Исследование взаимосвязи между износостойкостью при сухом трении и механическими свойствами спеченных композитов системы Al-Sn

Abstract

Effect of tin-insoluble alloying elements (Zn, Si) on the mechanical and tribological properties of the Al-40Sn sintered composite has been studied. Powder mixtures with alloying additions were sintered at a temperature above the melting point of tin (232°C). Sintered specimens had residual porosity, which negatively affected the strength, ductility, and wear resistance of the composite under dry friction. Compression in a closed die and equal channel angular pressing (ECAP) at a temperature of 250°C reduced the porosity of the material and significantly increased its strength and ductility. Regardless of the pressure treatment method, the compacted specimens showed good wear resistance. The main mechanism of composite wear is the exfoliation of matrix grains in the surface layer due to their shift along the tin interlayers in the direction of friction. The shear and peeling of grains were preceded by a strong deformation of the surface layer, in which the grain boundaries with tin interlayers were stretched in the direction of friction, that is, a layered structure was formed. Composites in which most of the grain boundaries of the aluminum matrix are oriented perpendicular to the sliding direction have the maximum wear resistance. A similar structure is formed in the plane of the material flow during ECAP processing. It was found that the wear resistance of a composite with a zinc-doped matrix is higher than with a silicon-doped matrix.