Galvanic corrosion behavior between Ti6Al4V and CoCrMo alloys in saline solution

摘要

The galvanic corrosion behaviours of two commonly used metallic materials used in artificial joints in saline solution are investigated. Electrochemical testing techniques such as open-circuit potential (OCP), galvanic current (I_g), dynamic polarisation curves and electrochemical impendence spectroscopy are used to evaluate the corrosion properties of the alloys under various immersion times. The following results are obtained: the galvanic current increases with increased immersion time; compared with static corrosion, the corrosion potential (E_(corr)) and corrosion current density (I_(corr)) of coupled Ti6Al4V alloys display inconspicuous changes, whereas the corrosion potential of CoCrMo alloys significantly decreases; corrosion current density and corrosion rate (CR) increase by at least two orders of magnitude; corrosion current density increases from 5.8397 × 10~(-9) Amp/cm~2 to 5.1889 × 10~(-7) Amp/cm~2; the corrosion rate increases from 6.8687 × 10~(-5) mm/a to 6.1033 × 10~(-3) mm/a; the electrochemical impendence of coupled CoCrMo alloy shows significant change because of anodic dissolution where the passive film does not easily form and stabilize. Although the galvanic current of the coupled alloys is found at a lower order of magnitude (3.8 × 10~(-8) A to 7 × 10~(-8) A) during the test period, the galvanic corrosion between Ti6Al4V and CoCrMo alloys significantly affects the electrochemical impendence of CoCrMo alloys.