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CP-Ti, Ti 6A l 4V (ELI), and Ti 6Al 7Nb are often used for manufacturing osteosynthesis products or implants. However, researches have revealed that Al and V can have detrimental effects on the human body. Therefore, several Al- and V-free near-α and (α+β) titanium alloys have been developed on the basis of CP-Ti Grade 4+ (Ti 0.4O 0.5Fe 0.08C). They should possess similar or better mechanical properties than Ti 6Al 4V (ELI) combined with an improved biocompatibility and good corrosion resistance. O, C, Fe, Au, Si, Nb, or Mo have been used as alloying elements, which are either already present in the human body or are biocompatible. Several of the studied alloys show a strength and ductility fulfilling the requirements of Ti 6Al 4V ELI as specified in ASTM F136. For instance, Ti 0.44O 0.5Fe 0.08C 2.0Mo exhibits a YTS of approx. 1005 MPa, an UTS of approx. 1015 MPa, and an elongation at rupture of at least 17%. Therefore, one or more of the studied alloys are promising candidates for replacing Ti 6Al 4V ELI in osteosynthesis and implant applications.

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Wear resistant ceramic coatings were generated on novel commercially pure titanium grade 4+ alloys by the plasma electrolytic oxidation technique (PEO) in an aluminate and zirconia containing electrolyte. The coatings were obtained adopting a full regular two-level factorial design of experiments (DoE) varying the PEO process parameters current density, repetition rate and duty cycle. The generated coatings were characterized with respect to its wear resistance and mechanical properties by reciprocal ball-on-flat tests and nanoindentation measurements. Thickness, morphology and phase formation of the PEO coatings was analyzed by scanning electron microscopy (SEM/EDS) and X-ray diffraction. XRD results indicate the formation of crystalline aluminium titanate (TiAl2O5) as well as t-ZrO2 and alumina leading to an increase in hardness and wear resistance of the PEO coatings. Evaluation of the DoE’s parameter interaction shows that the main effects for generating wear resistant coatings are current density and repetition rate. In particular, the formation of mechanically stable and adhesive corundum and zirconia containing coatings with increasing current density and frequency turned out to be responsible for the improvement of the tribological properties. Overall, the PEO processing significantly improves the wear resistance of the CP titanium base alloy.

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