Corrosion susceptibility investigation of Ti-O film modified cobalt-chromium alloy (L-605) vascular stents by cyclic potentiodynamic polarization measurement

摘要

Ti-O film was deposited on cobalt-chromium alloy (L-605) coronary stents by metal vacuum arc source deposition. The corrosion resistance of the Ti-O film modified and bare L-605 stents was investigated by cyclic potentiodynamic polarization tests in phosphate buffered solution (PBS, 37 ± 1. °C). The optical microscopy and scanning electron microscopy (SEM) images of the modified stents indicated that the surface of all stent cells was very smooth and uniform, and the thickness of Ti-O film was about 10 nm. There were not any cracks and delamination on stent surface after dilation by angioplasty. The polarization results showed that the natural corrosion potential of the Ti-O film modified and bare stents was similar. But the corrosion current density of Ti-O film modified stent was lower than that of the bare stent at all scanned potential range. Compared with Ti-O film modified stent, the bare stent was more susceptible to corrosion. After cyclic potentiodynamic polarization test, the slight localized corrosion was found on the surface of bare stents. But no film flakes or localized pitting can be observed on Ti-O film modified stent. All these results showed that Ti-O film modified stent had the better corrosion resistance, compared with the bare L605 stent.