Effects of Microstructure on Wear of Aluminium Bearing Alloys with Systematic Variation of Hard and Soft Phases

Abstract

By systematic variation of the amount and size of silicon and tin inclusions, two types of aluminium alloys are modified to display the effects of hard and soft phases on wear at low and high rates, using pin-on-disc testing devices. The predominant wear mechanism when sliding against steel is delamination. Three types of wear curves were found for the different alloys: constant rate, continuously dropping rate, and a transition from significant to zero wear. Enrichment of silicon in the pin surface and smoothening of the roughness of the disc are the major factors for decreasing wear rates. A sufficiently large size of the silicon particles is essential for preventing their break away. If the particle size in the cast alloy is below the critical size, this can be adjusted by heat treatment. The amount and size of the soft particles is found to affect seizure but to be less critical in mild wear. Therefore, synergistic effects become relevant when the wear mechanism is changing.