粉末押出しした黒鉛粒子分散Al-Si合金の摩耗特性

Abstract

Graphite-dispersed alloys with the Al-Si matrix phase consisting of various amounts and sizes of silicon particles were prepared by the powder extrusion. Effects of the dispersion of silicon and graphite particles on wear characteristic of the alloy were investigated at various sliding speeds. In the graphite-dispersed Al-Si(C) alloy with the matrix phase consisting of coarse silicon particles, the wear rate has a small value in the range of low sliding speed, but it is remarkably increased at high sliding speed. The increase of the wear rate is caused by plastic deformation of the aluminum phase and its breaking-away at silicon or graphite particles. In the case of the graphite-disparesed Al-Si(F) alloys with the matrix phase consisting of fine silicon particles, the sliding speed which causes a small wear rate is higher than that of the alloy with the matrix phase consisting of Al-Si(C) alloy. The wear rate increases with increasing sliding speed, but it decreased with the formation of hard layer containing aluminum oxide and fine silicon particles, accompanied by the lubricating effect of the graphite particles. This tendency becomes remarkable with increasing silicon and graphite contents. When the sliding surface with an angle θ=90° to the extrusion direction was rubbed, the increase of wear rate with the sliding speed is higher than that in the case of θ=0°. In the graphite-dispersed alloy with the matrix phase prepared from Al-12 wt%Si alloyed powder, the wear rate attains a maximum at a certain sliding speed, then decreases and reaches a minimum with increasing sliding speed. At higher sliding speed, the wear rate again increases rapidly.