Tribo-corrosion and Albumin Attachment of Nitrogen Ion-Implanted CoCrMo Alloy During Friction Onset

In this paper, CoCrMo alloy surface was implanted with 100 keV nitrogen ions to modify it. Bovine serum albumin (BSA) adsorption and the initial behavior of tribo-corrosion in the simulated system were studied. Nitrogen ion implantation can promote BSA dynamic adsorption due to the change of friction and wear mechanisms. From the tribo-corrosion test results, the open circuit potential (OCP) increased to about 0.6 V and the coefficient of friction (COF) decreased to about 0.2 for the nitrogen ion-implanted CoCrMo compared with the untreated sample before the modified layer failure. The point when the open circuit potential and the coefficient of friction changed during long wear time (1, 2 and 4 h) is considered the sign of the worn through modified layer. Then, the OCP of the implanted sample rose by 0.3 V compared with the untreated sample, and the COF remained at around 0.3, which is lower compared with the COF of untreated sample after the modified layer has been worn through. Thus, nitrogen ion implantation not only improved wear and corrosion resistance of the CoCrMo alloy, but also promoted BSA adsorption on the CoCrMo alloy surface, which effectively reduced the wear volume and metal ions release.