Microstructure and Properties of Thermally Sprayed Al-Sn-Based Alloys for Plain Bearing Applications

• Published in: Journal of thermal spray technology Vol. 15; no. 4; pp. 634 - 639
• Main Authors: Marrocco, T, Driver, L C, Harris, S J, McCartney, D G
• Format: Journal Article
• Language: English
• Published: New York Springer Nature B.V 01.12.2006
• Subjects: Alloys; Aluminum base alloys; Coatings; Heat treatment; Microstructure; Plain bearings; Spraying; Structural steels; Weight reduction; X-ray diffraction
• ISSN: 1059-9630; 1544-1016
• DOI: 10.1361/105996306X147009

Al-Sn plain bearings for automotive applications traditionally comprise a multilayer structure. Conventionally, bearing manufacturing involves casting the Al-Sn alloy and roll-bonding to a steel backing strip. Recently, high-velocity oxyfuel (HVOF) thermal spraying has been used as a novel alternative manufacturing route. The present project extends previous work on ternary Al-Sn-Cu alloys to quaternary systems, which contain specific additions for potentially enhanced properties. Two alloys were studied in detail, namely, Al-20wt.%Sn-1wt.%Cu-2wt.%Ni and Al-20wt.%Sn-1wt.%Cu-7wt.%Si. This article will describe the mi-crostructural evolution of these alloys following HVOF spraying onto steel substrates and subsequent heat treatment. The microstructures of powders and coatings were investigated by scanning electron microscopy, and the phases were identified by x-ray diffraction. Coating microhardnesses were determined under both as-sprayed and heat-treated conditions, and by the differences related to the microstructures that developed. Finally, the wear behavior of the sprayed and heat-treated coatings in hot engine oil was measured using an industry standard test and was compared with that of previous work on a ternary alloy.