Effect of Microstructures on Corrosion Properties of CP-Ti for Medical Applications

Abstract

The effect of microstructures on the corrosion behavior of commercially pure titanium (CP-Ti Grade 2) immersed in a simulated body fluid is investigated. The corrosion resistance of CP-Ti was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Ultrafine grained, Widmanstätten, martensitic and coarse equiaxial microstructure were obtained by equal channel angular pressing (ECAP), furnace cooled (FC), water quenched (WQ) and air cooled (AC) heat treatment, respectively. The results show that the corrosion resistance of ECAPed, WQ and AC CP-Ti is greatly higher than those of as-received and FC specimens. The microstructure of higher fraction of low angle boundary is presented in WQ and ECAPed CP-Ti, whereas a uniform equiaxial microstructure is presented in AC CP-Ti, which microstructural characteristics are related to higher corrosion resistance. The surface analysis by EIS method shows higher charge transfer resistance of the surface formed on ECAPed CP-Ti and lower Warburg capacitance of the surfaces formed on WQ and AC CP-Ti.