Development of a lead-free aluminium bearing alloy using powder metallurgy manufacturing techniques

Ward, Andrew (2015). Development of a lead-free aluminium bearing alloy using powder metallurgy manufacturing techniques. University of Birmingham. Eng.D.

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Abstract

This study, completed with the University of Birmingham, was sponsored by Controls and Data Services (CDS) and the Engineering and Physical Sciences Research Council (EPSRC). A range of materials and processes were evaluated with the aim of producing a lead-free, monolithic, machinable plain bearing to replace the leaded bronze gear pump bearings currently used.
The primary alloys investigated in this thesis were Al-20Sn-7Si-1Cu and an Al-20Sn-7Si- 1Cu-1Mg wt% composition; with the latter achieved by the controlled addition of Al- 50Mg wt% master alloy.
The project identified an aluminium-tin-silicon based alloy that could be sintered to near 100% of theoretical density in the manufacture of a ¾ scale rod form. The process and material produced should be capable of replacing the bearing alloys typically used in aerospace pump applications.
The addition of magnesium, with controlled morphology and size, and the parallel use of a nitrogen sintering atmosphere, significantly improved the heat treated density of these materials. Successful sintering, typically completed at 500°C, could be significantly reduced in time by the use of pressurised nitrogen from 20 hours to 5 hours. The sintered microstructure generated was a heat treatable aluminium / copper matrix with desirable, discrete regions of silicon (typically 3 – 4 microns in size) and reticular tin.

Type of Work:

Thesis (Doctorates > Eng.D.)

Award Type:

Doctorates > Eng.D.

Supervisor(s):