum load is higher, especially in filling wise, which means PTT/wool fabrics have better elastic. The bending hysteresis, shearing rigidity and shearing hysteresis of PTT/wool fabrics are higher than those of PET/wool fabrics, determining the fabrics having good formability. PTT/wool fabrics are easier to be compressed, and has a little higher surface friction coefficient, giving the fabrics better feeling of softness and fullness. The hand values show that PTT/wool blended fabrics are softer, and have the good bulkiness but not as good as that of PET/wool fabrics.

Abstract: This essay is the subject of national eleventh five support schemes(Number:2008BAB32B14). Applied with testing method, this essay makes a breakthrough in the high-value utilization of iron tailings. According to the tests datas, the cementuous materials acquired from the designed test proved to be qualified for pratical projects. According to the GB/175-2007, the cementuous material sample with 6% iron tailings has got the strenghth that is equal to 52.5# Portland cement; and the cementuous material sample with 10% iron tailings has got the strenghth that is equal to 42.5R Portland cement.

Abstract: Polypropylene(PP)/nano-TiO2 composites were prepared by the melt intercalation molding. Based on the assumption of continuum mechanics model for materials, a finite element analysis model for the composites was constructed using ANSYS 11.0 software. In the stage of deformation (pre-yield regime) the response mechanism of the stress and the strain for composites was investigated, and the von mises stress field of PP/nano-TiO2 composites has also been simulated. It was found that the simulation results are Consistent with the testing results at low volume strain level. The results simulated using the 2D model are accurate with the experimental results. If the volume fraction of particles is less, other particles have little influence on the local stress field of a certain particle, no obvious overlap or cross of the stress field could be found between two neighboring particles. While applying different loads, the stress jumps to maximum stress value in the interaction region of the two phase firstly, and then it occurs that the particles debond with the matrix.