Yiping Tang

Tribological behavior of short carbon fiber or hybrid with SiCp reinforced Al alloy composites

Abstract Aluminum alloy matrix samples reinforced with short carbon fibers or hybrid SiCp composites were prepared, and friction and wear tests were carried out on a wear test machine using a rotation ring on a stationary disk at high load. Optical microscopy, scanning electron microscopy and energy-dispersive analysis of X-rays were used to investigate the composites, worn surface, wear debris and composition changes after wear. By comparison with Al alloy, Al/SCF and Al/SCF/SiCp, the results indicate that the incorporation of SCF into Al alloys improves the wear resistance significantly, the combination of a mechanically mixed layer formed on the worn surface and hard SiCp are responsible for the good tribological properties of the hybrid Al/SCF/SiCp composites at high load. During sliding, an obvious decrease in the temperature rise with SCF addition is attributed to the good anti-friction of SCF.

Matrix induced synthesis of Y3Al5O12: Ce phosphor through the Pechini method

Abstract Trivalent cerium actived yttrium aluminum garnet (YAG: Ce) phosphor was prepared using the Pechini method. Phase transition during calcination was investigated through Fourier transform infrared spectroscopy and X-ray diffraction. The results show that the powders directly transform into the pure YAG phase at 80°C. The dimension of phosphor calcined at 1200°C is micro-scale, which consists of nanometer scale primary particles. The effect of Ce doping content and calcination temperature on the luminescence properties is also discussed. The maximum emission is obtained for about 1 at.% Ce additions. The concentration quench effect is observed when Ce content increases beyond this limit. With the increment of calcination temperature, the emission intensity and lifetime increase.

Investigation of Cu-graphite composites prepared by electroforming

Abstract In this work, Cu-graphite composites were prepared by electroforming technology in an acidic copper sulfate bath with graphite particles in suspension. The factors affecting the codeposition of graphite particles with copper were studied. At a particle concentration of 20gl−1, a current density of 3Adm−2 and a stirring rate of 100min−1 graphite content in the composites was 21.7vol.%. Microhardness and friction coefficient of the composites decreased with increasing graphite content. However, wear mass-loss decreased, but increased with graphite content above 21.7vol.%. The wear mechanisms of pure Cu and Cu-graphite composites were adhesive wear and delaminating wear, respectively.