Authors: R Bailey Y Sun
Publish Date: 2015/02/21
Volume: 24, Issue: 4, Pages: 1669-1678
Abstract
In the present work the corrosion and tribocorrosion characteristics of thermally oxidized commercially pure titanium in a 09 NaCl solution have been investigated Thermal oxidation TO of CPTi was carried out at a temperature of 625 °C for 20 h This treatment results in a multilayered structure consisting of a 1 µm rutile TiO2 film and a 9 µm αtitanium oxygen diffusion zone ODZ αTiO Electrochemical tests were carried out on surfaces created at various depths from the TOTi original surface It was found that the rutile film generated through TO offers excellent corrosion resistance over that of untreated Ti Testing also provided evidence that oxygen content in the upper part of the ODZ depths 5 µm from the surface helps accelerate passive film formation and thus reduce the corrosion of CPTi Triboelectrochemical testing of TOTi was carried out against an alumina counter face under a load of 2 N and various anodic and cathodic potentials It is initially shown that the rutile oxide layer offers both low friction and much better resistance to material removal during tribocorrosion than untreated CPTi During sliding wear at open circuit potential four frictional zones can be identified in a typical friction curve each having its own characteristics corresponding to the oxide layer the gradual or partial removal of the oxide layer the diffusion zone and the substrate An unusual anodic protection behavior of the oxide film has also been observed When the TOTi is polarized anodically during sliding the durability of the oxide layer is prolonged resulting in low friction and much reduced material loss When cathodically charged to −1500 mVSCE during sliding both the TOTi and untreated CPTi experience a reduction in material loss This is believed to be related to hydrogen evolution and titanium hydride formationOne of the authors RB would like to acknowledge the financial support of De Montfort University for providing a PhD scholarship Special thanks are also due to The Alderman Newton’s Educational Foundation The Sidney Perry Foundation and The Wyvernian Foundation for providing additional financial support during the course of this work
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