In this study, the effect of incorporation of carbon nanotubes into pure copper was investigated through friction stir processing (FSP). To this end, FSP has been performed using one and three passes. Moreover, the changes in peak temperature of one-pass friction stir processing performed by tools with different shoulder diameters have been recorded. It was found that for the tool with smaller shoulder, the process temperature peak has been significantly reduced. Remarkable reduction in grain size of Cu/carbon-nanotube nanocomposites was observed as compared with the pure copper. Raman spectroscopy results proved a higher extent of degradation of carbon nanotubes upon increasing the friction stir processing passes. On the other hand, microhardness and wear results showed that as the carbon nanotubes are introduced to the pure copper, hardness of composites processed via one-and three-friction stir processing passes showed enhancements of 65 and 105 %, respectively, and the weight losses were also decreased 31 and 68 %, respectively. It was also observed that friction coefficient of one-pass processed composite is lower than that of the pure copper due to the presence of carbon nanotube clusters. Whereas, the friction coefficient of three-pass processed composite was increased regarding to the pure copper. The reduction in slope of wear weight loss upon increasing the applied force at the wear test signified the higher efficiency of the processed composites under harsh conditions.
Friction stir processing (FSP) is a metal-working technique that causes microstructural modification and change in the upper surface of metal components. In this work the effects of tool pin profile on the microstructure and mechanical behavior of reinforced SiC particles metal matrix composites (MMCs) produced by friction stir processing were studied. Optical microscopy (OM) and Scanning electron microscopy (SEM) was employed to carry out the microstructural observations. Vickers Microhardness Machine used for microhardness evaluation. Results show that, tool pin profile play a major role in improvement of the surface quality, SiC particles dispersion in pure copper matrix, hardness behavior and wear resistance. Two different tool pin profile (straight cylindrical and square) were used to perform the process. It was found that, straight cylindrical tool pin profile led to finer grains, uniform dispersion of SiC particles, higher microhardness and wear resistance values.
The main aims of this study is to produce copper reinforced metal matrix composite (MMC) using micron sized chromium particles via friction stir processing (FSP) in order to studying effects of adding Cr particles to copper based matrix by FSP.Microstructures, microhardness and wear properties have been studied in order to evaluate the microstructures and mechanical properties of fabricated composites. the microstructure properties are evaluated by optical microscopy (OM) and field emission scanning electron microscopy (FESEM). The mechanical behaviors of the samples are determined by microhardness and wear tests. The results showed that the grain size of fabricated composite reduced. also it is indicated that in comparison to base copper microhardness of FSPed composites in stir zone (SZ) have been increased significantly. the results of wear test showed that in comparison with specimen with traverse speed of 80 mm/min , higher traverse speed of 160 mm/min increase wear rate of cylindrical pins.
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