Study of microstructure and tribological behaviour of spray cast high silicon hypereutectic Al-Si alloy

Abstract

ABSTRACT This paper presents the study of the microstructure, wear properties of spray-deposited and hot compressed Al-35Si and Al-45Si alloys. The microstructure analysis and wear mechanisms of spray formed and as cast alloys were studied by using optical and scanning electron microscope (SEM). The microstructure of the spray-formed alloys showed fine particulate of primary Si and eutectic phases distributed uniformly in the equiaxed Al- matrix. Microstructural refinement was further increased in the hot-compressed alloys. Hardness, dry friction and wear tests were performed on spray formed alloys and compared with as cast alloys. Friction coefficient (COF) and wear rate of the alloys were measured under different applied loads (10–50 N) and sliding velocities of 1 and 1.5 m/s at constant sliding distance of 5000 m. The results indicated that the hardness and wear resistance of spray formed and hot-pressed alloys were considerably high over that of the as cast alloys. The improvements in hardness and wear resistance of spray-formed alloys were mainly attributed to morphology, size and distribution of Si particles induced during spray deposition process. Analysis of worn surfaces by SEM showed dominant wear mechanism of spray-formed alloy was mainly abrasive wear and oxidation wear.