Influence of Duplex Treatment on Structural and Tribological Properties of Commercially Pure Titanium

Titanium and its alloys are widely used in many fields, including aerospace and the chemical and biomedical industries. This is due to their mechanical properties, excellent corrosion resistance, and biocompatibility although they do have poor wear resistance. In this study, a duplex layer was successfully formed on the commercially pure titanium surface by duplex treatments (plasma nitriding and physical vapor deposition (PVD)). In the initial treatment, plasma nitriding was performed on the pure titanium samples and in the second treatment, the nitrided samples were coated with CrN by PVD. The friction and wear properties of the duplex-treated samples were investigated for tribological applications. Surface morphology and microstructure of the duplex-treated samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). In addition, the tribological properties were investigated using pin-on-disc tribometer. A compound layer composed of epsilon-Ti2N and delta-TiN phases and a diffusion layer formed under the compound layer were obtained on the surface of pure titanium after the nitriding treatments. CrN coated on the nitrided surface provided an increase in the surface hardness and in the wear resistance.