SiCp/Cu composites prepared by the dual-directional extrusion process of floating die
SiCp/Cu composites were fabricated by the dual-directional extrusion process of the floating die. The microstructure, wear behavior and conductivity of SiCp/Cu composites were studied by optical microscope, abrasion test and current conductivity instrument. The results show that the SiCp/Cu composites with SiC particle distributed uniformly can be obtained, and the conductivity of composites decreased with the increasing of concentration of SiC particles, the wear resistance behavior of SiCp/Cu composites is evidently better than Cu with the increasing of concentration of SiC particles, the wearing mechanism of composites is a synthetically combined function of micro-cutting wearing and surface peeling off and grain wearing.
Influence of SiC_P Size on Oxidation Resistance and Wear Characterization of SiC_P/Cu Composites
The copper matrix composites reinforced by SiCP with the size of 10 μm, 20 μm and 40 μm were fabricated via powder metallurgy technique. The effects of particle size on the oxidation resistance and wear characterization of SiCP/Cu composites were investigated by oxidation test, wear experiment and SEM. The results indicate that the oxidation resistance of SiCP/Cu is evidently better than that of pure Cu between 400 ℃ and 700 ℃. The composites with SiCP of 20 μm possess the highest oxidation resistance. The wear characterization of SiCP/Cu composites differs obviously with the change of SiCP size. When the applied load is lower than 100 N, the SiCP with larger size is helpful to improve the wear resistance of SiCP/Cu composites, and the wear mechanism is mainly abrasive wear. When the applied load increases, SiCP with larger size is easy to mash. The mechanism is the combined action of abrasive wear and delamination wear. The wear rate is sharply enhanced.
Improved culture method for the isolation of Histoplasma capsulatum and Blastomyces dermatitidis form contaminated specimens.
Studies were performed to evaluate a method for selective isolation of Histoplasma capsulatum and Blastomyces dermatitidis from contaminated specimens. Ammonium hydroxide placed on an agar medium surface was found to inhibit the growth of many bacteria, yeasts, and saphrophytic fungi normally found in specimens such as animal tissues and sputum. In one study involving the culture of B. dermatitidis from canine tissues, 24% more isolations were obtained on a medium using NH4OH compared with a similar medium. Increases in the isolation of H. capusulatum from sputum specimens were also obtained, ranging from 20 to 32% compared with four other media without NH4OH.