STP1559

    Evaluation of the Effects of Anodization on the Fatigue Performance of Titanium Alloy

    Published: Sep 2013


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    Abstract

    Titanium is a widely accepted metal used to manufacture orthopaedic trauma implants that are typically anodized. Type II anodization potentially improves fatigue strength and provides an increased resistance to galling and fretting wear. Color anodization (Type III) imparts a color to the titanium surface, providing aesthetic appeal and aiding in identification. The purpose of this study was to compare the fatigue performance of Ti-6Al-4V alloy test specimens using both anodization processes. Simulated intramedullary nails and commercially available cortical screws were both evaluated. Cannulated rods with a transverse hole were used to simulate the distal geometry of an intramedullary nail; as-machined rods, color anodized rods, and Type II anodized rods were evaluated. For the cortex screws, one group was color anodized, the other was Type II anodized. Four-point bend fatigue testing based on the recommendations of ASTM F1264-03 was employed. The results showed that when the cross-sectional geometry of the test specimens are the same, as with the cannulated rods, there was a statistically significant difference (p < 0.05) between as-machined and Type II anodized rods. There were not statistically significant differences (p > 0.05) between either as-machined and color anodized rods, or between color anodized and Type II anodized rods. In the case of the cortical screws which had cross-sectional differences, the color anodized screws with the larger minor diameter showed an improved fatigue performance, at multiple force levels, over the Type II anodized screws, which had a smaller minor diameter. These results indicate that surface finish and design both play roles in the fatigue performance of trauma implants.

    Keywords:

    titanium, anodization, biomechanics, trauma, mechanical testing


    Author Information:

    Whitten, Andy
    Smith & Nephew, Inc., London,


    Paper ID: STP155920120205

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP155920120205


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