Surface treatment of a low-cost beta titanium alloy to combat wear

Redmore, Eleanor (2011). Surface treatment of a low-cost beta titanium alloy to combat wear. University of Birmingham. M.Res.

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Abstract

The development of an effective ceramic conversion treatment of TIMETAL LCB (Ti-6.8Mo-4.5Fe-1.5Al) has been investigated. Various characterisation methods were used to analyse samples in order to identify the best process conditions including SEM, EDX, XRD, GDS, micro-indentation and scratch testing. A solution treatment temperature of 850°C was used as this is the appropriate temperature for the mechanism of solution treatment according to the β-transus temperature of this alloy. The results show that a solution treatment of 0.5 hours produces an acceptable thickness of oxygen hardened case, an almost equal hardness to that of a longer treatment and a far better oxide layer, than a longer treatment time did, in terms of adherence to the substrate. An aging temperature of 500°C was found to be the best as a lower temperature than this produced too thin an oxide layer and a higher temperature meant the oxide layer became exceedingly brittle. An aging time of 8 hours was found to be best as this gave good hardness, good performance in both static and dynamic loading and good wear resistance. The wear testing results show that the tribological properties of the TIMETAL LCB alloy have been significantly enhanced by the new ceramic conversion treatment specifically developed for beta alloys. The improved friction and wear properties can be attributed to the low-friction TiO\(^2\) outer oxide surface layer supported by a Ti\(^3\)O\(^5\) inner oxide layer and an oxygen diffusion hardened case up to a depth of ~70μm.

Type of Work:

Thesis (Masters by Research > M.Res.)

Award Type:

Masters by Research > M.Res.

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