The University of Birmingham

Andrew Bloyce

Peter Harlow Morton

Hanshan Dong

Thomas Bell

A method of case hardening an article formed of titanium, zirconium or an alloy of titanium and/or zirconium is disclosed. First, the article is heat-treated in an oxidizing atmosphere at a temperature in the range of 700 to 1000&deg; C. so as to form an oxide layer on the article. Then, the article is further heat-treated in a vacuum or in a neutral or inert atmosphere at a temperature in the range of 700 to 1000&deg; C. so as to cause oxygen from the oxide layer to diffuse into the article.

Method of case hardening

The tribological behavior of titanium or titanium alloy article is improved by gaseous oxidation of the article at a temperature in the range of 500 to 725&deg; C. for 0.5 to 100 hours, the temperature and time being selected such as to produce an adherent surface compound layer containing at least 50% by weight of oxides of titanium having a rutile structure and a thickness of 0.2 to 2 &mgr;m on a solid solution-strengthened diffusion zone wherein the diffusing element is oxygen and the diffusion zone has a depth of 5 to 50 &mgr;m.

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Worcestershire, United Kingdom

Andrew Bloyce