| In recent years, medical materials have a continuous development, as a kind of potential medical material, pure titanium has attracted much attention in biomedical application because of better corrosion resistance and biocompatibility, especially without toxic element. But there is a complex physiological environment in human body, it is inevitable for pure titanium to generate corrosion phenomenon when it is implanted in the body, this situation will release metal ion and influence metabolism normally. It is significant for titanium in medical application to change its microstructure and improve its corrosion resistance, through the method of heat treatment and equal channel angular pressing(ECAP).In this paper, CP-Ti and Ti-0.2Pd have been chosen to be the object of study, different kinds of microstructure of CP-Ti and Ti-0.2Pd were made after heat treatment and ECAP technique which used ECAP die and heating furnace. The microstructures of two metal were observed by optical microscope. Electrochemical corrosion resistance of two metal were conducted by electrochemical workstation. Study changes of open circle potential, polarization curve and EIS during corrosion process and analyze the effect of different microstructures on corrosion resistance of two metal.The results show that corrosion potential was improved, corrosion current density was decreased, and polarization resistance was enhanced after ECAP and heat treatment, meanwhile charge transfer resistance of two metal was increased in EIS. Fine grained microstructure after ECAP and martensite microstructure after water quenched have more effects on corrosion resistance than lath-shaped microstructure after furnace cooled and equiaxed grain microstructure after air cooled. Ti-0.2Pd after ECAP has two time constant and which generate double layer structure to improve resistance. In a word, corrosion resistance of CP-Ti and Ti-0.2Pd can be improved effectively after ECAP and heat treatment. |
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