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Orthopaedic Proceedings
Vol. 101-B, Issue SUPP_5 | Pages 137 - 137
1 Apr 2019
Oladokun A Vangolu Y Aslam Z Harrington J Brown A Hall R Neville A Bryant M
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Introduction

Titanium and its alloys are attractive biomaterials attributable to their desirable corrosion, mechanical, biocompatibility and osseointegration properties. In particular, β – titanium alloys like the TMZF possess other advantages such as its lower modulus compared to Ti6Al4V alloy. This reduces stress shielding effect in Total Hip Arthroplasty (THA) and the replacement of V in the Ti6Al4V alloy, eliminates in-vivo V-induced toxicity. Unfortunately, implants made of TMZF were later recalled by the FDA due to higher than acceptable revision rates. The purpose of this study was to compare the fretting corrosion characteristics of Ti6Al4V and TMZF titanium alloys. It is hoped the findings will inform better design of β – titanium alloys for future applications in THA.

Method

A ball-on-flat configuration was utilised in this study to achieve a Hertzian point contact for CoCrMo – Ti6Al4V and CoCrMo – TMZF material combinations. These were assessed at a fretting displacement of ±50 µm at an initial contact pressure of 1 GPa. Each fretting test lasted 6000 cycles at a frequency of 1 Hz. A two-electrode cell set-up was used to monitor in-situ open circuit potential (OCP). The simulated physiological solution consisted of Foetal Bovine Serum (FBS) diluted to 25% with Phosphate Buffered Saline (PBS) and 0.03% Sodium Azide (SA) balance. The temperature was kept at ∼37°C. Corrosion products on the worn surfaces and subsurface transformations in both alloys were characterised using the Scanning and Transmission Electron Microscopy (SEM/TEM) to obtain high resolution micrographs. The samples were prepared using a FIB-SEM. Bright-field, dark-field and selected area electron diffraction (SAED) patterns were all captured using a scanning TEM (STEM) and Energy Dispersed X-Ray spectroscopy (EDX) mapping was carried out.