Comparative Tribological Study of NiTi Diffusion Coated Titanium with Pure Titanium

Dry tribological behaviors of commercial pure (Cp) titanium and Cp titanium diffusion coated with equiatomic NiTi intermetallic layer were studied and compared at room temperature. Wear tests were performed by a pin on disk tribometer using 52100 steel pins, under various normal loads of 10, 20, and 40 N. worn surfaces were examined by scanning electron microscope, equipped with EDS analyzer. The wear rates of the coated materials were lower than those of the Cp titanium at all loads. This was mainly attributed to the higher hardness of the NiTi intermetallic layer compared to that of the untreated titanium. Furthermore, under an applying load of 10 N, a tribological layer was formed which could protect the surface from severe wear. The results also demonstrated a lower coefficient of friction in the treated specimens compared to those of the Cp materials.