<p>Thermal oxidation of a porous Ti-23Nb alloy for wear related biomedical applications: Effect of oxidation duration</p>


Ibrahim M. K. , Kaba M. , Muhaffel F. , Ağaoğulları D. , Çimenoğlu H.

SURFACE & COATINGS TECHNOLOGY, vol.439, 2022 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 439
  • Publication Date: 2022
  • Doi Number: 10.1016/j.surfcoat.2022.128429
  • Title of Journal : SURFACE & COATINGS TECHNOLOGY
  • Keywords: Porous alloys, Ti-Nb alloys, Thermal oxidation, Wear, Simulated body fluid, TI-NB ALLOYS, MECHANICAL-PROPERTIES, SURFACE MODIFICATION, TI-6AL-4V ALLOY, TITANIUM, BEHAVIOR, SCAFFOLDS, MICROSTRUCTURE, BIOMATERIALS, IMPLANTS

Abstract

In this study, an attempt has been made for tailoring the surface features of an 18 vol% porosity containing Ti-23Nb alloy manufactured via powder metallurgy method. The aim was enhancing the wear resistance without sacrificing the mechanical properties. For this purpose, porous Ti-23Nb alloys having hardness of 280 HV0.025 were subjected to thermal oxidation (TO) at 600 ?C in air for two different holding times. TO duration of 6 h, which introduced a ~& nbsp;0.5 mu m thick TiO2-rutile type exterior oxide layer (OL), provided surface hardness of 620 HV0.025. Extension of TO duration to 60 h caused covering of the surfaces with a 3.0 mu m thick OL and increase of surface hardness to 980 HV0.025. As the result of the increased surface hardness, TO'ed. alloys showed superior sliding wear resistance coupled with a reduction in friction coefficient (COF) against alumina ball in 1.5x simulated body fluid (SBF) when compared to the as-sintered state. Despite having the highest surface hardness, the alloy TO'ed. for 60 h exhibited slightly higher wear loss and COF than the alloy TO'ed. for 6 h. More important than this, the alloy TO'ed. for 60 h collapsed at a compressive stress well below the yield strength of the alloy TO'ed. for 6 h, which exhibited almost similar compressive stress-strain curve with that of the as-sintered alloy. From this perspective 6 h appeared as a promising TO duration for the examined porous alloy to be used in biomedical applications as it preserves the mechanical properties while providing remarkable enhancement in the wear resistance.