Electro-codeposition of CeO2 nanoparticles into cobalt matrix to improve the tribocorrosion performances of Co/nano CeO2 composite layers in biological solution for medical applications

Co/nano-CeO₂ composite layers were developed by electro-codeposition method from a cobalt electrolyte containing dispersed CeO₂ nanoparticles. The tribocorrosion performances of both Co/nano-CeO₂ and pure Co layers were comparatively investigated by sliding friction tests under lubricated condition in biological Hank solution. The effect of embedded nano-CeO₂ on the corrosion electrochemical response, friction coefficient and wear loss volume is analyzed. The results show that the codeposited of nano-CeO₂ particles into cobalt matrix reduce the friction coefficient and wear weight loss as well as the shift of open circuit potential to active state, increasing the polarization resistance and reducing the corrosion damages.

Influence of proteins on the corrosion behavior of a chitosan-bioactive glass coated magnesium alloy

The current study explored the degradation behavior of a WE43 Mg alloy during immersion tests in Dulbecco's Modified Eagle's Medium (DMEM) for 3d and 7d, for a bare alloy surface as well as for samples with surface pre-treatment, and finally for samples coated with chitosan-bioactive glass. The immersion tests were conducted with and without addition of serum, to study the influence of proteins on the degradation process. Mass-loss was measured to determine the corrosion rate after 3d and 7d of immersion. The samples were analyzed by SEM with respect to their surface morphology and the chemical composition was screened by high-resolution XPS. The results demonstrate not only a significant, time-dependent influence of serum addition on the corrosion behavior of the materials studied, but noteworthy is that depending on the sample type, proteins in solution were observed to either accelerate or inhibit corrosion. These results are discussed in correlation to observed changes in surface chemistry taking place upon immersion in the absence and presence of proteins.