TRIBOLOGICAL BEHAVIOR OF POROUS AL ALLOYS

Abstract

Aluminium alloys are becoming attractive for critical structural applications for their light weight, high specific strength, high corrosion resistance and good heat conductivity. It is suitable for manufacturing many components such as clutch housings in the automotive industry. These alloys can be fabricated using powder metallurgy techniques in which porosity is a common feature. The presence of pores is responsible for decreasing the effective load bearing cross-sectional area and act as a stress concentration site for strain localization and damage, decreasing both strength and ductility. Not only the total area percentage of porosity influences the degradation in properties but the size, shape and inter connectivity of the porosity also play an important role. The present study aims to establish a better understanding of the relationship between surface porosity and corresponding wear behavior. In this study, porous specimens were produced using powder metallurgy techniques. The extent of wear damage and the type of wear was investigated under low load range of 1.5-5N against a AISI 52100 bearing steel ball using a reciprocating ball-on-flat wear configuration and frequency of 10 Hz. Scanning electron microscopy of the wear tracks and wear debris was carried out to identify wear mechanisms. This study revealed that due to the combined effect of the real area of contact and subsurface cracking, wear rate increased with increasing porosity content. The friction and wear behavior of Al A380M, pure Al and Al 6061 as a function of porosity content can be attributed to their hardness and corresponding wear mechanism.