Eiji Yuasa1, Toshimasa Morooka1 and Fusao Hayama2
1Department of Mecanical Engineering, Faculty of Engineering, Musashi Institute of Technology, Tokyo
Graphite-dispersed Al-Si alloys were prepared by the combined process of sintering and hot extrusion (sintering/hot-extruding process). The wear characteristics of the products were examined at various sliding speeds and compared with those of sand castings of Al-Si alloys (casting process) and of the graphite-dispersed Al-Si alloys prepared by re-melting and freezing in a quartz tube after extruding the mixture of aluminum, silicon and graphite powders (re-melting process). Effects of the matrix structure and graphite particles on the wear characteristics of these graphite-dispersed alloys were discussed. In the sintering/hot-extruding process the values of wear rates of these alloys with the matrix phase of fine eutectic structure were extremely small in the range of low sliding speeds. In all the alloys the wear rates increased with increasing sliding speed and then attained a peak value. The increment of the wear rate in this range of sliding speeds decreased with increasing silicon content in the matrix phase and with increasing volume fraction of the graphite particles. With a further increase of the sliding speed, the wear rate decreased and attained a small value. However, the contents of silicon and graphite in these alloys exerted a negligible effect on the decrement of the wear rate. When the alloy having a soft matrix phase as with a low silicon content was rubbed in the range of high sliding speeds, the wear rate showed a low value, but it was remarkably increased by adhesion to a counterface as the sliding speed increased.
particle-dispersed composite, aluminum-silicon alloy, graphite particle, solid lubricant, liquid-phase sintering, hot-extrusion, wear rate, sliding speed
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